Luminous Landscape Forum
Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: ErikKaffehr on December 18, 2010, 08:13:30 am
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Hi,
I have a short writeup on a comparison of the Pentax 645D with the Nikon D3X. The comparison is based on prints up to A0 size.
http://echophoto.dnsalias.net/ekr/index.php/photoarticles/51-a-closer-look-at-pentax-645d-image-quality
The article is still in progress and may be updated in the next couple of days.
The essence is: Pentax 645D delivers...
Best regards
Erik
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Really not sure what I am seeing here in terms of comparsion...
Of course looking at an image on the monitor zoomed at 100% doesn't tell how the print of this particular image will look like (grain, sharpness, contrast etc. etc.).
But still two images zoomed at 100% tell something about the difference of the two respective images in terms of comparision.
Or maybe zoom them both at 50%... or if you use OpenGL zoom them both to print size ... either way.
But when you are comparing actual prints you also compare the method of uprezzing, the sharpening technique and you name it.
So the entire printing workflow...
How will the prints look like without resampling, i.e. at native pixel size? For instance if you print the 645D image at 360ppi and the D3X at 300ppi (to achieve a comparable print size).
The Pentax simply resloves more details and the actual image is larger.
You can see that at any (useful) zoom magnification on the monitor.
Therefore it comes to now surprise that the difference is also apparent in a print.
Your 645D processing obviously doesn't match the D3x image by the way. It's darker, less contrasty and the white balance is warmer.
All three aspects are an advantage for the D3x print here... as the 645D looks a bit dull in comparision.
Bottom line... larger prints benefit from captures with higher resolution.
But I was already aware of that before...
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Hi,
Just in case you missed it, all images are scans from actual prints of A2 and A0 size. So the full pipeline is tested. Sorry for the color mismatch,I tried to adjust as well as I could, although I didn't spend that much effort.
I have also evaluated the prints visually but prints are hard to share over the net. This is the best approach I came up with,
Best regards
Erik
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I really think that 160mp'ish is going to be the sweet spot. Remember that 40mp is only a doubling of 20 and you must double to get appreciable gains. Of course I could be wrong if the future holds wall length paper thin LCD mounts in every home. :)
Personally I think that if a person is not happy with a 20mp system, they should move to at least 80mp. In the computer processing world, if a task takes 5 minutes on a 2Ghz system, it will take 2.5 minutes on a 4Ghz system. I would not want to spend that kind of money for such a small gain. Better to buy an 8Ghz system and get something that would change your life, you could feel every $ at work.
Just expressing a point of view...
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Hi,
I don't know. Lot of people invest in 60 MP backs right now. Would the Pentax go to 160 MP it would have a pixel pitch of 3 microns. This may be good for aliasing but may be less than optimal for DR. I guess that 20 MP is good enough for many uses.
Also, the 40 MP's now are probably not easy to utilize. Dead on focus, no vibration and don't stop down beyond f/11. With 160 MP that would be f/5.6!
Perhaps a good reason not to go much beyond 5 microns. P65+ has a larger sensor so sensor pitch is still around 6 microns although it has around 60 MP.
Best regards
Erik
I really think that 160mp'ish is going to be the sweet spot. Remember that 40mp is only a doubling of 20 and you must double to get appreciable gains. Of course I could be wrong if the future holds wall length paper thin LCD mounts in every home. :)
Personally I think that if a person is not happy with a 20mp system, they should move to at least 80mp. In the computer processing world, if a task takes 5 minutes on a 2Ghz system, it will take 2.5 minutes on a 4Ghz system. I would not want to spend that kind of money for such a small gain. Better to buy an 8Ghz system and get something that would change your life, you could feel every $ at work.
Just expressing a point of view...
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Erik, could you share what are now your preferred deconvolution sharpening methods for the D3x? As I recall, you put quite a bit of work into finding a near-optimal setting for reversing the effects of the OLP filter. I'm hoping I don't need CS5 to do it, or anything too expensive.
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Just in case you missed it, all images are scans from actual prints of A2 and A0 size. So the full pipeline is tested.
no, I did not miss it. Actually I was referring exactly to this particular kind of comparision. It's somehow useless as it involves a lot of image transformations (uprezzing, sharpening etc.). The printing worklfow for the D3x should be different to the workflow for the 645D... simply because the starting position is different.
For instance... I guess the D3x print would look somewhat better with less uprezzing but priniting at lower ppi. But that's just a guess as I don't know the actual resultion you applied to the prints.
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Hi,
480 PPI I think, but I'm not really sure. The idea was not to deliver the absolute truth but to give an idea to potential buyers of the P645D of the quality difference between a top end DSLR and an entry point MFDB. The comparison also discusses sharpness and none of the other purported advantages of medium format digital. Regarding resolution it seems to me that he Pentax 645D delivers.
Best regards
Erik
no, I did not miss it. Actually I was referring exactly to this particular kind of comparision. It's somehow useless as it involves a lot of image transformations (uprezzing, sharpening etc.). The printing worklfow for the D3x should be different to the workflow for the 645D... simply because the starting position is different.
For instance... I guess the D3x print would look somewhat better with less uprezzing but priniting at lower ppi. But that's just a guess as I don't know the actual resultion you applied to the prints.
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Hi,
I have used Lightroom 3.3. Develop has a slider called "detail" in the "detail" dialogue. This does unsharp masking at the left position and shifts to deconvolution at the rightmost position. Deconvolution is a way to restore detail. Normally deconvolution requires that the Point Spread Function, which is seldom the case. Lightroom estimates PSF using a model of a defocused image assuming a lens with a circular aperture, at least according to Eric Chan (Madmanchan) who is often posting on these forums.
Economical alternatives to CS5/Lightroom may be Iridient Raw Developer. Focus Magick or Topaz Labs In Focus (or their older product "Detail"). The settings I used in Lightroom are shown below.
By the way Bart van Der Wolf and others are much better references on the issue than myself!
Best regards
Erik
Erik, could you share what are now your preferred deconvolution sharpening methods for the D3x? As I recall, you put quite a bit of work into finding a near-optimal setting for reversing the effects of the OLP filter. I'm hoping I don't need CS5 to do it, or anything too expensive.
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480 PPI I think
why that high?
The idea was not to deliver the absolute truth but to give an idea to potential buyers of the P645D of the quality difference between a top end DSLR and an entry point MFDB.
well, I think the RAW files make that pretty clear.
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That's what I normally use.
I seldom print larger than A2, when I do I'll send the image to a pro lab printing on Durst Lambda. For large sizes they recommend 200 PPI, but at that density there are visible staircase artifacts.
Also, I don't think that excess resolution matters as I actually show scanned prints. I don't think any of the prints would be better using a lower resolution. Regarding CPU-time I simply don't care about wasted CPU cycles!
Best regards
ERik
why that high?
well, I think the RAW files make that pretty clear.
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Honestly, I don't get it…
Din A2 = 59,4 x 42 cm
printed @ 300ppi you need 7016x4961 pixels
printed @ 360ppi you need 8419x5953 pixles
printed @ 480ppi you need 11225x7937 pixles
So the higher the print resolution the more you have to uprez the actual pixels.
A print at 300ppi (RGB printer etc.) or 360ppi (Epson) is basically super sharp and detailed to our eyes. 240ppi on an Epson is still very good (mostly).
So you beat the files back and forth just to gain a resolution that nobody could tell from 360ppi (300ppi respectively).
Something simply doesn't add up…
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I dont argue...
That said there is some rationale behind using a high resolution...
- Jeff Schewe has indicated that it matters sometime, not often but sometimes
- I would scan the images and do some pixel peeping
- The printer driver will resize to native dimensions anyway. My guess is Lightroom may be better at resizing.
- I wanted to avoid a situation where Pentax image would be downsized and Nikon image upsized.
Best regards
Erik
Honestly, I don't get it…
Din A2 = 59,4 x 42 cm
printed @ 300ppi you need 7016x4961 pixels
printed @ 360ppi you need 8419x5953 pixles
printed @ 480ppi you need 11225x7937 pixles
So the higher the print resolution the more you have to uprez the actual pixels.
A print at 300ppi (RGB printer etc.) or 360ppi (Epson) is basically super sharp and detailed to our eyes. 240ppi on an Epson is still very good (mostly).
So you beat the files back and forth just to gain a resolution that nobody could tell from 360ppi (300ppi respectively).
Something simply doesn't add up…
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Jeff Schewe has indicated that it matters sometime, not often but sometimes
480ppi vs. 300ppi (360ppi) at the price of even more uprezzing???
I am curious to read about that...
The printer driver will resize to native dimensions anyway.
don't get the point I think...
if you prepare an image at a defined size and defined printer resolution... why should the printer resize anything??
I wanted to avoid a situation where Pentax image would be downsized and Nikon image upsized
see my suggstion in post #2... just print the D3x file without uprezzing at 300ppi and the 645D file without downrezzing at 360ppi.
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Most printer drivers do not process input images at arbitrary resolutions (e.g., pixels/inch). There are usually at most a handful of resolutions at which the driver can process the image. If your provided image does not match one of those accepted resolutions, the image will be resampled to meet one of the accepted resolutions.
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Honestly, I don't get it…
Din A2 = 59,4 x 42 cm
printed @ 300ppi you need 7016x4961 pixels
printed @ 360ppi you need 8419x5953 pixles
printed @ 480ppi you need 11225x7937 pixles
So the higher the print resolution the more you have to uprez the actual pixels.
A print at 300ppi (RGB printer etc.) or 360ppi (Epson) is basically super sharp and detailed to our eyes. 240ppi on an Epson is still very good (mostly).
So you beat the files back and forth just to gain a resolution that nobody could tell from 360ppi (300ppi respectively).
Something simply doesn't add up…
Hi Tho_mas,
While there will not be more image pixels carrying detail information, there will be more pixels to perform (output) sharpening on. This potentially boosts the possibility to render sharper detail and boost the MTF for the finest spatial frequencies that the image did record.
Cheers,
Bart
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While there will not be more image pixels carrying detail information, there will be more pixels to perform (output) sharpening on. This potentially boosts the possibility to render sharper detail and boost the MTF for the finest spatial frequencies that the image did record.
I'd like to see this in real prints...
While this might be true for certain images (probably only for certain details of certain images actually) I suspect it very much depends on the amount of uprezzing. In every image there is a certain limit (threshold) of uprezzing. If you uprez too high you are just introducing artefacts such like doubling of edges, a kind of ghosting in straight vertical or horizontal lines etc. (at least as long as we talk about bicubic smoother). You certainly won't enhance those pseudo details...?
Within reasonable values I think a higher enlargement is leveled out by higher printer resolution. But if the enlarged image is actually destroyed by too heavy uprezzing I seriously doubt that the higher printer resolution will level out the artefacts (i.e. "new" details that were actually not captured).
I do prefer a higher amount of uprezzing and printing at 300ppi over less uprezzing and printing at 200ppi on a Chromira RGB printer. However printing on an Epson I would prefer 240ppi over 360ppi with some critical images. Though mostly I print at 360ppi. But I can't imagine that I would gain anything printing at 480ppi... at least not when heavy uprezzing is required to meet a printer resolution that high.
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for any non-subscribers, Lloyd Chambers is not testing the 645 (diglloyd.com) and finding his copy of the 55mm lens very disappointing - even compared to a 5DII and 24-70!
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Hi,
Yes, I have seen it. A note on the issue has been added to my article.
Best regards
Erik
for any non-subscribers, Lloyd Chambers is not testing the 645 (diglloyd.com) and finding his copy of the 55mm lens very disappointing - even compared to a 5DII and 24-70!
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for any non-subscribers, Lloyd Chambers is not testing the 645 (diglloyd.com) and finding his copy of the 55mm lens very disappointing - even compared to a 5DII and 24-70!
I think you mean "now testing"
http://diglloyd.com/dap/index.html#Pentax645D
http://diglloyd.com/diglloyd/index.html
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Hi!
Let's put it this way, my article is about what we can expect from Pentax 645D, not about uprezzing for printing. I don't think my choice of uprezzing falsifies the results of the comparison.
Diglloyd has noted that off axis performance on the 55/2.8 is bad. That would be not seen in my comparison as it looks at central detail. I have actually noted lack of sharpness on the "brush" on the right edge but attributed it to being out of focus.
Best regards
Erik
I'd like to see this in real prints...
While this might be true for certain images (probably only for certain details of certain images actually) I suspect it very much depends on the amount of uprezzing. In every image there is a certain limit (threshold) of uprezzing. If you uprez too high you are just introducing artefacts such like doubling of edges, a kind of ghosting in straight vertical or horizontal lines etc. (at least as long as we talk about bicubic smoother). You certainly won't enhance those pseudo details...?
Within reasonable values I think a higher enlargement is leveled out by higher printer resolution. But if the enlarged image is actually destroyed by too heavy uprezzing I seriously doubt that the higher printer resolution will level out the artefacts (i.e. "new" details that were actually not captured).
I do prefer a higher amount of uprezzing and printing at 300ppi over less uprezzing and printing at 200ppi on a Chromira RGB printer. However printing on an Epson I would prefer 240ppi over 360ppi with some critical images. Though mostly I print at 360ppi. But I can't imagine that I would gain anything printing at 480ppi... at least not when heavy uprezzing is required to meet a printer resolution that high.
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I really think that 160mp'ish is going to be the sweet spot.
If, and only if, we are talking about a FF 6x7 sensor, or something like that. The lenses and the AF systems already don't support the resolution at 40MP, much less 60 or 80. Smaller pixels suck. Nothing has quite matched what the big 9 micron sensors in the P25 and D3 can do. Images off those cameras, while not as enlargable, always have a tangibly different feel' to them, imho.
- N.
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Hi,
In my view resolution does not hurt. DR in the DxO sense will go down, but in my opinion practical photography is dominated by shot noise and that is pretty independent on the number of pixels. With improved resolution we won't get much better detail so long as lenses and AF systems don't keep up with the smaller pixels, but we will have less aliasing artifacts.
To put it shortly, I don't think that small pixels suck, but they will not result in a sharper image. The improvement is less artifacts.
Best regards
Erik
If, and only if, we are talking about a FF 6x7 sensor, or something like that. The lenses and the AF systems already don't support the resolution at 40MP, much less 60 or 80. Smaller pixels suck. Nothing has quite matched what the big 9 micron sensors in the P25 and D3 can do. Images off those cameras, while not as enlargable, always have a tangibly different feel' to them, imho.
- N.
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Hi Erik,
The problem of your comparison, as well as many similar ones has been that, you put "enlarge-ability" of D3x image into the formula while did not consider the same aspect for the higher resolution side.
To me 645D images provide about the best upsampling experience over all Bayer type sensor based examples. Usually no matter how careful you are and what method and software you use, you only need factors like 135% to turn DSLR images into really ugly.
I have been really impressed with the D3x image quality, but when I upsampled 645D's images to 30x40 at 300dpi, I see very low levels of demosaicing artifacts and still nearly pixel level details. The D3x file totally broke down at this level.
If you email me I will send you some 100% unsampling samples in private. Thanks.
P.S.: I just added an example, 645D and D3x imaging-resource images, both carefully blow up to 24" high at 300dpi. See difference in small letters ("AUTHENTIC BEERS", etc.) Yes this is pixel peeping and as you put a ruler on screen and see how big an inch is there you realized on prints the difference tend to diminish. However, the difference will be there is you were printing 48" high, I am sure.
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Hi,
I don't really understand your point on the aspect ratio. I guess that what my scanned print samples show is that the P645D is superior to D3X in the aspects I looked at. I'm fully aware that the two cameras have different aspect ratios and the numerical figures are for the short size on each.
I'm glad that you are happy with your Pentax P645D, seems to be a very good camera to me. Lloyd Chambers is testing it and is quite unhappy with the new 55/2.8 lens (although he has two samples).
Best regards
Erik
The problem of your comparison, as well as many similar ones has been that, you put "enlarge-ability" of D3x image into the formula while did not consider the same aspect for the higher resolution side.
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Yes we looked over a dozen 55mm/f2.8 examples, Japanese, Russian, and even imaging-resource (the "house" shot), and they are all the same -- out of the center 2/3 (or 1/2 as Lloyd said today) it is not sharp at all.
However, he did find the 75mm OK to the sensor, and online we could see good examples of corner-to-corner sharpness off the 45-85mm zoom and the 120mm macro lens. We were also quite amused that there were no 55mm examples in the Pentax's own official 645 sample images. Just as he said, how could Pentax released such a lens, and termed it "outstanding", is well beyond me.
On the other hand, I am a practical photographer and I do need DOF with MF in the real world. I modified a 55mm P67 lens with fixed ~1 degree down tilt to help me in near-far type wide angle compositions just to deal with the DOF issue, for example. With film f/16 to f/22 was the norm, and I was aware loss of sharpness due to diffractions. However the softness can be at least partially corrected in sharpening, while the out-of-focus objects are hopeless. For the same reason Ansel started the f/64 school and virtually turned every of their lenses pinhole. When you look up close his large prints are not really sharp at all, but sharpness is only part of artistic expression, to the most. I believe, select samples carefully (even the MF lens variations is smaller than that of 35mm to my experience), I can comfortably work with the 645D with many old FA and A lenses at f/11 to f/16 and make great prints that is beyond my 6x7 chrome level, technically. The Velvia color pallet, the long exposure ability (star trails, light painting, etc.) is likely a totally different discussion though.
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Hi,
Yes I just checked out Diglloyd's article for the second time. The 75 lens is much better. I would be interested in your experience of Pentax 67 lenses on the 645D, because I have a handful of those (45, 90, 165/2.8, 300 and the fisheye).
Are you drum scanning Velvia? The reason I'm asking was that I was doing some testing on Velvia 67 vs. full frame digital last year and my Velvia scans were not that impressive. I was scanning on a Minolta Dimage Scan Multi Pro at 3200 PPI. Not high end digital but not exactly a cheap flatbed either...
Best regards
Erik
Yes we looked over a dozen 55mm/f2.8 examples, Japanese, Russian, and even imaging-resource (the "house" shot), and they are all the same -- out of the center 2/3 (or 1/2 as Lloyd said today) it is not sharp at all.
However, he did find the 75mm OK to the sensor, and online we could see good examples of corner-to-corner sharpness off the 45-85mm zoom and the 120mm macro lens. We were also quite amused that there were no 55mm examples in the Pentax's own official 645 sample images. Just as he said, how could Pentax released such a lens, and termed it "outstanding", is well beyond me.
On the other hand, I am a practical photographer and I do need DOF with MF in the real world. I modified a 55mm P67 lens with fixed ~1 degree down tilt to help me in near-far type wide angle compositions just to deal with the DOF issue, for example. With film f/16 to f/22 was the norm, and I was aware loss of sharpness due to diffractions. However the softness can be at least partially corrected in sharpening, while the out-of-focus objects are hopeless. For the same reason Ansel started the f/64 school and virtually turned every of their lenses pinhole. When you look up close his large prints are not really sharp at all, but sharpness is only part of artistic expression, to the most. I believe, select samples carefully (even the MF lens variations is smaller than that of 35mm to my experience), I can comfortably work with the 645D with many old FA and A lenses at f/11 to f/16 and make great prints that is beyond my 6x7 chrome level, technically. The Velvia color pallet, the long exposure ability (star trails, light painting, etc.) is likely a totally different discussion though.
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Yes but very very few. I found the best way for Velvia is Imacon (now Hasselblad) -- the diffused light source hide Velvia "popcorn" (actually "pepper" -- see my correction below) grains and like the 645D images the results withhold a lot of abuse (sharpening) even they look soft to begin with. Drum scans use very harsh point light source and actually emphasize film grain, making it hard to work with.
Of course I can't afford an Imacon but I found (at least in SF Bay area where I used to live) I can rent for hours or a day, and productivity was restricted by film mounting and cleaning not scanning. Thus I bought additional 6x7 and 4x5 film holders from B&H and keep mounting while scanning. This way my cost is typically below $2.50 per ~450MB 16-bit scan. Don't attempt to do anything (color and contrast correct, cropping, etc.) and just straight 16-bit with the level fixed at 0 and 255. With 16-bit you have a lot of room later. Of course never spend time burning CDs or DVDs, bring firewire drives and write straight.
These two works were both off my P67 300mm ED-IF. I tested with a Canon 5DII and found all my P67 lenses resolves to the 21MP sensor limit at f/8. The myth that MF lenses are not as sharp as 35mm ones is totally untrue.
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I think we can all agree that the 645 outresolves the current Nikon, because that was the design goal.
It is a newer camera, pitted against a 2 year older camera! This usually means a resolution disadvantage!
Things will get interesting when the comparison matches generations.
Edmund
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Hi,
Great images! But not a surprise as I already have checked out your homepage.
Best regards
Erik
Yes but very very few. I found the best way for Velvia is Imacon (now Hasselblad) -- the diffused light source hide Velvia "popcorn" grains and like the 645D images the results withhold a lot of abuse (sharpening) even they look soft to begin with. Drum scans use very harsh point light source and actually emphasize film grain, making it hard to work with.
Of course I can't afford an Imacon but I found (at least in SF Bay area where I used to live) I can rent for hours or a day, and productivity was restricted by film mounting and cleaning not scanning. Thus I bought additional 6x7 and 4x5 film holders from B&H and keep mounting while scanning. This way my cost is typically below $2.50 per ~450MB 16-bit scan. Don't attempt to do anything (color and contrast correct, cropping, etc.) and just straight 16-bit with the level fixed at 0 and 255. With 16-bit you have a lot of room later. Of course never spend time burning CDs or DVDs, bring firewire drives and write straight.
These two works were both off my P67 300mm ED-IF. I tested with a Canon 5DII and found all my P67 lenses resolves to the 21MP sensor limit at f/8. The myth that MF lenses are not as sharp as 35mm ones is totally untrue.
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Leaping
What is the 'popcorn' grain you refer to when speaking of Velvia?
Mark
www.marktomalty.com
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I think Digilloyd has proved, yet again that the full-system behavior of the 645 cameras is not always as good as their sensor. And that they work well as landscape cameras.
Edmund
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Lepig: Your two images blew me away. I do seascapes, but those two landsapes are in a different league.
Dave
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Hi Mark,
My bad! It is "pepper grain" not "popcorn". I was indeed hungry but we don't put peppr on popcorn normally. :)
I could not find the orginal page of the term now but here is a discussion on the issue:
http://photo.net/digital-darkroom-forum/00Ok5u
Sorry again,
Leping
P.S.: Dave: thank you for your very kind words, but the only thing hard in making such images was luck and patience, not "level" of the maker.
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I tested with a Canon 5DII and found all my P67 lenses resolves to the 21MP sensor limit at f/8. The myth that MF lenses are not as sharp as 35mm ones is totally untrue.
Comparing at f/8 might not tell the whole story: maybe it is another myth, but it is often said that "all lenses are equally sharp at f/8", perhaps because for most good primes (aberration effects are far less than diffraction at f/8 and above. (Maybe less true for LF lenses.) So I think that the claims of higher resolution (l/mm) for good 35mm format lenses refers to their optimum resolution, occurring below f/8.
But on the other hand, I suppose that the great majority of high resolution photography done in formats like 6x7 and larger is done at aperture ratios of f/8 and up, where the lenses are close to "diffraction limited" (which is a good thing, despite many opinions to the contrary!) The ability to more often use lenses at aperture ratios high enough to be more or less diffraction limited is one optical advantage of a larger format.
And if you are seeing "sensor limited" resolution at f/8 and 21MP, there is clearly room for increasing overall resolution in 35mm format by moving to more, smaller photosites, like those of the recent 16-18MP sensors of some recent DSLRs.
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Hi,
From what I have seen from my Pentax 67 lenses I'm not really of the impression that they have really good MTF at 80 lp/mm (corresponding to 6 micron pitch). Using Imatest I estimated 2271 LW/PH for my Pentax 67 with 90/2.8 lens using Velvia and 2890 LW/PH for the Sony Alpha. This pretty much corresponds to my visual impression of scanned Velvia from the P67. I also tried microphotography using an enlarger lens and got results very close to the scanned slides.
I general I see a lot of color fringing on scanned Velvia with all lenses I have (45/4.5, 90/2., 165/2.8 and 300/4). I did not test the P67 lenses on a Sony 900 or Canon 5DII body. But from what I have seen from slides I would not expect that good resolution.
The article here contains a lot of samples: http://echophoto.dnsalias.net/ekr/index.php/photoarticles/16-pentax67velvia-vs-sony-alpha-900
Best regards
Erik
Comparing at f/8 might not tell the whole story: maybe it is another myth, but it is often said that "all lenses are equally sharp at f/8", perhaps because for most good primes (aberration effects are far less than diffraction at f/8 and above. (Maybe less true for LF lenses.) So I think that the claims of higher resolution (l/mm) for good 35mm format lenses refers to their optimum resolution, occurring below f/8.
But on the other hand, I suppose that the great majority of high resolution photography done in formats like 6x7 and larger is done at aperture ratios of f/8 and up, where the lenses are close to "diffraction limited" (which is a good thing, despite many opinions to the contrary!) The ability to more often use lenses at aperture ratios high enough to be more or less diffraction limited is one optical advantage of a larger format.
And if you are seeing "sensor limited" resolution at f/8 and 21MP, there is clearly room for increasing overall resolution in 35mm format by moving to more, smaller photosites, like those of the recent 16-18MP sensors of some recent DSLRs.
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Hi Erik,
Very interesting post, but I think you did not pick the sharpest P67 lenses: from my tests the 45mm is not as sharp as the 55mm/f4 (new style), the 90mm and the 300mm/f4 non ED IF are not the sharpest as well (the 300mm ED IF is extremely sharp and the 55-100mm zoom easily beats the 90mm at f/8, and sorry I did not own the 165/2.8 ) ::)
A while ago I posted a test chart shot showing my copy of the P67 90-180mm zoom resolved to approximately the 5DMKII's sensor limit at 135mm f/8:
http://forums.dpreview.com/forums/readflat.asp?forum=1021&message=31210966
and after tests (on film) I put away and sold most of my P67 prime lenses since the two zooms are indeed that good (except for visual focusing uncertainties with the 90-180mm since the f/5.6 maximam aperfure).
Thanks,
Leping
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....you only need factors like 135% to turn DSLR images into really ugly...
Cough.
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Cough.
I should have said Bayer sensor based DSLRs with AA filter, ugly looking on screen at 100%. One other common problem is thickening of single pixel details into a couple of pixels -- you usually don't realize until checking at the same shot with MF gear or scanned film.
Thanks.