Luminous Landscape Forum
Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: Provokot on December 21, 2007, 05:57:56 am
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On another site, I saw a discussion about the possibility of Canon putting IS into their bodies.
Most people were quick to dismiss this with the argument that Canon has IS in their lenses - where they make their real money. But is that sustainable? Surely their competitors who don't have so much invested in IS lenses will have a powerful tool to prise customers away from Canon...
I see the race for pixel count as pretty much over. The race for lowest noise at High ISO seems to be nearing the finishing tape. The race for fast high-res. bursts has a few more laps to do but where will manufacturers go next?
Thoughts?
Regards, Paul
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I forsee the 1.6x crop canon's having IS in body unless there is a drastic reduction in IS lens price, if they don't they'll be losing business from people moving up from compacts who are used to it.
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In-camera IS has the disadvantage of being less effective as focal length increases, which of course is where it is the most useful. With a 600mm lens, the sensor would have to move around in an area well outside the image circle of the lens to provide effective stabilization. On an interchangeable-lens camera, that simply isn't practical, as the lens mount would block the sensor's view of the lens. In contrast, putting the IS in the lens works just fine, as moving a fairly small, low-mass lens element accomplishes the same effect in a far more elegant manner. I can see value in a hybrid system where the body has IS used for short-to-medium focal lengths with non-IS lenses, but for longer focal lengths only lens-based IS would be used.
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I forsee the 1.6x crop canon's having IS in body unless there is a drastic reduction in IS lens price, if they don't they'll be losing business from people moving up from compacts who are used to it.
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Both canon and nikon have 18-55 and 55-200 lenses with IS. So the point and shooters will be happy.
The people that can afford the really good glass would prefer to get the really good IS with it. So they don't have a problem.
It is the people in the middle that get squeezed. Those of us who would like IS with our Tamron 17-50 f2.8 but who do not want to shell out for a 17-55 f2.8 IS.
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In-camera IS has the disadvantage of being less effective as focal length increases, which of course is where it is the most useful. With a 600mm lens, the sensor would have to move around in an area well outside the image circle of the lens to provide effective stabilization. On an interchangeable-lens camera, that simply isn't practical, as the lens mount would block the sensor's view of the lens. In contrast, putting the IS in the lens works just fine, as moving a fairly small, low-mass lens element accomplishes the same effect in a far more elegant manner. I can see value in a hybrid system where the body has IS used for short-to-medium focal lengths with non-IS lenses, but for longer focal lengths only lens-based IS would be used.
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Hmmm.. I am fairly sure that both Nikon and Canon and several other brands are holding/developing in-camera IS technology that eclipses that of their lenses... their competitors could very easily steal a march on them. If Sony can do it...
...or maybe they'll just have to lower the price of their IS lenses. I could live with that!
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Hmmm.. I am fairly sure that both Nikon and Canon and several other brands are holding/developing in-camera IS technology that eclipses that of their lenses... their competitors could very easily steal a march on them. If Sony can do it...
What do you base that on?
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Hmmm.. I am fairly sure that both Nikon and Canon and several other brands are holding/developing in-camera IS technology that eclipses that of their lenses... their competitors could very easily steal a march on them. If Sony can do it...
And does Sony have any long telephoto lenses available (400mm or longer), and if so, how effective is in-camera IS compared to lens-based IS of Canon or Nikon?
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I can see value in a hybrid system where the body has IS used for short-to-medium focal lengths with non-IS lenses, but for longer focal lengths only lens-based IS would be used.
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I think that's what we'll end up with. As long as it can be turned off when neccessary i'll be happy.
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And does Sony have any long telephoto lenses available (400mm or longer), and if so, how effective is in-camera IS compared to lens-based IS of Canon or Nikon?
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I personally feel an in-lens IS would be more effective than an in-camera IS (with sensor shift), primarily because the IS response can be tailored to the FL. I also think that Sony will be introducing in-lens IS for their longer lenses, including their 70-200 f/2.8, which is being replaced with a new one....and have the in-camera IS automatically switch off, when the camera senses a stabilized lens as having been mounted.
I think Sony has quite a few longer lenses coming up (including a 600mm), as per their mockup during PMA 2007 (picture below). The mockup also includes 2 camera bodies, with the one on the left (smaller one) already being sold as the A700 (as of October, 2007) and the one on the right, with the large mirror box and no built-in flash, is supposed to be the Full-frame pro-oriented model (A900?) expected during PMA 2008.
One of the lenses shown during the mockup has already broken cover as the Carl Zeiss Vario-Sonnar 24-70 f/2.8 SSM and there is also a rumored Carl Zeiss Vario-Sonnar 16-35 f/2.8 SSM or a Carl Zeiss Vario-Sonnar 14-24 f/2.8 SSM. In addition to that, Sony is pulling their 70-200 f/2.8G from the market and is replacing it with a rumored Carl Zeiss Vario-Sonnar 70-200 f/2.8 SSM. Obviously all of the above, in addition to the longer primes, will be supplementing their current lens range that also includes a Carl Zeiss Planar 85mm f/1.4 and the Carl Zeiss Sonnar 135mm f/1.8.
[a href=\"http://www.dpreview.com/articles/pma2007/Sony/IMG_4806.jpg]http://www.dpreview.com/articles/pma2007/Sony/IMG_4806.jpg[/url]
I think their strategy of bringing out ultra-premium Carl Zeiss FF lenses (with expected mind-blowing performance corner-to-corner) is a sound one, in terms of establishing an immediate credibility in the market, when their pro-oriented FF model (essentially a more robustly built 5D) hits the road.
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I personally feel an in-lens IS would be more effective than an in-camera IS (with sensor shift), primarily because the IS response can be tailored to the FL. I also think that Sony will be introducing in-lens IS for their longer lenses, including their 70-200 f/2.8, which is being replaced with a new one....and have the in-camera IS automatically switch off, when the camera senses a stabilized lens as having been mounted.
That would be the sensible way to make it work...
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And does Sony have any long telephoto lenses available (400mm or longer), and if so, how effective is in-camera IS compared to lens-based IS of Canon or Nikon?
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I've used the KM7D with 100-300mm and 70-210mm natively and with 2x t/c and 500mm reflex with the AnitShake as it was called then. Actually, have even used it with the 500mm reflex with 2x t/c without terrible results. Performance is good - a genuine 1.5 to 2 stops allowing hand held at shutter speeds below 1/focal length. The limitations were the t/c and the reflex lens.
The higher end Canon lenses perform better, but then so would higher quality lenses if I'd had them for the KM7D.
The Sony system is meant to be improved from the KM by all accounts - I'll have an Alpha 700 in the new year so I'll be able to see then.
Where the IS lenses certainly have an advantage is things such as tripod mode, that isn't available with the Sony system and some people much prefer to see the stabilised image in the view finder (I have no preference, having used both).
The main issue has always been how in-camera would function with a FF sensor. The 1.5 crop obviously has a lot of real estate to play with and it would seem prohibitively expensive to put an oversized sensor in place in order to provide in-camera stablisation. I support we shall see if the rumours are true and the Alpha 900 is FF.
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For example, for non-interleaved RGB recording, with floating sensor and automatic triple exposure, one can get each image pixel with all three RGB sensors (time multiplexed 3-CCD or 3-CMOS). With automatic 6-expsosure, one can take the same image pont with multiple-redundancy for error or noise correction.
Due to the GR-GB checkerboard layout of the sensor, you need 4 shots to record true RGB, not 3. Some medium-format backs do this, but only when tethered to a computer. The computer has to take the multiple frames and combine them; the back doesn't have the CPU horsepower/memory to do so by itself.
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... The key is more in the repetitive/data-transfer rate of the multi-exposure. It would be much easier for landscape, close-up and anything not moving fast.
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If Canon can solve that problem with multiple data pipes off the sensor (to read images so quickly that it allows 3 data sets in, say, 1/250 or 1/500 initially) they could actually use their [a href=\"http://patft.uspto.gov/netacgi/nph-Parser?u=%2Fnetahtml%2Fsrchnum.htm&Sect1=PTO1&Sect2=HITOFF&p=1&r=1&l=50&f=G&d=PALL&s1=6388709.PN.&OS=PN/6388709&RS=PN/6388709]patent[/url] to get sequential R, G and B values from the same photosensor element (like a Foveon but using a temporal rather than spatial array) that would be kewl! However, such read rates seem to be a long way off...
Andy
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What do you base that on?
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I base that on the knowledge that these companies have vast sums of cash for R&D and no doubt a steady trickle of ultra clever boffins coming through their doors with nifty pieces of patented technology available at the right price...
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It actually not as hard you might think. To continoue multi-exposure in high speed is one thing, but to get fast but triple (fix number) exposure is much easier. I'll leave it for your mental exercise if you can access to eletroinc enginnering knowledge.
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Well, my poor mental exercise capability helped me find a Cypress " high speed CMOS [a href=\"http://www.sensorsmag.com/sensors/Sensor+News/Cypress-Introduces-High-Speed-SXGA-CMOS-Image-Sens/ArticleStandard/Article/detail/466473]sensor[/url] " announced in October of this year, running 500 f/s for 1.3 MP, so ~ reading at 650 MP/s. For a 1/500 sequential RGB exposure(as Canon's patent envisions), you need to read 3 x 1/1500 off the chip (one each for RG and B right?) For a 6MP sensor (which for still objects might represent the info of a 12MP Bayer) this would be 9,000 MP/s. Still a ways off, I think
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My view is that Nikon and Canon will have to follow.
It seems that building FF pro zoom lenses (24-70 f2.8) with built in VR/IS is still technically very challenging since neither Canon nor Nikon have managed yet to release such lenses. It probably is related to the size of the lens that would need to be moved to stabililize such lenses.
This will probably be the main driver for these companies to adopt in body VR.
Another possible reason is that it could in theory be possible to use both lens VR and body VR to have even larger gains. My guess is that Canon and Nikon have not released such bodies yet because they have not found yet a good way to mix in body VR with lenses VR. The challenge is of course to keep selling VR lenses after the release of VR bodies...
Regards,
Bernard
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Canon and Nikon already do this with their P&S cameras where it makes sense. For DSLRs better results are obtained with IS in the lens.
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And it is no fundamental that IS body can't be superior to IS lens.
Not true. Lens IS will work at any focal length, while body IS is limited by how far the sensor can travel. This means that body IS becomes less effective as focal length increases, which is where it is needed most. Lens-based IS does not have this limitation; it is equally practical and effective at any focal length.
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John - is there some reason for us laymen, why future technology could not address this in some way? One might think it is a frequency issue to the movement with increasing focal length as much as just the distance the sensor has to move? But that is from a layman's perspective... With all the coding built in these days, any reason why the camera could not adjust its sensor movement to the specific requirements needed for a particular focal length, within the limits of a particular sensor...just wondering??
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Another aspect is focus accuracy. A camera with lens IS and a fixed sensor should have more reliable or more accurate initial focusing than a floating sensor.
With both systems, the focus detectors are not on the image sensor itself, they're on the path split off by the mirror. The lens focus will be adjusted so the image will be in-focus at the plane where the sensor is expected to be. On a camera without sensor IS, the sensor is always at that plane, it's never shifted.
On a camera with sensor IS, the sensor can be moved in several axis, and it would seem there is a possibility the sensor will not be dead center and parallel to the focus plane when focus is adjusted, and may therefore be slightly off.
This would certainly be something the sensor IS designers have solutions for, but it seems more controllable to have the sensor in a known position and control the image path upstream of the sensor and focus so both see the same results.
Andy
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John - is there some reason for us laymen, why future technology could not address this in some way? One might think it is a frequency issue to the movement with increasing focal length as much as just the distance the sensor has to move? But that is from a layman's perspective... With all the coding built in these days, any reason why the camera could not adjust its sensor movement to the specific requirements needed for a particular focal length, within the limits of a particular sensor...just wondering??
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The issue is one of geometry. IS (body or lens based) is introduced to address what we can affectionately call shooter shake. Slight shake in your hands typically has a component that translates to wobble in the optical axis (straight out from the sensor through the lens). Thus, if you want to think of it, your lens sways with an arcuate motion (I'm simplifying a bit...)
At a short focal length, a shake of a couple of millimeters isn't really noticable since it might end up being 1 degree, from a 45 degree field of view. However, at a long focal length, the same shake might be 1 degree from an 8 degree field of view.
To perform IS, the sensor has to move so that the center of the image remains somewhat centered. If it needs to move 1/45th of its size that isn't a big deal (especially since on a reduced size frame, a conventional lens has an image circle bigger than the sensor). But if you want it to work just as well at a long focal length, the sensor has to move 1/8th of its size, in each direction. Not only is there not usually enough space in the body, but the image circle cast by the lens isn't usually big enough to accomodate that. Thus, in body IS doesn't perform as well at long focal lengths. (though it is likely that the degree to which the sensor is moved is calculated using the focal length of the lens as one of the inputs)
If we're putting the IS in the lens, we're using gyroscopes to detect movement, and then we have floating elements that can adjust to move the placement of the image. If you have a 600mm lens with IS, the IS system is tuned for that focal length. If you have a 70-200mm lens, the IS system can be tuned to work in that range, and in theory you can feedback the focal length to the logic processor to change how the floating elements are moved. You cannot get that sort of tuning with a body that has to work with lots of different lenses.
wow... that took more explaining than I thought it would.
--dilip
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Thanks Dilip - you gave a great explanation of the current issue of why body IS is not effecticve to present. I guess my understanding is incomplete though, as this does not explain why some of these concerns might not be solved down the road i.e. in the near future. It was not so long ago, that IS or VR tech gave only 1-2 stops of motion compensation , now we have lenses where 3-4 stops are possible under certain circumstances. Why could not the focal length information be transmitted to the body and thus have the body IS or VR adjust in parameters to yield the same compensation that the in lens system would accomplish. I always thought on a separate issue that IS was less effective for wide angles? Is this incorrect? Just trying to gain a greater understanding of how things work but have no engineering credentials to assist....Thanks again, Don
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Thanks Dilip - you gave a great explanation of the current issue of why body IS is not effecticve to present. I guess my understanding is incomplete though, as this does not explain why some of these concerns might not be solved down the road i.e. in the near future. <snip>
The following will ask you to take some assumptions, and is somewhat general.
In order to give you an enhanced IS-system, an in body system has to be move the sensor around both faster and farther. Faster allows it to track small deviations that happen quickly. This will happen. Farther is needed to compensate for bigger swings in the image, which happen at the longer focal lengths. A 600 mm lens gives you a field of view of 4 degrees. If your vibration changes the angle 1 degree, the sensor has to be moved 1/4 of it size away from the centred position. At that point, most lenses aren't going to be projecting the image correctly (if at all).
In theory a 600mm lens with IS can be designed to deal with this much better.
The use of in lens IS does not mean that in body IS cannot also be used. There is nothing, other than complexity, to prevent hybridized systems. But remember that complexity is often underestimated.
And we should also remember that full frame sensors are unlikely to be shifted around in body due largely to the fact that something like the 1Ds Mark II or Mark III already push the optical quality of lots of lenses in the corners. Shifting a sensor like that around would result in bringing those bad edges in towards the centre of the sensor, and push the edges either into the dark or at least into really bad parts of the image.
--dilip
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I admire your fancy imagination, but the floating element only has very limited usible movement for its purpose. Don;t forget even when there is no vibration, the effective image circle is still limited to that 36mm x 24mm region. If the vibration is too large for the moving sensor, it would be too large for the floating lens to maintain the good image quality.
Your technical cluelessness is showing here. With long lenses, the image circle is constrained primarily by the shape and size of the lens mount, not the lens itself. The longer the lens, the larger the image circle can be while still maintaing a reasonably high MTF. A Canon 600mm prime could easily cover 4x5 film with only a small MTF falloff in the corners.
Let's look at a scenario where the camera shake is such that the subject motion is 30mm at the sensor plane. With lens-based IS, moving a small lens element to keep the subject steady on the sensor is not that hard. The lens has plenty of spare image circle to keep the quality level up. Now given the same scenario with in-body IS, you have a serious problem. Even if you can move the sensor far enough and fast enough to stabilize the image (which is not bloody likely), the lens mount is going to cause vignetting.
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I can't help but see this entire discussion is solely based on the simple premise that Nikon and Canon lenses are so gigantic that they really do need in-lens IS.
But for a successful in-body IS system, like Olympus use, it is perfectly feasible to get four stops usable IS on say a 600mm (equiv) lens simply because it is so short (tiny) compared to a Canikon lens of the same reach. The geometry works for Olympus. So 'if' Canon are thinking of in-body IS, are they just fumbling around looking for another marketing ploy to hook people with, or perhaps looking towards a fundamental change of direction for the future? Perhaps a dedicated range of digital lenses that are smaller and lighter, and that don't need IS built in. And perhaps designed around the smaller APS-C sensor given the full format sensor is out performing the current legacy lenses anyway? There may be a big shake up of Canon culture to come, and in-body IS may be a positive move if seen perhaps in context of what else may be around the corner.
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But for a successful in-body IS system, like Olympus use, it is perfectly feasible to get four stops usable IS on say a 600mm (equiv) lens simply because it is so short (tiny) compared to a Canikon lens of the same reach. The geometry works for Olympus.
Did you fail math or something? If you're shooting an Olympus of equivalent focal length to the Canon 600mm, in an equal-shake comparison, the Olympus sensor is going to have to move the exact same proportion of its size as the Canon sensor to achieve the same degree of stabilization, and both would have exactly the same amount of lens-mount vignetting of both used body IS.
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One additional thing we have to keep in mind (and I rarely hear any discussion on when talking about IS systems) is that it is VERY challenging trying to spot-focus or spot-meter a view-finder image that is not steady.
An in-body stabilization system does not stabilize the image in the viewfinder and only enables a stabilized image to be CAPTURED.
This is okay, with short (equiv) focal lengths, where the viewfinder shake is not that visible. But at longer focal lengths, spot-metering/focusing would present challenges that are not present in the In-lens stabilized arrangement, where the image that gets to the viewfinder is stabilized (along with the captured image, obviously).
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Did you fail math or something? If you're shooting an Olympus of equivalent focal length to the Canon 600mm, in an equal-shake comparison, the Olympus sensor is going to have to move the exact same proportion of its size as the Canon sensor to achieve the same degree of stabilization, and both would have exactly the same amount of lens-mount vignetting of both used body IS.
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I'd have thought it was geometry I had failed?
As a very rough example Canon user moves the camera body accidentally up one degree and end of the lens moves 'say' an exaggerated ten millimeters off target if it is moving around the axis of the body. One degree movement for the Oly user becomes a five millimeter movement at the end of the lens because the lens is 'say' half the length. Likewise a similar thing happens when you balance the lens axis in the centre or reverse the whole thing and rest the lens hood on a wall. The amount of movement is amplified by a lens of longer physical length. So whatever the focal length the Oly body IS has to move a smaller distance to compensate for the same amount of movement.
You can work it out for yourself with some graph paper (thats paper with lines on it).
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The amount of movement is amplified by a lens of longer physical length. So whatever the focal length the Oly body IS has to move a smaller distance to compensate for the same amount of movement.
You can work it out for yourself with some graph paper (thats paper with lines on it).
Geometry is a branch of mathematics.
And you're ignoring the fact that the Olympus lens mount is smaller than that of Canon, which is one side effect of designing the entire system for a smaller sensor and image circle. Though the subject movement in millimeters on the sensor plane for a given shake level is smaller with the Olympus than Canon, the amount of camera shake necessary to cause lens-mount vignetting is similar with both systems. B for effort, F for validity of arguments.
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Hi,
I use an Minolta 400/4.5 frequently with an 1.4x converter on Sony Alpha and can say that image stabilization works. If it works as well as other solutions I can't tell. My feeling is that 1/125 is possible hand held with this combo.
I don't think that the sensor need to move a lot, because it just moving during exposure.
Best regards
Erik
And does Sony have any long telephoto lenses available (400mm or longer), and if so, how effective is in-camera IS compared to lens-based IS of Canon or Nikon?
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Geometry is a branch of mathematics.
And you're ignoring the fact that the Olympus lens mount is smaller than that of Canon, which is one side effect of designing the entire system for a smaller sensor and image circle. Though the subject movement in millimeters on the sensor plane for a given shake level is smaller with the Olympus than Canon, the amount of camera shake necessary to cause lens-mount vignetting is similar with both systems. B for effort, F for validity of arguments.
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Hmmm, B for effort and F for validity?
I'm sure you will put me right on this, but here goes. So you say the lens mount vignetting is similar on both systems, which so you don't get confused can both be called 'full frame' (in the sense that both systems have lens and sensor matched by design), yes?
OK, off the top of my head the minimum image circle for a 35mm lens is 43mm diameter? The Canon lens mount is 54mm diameter? The minimum Olympus image circle is 22.5mm diameter and the lens mount is 47mm internal diameter? So the Olympus lens mount is over twice as big a diameter as the minimum image circle needed. The Canon mount would have to be 86mm to be comparable, no? Is this the 'similar lens mount vignetting' you are suggesting? I'm obviously missing something in the equation given I failed maths and geometry.
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(http://www.imaging-resource.com/PRODS/E3/ZYFRONT-MD.JPG)
And the E-3 mirror box is about 27mm wide. The sensor can only move 4-5mm before the mirror box or other bits of mechanism start getting in the way. And then there's the issue of the light trap at the rear of the longer lenses; how large is the opening on the back of the lens? At best, the Olympus can compensate for camera shake of about 1/2 the frame width.
OTOH, lens-based IS systems are not constrained by these limits; moving a small lens element in the right place can easily move the image circle projected by the lens the entire frame width.
And lens-based IS stabilizes the viewfinder image; body-based IS does not, at least when you're using the optical viewfinder. This can be a significant issue when trying to compose an image.
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But going back to geometry, it could be that a Canon in-body IS sensor (using the legacy designed lenses we are talking about) would need to move a larger amount than a 4/3rds sensor. This is because the light rays as you know fan out (with 'some' correction) as they leave the rear element, spreading wider and wider. The more the camera is shaken off its central axis (the direct line between subject and centre of the sensor), so the sensor would need to move exponentially further to 'catch up' with the image given the focal point has to remain fixed, and with the light hitting the sensor at an increasingly oblique angle. So an in-body IS system on a Canon would be a poor idea without some new lenses (and design philosophy), as I originally mooted. The soft edges sometimes produced by Canon lenses would also be further exaggerated.
On the other hand, the image projected onto the 4/3rds sensor is far more linear, and while not exactly parrallel the light rays hit the sensor square on. And it is within a proportionally much larger and usable image circle compared to your Canon lens design. So the problem of an exponential growth of the angle due to sensor movement is largely avoided. Thus the sensor has to move a shorter distance to achieve the same thing, and all within a very large image circle devoid of the problems of vignetting. And if as you say the the 4/3rds sensor could 'only' move half the frame width, then this would be a mighty difference in where the camera is pointing, never mind simply stabilising the image.
If the number of words written on the subject were soldiers you should have won. But just like the Romans encountering a much smaller army at Cannae, few of them stood up in the end
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Well I think thats a comprehensive out flank and encirclement by me. Having been wrong about the lens mount you fudge a change of direction.
My first instinct would be to suggest that if the sensor needed to be moved 4-5mm by the image stabilisation, then a tripod should be used
And when shooting from a car, boat, or airplane, a tripod would accomplish what? Or what about shooting in venues where tripods are not allowed? Or you are shooting from a tripod, and there is a strong wind that is still causing camera shake? I've encountered all of these situations when shooting.
You still have said nothing that refutes my original point--that body-based IS becomes less effective as focal length increases, because the mirror box/lens mount imposes a hard limit on how much shake body-based IS can correct. And longer focal lengths are where IS is needed most.
Yes, the outer diameter of the Olympus mount is somewhat larger in proportion to the sensor size compared to Canon's lens mount. But that still imposes a physical limit to the effectiveness of Olympus' IS system that does not apply to the Canon. Focal length has little effect on lens-based IS system's effectiveness. With lens-based IS, the corrections made by the IS mechanism are magnified in direct proportion to the focal length of the lens, so lens-based IS is equally effective at all focal lengths. But with body-based IS, the distance and velocity that the sensor must move to provide a consistent level of shake compensation increases in direct proportion to focal length, and the hard limits of how fast and how far the sensor can be moved impose a hard limit to the maximum focal length at which effective IS can be achieved.
With lens-based IS, if you have a 600mm lens and add on a 2x teleconverter, the lens-based IS will be just as effective; if IS was eliminating 80% of the shake before adding the TC, it will continue to eliminate 80% of the shake afterwards. But with body-based IS, the limitations on the distance the sensor can travel and how fast the sensor can be moved will reduce the percentage of shake that can be compensated for by the mechanism. If the 600mm lens is already causing the body-based IS to work at 100% of its capacity to reduce shake by 80%, then adding the 2x converter means that the body-based IS mechanism will only be able to reduce shake by 40%.
Since I don't have an E-3, I can't test to determine the focal length at which its IS mechanism is operating at 100% capacity in terms of sensor movement speed and travel distance. But the effectiveness of it's IS mechanism in reducing shake beyond that point will fall off dramatically, with the percentage of shake being compensated for decreasing at the same time overall shake levels are increasing.
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Until such time as it is determined at which focal length this fall off occurs, there's no valid data to determine if it matters. If it falls off at 2000mm (for example) it's hardly going to be an issue for 99.9% of all photogs. If it falls off at 200mm then it's a big issue.
There are also limits to the amount of movement that any system, even lens based, will be able to deal with based simply on the ability to received light reflected from the intended target. By the time you place a normal hood on the lens, there is a limited window through which light from the target can pass to the lens. Certainly this is a reasonably sized window, but it's not as if lens based IS has an infinite capacity to deal with lens movement.
Anecdotal evidence suggests that in lens IS has perhaps a 1 to 1.5 stop advantage at the longer focal lengths (perhaps more in some cases - different lenses and different in camera systems make any generalisation difficult and, in reality, poor). That doesn't mean that in most situations the in camera system isn't going to provide sufficient compensation. With the added benefit of working with all lenses (the capacity added to something like a 50mm f/1.4 makes for an amazing capacity to capture in low light for example) the in camera system has tremendous appeal.
As we would all know, it's often about the perceived general application, usability and cost rather than which system is technically superior (which is often debatable - take the old Beta vs VHS scenario). At the highest end, it seems a hybrid system will possibly be available (partciularly for Canon and Nikon who already have lenses with IS - it's more of a challenge for Oly, Sony, etc to add lenses to their in camera system than vice versa for Canon and Nikon).
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There are also limits to the amount of movement that any system, even lens based, will be able to deal with based simply on the ability to received light reflected from the intended target.
Nope. Canon's IS system is gyro-based; it will work just fine even with a lens cap on. It is equally effective no matter what the light level is. You can hear a faint whirring noise when the gyros spin up while IS is active.
Anecdotal evidence suggests that in lens IS has perhaps a 1 to 1.5 stop advantage at the longer focal lengths (perhaps more in some cases - different lenses and different in camera systems make any generalisation difficult and, in reality, poor).
Most tests of Canon's IS lenses indicate 2-3 stops of stabilization. My personal experience agrees with this.
Until such time as it is determined at which focal length this fall off occurs, there's no valid data to determine if it matters. If it falls off at 2000mm (for example) it's hardly going to be an issue for 99.9% of all photogs. If it falls off at 200mm then it's a big issue.
The anecdotal comments I've seen from Olympus users would seem to indicate that the fall-off point is a lot closer to 200mm than 2000mm. But I can't claim rigorous testing for this.
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Nope. Canon's IS system is gyro-based; it will work just fine even with a lens cap on. It is equally effective no matter what the light level is. You can hear a faint whirring noise when the gyros spin up while IS is active.[a href=\"index.php?act=findpost&pid=166109\"][{POST_SNAPBACK}][/a]
Sorry, I was unclear. I meant that if the movement is so much that there is no longer a path for the light of the subject to reach the lens then it doesn't matter how well stablised you are, you can't take the picture. No system can make light bend around a hood and back into the lens :-) In other words, there's a point at which it doesn't matter if the system could theoretically compensate because the path is physically blocked.
In camera systems functiong fine with the lens cap on too, of course.
Most tests of Canon's IS lenses indicate 2-3 stops of stabilization. My personal experience agrees with this.
This doesn't tally with my experience up to 600mm comparing Canon with Konica-Minolta where I would say it's 1.5 - 2 stops. The newer Sony update to the system is roundly accepted as superior to the original KM implimentation.
If you've been using glass longer than 600mm then I will take your word for it as I have no experience of my own.
The anecdotal comments I've seen from Olympus users would seem to indicate that the fall-off point is a lot closer to 200mm than 2000mm. But I can't claim rigorous testing for this.
I've not used the Olly system. The KM system (and from reports the Sony version) continues to function without noticable drop-off up to the 500-600 range, but that is not tested with any scientific rigour.
Again, I don't think there's any doubt that the in lens systems have an advantage at longer focal lengths, but for the majority of users, over 600mm is not something they're going to experience (remember, the DSLR market is again growing and it's heading down the track, away from high end users because that market is already saturated), so it probably doesn't matter because either system is going to function just fine for them. Also, developing in camera technology will help to support any company's non-DSLR range.
The idea of a hybrid system for high end users could offer the absolute best at the appropriate price point.
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In camera stabilization doesn't get rid of the viewfinder bouncies.
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Of course, but some people find that more or less useful depending on what they're shooting and their own personal preference. That feature of in lens stablisation can also be annoying at times when you *want* to quickly adjust a small amount to see what's just out of frame and you have to wait. That's a minor, minor issue and overall it's a useful feature, but it's not anywhere near in the same league of being useful as the actual stablisation and stop gains possible as a result.
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Some additional grist for the talk mill (from the dpreview Sony forum):
http://forums.dpreview.com/forums/read.asp...essage=26363845 (http://forums.dpreview.com/forums/read.asp?forum=1037&message=26363845)
http://forums.dpreview.com/forums/read.asp...essage=26364194 (http://forums.dpreview.com/forums/read.asp?forum=1037&message=26364194)
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And when shooting from a car, boat, or airplane, a tripod would accomplish what? Or what about shooting in venues where tripods are not allowed? Or you are shooting from a tripod, and there is a strong wind that is still causing camera shake? I've encountered all of these situations when shooting.
[a href=\"index.php?act=findpost&pid=165888\"][{POST_SNAPBACK}][/a]
Then a mono pod, resting the lens on somebodies shoulder, whatever. Its the 'can do' attitude people had before IS became a crutch.
A point is well made by Farmer and it pretty well answers your conjecture re in-body IS being inferior to in-lens IS for the examples you give. There is a ratio where it no longer matters what your IS is capable of, or how big the mirror box or image circle is. The logic of this ratio says that the more stops of IS compensation there are, the less likely it is that the camera will be even pointing in the right direction. The camera will provide a perfectly sharp picture, but not of what you pointed it at. It changes from lens to lens, but the laws of physic's can't change, if you move or shake a 1000mm lens enough, on your swaying boat, it won't be centred or even focused on the subject, and light rays can't bend and the camera can't read your mind, yet.
So whichever way you look at it, with the current design of the cameras the lens based IS is at best limited in the sense there isn't much further to go with it anyway, other than finessing it. Which brings me back to my first point. Canon sensors are out out resolving the lenses so there is limited growth in the full frame system. APS-C sensors are getting better and it won't be long before they are as good in every way as whatever the equivalent full frame sensor will be, perhaps better. Experience from all other walks of life suggests technology gets smaller AND better. So, a new range of lens (based around APS-C), with a shorter length and size, al la Olympus, would eventually yield a more significant gain in resolution and overall performance than the outdated legacy designs. And given this philosophy I am arguing for the idea of in body IS. It becomes workable for as many stops as is feasible before the 'ratio' takes over.
I can only think of one good reason why photographers would want to carry around the large monstrosities they do now, given an equal choice. But take that choice away and make a better range of leses and they'll just go and buy a bigger car instead.
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Can I ask where the rumour that in-body IS has to move too far for it to be effective at longer focal lengths comes from?
All the testing I've seen indicated that a 500mm lens would need about 0.33mm of travel. That's nothing. I'd be interested to see what people make of the 2 DPreview threads listed above, which measure the distance the sensor travels using a 500mm lens.