Luminous Landscape Forum
Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: cmox on March 30, 2009, 11:35:57 am
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This is an invitation to discuss about lenses with a focal length beyond 400mm.
Today, not everybody wants to spend much money on the super telephoto lenses made by the camera manufacturers. They are excellent, but very expensive. When it comes to focal lengths of 500mm these primes cost a fortune, beyond 600mm they cost even more.
I use an old Novoflex lens with a Leitz Telyt 6,8/560mm head, often with a 1.5x or 2x converter. This lens is long and heavy, but that does not bother me. The main problem is that f6.8 is not much, and it is a manual focus lens. Focussing at 6.8 is well possible, an adapter with "focus confirmation" for my EOS helps.
Discovering the world beyond 560mm is different...enter the converters. Imagine a focal length of 1120mm at f/16. The image quality is acceptable but not great, and it really takes times and energy to use this combo. Just imagine me carrying two big wooden tripods (6 Kilos each), a 5 Kilo lens plus the camera. MLU, a wind deflector, cable release. It takes 10 minutes to setup and 10 more minutes for focussing one single shot, it's like using a 4x5" camera.
Here is an old, analog, unsharpened example:
(http://farm4.static.flickr.com/3441/3382916500_6ef7a7e669_b.jpg)
1/30 at f16, 3,600 feet distance.
I could imagine that I am not the only one looking for sharp, affordable alternatives.
What do you use for long distance shots?
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This is an invitation to discuss about lenses with a focal length beyond 400mm.
Today, not everybody wants to spend much money on the super telephoto lenses made by the camera manufacturers. They are excellent, but very expensive. When it comes to focal lengths of 500mm these primes cost a fortune, beyond 600mm they cost even more.
I use an old Novoflex lens with a Leitz Telyt 6,8/560mm head, often with a 1.5x or 2x converter. This lens is long and heavy, but that does not bother me. The main problem is that f6.8 is not much, and it is a manual focus lens. Focussing at 6.8 is well possible, an adapter with "focus confirmation" for my EOS helps.
Discovering the world beyond 560mm is different...enter the converters. Imagine a focal length of 1120mm at f/16. The image quality is acceptable but not great, and it really takes times and energy to use this combo. Just imagine me carrying two big wooden tripods (6 Kilos each), a 5 Kilo lens plus the camera. MLU, a wind deflector, cable release. It takes 10 minutes to setup and 10 more minutes for focussing one single shot, it's like using a 4x5" camera.
Here is an old, analog, unsharpened example:
(http://farm4.static.flickr.com/3441/3382916500_6ef7a7e669_b.jpg)
1/30 at f16, 3,600 feet distance.
I could imagine that I am not the only one looking for sharp, affordable alternatives.
What do you use for long distance shots?
I would think that at this distance, atmospheric distortion could be as great or moreso than lens distortion.
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I would think that at this distance, atmospheric distortion could be as great or moreso than lens distortion.
One simple rule with these lenses ist: if you want sharp images, don't photograph on a hot day at noon. It's much better in the early morning.
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I'm actually more curious as to what subject warrants such a zoom? Obviously you're not going for wildlife @ f16 early in the morning. I'm not being sarcastic, just curious. 1120mm is alot!
{}
KT
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This is an invitation to discuss about lenses with a focal length beyond 400mm.
What do you use for long distance shots?
Roger Hicks has published several interesting articles on the same subject, with the same conclusion; that a reasonably sharp but slow old Leitz Telyt was good enough for his infrequent use. Given how good modern D-SLR's are at higher ISO, it's possible to get surprisingly good results with such a lens, provided you have plenty of time to focus and aren't shooting anything moving.
There's always a distinction between "the best you can get" and "good enough". I do own a Canon 500 f:4 IS L lens, and it is indeed incredibly sharp. Autofocus and IS are great, and with enough light to keep the shutter speed up the results are terrific. Image quality is almost as good with the 1.4x L teleconverter. However...despite all that magnesium construction and its relatively light weight, it still feels like you're handling a bazooka made of glass. Bringing it with you is a commitment, not an afterthought.
For everyday use I still find myself turning to Canon's relatively elderly 100-400 f:5.6 IS zoom. It's reasonably compact, reasonably light, reasonably handy...with perfect technique and a heavy hand pressing it down on the tripod, sharpness at the long end is...well, not too awful. I do find the ability to fine-tune the focal length very useful for landscapes. I don't even try to use it with a teleconverter. It does best with images that don't depend on intense acuity, like the one attached. It's often worth simply trying to get closer and using a shorter, sharper lens shooting through less air.
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The 560mm f/6.8 Telyt suits me fine. I'm using the Leica-mount version which is light enough to carry on day-long hikes and not regret having brought it. Sample photos:
http://www.wildlightphoto.com/560r68.html (http://www.wildlightphoto.com/560r68.html)
Its primary disadvantages are a curved field (not a problem with most wildlife) and a manual aperture (I use it wide-open most of the time).
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I would think that at this distance, atmospheric distortion could be as great or moreso than lens distortion.
Distortion is caused by heat waves or variations in air density so the air acts like a distorting lens. Three things determine how much it effects your image:
1. The diameter of the front element of the lens. The wider, the worse it is.
2. The magnification that lens produces, more = worse.
3. The shutter speed you use to record the image. This can help or hurt the image, depending on the air mass you are shooting through.
The longer the air mass (distance) you shoot over, the worse the effect. Shooting over heat sinks (things that reflect heat or release it) is the worst. Concrete, heated buildings, roadways, they are all bad.
Early morning is probably the best time, with mid-day and late evening being the worst because of heat (solar) reflection and re-radiating. Shooting over grassland, forest or (best) water is the best way to avoid heat distortion.
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I'm actually more curious as to what subject warrants such a zoom? Obviously you're not going for wildlife @ f16 early in the morning. I'm not being sarcastic, just curious. 1120mm is alot!
{}
KT
Many of my stories are environmental subjects. What you see in the photo is a chemical factory near an airport that will be relocated due to airport expansion plans. As you can imagine, chemical factories, airports etc. are not enthusiastic supporters of photographers revealing their sins.
Well, and I shoot landscapes.
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To my mind I think you have to give it to Olympus if you want a balance between 'top' 400mm plus tele lenses and 'good enough' in one camera system.
There are two, the 300mm (600mm equiv) f 2.8, a large lens for Olympus at 3290 grams (and £5000) and the 70-300mm (140 - 600mm equiv) f4 - 5.6 at just 620gm (and £299), and it fits in your pocket. Naturally the consumer grade 70 - 300mm isn't a patch on the 300mm, but even so its plenty 'good enough' for a double page spread. The big downside is that its a slow f5.6 at the 300mm end. The irony is that the whole setup of a 70-300 is smaller, lighter, and cheaper even adding a body to use it with, than most if not all 600mm lenses on their own.
Steve
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To my mind I think you have to give it to Olympus if you want a balance between 'top' 400mm plus tele lenses and 'good enough' in one camera system.
If I had not purchased an EOS 5D2 recently...full format, 21 MP... I know Olympus has built many good lenses, and I heard of a 11/1000mm lens for the old OM series.
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For me, the main advantage of the APS-C format has always been the facility to extend one's longest telephoto lens by a factor of 1.6x. A 400mm lens effectively becomes a 640mm lens in terms of FoV on the Canon cropped format. In fact, the existence of the Canon 100-400 IS lens was a major attraction for me when I switched from Minolta to Canon several years ago, although I didn't buy a 100-400 until I'd bought a D60.
It's relatively light, certainly hand-holdable and portable, flexible because of its zoom range, and has the advantage of IS. It's a puzzle why Canon does not upgrade this lens. Increasing sensor pixel density is fine. However, if you don't also increase lens resolution, the benefits of the increased pixel desity tend to be small.
I can't help wonder what the problem is. Is it really so difficult to design a 100-400 F5.6 zoom that is sharp at full aperture and at F8? If you compare the 50% MTF results for the Canon 100-400 IS with the 70-200 IS at Photozone, you can see that the 70-200 has much better resolution at any focal length. The 100-400 IS is sharpest in the middle of the range, around 200mm, as one might expect. However, at this focal length it's still not nearly as sharp at the 70-200 fully extended. In fact the 70-200 is sharper even at F11 where all lenses tend to be equally bad.
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For me, the main advantage of the APS-C format has always been the facility to extend one's longest telephoto lens by a factor of 1.6x.
I don't understand the logic of this. How is throwing away almost half of the lens' image circle an advantage? Given sensors of equal pixel density and quality I'd rather have more of the image circle to work with (and a bigger viewfinder) and crop as needed. IMHO this "advantage" is a case of camera makers convincing buyers that its lemons are really lemonade.
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I don't understand the logic of this. How is throwing away almost half of the lens' image circle an advantage? Given sensors of equal pixel density and quality I'd rather have more of the image circle to work with (and a bigger viewfinder) and crop as needed. IMHO this "advantage" is a case of camera makers convincing buyers that its lemons are really lemonade.
I would agree with your logic if the body cost was equal, but usually the same pixel density FF cameras are at least 3x more expensive vs. their APS-C counterpart. You obviously lose some lens resolution vs. an equal MP count FF sensor, but with good glass the difference isn't that huge since you're only using the best part of the image circle, and even these bodies are quite a bit more expensive vs. APS-C with the same pixel count.
I know you can't have everything and FF (and MF) do have their place, but for an amateur on a budget APS-C and 4/3rd formats are not bad choices
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I would agree with your logic if the body cost was equal, but usually the same pixel density FF cameras are at least 3x more expensive vs. their APS-C counterpart. You obviously lose some lens resolution vs. an equal MP count FF sensor, but with good glass the difference isn't that huge since you're only using the best part of the image circle, and even these bodies are quite a bit more expensive vs. APS-C with the same pixel count.
I know you can't have everything and FF (and MF) do have their place, but for an amateur on a budget APS-C and 4/3rd formats are not bad choices
It is actually quite simple: for someone who has no digital camera yet there is a choice, and the high crop factor might be a feature that changes his mind when it comes to buying.
If someone already has a new 21MP FF camera like me, that is not really an attractive option.
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Given sensors of equal pixel density and quality I'd rather have more of the image circle to work with (and a bigger viewfinder) and crop as needed. IMHO this "advantage" is a case of camera makers convincing buyers that its lemons are really lemonade.
Of course you would, and so would I. When full frame 35mm cameras reach the pixel density of the cropped format cameras, there's absolutely no image quality advantage in respect of one's longest telephoto lens, with the cropped format. The only advantage, as Pegelli mentions, is the lower cost and weight of the cropped format.
However, Canon FF sensors are always behind the cropped format in terms of pixel density. The 1Ds2 has the same pixel density as the 6 year old 6mp D60, and the 1Ds3 and 5D2 have the pixel density of the 4 year old 20D. The 50D has almost double the pixel count of the 20D. For a full frame sensor to match the pixel density of the 50D, it would need 39mp, the pixel count of the P45+.
The other issue is edge performance. All 35mm lenses have noticeably worse performance at the edges of the 35mm full frame. The Canon 100-400 IS has much better edge performance on a cropped format camera. However, even on a cropped format, there can be noticeable resolution fall-off in the corners.
Recorded image resolution is always a combination of sensor resolution and lens resolution. If you increase either one, you inevitably increase image resolution, by at least some degree. Whether or not that increased resolution is noticeable on a print of a particular size, is another issue.
Sensor resolution is limited by its pixel count. There's a fairly sharp cut-off point at the Nyquist limit, in absolute terms. In practical terms, the cut-off point is reached before the Nyquist limit. In other words, we're talking about 2 1/2 to 3 pixels per line pair in a Bayer type array.
Lenses do not have such a sharp cut-off point with regard to resolution. They keep on resolving more and more detail, but at an increasingly lower contrast. Even at F16 a lens can resolve 100 lp/mm, but at just 10% of their original contrast.
Since image resolution is always a product of lens resolution and sensor resolution, if you keep increasing one without increasing the other, the advantages in respect of recorded image resolution become less and less relevant. There's a law of diminishing returns at work.
The Canon 100-400 IS is 'out-resolved' by the 50D. It needs upgrading. A good quality EF-S 100-400/f5.6 would be fine .
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It is actually quite simple: for someone who has no digital camera yet there is a choice, and the high crop factor might be a feature that changes his mind when it comes to buying.
If someone already has a new 21MP FF camera like me, that is not really an attractive option.
Fully agree, and I would add one more. If someone already has a decent MP count APS-C body he also has a choice, keep it or upgrade to FF. There the financial difference is even bigger.
However, Canon FF sensors are always behind the cropped format in terms of pixel density. The 1Ds2 has the same pixel density as the 6 year old 6mp D60, and the 1Ds3 and 5D2 have the pixel density of the 4 year old 20D. The 50D has almost double the pixel count of the 20D. For a full frame sensor to match the pixel density of the 50D, it would need 39mp, the pixel count of the P45+.
True, but for Nikon and Sony the difference is almost negligible. An APS-C size crop from the D3x and A900 is 11 MP while the D90/D300/A700 are 12 MP.
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True, but for Nikon and Sony the difference is almost negligible. An APS-C size crop from the D3x and A900 is 11 MP while the D90/D300/A700 are 12 MP.
Yes. The Nikon APS-C is a slightly larger sensor than the Canon cropped format, and the D3X and A900 have a slightly greater pixel density than the 5D2. But the fact remains that the Canon 100-400 IS needs upgrading. The Nikon equivalent is no better.
A higher quality EF-S 100-400/F5.6 would still produce a 640mm FF equivalent, but could be lighter than the current FF 100-400/F5.6 and therefore more useful. I'm thinking here of the Canon EF-S 17-55/2.8. It's a sharper and lighter lens than the Canon EF 16-35/2.8. There must be a huge potential market for a high quality EF-S 100-400/F5.6 IS.
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As to the advantages of the smaller pixel size and thus higher sensor resolution in l/mm typically offered by smaller formats:
... for Nikon and Sony the difference is almost negligible. An APS-C size crop from the D3x and A900 is 11 MP while the D90/D300/A700 are 12 MP.
APS-C offers up to 15MP, which with the 1.6x crop of the 50D and 500D compares to 24.5MP/1.6^2= 9.6MP crop from the D3X or A900.
And the original example was Olympus, meaning Four Thirds. Cropping from 24x36mm (35mm) format to the 13x17.3mm frame of FourThirds retains about 26% of the pixels, so the highest resolution current 35mm format options would give about 6.3MP, vs the 10MP and 12MP currently available.
As to the ISO speed difference: we seem to be talking about using long, slowish lenses here, and when a smaller format gives the same pixel count on the subject while using a focal length that is shorter by a factor of 1.25x (50D and 500D vs A900 and D3X) or 1.4x (Olympus E-620 or E-30 or Panasonic G1 vs D3X or A900), that shorter lens can probably be brighter by half to one stop for about the same cost and weight, allowing a corresponding reduction in ISO speed, unless one has already bottomed out at minimum ISO speed.
The easiest comparison is the roughly 1.4x difference in l/mm resolution from Four Thirds to 35mm: the difference could be using basically the same lens, but with a 1.4x TC in 35mm, without in Four Thirds, with a one-stop lens brightness (minimum f-stop) advantage to not using the TC.
For occasional usage, an inexpensive Four Thirds body and lens mount adaptor to use telephoto lenses from another 35mm format SLR system on it could be a decent, low budget way to stretch telephoto reach. Manual focus and stop-down metering required though.
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In other words, BJL, to simplify your rather convoluted explanation (although my explanations might be equally convoluted to others, but not to me ), an EF-S 100-400 could be F4 across the range and still no heavier than the current full frame EF-100-400/F4.5-F5.6. Right?
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In other words, BJL, to simplify your rather convoluted explanation (although my explanations might be equally convoluted to others, but not to me ), an EF-S 100-400 could be F4 across the range and still no heavier than the current full frame EF-100-400/F4.5-F5.6. Right?
No, not if one is talking true focal lengths.
What I mean is that for example a 400/5.6 and a 600/8 can be comparable in size and cost, and if used on cameras with pixel spacing differing in the same proportions of 2:3, both will give equal pixel count on the same subject, same framing. And for "equal shutter speed and equal pixel count after possible cropping to same FOV" one could be looking at, for example, the following imaginary lenses with equally large front elements, and so comparable cost and weight:
400mm, f/5.6, ISO 400 with the 4.3 micron pixels of an Olympus E-620 or E-30 or a Panasonic G1 or GH1
vs
500mm, f/7, ISO 500 with the 4.7 micron pixels of the Canon 50D and 500D
vs
550mm f/8, ISO 800 with the 5.95 micron pixels of a Nikon D3X or Sony A900,
vs
600mm f/8.4, ISO 900 with the 6.4 micron pixel spacing of a Canon 5DMkII or 1DsMkIII.
These are for exactly equal aperture diameter, as achieved with TC's for example. In practice the longer focal length options tend to be a bit heavier for equal aperture size. This is clear if the longer focal length is achieved by adding a TC!
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No, not if one is talking true focal lengths.
That's an interesting point. There's a perception that lenses designed for the smaller format will always be lighter. A good example which belies this notion is the Zuiko 300/2.8 designed for the 4/3rds format. It's actually heavier than the Canon EF 300/2.8 which is designed for full frame 35mm. (3290gms as opposed to 2550gms for the Canon).
It seems that most of the EF-S lenses which appear to be lighter than the nearest full frame equivalent are wide angle zooms with a different design to FF lenses; a design with a short back focus where the rear element is closer to the sensor. With telephoto lenses this design advantage apparently doesn't exist.
It would be interesting to see a comparison between the Olympus E-620 with the Zuiko 300/2.8, and the Canon 50D with Canon 300/2.8 IS. If we crop the 50D to the 4:3 aspect ratio of the E-620, we reduce the pixel count of the 50D to about 13.47mp. If we crop the 50D image again to the same FoV as the E-620 image, the pixel count of the 50D is further reduced to just 10.21mp. The Olympus sensor has the edge in terms of resolution, but the Canon might have the edge in terms of noise. However, if we crop the E-620's sensor to the 3:2 aspect ratio of the 50D, that edge in pixel density becomes so small as to be irrelevant.
If it's not possible to design a good quality 100-400/F4 IS lens that is no heavier than the current 100-400, then an improved 100-400/F5.6 will be very welcome. Give me a lens that is good enough to make a worthwhile difference with a 1.4x extender.
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... There's a perception that lenses designed for the smaller format will always be lighter. ...
It seems that most of the EF-S lenses which appear to be lighter than the nearest full frame equivalent are wide angle zooms with a different design to FF lenses; a design with a short back focus where the rear element is closer to the sensor. With telephoto lenses this design advantage apparently doesn't exist.
I thought thaqt issue had been resolved years ago: the size advantage for lenses of equal focal length and aperture when designed for a small format is essentially when the larger format lens needs to be a wide angle design while the smaller format uses a normal or telephoto design, or when both are wide but the larger format lens is even wider. In the telephoto regime, the only advantages I know of to designing specifically for a smaller format are
(1) aberration corrections can be optimized over the smaller image circle, potentially getting better IQ there at the expense of worse in the unused regions outside the smaller format's image circle but inside the larger format's image circle.
(2) lens hoods and anti-flare baffling that is tighter, blocking light coming from outside the smaller image circle but within the larger image circle.
Both could be true for the Olympus 150/2, 90-250/2.8 and 300/2.8, and for the recent Pentax DA telephoto lenses.
It would be interesting to see a comparison between the Olympus E-620 with the Zuiko 300/2.8, and the Canon 50D with Canon 300/2.8 IS. The Olympus sensor has the edge in terms of resolution, but the Canon might have the edge in terms of noise.
Of course per pixel noise comparison are of little direct practical relevance when pixel counts are different: at least the higher pixel count image is entitled to a greater degree of NR processing so that resolution after NR is equalized. (The default high ISO NR of some cameras seem effectively to do this, holding the line on noise levels so that res. declines as ISO increases. That makes sense to me so long as it is only a JPEG default, not mandatory.)
However, if we crop the E-620's sensor to the 3:2 aspect ratio of the 50D, that edge in pixel density becomes so small as to be irrelevant.
It has no effect whatsoever if the objective is equal pixel count on equal field of view. A 3:2 image from a sensor with 4.3 micron cell spacing (12MP 4/3 sensors) is still smaller than a 3:2 image from a sensor with 4.7 micron pixel spacing (50D, 500D) by a linear factor of 4.3/4.7, about 0.9, and so one gets the same framing with a focal length 10% shorter. Not huge but my main comparison was the far more clear-cut gap between 4/3 and 35mm, not the modest 10-20% linear size gap between 4/3 and EF-S.
The question of different aspect ratios is partly why I threw in the Panasonic GH1 with its wider "multi-aspect ratio" sensor that optimizes image circle usage for various shapes. 3:2 is given by cutting a wider but lower rectangle out of the same 21.5mm image circle, and 16:9 even wider and lower, all about 12MP. The options are 4000x3000 for 4:3, 4128 x 2752 for 3:2, and 4352x2448 for 16:9, so the sensor active area is 4352x3000 pixels, 13x18.9mm.
I hope for this multi-aspect ratio option in many Micro Four Thirds cameras; it will kill the debate over which aspect ratio is most useful.
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It would be interesting to see a comparison between the Olympus E-620 with the Zuiko 300/2.8, and the Canon 50D with Canon 300/2.8 IS..............snip...... However, if we crop the E-620's sensor to the 3:2 aspect ratio of the 50D, that edge in pixel density becomes so small as to be irrelevant.
Sorry for the hefty crop from your post Ray.
But the 300 f2.8 Olympus lens is a 600mm lens in equivalency, so it is twice long as the Canon 300/2.8, and so I don't see how you can compare it unless with a Canon 600mm f2.8 lens? Is there one? Is the Olympus heavier or lighter than the Canon 600mm lens?
The other thing is the 'crop to 3:2' idea. In pretty well all periodicals I know of, it is the 3:2 ratio from FF or APS-C that is cropped down, not the other way around and 4/3thirds provides an ideal sales format. So if you take a good chunk off the ends of each 3:2 photo you start to get the true idea of how much 'resolution' is being used to fill a page.
Steve
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Sorry for the hefty crop from your post Ray.
But the 300 f2.8 Olympus lens is a 600mm lens in equivalency, so it is twice long as the Canon 300/2.8, and so I don't see how you can compare it unless with a Canon 600mm f2.8 lens? Is there one? Is the Olympus heavier or lighter than the Canon 600mm lens?
You really shouldn't think of it this way. 300mm is 300mm. The smaller format just crops and therefore one can make a lens that has a smaller image. The only thing that determines the "reach" is the pixel density, not the sensor format.
Take for example, the 1.5x crop Sony A700 and the full frame A900. The A700 is about 12mp and the A900 is about 24mp which gives them almost the same pixel density. When taking a shot with a 400mm lens, the A700 photo is equivalent to cropping the same photo with the A900. The A900 just captures more around it, and the A700 does not have magical extra reach or focal length.
One should only use "focal length equivalence" when buying lenses to have an idea about the FOV, but one should not use it when discussing the advantages of different formats. I think the reasoning should really be that "high-density (small) sensors are better for wildlife photography as you can use lighter lens with less focal length to get the same shot as with a low-density (larger) sensor with a heavier longer focal length".
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But the 300 f2.8 Olympus lens is a 600mm lens in equivalency, so it is twice long as the Canon 300/2.8, and so I don't see how you can compare it unless with a Canon 600mm f2.8 lens? Is there one? Is the Olympus heavier or lighter than the Canon 600mm lens?
A 300mm lens is a 300mm lens whatever camera the lens is attached to. The equivalent focal length in full-frame 35mm terms can always be increased to almost any degree you want by simply cropping the image. Whether the image is cropped at the recording stage, as a result of the sensor being smaller than FF 35mm, or whether it's cropped later in post processing, in Photoshop, makes no difference.
A 300mm lens on a 50D results in an image with the same field of view as a 480mm lens on a FF 35mm DSLR. If I crop that 50D image in post processing to the same FoV that the Olympus 4/3rds sensor produces, using the same FL of lens, I have the same equivalent lens in 35mm terms that any 4/3rds sensor would produce, but the Olympus E-620 would have a slight advantage in terms of pixel count (12.3 as opposed to 10.2).
If I crop a 50D image from a 300mm lens to 1/4 of its original area, I get a 960mm lens equivalent on a full frame camera, but the pixel count of the resulting image is reduced to 3.75mp, so I might prefer to use a 2x extender, although a 2x extender is not necessarily going to produce a better result. The choice is really between (1) a low resolving sensor in terms of LW/PH (3.75mp) used with a high quality lens, or (2) a high resolving sensor (15.1mp) used with a low resolving lens. A 2x extender always reduces the quality of a lens by a significant degree.
The other thing is the 'crop to 3:2' idea. In pretty well all periodicals I know of, it is the 3:2 ratio from FF or APS-C that is cropped down, not the other way around and 4/3thirds provides an ideal sales format. So if you take a good chunk off the ends of each 3:2 photo you start to get the true idea of how much 'resolution' is being used to fill a page.
One should always try to use the best tool for the job. 3:2 tends to be more useful for landscapes and cropping to the 16:9 aspect ratio for HDTV. Most of my shots are landscapes. The square format would seem to most efficiently cover the image circle of the lens (without resorting to a circular sensor which is impractical).
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A 300mm lens is a 300mm lens whatever camera the lens is attached to. The equivalent focal length in full-frame 35mm terms can always be increased to almost any degree you want by simply cropping the image. Whether the image is cropped at the recording stage, as a result of the sensor being smaller than FF 35mm, or whether it's cropped later in post processing, in Photoshop, makes no difference.
A 300mm lens on a 50D results in an image with the same field of view as a 480mm lens on a FF 35mm DSLR. If I crop that 50D image in post processing to the same FoV that the Olympus 4/3rds sensor produces, using the same FL of lens, I have the same equivalent lens in 35mm terms that any 4/3rds sensor would produce, but the Olympus E-620 would have a slight advantage in terms of pixel count (12.3 as opposed to 10.2).
If I crop a 50D image from a 300mm lens to 1/4 of its original area, I get a 960mm lens equivalent on a full frame camera, but the pixel count of the resulting image is reduced to 3.75mp, so I might prefer to use a 2x extender, although a 2x extender is not necessarily going to produce a better result. The choice is really between (1) a low resolving sensor in terms of LW/PH (3.75mp) used with a high quality lens, or (2) a high resolving sensor (15.1mp) used with a low resolving lens. A 2x extender always reduces the quality of a lens by a significant degree.
One should always try to use the best tool for the job. 3:2 tends to be more useful for landscapes and cropping to the 16:9 aspect ratio for HDTV. Most of my shots are landscapes. The square format would seem to most efficiently cover the image circle of the lens (without resorting to a circular sensor which is impractical).
The whole idea is to place as many pixels as possible on the subject you are interested in. Now, if you can do this with a 35mm-sized sensor camera, that's fine. But if you can't, at some point the crop-frame sensored camera is going to put more pixels into the crop area than the 35mm camera can, thus more resolution. Wildlife photogs in particular would benefit from a crop frame camera because they tend to crop their images because their subjects rarely occupy the entire frame. But if you are comparing a 12 megapixel 4/3rds camera with a 12 megapixel 1.5 crop camera, the pixel on cropped subject advantage of the 4/3rds camera is so small it is practically non-existent. However, a 4/3rd and 1.5 crop cameras, both being smaller by far than a 35mm camera may see a benefit as the subject pixel content in the 35mm camera (with the same lens) is going to be far less than with either of the smaller sensor bodies.
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The only thing that determines the "reach" is the pixel density, not the sensor format.
Indeed. Or to use a hopelessly old-fashioned name, the sensor's resolution, measured in lines per mm.
Though to be careful, lens resolution is also a factor, and there is some tendency for this to be higher when a lens of a given focal length is designed for a smaller image circle.
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But if you are comparing a 12 megapixel 4/3rds camera with a 12 megapixel 1.5 crop camera, the pixel on cropped subject advantage of the 4/3rds camera is so small it is practically non-existent.
Using lenses of identical quality with both formats, the differences would probably be noticeable only on large prints or at 100% view on the monitor. When the 1.6 crop 15.1mp 50D is reduced to the size and aspect ratio of the 4/3rds format, it becomes 10.21mp (according to my maths). A 12mp 1.6 cropped format, such as the 450D, would be reduced to 8mp. The 1.5 crop formats (such as the Nikons) would be reduced to less than 8mp. A 50% increase in pixel count is supposed to be worth something, on a sufficiently large print. It's the difference between a Canon 1Ds2 and an A900 or D3X.
However, when increased pixel density is combined with increased lens resolution, then one could expect a clear resolution benefit from the sensor with the greater pixel density.
I imagine a 12mp 4/3rds sensor combined with a Zuiko 300/2.8 would produce a sharper and more detailed result than either a 450D or 50D used with the Canon 300/2.8, after cropping in post processing to the same FoV as the 4/3rds sensor.
I'm assuming that the Zuiko 300/2.8 is sharper than the Canon 300/2.8. It's heavier and more expensive and, as I recall, was once considered by NASA to be the finest lens they had ever tested.
Just out of interest, I see that Photozone have retested the Canon EF-S 17-55/2.8 with the 50D. The original test was done with the 8mp 350D, so we now have a comparison showing the degree of improvement one can expect when moving from an 8mp to a 15mp DSLR, using the same lens (although it might have been a different copy of the same model for all I know).
Assuming both copies were typical, you can see from the following charts showing 'line widths per picture height' at 50% MTF, that a roughly 50% increase in pixel count seems to produce a worthwhile increase in detail when a good lens is used at its sharpest aperture. I've also included the results for the Canon 16-35 which was tested with the 350D and which appears to be a slightly less sharp lens than the EF-S 17-55. Comparing both lenses at 24mm and their sharpest aperture of F4, the 16-35 produces 2083 LW/PH on the 350D, and the EF-S 17-55 produces 2537 LW/PH on the 50D, or roughly a 25% increase in resolution.
[attachment=12692:17_55_16...PZ_tests.jpg]
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It has no effect whatsoever if the objective is equal pixel count on equal field of view. A 3:2 image from a sensor with 4.3 micron cell spacing (12MP 4/3 sensors) is still smaller than a 3:2 image from a sensor with 4.7 micron pixel spacing (50D, 500D) by a linear factor of 4.3/4.7, about 0.9, and so one gets the same framing with a focal length 10% shorter. Not huge but my main comparison was the far more clear-cut gap between 4/3 and 35mm, not the modest 10-20% linear size gap between 4/3 and EF-S.
Yes you're right. I wasn't thinking clearly about that. If both images are cropped to the same FoV in both dimensions, the E-620 will retain its greater pixel count (and pixel density) whatever the choice of aspect ratio. However, if one crops either camera only to change to the aspect ratio of the other, the 50D retains the higher pixel count and lower noise in all circumstances. Right?
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A 300mm lens is a 300mm lens whatever camera the lens is attached to. The equivalent focal length in full-frame 35mm terms can always be increased to almost any degree you want by simply cropping the image. Whether the image is cropped at the recording stage, as a result of the sensor being smaller than FF 35mm, or whether it's cropped later in post processing, in Photoshop, makes no difference.
So you'd use a 300mm lens on a FF camera and crop the image to the equivalent of a 600mm lens, or you'd use a Canon '600mm' lens? If you want to compare the weight and size of an Olympus 300mm f2.8 it has to be with a Canon 600mm f2.8, not a Canon 300mm f2.8, unless you genuinely mean you'd crop the FF image?
Steve
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So you'd use a 300mm lens on a FF camera and crop the image to the equivalent of a 600mm lens, or you'd use a Canon '600mm' lens?
If your FF camera has sufficient pixel density, the pixel density of the latest cropped format, then yes, you could crop the image to the equivalent of a 600mm lens, and get the same effect as using that 300mm lens on the cropped format.
However, as I mentioned before, the pixel density of the FF formats lag behind those of the cropped format. The pixel density of the 1Ds3 and 5D2 is no greater than that of the old-fashioned 8mp 20D. The 50D with almost twice the pixel density of the 20D therfore still serves a purpose for those who own a 1Ds3 or 5D2.
However, a 300mm lens on the 12.3mp E-620 would likely not produce as good a result as a 600mm lens on the 5D2 because we're comparing 12.3 mp with 21mp. But we don't know for sure the extent of the difference because no-one is producing the comparisons. Very slack!
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However, a 300mm lens on the 12.3mp E-620 would likely not produce as good a result as a 600mm lens on the 5D2 because we're comparing 12.3 mp with 21mp. But we don't know for sure the extent of the difference because no-one is producing the comparisons. Very slack!
I'm not convinced.....was outside some bank in London the other day joking with a pj with a 600mm about how I could cope with only a 35mm. He tossed me his 1 series with 600 attached, initially I buckled under it's weight before getting it up to my eye. For hand holding, I'm convinced I'd be better stacking 4 2x convertors on a 50mm! I know it's got IS but all the same I doubt I could hold it at under 1/1000 and I certainly couldn't run with it. I asked it's owner how he carried it all day, especially given the kettling that was going on. He showed me an AP pass and pointed to a truck only 30 yards from where we stood.
All jokes aside, surely weight must become a major factor when we are talking of megaphoto lenese....and given the OPs original intentions for using the lens, I would suggest that the ability to "get the **** out quick" would tip the balance firmly in favour of the Olympus or even some hypermegaminizoom compact - many of which now hit 400mm equiv before sticking a 2x lens on them.
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I'm not convinced.....was outside some bank in London the other day joking with a pj with a 600mm about how I could cope with only a 35mm. He tossed me his 1 series with 600 attached, initially I buckled under it's weight before getting it up to my eye. For hand holding, I'm convinced I'd be better stacking 4 2x convertors on a 50mm! I know it's got IS but all the same I doubt I could hold it at under 1/1000 and I certainly couldn't run with it. I asked it's owner how he carried it all day, especially given the kettling that was going on. He showed me an AP pass and pointed to a truck only 30 yards from where we stood.
All jokes aside, surely weight must become a major factor when we are talking of megaphoto lenese....and given the OPs original intentions for using the lens, I would suggest that the ability to "get the **** out quick" would tip the balance firmly in favour of the Olympus or even some hypermegaminizoom compact - many of which now hit 400mm equiv before sticking a 2x lens on them.
Absolutely! Convenience counts for a lot. It's why the Canon 100-400 IS is so popular. It's not a stellar performer, but it's light, has the flexibility of a zoom and doesn't require a heavy tripod. There's no way I would buy a 400/2.8 to get a sharper result, because it's simply too heavy. I thought I might get a sharper result with the Canon 400/5.6 prime, but it didn't work out. Maybe I tested a dud.
However, the Zuiko 300/2.8 is quite heavy at 3.3Kg. I'd really prefer to have a top quality 400/5.6 which is really sharp at full aperture. I'm sure it can be done.
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one lens that hasn't been mentioned extensively is the canon 300mm f/2.8 L with a 1.4x teleconverter mounted. Its results substantially surpass the 100-400 and while it is definitely larger than a 100-400, it isn't ridiculously so.
There is always someone in a thread like this that objects when you use focal length equivalency to describe the effective reach of a lens when mounted on a cropped sensor. This thread was no exception to that. I disagree with the purists who say that the nomenclature is misleading. I understand the technical difference, but the most effective way to describe the field of view is to equate it to a lens in 35mm terms. You can't otherwise describe it without going into an arcane and complex explanation of the difference, that while well understood here at LL, is lost on all but the most savvy photographers. I like to say my 100-400 has a reach that is like a 160-640mm lens. It is the least confusing way to explain my equipment setup.
I have said many times on these and other forums that a fascinating analysis would be a 5DMkII versus a 30D but with one difference. The lens field of view shouldn't be normalized. What I mean by this is that you should mount and photograph a test chart with the 30D and a good lens like a 50mm f/1.4. Then, without moving the camera/tripod fore or aft, mount the 5DMkII and reshoot the same target. With the 5DMkII the target will not fill the image area--intentionally. This will compare resolving power of these two cameras with identical pixel densities. Then use the same procedure and throw in the 50D. More detail will be resolved by the 50D and my hypothesis is that at 100 ISO, the same detail will be resolved by the 30D and the 5DMkII. We will then be able to isolate (without resizing) the effect of the mythical "good pixels."
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one lens that hasn't been mentioned extensively is the canon 300mm f/2.8 L with a 1.4x teleconverter mounted. Its results substantially surpass the 100-400 and while it is definitely larger than a 100-400, it isn't ridiculously so.
Can you show me some results? The 300/2.8 with 1.4x extender will certainly be faster than the 100-400 and will no doubt surpass it at F5.6, but will it be sharper than the 100-400 at F8, its sharpest aperture? I always prefer to use my 100-400 at F8 or F11 when the light permits. To be able to get results at F4 and F5.6 that are at least as sharp as the 100-400 produces at F8 would be worth something, but would the 300/1.4x combination produce sharper results than the best the 100-400 can do? The 300/F4 IS with extender doesn't appear to be able to surpass the 100-400, according to Photozone tests, except at F5.6 in the centre. Edge resolution at F5.6 is about the same as the 100-400. At F8 and F11, centre resolution is also about the same, but edge resolution is substantially worse with the 300/F4/1.4x.
[attachment=12714:300_F4_w...extender.jpg]
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Can you show me some results? The 300/2.8 with 1.4x extender will certainly be faster than the 100-400 and will no doubt surpass it at F5.6, but will it be sharper than the 100-400 at F8, its sharpest aperture? I always prefer to use my 100-400 at F8 or F11 when the light permits. To be able to get results at F4 and F5.6 that are at least as sharp as the 100-400 produces at F8 would be worth something, but would the 300/1.4x combination produce sharper results than the best the 100-400 can do? The 300/F4 IS with extender doesn't appear to be able to surpass the 100-400, according to Photozone tests, except at F5.6 in the centre. Edge resolution at F5.6 is about the same as the 100-400. At F8 and F11, centre resolution is also about the same, but edge resolution is substantially worse with the 300/F4/1.4x.
[attachment=12714:300_F4_w...extender.jpg]
I don't own the lens. A friend does. Here is a photo that is representative of the bird work he has been able to do with that lens and converter combo. Most of the bird work at this gallery is with that lens. Another benefit of the 300 f/2.8 is much faster and more accurate focusing than the 100-400 even with a teleconverter.
Bird Photos Using 300 f/2.8 L with 1.4X Teleconverter (http://martinradigan.smugmug.com/gallery/1582310_fWtnT#486790010_M4bqY-A-LB)
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i find the 300 f4 +1.4x no better than my 100-400 at any aperture. the 300 2.8 which i've tested (but don't own because of weight) with a 1.4x is far superior to the 100-400 at all apertures and still very good with a 2x. I'd also say that the 400 DO at from f4 to f8 doesn't significantly change and is better than the 100-400 at f8 (although maybe not true of a really good 100-400 which seems to have significant lens-lens variation over time - current production may be better)
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The Canon 100-400 IS is 'out-resolved' by the 50D. It needs upgrading. A good quality EF-S 100-400/f5.6 would be fine .
Hi Ray,
Do you happen to have links to tests that show the 100-400 is outresolved by the 50D? I have this lens too and I'd be interested to see how it performs with such small pixels.
Romy
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Hi Ray,
Do you happen to have links to tests that show the 100-400 is outresolved by the 50D? I have this lens too and I'd be interested to see how it performs with such small pixels.
Romy
I've compared the 5D with the 50D using my 100-400 at 400mm and at various apertures, and I find that the 50D will contine to record finer detail than the 5D even at F16. However, comparing the 50D with the 40D using the 100-400 seemed a waste of time. The differences are too trivial to bother with, even at F8. Looking at the test charts at photozone, I get the impression there are many lenses which are sharper at F11 than the 100-400 is at F8. One such lens is the 70-200/F4 IS. At 200mm and F11, resolution is 1952.5 LW/PH. The 100-400 at 400mm and F8 (its sharpest aperture) is just 1785 LW/PH, at the centre. (Both tests carried out using a 350D).
I don't think I kept the test results comparing the 40D with the 50D, for the 100-400. But here's a shot I found comparing the 5D with the 50D at F16. Instead of upsampling the 5D shot, I've shown it at a greater magnification. The 50D at 100%, which represents a huge print of course, shows clearly finer detail, particularly noticeable on the roof.
[attachment=12721:5D_v_50D_400mm_F16.jpg]
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I've compared the 5D with the 50D using my 100-400 at 400mm and at various apertures, and I find that the 50D will contine to record finer detail than the 5D even at F16. However, comparing the 50D with the 40D using the 100-400 seemed a waste of time. The differences are too trivial to bother with, even at F8. Looking at the test charts at photozone, I get the impression there are many lenses which are sharper at F11 than the 100-400 is at F8. One such lens is the 70-200/F4 IS. At 200mm and F11, resolution is 1952.5 LW/PH. The 100-400 at 400mm and F8 (its sharpest aperture) is just 1785 LW/PH, at the centre. (Both tests carried out using a 350D).
I don't think I kept the test results comparing the 40D with the 50D, for the 100-400. But here's a shot I found comparing the 5D with the 50D at F16. Instead of upsampling the 5D shot, I've shown it at a greater magnification. The 50D at 100%, which represents a huge print of course, shows clearly finer detail, particularly noticeable on the roof.
[attachment=12721:5D_v_50D_400mm_F16.jpg]
Hi Ray,
Thanks for the reply and the info. I have a great copy of the 100-400 which is as sharp as my 400 5.6L at 400 mm f/5.6. My 100-400 even compares well vs. my 500 f4 IS at the center of the frame. I believe my copy of the 100-400 can harness the resolution of the 50D's sensor very well, at least in the central portion of the frame where it matters for my bird photography. This is because I see a good improvement of captured detail on a per frame basis (as opposed to per pixel basis) when using this lens with a 1.4x TC on a 40D, which use effectively doubles the pixels/bird from the same distance.
Here are links to my user report:
1. 100-400 vs 400 5.6L - http://birdphotoph.proboards.com/index.cgi...&thread=352 (http://birdphotoph.proboards.com/index.cgi?board=review&action=display&thread=352)
2. 100-400 compared to my 500 f4 IS - http://birdphotoph.proboards.com/index.cgi...&thread=353 (http://birdphotoph.proboards.com/index.cgi?board=review&action=display&thread=353)
Romy
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Hi Ray,
Thanks for the reply and the info. I have a great copy of the 100-400 which is as sharp as my 400 5.6L at 400 mm f/5.6. My 100-400 even compares well vs. my 500 f4 IS at the center of the frame. I believe my copy of the 100-400 can harness the resolution of the 50D's sensor very well, at least in the central portion of the frame where it matters for my bird photography. This is because I see a good improvement of captured detail on a per frame basis (as opposed to per pixel basis) when using this lens with a 1.4x TC on a 40D, which use effectively doubles the pixels/bird from the same distance.
Here are links to my user report:
1. 100-400 vs 400 5.6L - http://birdphotoph.proboards.com/index.cgi...&thread=352 (http://birdphotoph.proboards.com/index.cgi?board=review&action=display&thread=352)
2. 100-400 compared to my 500 f4 IS - http://birdphotoph.proboards.com/index.cgi...&thread=353 (http://birdphotoph.proboards.com/index.cgi?board=review&action=display&thread=353)
Romy
Romy,
You are very lucky to get a 100-400 which appears to be so good. For a long time I've been a strong advocate of thorough MTF lens testing according to international (ISO) standards. I believe that every lens shipped, for serious photography, should come with extensive MTF charts so the customer knows exactly what he/she is buying.
The alternative is 'cherry picking'. This can be very time-wasting, and also requires a co-operative retailer. In general, it's a very unsatisfactory approach, because those who have the relationships which facilitate such cherry picking, benefit, and those who don't, and who pay the same price for their lens, get the rejects.
However, I'm impressed with the thoroughness of your tests. Can I persuade you to buy a 300/F2.8 IS and do comparisons with the 1.4x and 2x extenders?
Fike makes a very valid point, that the 300/1.4x combination gives you an 420/F4 lens which has faster and more accurate autofocussing than the 100-400 at 400mm. I can only assume, because I can find absolutely no comparisons on the internet between the 300/1.4x and the 100-400 at 400mm, that the differences in absolute resolution are too small to be an issue.
It's a fact of photography that sharp results are often a combination of accurate focussing and high shutter speed, rather than some slight instrinsic resolution advatage of one lens over another.
I know my 100-400 is not as sharp at F5.6 as it is at F8, but the difference is very marginal. The difference in DoF between F5.6 and F8 is far greater. This is where practical considerations come into play and often reveal the irrelevance of pixel-peeping advantages. If focussing is not 'spot on' then a bird's eye at F5.6 might look disturbingly less sharp than at F8. However, it's not always possible to get focussing spot on. Using F5.6, it's more critical to get accurate focussing. Using F2.8 must be a nightmare.
The 50D with its very high resolution LiveView LCD screen, facilitates tremendously accurate manual focussing. At 10x magnification, a 400mm lens becomes a 4,000 mm lens (compared with an actual 4,000mm lens with no magnifiaction on the same LCD screen.) Of course we don't have any real 4,000mm lenses for DSLRs. The Canon 1200/F5.6 costs as much as a house.
There's simply no excuse for misfocussing with the 50D when manual foussing is practicable.
Out of interest, I went back to my 5D/50D comparisons, and selected images comparing the 50D at F5.6 with the 50D at F8, at 400mm. Whilst the the 100-400 is very marginal sharper, in the plane of focus, at F8, the most significant increase in sharpness results from the increased DoF that F8 offers.
Below, I've taken the same scene at F5.6 and at F8, and cropped a vertical strip from the centre to show the variation in DoF. In my opinion, the resolution differences that occur due to DoF are far more significant than resolution differences at the plane of focus. This scene was taken in the late evening and is across a river, from one bank to the other. Atmospheric distortion is minimal. (It's fortunate that my neighbours are not given to prancing around in the nude, otherwise they might be quite concerned about a guy across the river with a telephoto lens ).
The plane of focus is shown in the lower half of the middle image. Above that and below, you can see the loss of reolution in the F5.6 shot due to DoF. At the plane of focus, we're nitpicking.
[attachment=12738:0013_50D...ll_scene.jpg] [attachment=12739:top_of_c...5_6_v_F8.jpg] [attachment=12740:middle_o...5_6_v_F8.jpg] [attachment=12741:bottom_o...5_6_v_F8.jpg]
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I have also found that my keeper rate with the 100-400 is much better after calibrating it with the 50D's auto-focus micro adjustment. I adjusted about 5 units from center. Makes a big difference for bird work.
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I have also found that my keeper rate with the 100-400 is much better after calibrating it with the 50D's auto-focus micro adjustment. I adjusted about 5 units from center. Makes a big difference for bird work.
This is a feature I've yet to try. Been busy doing other things. But the micro-adjustment was definitely a major consideration for me when deciding to upgrade from a 40D to 50D.
However, assuming perfect focus, it still appears to be the case that the 100-400 is not as sharp as it could be at all 3 apertures of F5.6, F8 and F11. Whilst Romy's tests suggest that his copy of the 100-400 really is as sharp as can be expected and on a par with the 400/5.6 prime, we can't be sure in absolute terms just how sharp it is. The 400/f5.6 and 500/f4 are lenses that also vary in quality.
When I bought a 400/5.6 some years ago, I was surprised to find that it wasn't any sharper than, and sometimes not quite as sharp as, my 100-400 at all apertures. I returned the lens, of course. In such circumstances, it wasn't clear to me whether my copy of the 100-400 was above average and the copy of the 400/5.6 I tested just average, or whether my copy of the 100-400 was just typical and the 400/4.6 a lemon. Perhaps they were both average. I notice that the copies of these lenses that Photozone tested with a 350D appear to be about equally matched at 400mm from F5.6 to F11. The 400/5.6 prime appears to be slightly sharper at the edges of the cropped format frame at F5.6. One might assume that on a FF 35mm DSLR, the better edge performance at F5.6 would be more obvious. However, the 100-400 at both F5.6 and F8 appears to be very marginally sharper in the centre, in the Photozone tests.
Such small differences are irrelevant. For all practical purpose the 400/5.6 prime and the 100-400 zoom at 400mm are about equal in the PZ tests, but that doesn't mean that the 100-400 is a sharp lens. Of course, it goes without saying that the IS feature of the 100-400 can have great practical benefit. I would bother to use a 400/5.6 in place of the 100-400 zoom unless the prime was substantially sharper.
[attachment=12772:PZ_400_5..._100_400.jpg]
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The 50D with its very high resolution LiveView LCD screen, facilitates tremendously accurate manual focussing. At 10x magnification, a 400mm lens becomes a 4,000 mm lens (compared with an actual 4,000mm lens with no magnifiaction on the same LCD screen.) Of course we don't have any real 4,000mm lenses for DSLRs. The Canon 1200/F5.6 costs as much as a house.
There's simply no excuse for misfocussing with the 50D when manual foussing is practicable.
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I haven't found this to be true. At 400mm and 10x magnification, even with image stabilization on, the smallest vibration of the camera makes focusing very hard because it moves the entire viewable area. I kind of gave up using live preview with manual focus at those long focal lengths. It might be better if I used a heavier tripod, but as it is I use a carbon traveller tripod--fairly steady, but not that steady.
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I haven't found this to be true. At 400mm and 10x magnification, even with image stabilization on, the smallest vibration of the camera makes focusing very hard because it moves the entire viewable area.
What if you back off to 5x, for an image still larger and better resolved than the corresponding part of the OVF image? 5x displays a roughly 950x640 crop, and the 50D LCD is really about VGA resolution of 640x480 (with dodgy "x3" pixel counting), so that is close to full sensor resolution anyway, and way ahead of the resolution of the image that the OVF gets off the ground glass. The step up from 5x to 10x goes well beyond "100%" and adds little detail to the LCD preview image.
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I haven't found this to be true. At 400mm and 10x magnification, even with image stabilization on, the smallest vibration of the camera makes focusing very hard because it moves the entire viewable area. I kind of gave up using live preview with manual focus at those long focal lengths. It might be better if I used a heavier tripod, but as it is I use a carbon traveller tripod--fairly steady, but not that steady.
Fike,
My travel tripod is the Manfrotto Carbon Fibre 190CXPRO4 with 460MG head. With the 100-400 it's amazing to see just how much that 10x image on the camera's LCD screen quivers and wobbles on that tripod with the slightest breeze, so slight in fact one can hardly notice that there is a breeze.
But it's equally amazing how steady that image becomes when IS is enabled. With the older versions of IS, one is advised not to use IS when the lens is mounted on a tripod. However, movement is movement. That LiveView is an excellent device for letting one know when IS should be enabled, if the camera is tripod mounted.
Manual focussing with LiveView when IS is enabled is no problem, when camera is on a tripod. However, it's still a bit awkward when the lens is hand-held.
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What if you back off to 5x, for an image still larger and better resolved than the corresponding part of the OVF image? 5x displays a roughly 950x640 crop, and the 50D LCD is really about VGA resolution of 640x480 (with dodgy "x3" pixel counting), so that is close to full sensor resolution anyway, and way ahead of the resolution of the image that the OVF gets off the ground glass. The step up from 5x to 10x goes well beyond "100%" and adds little detail to the LCD preview image.
BJL,
For really critical, hairsplittingly accurate focussing, it's surprising how much easier it is to focus with the higher resolution screen of the 50D at 10X, compared with the 230,000 dot screen of the 40D at 10X.
Recently, when comparing resolution differences between the 50D and 40D, photographing a banknote using the Canon 50/1.4 at various apertures, I was concerned that at wide apertures, the results from the 50D would show more of an advantage than was warranted because more accurate focussing was possible. With the 40D, I was never quite sure if focussing was really spot on, even at 10x magnification. After some trial and error, I decided the presence of faint color aliasing artifacts on the LiveView screen, due to a particular spacing of lines on the banknote, was a more certain indication of dead-accurate focussing.
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Fike,
My travel tripod is the Manfrotto Carbon Fibre 190CXPRO4 with 460MG head. With the 100-400 it's amazing to see just how much that 10x image on the camera's LCD screen quivers and wobbles on that tripod with the slightest breeze, so slight in fact one can hardly notice that there is a breeze.
But it's equally amazing how steady that image becomes when IS is enabled. With the older versions of IS, one is advised not to use IS when the lens is mounted on a tripod. However, movement is movement. That LiveView is an excellent device for letting one know when IS should be enabled, if the camera is tripod mounted.
Manual focussing with LiveView when IS is enabled is no problem, when camera is on a tripod. However, it's still a bit awkward when the lens is hand-held.
After some unpleasant and very costly experiences with aluminium, carbon fibre and basalt tripods I followed the advice of some nature photographers. Many of them here in Germany swear by Berlebach tripods. They are made of ashwood and dampen vibrations. Price and weight are in between aluminium and carbon fibre. Stability outclasses even Gitzo carbon tripods that cost a lot more.
The one I use most is this one here:
http://www.berlebach.de/?bereich=details&a...sprache=english (http://www.berlebach.de/?bereich=details&id=317&sprache=english)
It is more than stable enough for the 560mm in bright daylight without the converter at 1/125.
For the 560mm plus 2x converter I prefer to set the camera and lens in concrete... I have an older version of this one plus this one borrowed from a friend:
http://www.berlebach.de/?bereich=details&a...sprache=english (http://www.berlebach.de/?bereich=details&id=247&sprache=english)
One of them is attached directly to the lens, the other directly to the camera, without a quick release system. If my Telyt were an "IS" lens I could probably leave one of those at home :-)
They also have a "Conan the Barbarian" edition for the tough guys:
http://www.berlebach.de/?bereich=details&a...sprache=english (http://www.berlebach.de/?bereich=details&id=350&sprache=english)
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After some unpleasant and very costly experiences with aluminium, carbon fibre and basalt tripods I followed the advice of some nature photographers. Many of them here in Germany swear by Berlebach tripods. They are made of ashwood and dampen vibrations. Price and weight are in between aluminium and carbon fibre. Stability outclasses even Gitzo carbon tripods that cost a lot more.
The one I use most is this one here:
http://www.berlebach.de/?bereich=details&a...sprache=english (http://www.berlebach.de/?bereich=details&id=317&sprache=english)
It is more than stable enough for the 560mm in bright daylight without the converter at 1/125.
For the 560mm plus 2x converter I prefer to set the camera and lens in concrete... I have an older version of this one plus this one borrowed from a friend:
http://www.berlebach.de/?bereich=details&a...sprache=english (http://www.berlebach.de/?bereich=details&id=247&sprache=english)
One of them is attached directly to the lens, the other directly to the camera, without a quick release system. If my Telyt were an "IS" lens I could probably leave one of those at home :-)
They also have a "Conan the Barbarian" edition for the tough guys:
http://www.berlebach.de/?bereich=details&a...sprache=english (http://www.berlebach.de/?bereich=details&id=350&sprache=english)
I'm afraid my enthusiasm for photography does not extend to humping around an 11Kg tripod, or even a 5Kg tripod. I want a 150-400/F5.6 IS lens which is as sharp at F5.6, F8 and F11, as the Canon 70-200/F4 IS is at F5.6, F8 and F11. That's not too much to ask, is it?
I'm prepared to pay a reasonable premium.
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For really critical, hairsplittingly accurate focussing, it's surprising how much easier it is to focus with the higher resolution screen of the 50D at 10X, compared with the 230,000 dot screen of the 40D at 10X.
No surprise: at 10x, the 50D is giving about a 480x360 crop displayed at 640x480 vs the 40D's roughly 390x290 crop displayed at 320x240; the lower res. of the 40D LCD itself would surely give the 50D a visible advantage. But that is a different comparison that my 5x vs 10x.
P. S. Nice to see you acknowledge elsewhere in this thread that there is such a thing as equipment that is too heavy to justify the IQ improvements that it can bring! In your case, 11Kg tripods; in my case, lenses with effective aperture diameters bigger than about the 70mm of a 200/2.8 or 300/4 [edit: or a 400/5.6]
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I'm afraid my enthusiasm for photography does not extend to humping around an 11Kg tripod, or even a 5Kg tripod. I want a 150-400/F5.6 IS lens which is as sharp at F5.6, F8 and F11, as the Canon 70-200/F4 IS is at F5.6, F8 and F11. That's not too much to ask, is it?
I'm prepared to pay a reasonable premium.
My enthusiasm for photography does not extend to buying an IS lens with a focal length beyond 400mm... that's the sonic barrier where prices become really nasty. Sure, I would love to own a 4/600 lens. But as I do not use such a beast every day, I prefer to carry some more weight. In most cases it is that 3 Kilo tripod which is more than sufficient for my purposes in 80% of the cases. If I had a 150-400/F5.6 IS lens I would defintely buy a lighter tripod.
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No surprise: at 10x, the 50D is giving about a 480x360 crop displayed at 640x480 vs the 40D's roughly 390x290 crop displayed at 320x240; the lower res. of the 40D LCD itself would surely give the 50D a visible advantage. But that is a different comparison that my 5x vs 10x.
BJL,
Perhaps you can clear up a point I'm not sure about. Is the anti-shake sensor in the Olympus 4/3rds cameras continuously in operation during focussing, or does it spring into action only at the time the shutter is fully pressed?
If it's not continuously active during focussing, then I can understand that you would often prefer to use the 5x magnification instead of 10x. That would also explain why Olympus have not provided a 960,000 dot LCD screen on their latest models.
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Is the anti-shake sensor in the Olympus 4/3rds cameras continuously in operation during focussing, or does it spring into action only at the time the shutter is fully pressed?
I do not have an IS body yet, but I am rather sure that stabilization is continuous in Live View mode. My comment about 5x vs 10x was mostly a question, about whether zooming in on 4% if the image area might work better than zooming in on 1% of it, when working without stabilization.
That would also explain why Olympus have not provided a 960,000 dot LCD screen on their latest models.
No, the reason for that is simple: the new VGA resolution (640x280x3) LCD is a 3" model, whereas the FourThirds bodies so far use smaller 2.7" screens. An articulated 3" LCD probably fits poorly with the 4/3 DSLR body size targets, at least for models like the E-620. Likewise, the Nikon D60X, hotly rumored to be announced on April 14, supposedly stays with the 2.5" LCD of the D60 and D40 for its articulated LCD, hence staying at about 240,000 dots.
P. S. AFAIK, the 3" LCD's are all this one from Samsung:
http://www.digitalcamerainfo.com/content/S...ch-VGA-LCD-.htm (http://www.digitalcamerainfo.com/content/Samsung-Presents-3-inch-VGA-LCD-.htm)
http://www.gizmag.com/go/5999/ (http://www.gizmag.com/go/5999/)
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I do not have an IS body yet, but I am rather sure that stabilization is continuous in Live View mode. My comment about 5x vs 10x was mostly a question, about whether zooming in on 4% if the image area might work better than zooming in on 1% of it, when working without stabilization.
BJL,
I would have thought so too. However, the mysterious lack of Live View on the Sony A900 got me wondering about this issue. The fact is, when looking through the optical viewfinder, sensor shift can have no effect on the viewed image during focussing. It therefore does not make sense to have the anti-shake sensor active for no good reason, which is why I thought that perhaps the intital anti-shake designs allowed a very brief anti-shake movement of sensor just prior to, and during, the flipping of the mirror. There's no point in making something more durable than it needs to be, as Henry Ford would agree, if he were still alive.
Creating a full frame anti-shake sensor appears to have been something of a technological challenge for Sony. Perhaps the technological challenge of creating a FF sensor which could shake continuously during manual focus in Live View mode, was too much, or too expensive. Hence, no Live View for the A900.
If image wobble is exaggerated in Live View with magnification, then 10X magnification will exaggerate it to a greater degree than 5x magnification or no magnification. The choice is really about how critical the focussing needs to be. With the 100-400 and 1.4x extender, I see no advantage in trying to focus in Live View mode when the camera is hand-held. The movements are too great for IS to stabilise the image. I prefer to manually focus through the optical viewfinder with such a lens, with IS enabled. Shorter focal lengths are more manageable in Live View mode.
Out of curiosity, and because there was a clear moon last night and little breeze, I mounted my 50D with 100-400 and 1.4x extender on my main tripod, the rather basic but too-heavy-to-travel (2.55kg) Manfrotto 141RC, to check out image stability in Live View mode.
One curious effect of such high magnification on the LCD screen, was the visible real time movement of the moon across the LCD screen. I had to keep re-adjusting my tripod to get the moon in the centre of the screen, during the few minutes of the experiment. I could actually see the movement of the moon from right to left of the screen.
With tripod firmly on the concrete floor of the verandah, the image was rock-steady (apart from this gradual drift), even at 10x magnification. At this degree of magnification, one sees only a portion of the moon on the LCD screen. Quite amazing! If only my lens were better! Unfortunately, as soon as one touches the focussing ring, the wobble begins.
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Just general comments on an interesting thread:
Nobody seems to worry about "seeing", the shimmering unsteadiness of the atmosphere that made astronomers launch the Hubble Space Telescope. An irrelevance? Definitely not, if you are using a 400mm lens on a current Canon DSLR with the 5micron or finer pixel pitches. Any astrophotographer will notice it on the very first pixel peep! At normal daytime temperatures seeing is a much worse threat than misfocusing if you are shooting anything at more than a 100m away with 400mm or longer teles. Just shoot outside your window at dawn and at noon and pixel peep. Even in the dead of night, seeing at zenith is between 2 and 3 arc-seconds FWHM (Full Width at Half Max). During the daytime it probably shoots up a few to several times larger. With a 400mm focal length and a 50D you are sampling that shimmering stew at 2.5arc-sec per pixel and no amount of IS nor tripod rigidity, nor super accurate focusing will alleviate it. And for Heaven's sake, you are shooting horizontally through that stew! Welcome to the new world of pixel peeping.
The theoretical best that Canon lenses can do may be seen from their published MTF curves. I put them up on my website for easy reference, including for when they are used with 1.4x and 2x extenders:
http://www.pbase.com/samirkharusi/canon_mtf_curves (http://www.pbase.com/samirkharusi/canon_mtf_curves)
It looks to me that it is wishful thinking to expect the average 100-400mm to equal the 400mm/5.6 when used wide open at 400mm. One would have to be super-lucky with his sample of the zoom and super-unlucky with his sample of the prime, or else be examining only the on-axis performance. Owning and having owned more than 10 Canon primes and zooms (all the way to the 600mm), and having compared a couple of them to a couple of premium astro-imaging scopes, I have come to the conclusion that these MTF data are actually excellent indicators of the lens' imaging abilities, despite all my purchases having been random, not cherry picks.
Ah, I also have a small gallery of astrophotos (where every pixel is stuffed carefully with photons over many hours, drip by drip, and then massaged lovingly over many days and nights in postprocessing, to squeeze any peformance the camera or the lens might be capable of!) displaying a whole range of focal lengths from 14mm to 4000mm here:
http://www.pbase.com/samirkharusi/focal_lengths (http://www.pbase.com/samirkharusi/focal_lengths)
Sorry, this stuff is not really for zooms, but the occasional extender was deployed.
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Nobody seems to worry about "seeing", the shimmering unsteadiness of the atmosphere that made astronomers launch the Hubble Space Telescope. An irrelevance? Definitely not, if you are using a 400mm lens on a current Canon DSLR with the 5micron or finer pixel pitches. Any astrophotographer will notice it on the very first pixel peep! At normal daytime temperatures seeing is a much worse threat than misfocusing if you are shooting anything at more than a 100m away with 400mm or longer teles. Just shoot outside your window at dawn and at noon and pixel peep.
We're aware of this problem, Samir . The second post in this thread makes reference to the problem. It was very apparent when taking my test shots across the river, just a couple of hundred metres away. Any time other than early morning or late afternoon was pointless. Heat shimmering, dust and atmospheric pollution are a great barrier to getting sharp images with a long telephoto lens.
I presume that an indication of the clarity of the night sky would be the number of stars one can see. Often, in the countryside where I am, the night sky is ablaze with stars which one simply doesn't see in the city because of the lights and the pollution.
It looks to me that it is wishful thinking to expect the average 100-400mm to equal the 400mm/5.6 when used wide open at 400mm.
For me the wishful thinking that the 400/5.6 prime would be sharper than my 100-400 at 400mm at F5.6 and at any aperture were dashed when I compared them. Photozone also found these two lenses to be about equal at all apertures.
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Even in the dead of night, seeing at zenith is between 2 and 3 arc-seconds FWHM (Full Width at Half Max). During the daytime it probably shoots up a few to several times larger. With a 400mm focal length and a 50D you are sampling that shimmering stew at 2.5arc-sec per pixel ...
Does this suggest that once the focal length is about 100,000 times the pixel spacing, seeing will limit resolution even with cool night air? And so probably "50,000 times pixel spacing" or less during the day? (And less for Ray in the Australian tropics!?)
If so, it seems that focal lengths beyond "100,000x" will rarely improve resolution of the subject, and one might as well just stay at that maximum focal length (really a maximum angular resolution) and crop when a narrower field of view is wanted?
I would like to think so, since my future cameras will almost certainly all have a pixel size under 5 microns, which would make 400mm the most that I need worry about being able to afford or carry, with a 400/5.6 sitting at my maximum lens size target.
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Does this suggest that once the focal length is about 100,000 times the pixel spacing, seeing will limit resolution even with cool night air? And so probably "50,000 times pixel spacing" or less during the day? (And less for Ray in the Australian tropics!?)
If so, it seems that focal lengths beyond "100,000x" will rarely improve resolution of the subject, and one might as well just stay at that maximum focal length (really a maximum angular resolution) and crop when a narrower field of view is wanted?
I would like to think so, since my future cameras will almost certainly all have a pixel size under 5 microns, which would make 400mm the most that I need worry about being able to afford or carry, with a 400/5.6 sitting at my maximum lens size target.
Not too long ago, when pixels were still very expensive, astrophotographers would very carefully match their focal lengths to their seeing, using Nyquist Critical Sampling, i.e. 2 pixels for FWHM. For long-exposures, seeing is indeed the limiter. For short exposures (say, under a tenth of a second) seeing does not blur the image so much as it distorts the image. Nobody wants his straight walls to come out wavy. This is, in my opinion, a bigger headache for daytime exposures than for astro planetary imaging. Planetary imaging is normally done using video, with the distorted frames later stacked. I have not yet seen this technique used for daytime photography of static subjects, but in theory it could enable much longer focal lengths. It works very well on the Moon (which is a sunlit landscape). The relevant FWHM in this usage becomes the diffraction limit of the lens aperture, not the seeing FWHM. I.e. we will then be chasing large aperture optics, focal length is easily adjustable using tele-extenders (Barlows in astro usage).
The highest resolution planetary images, still limited by our atmosphere, can be obtained with a C14, a fairly common 14" aperture amateur scope. Larger apertures have so far not proven capable of ever higher resolution from ground level, beneath the atmosphere, with current amateur image processing software. For a 5 micron pixel pitch we can achieve diffraction-limit critical sampling with a 7,000mm focal length on a C14. So I would expect that the ultimate daytime, long tele, would be a C14 at 4000mm to 7000mm focal length, shooting video (not stills) and later stacking the frames. For planetary imaging I typically shoot 2000 frames, grade and parse them down to the best 15%, and stack those. I get planetary images that look far better and more detailed than if I look visually through the same scope. Only one catch, a C14 is large and heavy, not something to carry to the beach, but could still be useful to somebody doing technology spying on static subjects. Here is how small a Canon 1Ds looks like on a C14:
http://www.pbase.com/samirkharusi/image/37431993 (http://www.pbase.com/samirkharusi/image/37431993)
OK, the front shiny half is only the lenshood (dew shield)
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For short exposures (say, under a tenth of a second) seeing does not blur the image so much as it distorts the image. Nobody wants his straight walls to come out wavy.
That is better news for me then. My super-telephoto subjects are usually animals and other nature scenes, not industrial espionage, so if the dominant effect of seeing is a little bit of waviness, I can live with that.
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That is better news for me then. My super-telephoto subjects are usually animals and other nature scenes, not industrial espionage, so if the dominant effect of seeing is a little bit of waviness, I can live with that.
Yes. And for static subjects you can still use stacking to get rid of it. I have an image of Saturn, taken with a standard Canon 600mm/4.0L IS using the video stack technique, and a 1.4x extender coupled to a 5x extender to yield a focal length of 4200mm, through 27 lens elements! I used a $100 webcam with its lens (and UV/IR blocker) removed. It is possible that one could do better using an IR blocker, but I simply forgot to use one; force of habit since I normally use the C14 mirror scope for planetary videos and that yields better images with IR included (allowing faster frame rates and possibly more steady seeing in IR):
http://www.samirkharusi.net/televue_canon.html (http://www.samirkharusi.net/televue_canon.html)
These days with the video-capable new DSLRs, such exercises would be simpler to try out. And the DSLR sensors are way better than in a 5-year old webcam...
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Yes. And for static subjects you can still use stacking to get rid of it. I have an image of Saturn, taken with a standard Canon 600mm/4.0L IS using the video stack technique, and a 1.4x extender coupled to a 5x extender to yield a focal length of 4200mm, through 27 lens elements! I used a $100 webcam with its lens (and UV/IR blocker) removed. It is possible that one could do better using an IR blocker, but I simply forgot to use one; force of habit since I normally use the C14 mirror scope for planetary videos and that yields better images with IR included (allowing faster frame rates and possibly more steady seeing in IR):
http://www.samirkharusi.net/televue_canon.html (http://www.samirkharusi.net/televue_canon.html)
These days with the video-capable new DSLRs, such exercises would be simpler to try out. And the DSLR sensors are way better than in a 5-year old webcam...
Hi Samir,
Which DSLR will you recommend to video planetary objects, with high enough pixel density? The soon-to-come-out 500D has a video pixel density of only 1080p on an APS-C sensor (albeit 20 fps only). The 5D2 has even sparser pixel density - 1080p on a 24x36 mm sensor.
Romy
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Hi Samir,
Which DSLR will you recommend to video planetary objects, with high enough pixel density? The soon-to-come-out 500D has a video pixel density of only 1080p on an APS-C sensor (albeit 20 fps only). The 5D2 has even sparser pixel density - 1080p on a 24x36 mm sensor.
Romy
Hi, the pixel size does not matter all that much provided you know what it is effectively and you use sufficient magnification. Not having played with one of these HD-capable DSLRs as yet, I am still unclear as to what "effective pixel size" would mean in this context. Eg when one is shooting 1080 HD (2 megapixel screen size), is the Field of View (FoV) that of the full frame of the camera? be it APS-C or full 35mm format, or is it a 2 megapixel crop of the stills FoV? A full stills-frame FoV would imply that the pixels are binned in the firmware and that the effective pixel size is much larger than the native pixel pitch of the sensor. There is also another way of extracting video captures from DSLRs that have LiveView but no HD output, eg Canon 40D. The astro software ImagesPlus enables capturing the magnified LiveView as a video capture that can be processed very well for planetary imaging. In this context the effective pixel size, I suspect, is equal to the native pixel pitch. So, for successful planetary capture you need to know what is the effective pixel size, something trivially easy to do once you start playing with the actual camera body. Just compare the FoV using your chosen video capture (HD or from magnified LiveView) to the stills FoV.
Next you need some kind of tele-extender that will make your lens or telescope have a focal length that corresponds to a focal-ratio (f-number) that is at least 4x the effective pixel size in microns. Let us say that you have determined that the effective pixel size of your video captures is 4.7microns (this happens to be the native pixel pitch of a 50D but I could have picked any other number if the camera bins the pixels). 4*4.7 yields a desirable focal ratio of 19. If your lens wide open is f4 you will need a tele-extender that multiplies that 5x to get to f20. So, eg a TeleVue 5x Powermate will do the job, but a 1.4x + a 2x will be insufficient magnification (makes it an f4*1.4*2 = f11) for Nyquist Critical Sampling. If you are using an f10 SC Telescope, a 2x tele-extender already gets you to f20. I have a write-up that explains why you need that magical 4*(pixel pitch) as an f-ratio for Nyquist Critical Sampling here:
http://www.geocities.com/ultimaoptix/sampling_saturn.html (http://www.geocities.com/ultimaoptix/sampling_saturn.html)
Sampling at less than Nyquist Critical will yield planetary images that are way below what your lens or telescope is capable of. If the magnification is way above Nyquist Critical you end up with dimmer videos and more noise than desirable, so Nyquist Critical Sampling is the best compromise, a little more magnification does little harm, but 2x or 3x that adds too much noise to your videos.
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Hi, the pixel size does not matter all that much provided you know what it is effectively and you use sufficient magnification. Not having played with one of these HD-capable DSLRs as yet, I am still unclear as to what "effective pixel size" would mean in this context. Eg when one is shooting 1080 HD (2 megapixel screen size), is the Field of View (FoV) that of the full frame of the camera? be it APS-C or full 35mm format, or is it a 2 megapixel crop of the stills FoV? A full stills-frame FoV would imply that the pixels are binned in the firmware and that the effective pixel size is much larger than the native pixel pitch of the sensor. There is also another way of extracting video captures from DSLRs that have LiveView but no HD output, eg Canon 40D. The astro software ImagesPlus enables capturing the magnified LiveView as a video capture that can be processed very well for planetary imaging. In this context the effective pixel size, I suspect, is equal to the native pixel pitch. So, for successful planetary capture you need to know what is the effective pixel size, something trivially easy to do once you start playing with the actual camera body. Just compare the FoV using your chosen video capture (HD or from magnified LiveView) to the stills FoV.
Next you need some kind of tele-extender that will make your lens or telescope have a focal length that corresponds to a focal-ratio (f-number) that is at least 4x the effective pixel size in microns. Let us say that you have determined that the effective pixel size of your video captures is 4.7microns (this happens to be the native pixel pitch of a 50D but I could have picked any other number if the camera bins the pixels). 4*4.7 yields a desirable focal ratio of 19. If your lens wide open is f4 you will need a tele-extender that multiplies that 5x to get to f20. So, eg a TeleVue 5x Powermate will do the job, but a 1.4x + a 2x will be insufficient magnification (makes it an f4*1.4*2 = f11) for Nyquist Critical Sampling. If you are using an f10 SC Telescope, a 2x tele-extender already gets you to f20. I have a write-up that explains why you need that magical 4*(pixel pitch) as an f-ratio for Nyquist Critical Sampling here:
http://www.geocities.com/ultimaoptix/sampling_saturn.html (http://www.geocities.com/ultimaoptix/sampling_saturn.html)
Sampling at less than Nyquist Critical will yield planetary images that are way below what your lens or telescope is capable of. If the magnification is way above Nyquist Critical you end up with dimmer videos and more noise than desirable, so Nyquist Critical Sampling is the best compromise, a little more magnification does little harm, but 2x or 3x that adds too much noise to your videos.
For the 5D2 (and for the 500D too, as far as I understand from early product literature), the effective video pixel size is much larger than the native pixel size, as the 21 MP capture is downressed/binned to 2 MP HD video. Hence, the 5D2 is actually a 2MP video imager on a 24x36 mm sensor, while the 500D has somewhat "more reach" - a 2 MP video imager on an APS-C size sensor. OTOH, the extracted video capture from Live View on other DSLRs has a resolution no greater than 1080p. I guess one needs to use massive focal lengths to use well the very large effective video pixel size of these DSLRs.
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For the 5D2 (and for the 500D too, as far as I understand from early product literature), the effective video pixel size is much larger than the native pixel size, as the 21 MP capture is downressed/binned to 2 MP HD video. Hence, the 5D2 is actually a 2MP video imager on a 24x36 mm sensor, while the 500D has somewhat "more reach" - a 2 MP video imager on an APS-C size sensor. OTOH, the extracted video capture from Live View on other DSLRs has a resolution no greater than 1080p. I guess one needs to use massive focal lengths to use well the very large effective video pixel size of these DSLRs.
Looks like the binning is 3x3. If correct, then the effective pixel size is about 14 microns and you need tele-extending to get the focal ratio to f/55 to f/60. In my film days I used f/120, employing eyepiece projection, not difficult with a suitable adapter on an SCT, but could be unwieldy with a camera lens. Presumably one could still use magnified LiveView as the video capture mode. In that case f/20 should be enough. But LiveView capture requires ImagesPlus, version for 500D not yet released.
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For the 5D2 (and for the 500D too, as far as I understand from early product literature), the effective video pixel size is much larger than the native pixel size, as the 21 MP capture is downressed/binned to 2 MP HD video.
Is it downressed/binned or simply sub-sampled, reading only every third row and column of pixels and discarding the rest? I suspect the latter, as I doubt that the 5DMkII is capable of reading all 22 million pixels at video frame rates: after all, its stills frame rate of only 4fps is slow compared to comparable film bodies, and so almost certainly due to a speed limit in read-out and processing, and active pixel CMOS sensors like Canon's have to do some amplification on-chip for each pixel read, even if then binned. Also, 3x3 is natural for sub-sampling from a Bayer CFA, since 2x2 sub-sampling would give all pixels of the same color!
Likewise, all video-output DSLR's probably use sub-sampling, not binning.
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Is it downressed/binned or simply sub-sampled, reading only every third row and column of pixels and discarding the rest? I suspect the latter, as I doubt that the 5DMkII is capable of reading all 22 million pixels at video frame rates: after all, its stills frame rate of only 4fps is slow compared to comparable film bodies, and so almost certainly due to a speed limit in read-out and processing, and active pixel CMOS sensors like Canon's have to do some amplification on-chip for each pixel read, even if then binned. Also, 3x3 is natural for sub-sampling from a Bayer CFA, since 2x2 sub-sampling would give all pixels of the same color!
Likewise, all video-output DSLR's probably use sub-sampling, not binning.
I used the terms downressing/binning loosely (and inaccurately) to mean that the 2 MP HD video output used the angle of view of the whole 24 mm x 36 mm sensor of the 5D2, rather than just cropping a 1920x1080 pixel portion of the sensor. This was in light of the resolving properties of the 5D2's video.
As regards the actual method of extracting a 2 MP video output from the sensor, I've not seen any technical literature yet from Canon that describes this. However, given the apparent limited processing and throughput capacity of the 5D2, I'd tend to agree with you that sub-sampling is the most logical method that's used, rather than downressing or binning in the strict sense.
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One claim that I read recently, supposedly based on image analysis, is that the 5DMkII reads only every third row, but uses all pixels in each row read, with some kind of downsampling/binning.
Yes, there is no question that the full width of the sensor is being used by these DSLR video modes, not just a central crop.
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my long lens is a Tele Vue TV85 scope,, is f7 - 600mm,, I use an Oly E3 on it and love the resolution the system offers,, have included a photo of it,, some want to say it is 1200mm due to the Oly E3 2X crop factor but I just call it 600mm and any of my Oly lens as they are built to the 4/3 format so I don't consider any crop factor these days, just the X factor,,
not the most portable and certainly not to be considered hand holdable but certainly light enough to haul through the woods on the shoulder a brief distance,, I use the system mainly for my bird and wildlife photography,, I normally try to capture my species in the 100 feet or less range and will use a blind or hide when needed,,
I did a crop on the birds breast so you can see the fine feather detail the scope is capable of providing,, the bird was at a measured distance of 60 feet,,
as for those real long distance photos here is one about 250,000 miles out taken with an Old Nikon 990, 3.3 meg camera back in 2001 on the TV85,,
Derry
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By the way, here I have some examples you might be interested in. I used my Noflexar 5,6/400mm and my Telyt 560mm with the 1,5x and 2x converters, and with both converters. All images with EOS 5D2, 100 ASA, captured in RAW, converted to small JPGs, no sharpening. All images with converters are 2 f-stops down.
400mm Noflexar, this is the scene how it looks through a 400mm lens:
[attachment=13590:2_400stop2at72.JPG]
And here all cropped results. I did not check the corners, though, I was looking at the center only.
1. at 5.6: [attachment=13592:3_400_open2.jpg] f11: [attachment=13591:2_400stop2crop.JPG]
1.5x: [attachment=13599:_5_Novo_..._Cropped.jpg] 2x: [attachment=13600:5_Novo_2..._Cropped.jpg] Both: [attachment=13601:5_Novo_2..._Cropped.jpg]
3. Telyt 6,8/560
At 6.8: [attachment=13594:4_Telyto..._Cropped.jpg]
2 stops: [attachment=13595:4_Telyts..._Cropped.jpg] 1.5x [attachment=13596:6_Telyt_..._Cropped.jpg] 2x [attachment=13597:6_Telyt_..._Cropped.jpg] Both: [attachment=13598:7_Telyt_..._Cropped.jpg]
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Can someone chip in some examples with a similar subject using a good mirror lens like a Mirorat, Reflex-Nikkor or similar?
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Dinner is almost ready, but I just wanted to address this topic and get started with it.
I have a Pentax 600mm for a 6x7 camera, an adaptor for a Canon 5D digital, teleconvertors but not tried them yet.
I went wild with large format and got one 8x10 that extends over 48" long.
My subject matter is city pictures of buildings on hills or seen from hills and bridges.
Now to read all of the pages here...........
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After dinner the Luminous Landscape LLVJ 04 was purchased, loaded, and finally uncompressed and viewed correctly. It has a video all about the Pentax 600mm lens and 6x7 camera on a special tripod mount set. I GOTTA HAVE IT! I got the video, now I must get the holder and the other holder.
How does that air release work? Where does one get one? I never saw anything like that for the 6x7.