>>And yes we also have lenses for digital applications and yes they do produce better images then traditional optics...<<
I love reading DRIVEL like this, which is tantamount to an admission of making inferior lenses for other purposes. Now THAT'S marketing.
Chad:
Drivel is an unfair characterization of both the issue and Bob's words. Traditional LF lenses aren't inferior, but they do tradeoff some resolution and other corrections in the center of the field for a larger usable image circle demanded by LF photography. All product designs are balances of features and performance. It helps to know what the tradeoffs are in each.
Chad,
That's not really fair. We all accept that the small format 35mm lenses of necessity must be and are a lot sharper than MF and LF. It's the same with digital sensors. They are tiny compared to 4 x 5 film and need sharper lenses. There are economics involved here. We have not wanted to pay for ultimately sharp lenses for LF work because they were not necessary. Have you checked the prices of the 'digital' lenses?
Chad,
Prior to commenting you might want to study the plentiful literature on the how and whys of digital lenses. We, Rodenstock, have several technical brochures explaining the uses and need for these lenses and Schneider must have some also.
Then make your comments.
Didn't Rodenstock write them for Schneider?
"my guess is that the difference lies in aliasing, particularly with Bayer sensors."
I am waiting to change over til they get Tylenol sensors. Then the headaches will be worked out.
Seriously, there is a lot to the aliasing factor and the angle of acceptance of the sensor - I think those are the two big factors. Feeding each tiny receptor on the sensor is a difficult task and software and tricks can't correct fully for the mechanical shortfall. And aliasing is voodoo as far as I can tell. Its not entirely predictable and very difficult to eliminate without loss of image quality.
I think a lot of the surprise by DSLR owners is a result of having never seen what their photos looked like under high magnification. If you've been turning in 35mm tranparencies picked with a loupe as finished work, then viewing your digital camera files at high magnifications must be very disconcerting. I suspect that on the printed page, the files that have so many wailing and gnashing their teeth, look just fine. That little bit of CA in the corners just dissappears at 150 line screen 4X6 inch repro. ; >)
I doubt that we'll find the new "digital" LF lenses to be necessarily and consistently better on film than the standard models. And its a matching of lens performance to sensor performance. The digital lenses will be corrected and adjusted for a chip instead of film. Just as a process lens is purpose made for close range reproduction and a standard lens for photographing more distant objects. Tuned for the job so to speak.
It'll be interesting to see what Glenn finds about his new APO Sironar Digital. Glenn, I'd really like to hear back about your test results and impressions.
From Bob Solamon: "So does Linos - that is Rodenstock's owner."
Terrific! I hadn't yet seen this website. For a long time, Rodenstock went without a webpage. I was curious about what Rodenstock offers and now have the opportunity to find out. Thanks for the heads up.
It is interesting to see the origins of the different German companies merged into the Linos group. Among them you find Spindler & Hoyer, a highly-regarded brand of laboratory optics. So it does make sense if Rodenstock concentrates on ophtalmic glasses, that Rodenstock-photo-lenses becomes the companion of a scientific optical company. Good for us who insist on top-class instruments, be they lab intruments or photographic or scanning instruments.
Since I use a 6x9 view camera I have always regretted the limited number of view camera lenses specifically designed for 6x7-6x8-6x9 on film. I'm not speaking about dedicated brands of 6x7-6x8-6x9 lenses, but view camera lenses adaptable to all kinds of view cameras. To me a 90mm would be a good general puropose lens for 6x9 like the 135 is preferred by some 4"x5" users.
For 6x7 and 6x9, 90mm was the focal length on the Linhof 220, the rangefinder Fujis 6x7 and 6x9, etc.. 90mm lenses designed for 4"x5" have their optimum f-stop at f/22 and offer too much image circle. So I thought by reading the specs on paper that the 90 apo sironar digital could be an excellent lens for me on rollfilm, only the high premium to pay vs. a conventional 90, 100 or 120 and the lack of used ones has prevented me to seriously consider this 90mm 'digital' lens.
So I'm happy if Glenn shares his experience with this 90mm lens, be it on silicon or on film.
Going off-topic for one minute : 6x9 aficionados are really happy to see the apo-sironar-S introduced in 100mm. And the only regret that we could have is that all the effort by Linos-Rodenstock on new digital lenses might have deprived the company from the required workforce and money to maintain or (even introduce new) long focal lenses on catalog. Probably the market was not there... but I know at least 3 competitors who keep attractive long focal lenses ;-);-) Even if we acknowledge, reading Rodenstock's recent litterature, that the 210 apo-sironar-N is an excellent, not too heavy and affordable long focal length for 6x9 and 4"x5", even if one might dream of a 300 apo-sironar-S, as a long focal length for my 6x9 (and even for 4"x5") is concerned (if I had the budget) for a 300 I would still prefer something lighter and with less image circle like the apo-ronar... so here for the moment our shopping basket will aim at used or non-Rodenstock lenses ;-);-)
Back to the subject ; to Struan : I understand the point of refining the correction of chromatic aberrations for 'digital' lenses. It would be interesting to see if multilayer sensors like the foveon® is subject or not to the same problems as one-layer "bayer-headache" ;-) sensors.
Speaking about the above mentioned test on the new Canon 1DsMkII vs a 645 Contax plus a Kodak 16 Mpix sensor, the colored effects you mention are very subtle, whereas if you look at the "York" letters in the Canon image, they show an obvious "staircase effect" not present on the Contax-Kodak side. Well "obvious" only at such magnifications that this doesn not probably change anything in real-world printed images as seen with the naked eye
However I am not totally satisfied with the statement : silicon sensors are now better than film lenses. The mere fact that aliasing is invoked to explain some artefacts in digital images proves that fine periodic structures beyond the sampling limit of the sensor are actually imaged by the lens with a minimum, non-zero contrast. So on this issue, I'm tempted to argue : one cannot say at the same time "film lenses have a lesser resolution than the sensor" and : "aliasing generates artefacts". You have to choose. Either it is not aliasing, or the lens is better in terms of its ability to transfer fine periodic objects. You cannot get true aliasing (at least as far as I remember my course on signal processing) and a lesser lens resolution at the same time. Except if... what follows is valid, which is just a conjecture proposed to the group's criticism.
What is subtle is the fact that the absolute diffraction limit is very far away from the sensor sampling limit, except @f/22 or f/32 for view camera lenses. So the conjecture is : residual geometrical aberrations, like plain de-focusing, do not actually prohibit that images of periodic objects can actually be recorded with a certain contrast. Those of you who have imaged radial targets like the Siemens' star know what I mean : even de-focused, the star is still visible but with some parts exhibiting a low-contrast, sometimes inverted. The MTF for de-focusing and some geometrical aberrations is oscillating and you can get some reversed contrast for periodic objects beyond the first zero of the MTF. Only diffraction generates an absolute zero of the MTF. So may be the issue is here, residual aberrations do not prohibit that periodic objects generate periodic images beyond the first zero of the de-focused or aberration MTF, those images generating cahotic, "voodoo-style" ;-) aliasing, so improving aberration correction and not only chromatic will counter-fight certain aliasing effects (??) but could introduce others, I do not know.
This would not show up on film due to the random dithering film pattern. But modern slide film being credited of 150 lp/mm, I am still tempted to say : digital sensors can still be improved in terms of a finer pixel mesh, the finer the better... as long as noise does not show up... imagine the noise figure of a 1 micron square pixel ? if you have to average them ten by ten, you'd better stay with present state of the art...
Emmanuel:
Given the choice between a 10 micron image element, and averaging over a 10x10 group of 1 micron elements, I would much prefer the latter! Assuming the CPU power to do the computation, I would retain the same luminance sampling frequency, but would greatly increase the sampling frequency in chroma and eliminate much of the color aliasing problem. So in some sense, it is the size of the Bayer filter pattern that still needs to shrink.
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