Rodenstock "Digital" Lenses - The Best (?)

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Hi,

I want to start out in large format photography in 6x9 format using a roll film back. I am now at a stage of choosing lenses and have been looking for the ultimate lenses. Since I will be shooting a relatively small format, lens performance will be vital to me. I want to get the best lenses and not want to look back and wonder if I made the right choices.

Anyway I am now looking at the range of Rodenstock ďDigitalĒ lenses. I want to share some information about them and also hopefully get some input from shooters (if any) who use these lenses.

These lenses do seem incredible. Despite their name they are regular large format lenses in Copal shutters. They are not for 4x5 shooters since the largest image circle is 150mm.

They come in three different designs. The first is the Apo-Sironar Digital. The second is the Apo-Sironar Digital HR and the last is the Apo-Macro-Sironar Digital.

Sadly the Rodenstock brochure on these lenses is very poor. It is very confusing and there is little useful information on them. There is an MTF chart on only one of the lenses, the Apo-Sironar HR 60mm. But that MTF chart is VERY impressive. If that chart is true then this lens is the sharpest lens, period. It has an even better MTF curve than the Zeiss Planar 50/1.4 for the 35mm Contax cameras. And that lens is regarded by many as the sharpest ever.

But sadly, this lens or the other two from that HR series, the 35mm and 100mm are useless for me since their image circles are only 70mm. However I read that at the recent Photokina show they introduced two more lenses in the HR series. Does anyone know much about them? What their image circles are?

But the question remains about the MTF curves of the other lenses. Why did they not publish it in the brochures? Very frustrating.

Here is more confusion. In one brochure the Apo-Sironar Digital is listed has having 7 elements in 5 groups. Yet the other brochure says 8 elements in 6 groups. In one brochure the coverage for 90mm lens is shown as 140mm and in the other it is listed as 125mm.

Another confusing thing. There are 8 lenses in this series from 35mm all the way to 180mm. One would expect the image circle, weight and price to rise proportionally with the focal length as is the custom. But it does not! The 105mm (170g) weighs less than half as the 90mm (460g)! It also costs almost half as much! Why? The image circle for both is listed as 125mm. Image circles do rise with the focal lengths but not proportionally.

The bottom line. If the MTF curves of all the lenses are as good or even close to the one they print (the 60mm HR) then these are truly amazing lenses.

If only I could get more information on them!!!

-- Mike Foster (mike567@acgecorp.com), December 14, 2000

Answers

Bob Solomon of HP Marketing has sent me the MTF curves of all of the Apo-Sironar-Digital and Apo-Sironar-Digital HR lenses... on the other hand, I don't have the actual brochure, so I don't have any of the mechanical info such as weight, size, filter size, flange focal length, etc. I would love to swap info with you since I am also considering some of these lenses for roll film use. It is not yet clear to me that they will be worth the extra cost for most work. While they are clearly optimized to perform very well at wider apertures, such as f/8, by the time you get to f/11 - f/16 (a more typical aperture for roll film work) they aren't much better than the best LF lenses since, for the most part, both become diffraction limited. For example, I have been comparing the 55 Apo- Grandagon to the 55 Apo-Sironar-Digital. At f/11, the digital is slightly better at the corner (50mm off axis) but you lose a lot of image circle, 125mm vs 163mm. It's not clear that is a good trade-off since both lenses are probably better than most films at those apertures. By the way, for roll-film use, I love to see MTFs at 40 lp/mm for lenses. These data are available for the digital lenses, but not for most of the regular LF lenses. However, if you go to the Hasselblad web site (www.hasselblad.com) and check out ArcBody lenses, you can get these data for the 35 and 45 Apo-Grandagon, and the 75 f/4.5 Grandagon-N. And these data are impressive, particularly since they handily outperform most of the Zeiss wide angles (which are handicapped by the necessity of retro-focus design).

-- Glenn Kroeger (gkroeger@trinity.edu), December 14, 2000.

Mike: Not be outdone in the length of your question I now offer an appropriately lenghty answer to test your assertion these digital optics are amazing. In this, I used the very excellent data from Schneider for the Digitars, rather than Rodenstockís because I do not have it. I will use the Digitar 150 as a base. Digital lenses replace the old process lenses and their design reflects that. One of its limitations for landscape and architectural photography is their small IC which is given as 150mm. However, we canít infer that from the specs with complete certainty for applications other than for process work, since at the limit of the IC the MTF and illumination are extremely high, -more of that later. It may be that the ultra high standards set for digital work can not be maintained beyond the 150mm IC, while within the standards expected of the best plasmats, the IC rating would be much larger. This is something for the Schneider scientists to say; I do not know. This lens is clearly optimized for 1:8 magnification, as is obvious from studying the MTFs. As for the MTFs: The ones provided cover the range of 1:20 (which some manufacturers use as an approximation to infinity and 1:8 and 1:4. Within those ranges, they are provided for F5.6, F8 and F11. The MTFs at 1:20 indicate that diffraction limiting is still well away at F11.

Yes Mike, The MTFs are totally amazing and I say that for two reasons: a) at the edge of the IC, and at F11, and at 20 lines/mm, (the highest frequency normally used in LF lens data), the MTF response is close to 80%! -For the Sironar S of the same focal length and also at F11, it is 50% and 65% (radial / tangential) at the 75mm mark in the IC. Even more amazing, the radial and tangential responses for the Digitars almost overlap throughout the range! This indicates an extremely high level of correction. Thus, not only image contrast will be extremely high but resolution also, and both well above any attained by the best plasmats available today, bar none. In comparison, the Apo Symmarís response at 20 lines/pm at the same point in the IC, i.e. 75mm is about 65% at F22. For f5.6, the response is 50% for the Apo Symmar and 70% for the Digitar. Incidentally, for some reason, the Apo Symmar also exhibits almost overlapping response but only at 20 lines/mm. At 5 and 10 lines /mm, they diverge. Finally, the Digitarís response at 40 lines /mm is nearly the same to that of the Symmar at 20 lines / mm.

The lateral chromatic aberration is quite low for the Digitar, but I am not able to do a one to one comparison with the Symmar because the same data is not available for it. Geometric distortion is about the same for both lenses, i.e. negligible. Relative illumination for both lenses at 75mm from centre for both lenses is about 90% for both lenses.

From the foregoing, yes, the Digitars are certainly amazing lenses. However, we are in the wrong forum: the 150mm lens really doesnít belong here. With its limited IC (if indeed it is only 150mm) it belongs to Medium Format Forum. Sorry! PS: Glen, I think you misread the frequencies in your comparisons with plasmats.

-- Julio Fernandez (gluemax@ora.auracom.com), December 15, 2000.


Julio: I didn't misread the frequencies, nor did I compare with plasmat design... the Apo-Grandagon is not a plasmat design, and the comparison I mentioned was a 20 lp/mm. I did refer to 40 lp/mm a desirable data, which I have for the digital lenses, and some LF lenses, but not for the 55 Apo-Grandagon.

-- Glenn Kroeger (gkroeger@trinity.edu), December 15, 2000.

Julio's analysis shows that the digital lenses clearly perform better at wider apertures than even the best standard LF lenses. Given their smaller ICs, we are clearly talking about roll-film use only, which was the topic of Mike's original post. My concerns with the digital lenses are 1) that even for roll-film use, the ICs are a bit limiting, and 2) in field work, I am usually at f/16-f/22. At these apertures, the differences are less striking since both lenses tend to become diffraction limited, at least for 20 lp/mm. So I think there remains a practical question about the advantages of these lenses for roll-film work given the externalities of actual working f- stops, film flatness, focusing accuracy, etc. Would there be actual visible advantages that are worth the approximately 60% price premium on the digital lenses? I am attempting to answer that with a controlled field test.

By the way, Bob Solomon of HP Marketing has informed me that the abrupt cutoff of the MTFs at the edge of the IC is a mechanical limitation in the Apo-Sironar-Digital series, so that might also be the case for the Schneider Digitar lenses.

-- Glenn Kroeger (gkroeger@trinity.edu), December 15, 2000.


Just an admin remark: Julio, this forum is open to discussion of MF cameras as long as they operate like larger view/field cameras (ie with ground glass viewing and movements). There isn't much difference between working with such a camera, and working with an LF camera, certainly less than with a rigid MF.

-- Q.-Tuan Luong (qtl@ai.sri.com), December 15, 2000.


Glen: Bob S's info about the mechanical cut-off is good to know, thanks for sharing the info.

As to whether the Digitars do perform better at larger apertures than even the best standard lenses, I am not sure that is quite the case. I had only up to f/11 Schneider data, and could not refer to smaller apertures. The MTFís provided for the 150 and 120mm lenses do indicate that peak performance at centre is reached with the Digitar at f/8, (because of a slight decrease from 85% to about 82% at f/11. For the Sironar S 150mm, MTF at centre is 82%, at f/11, thus both lenses are in fact equally capable at centre, at F11 and 20 lines/mm. One of the problems is that we do not know the performance of the Digitars at smaller apertures, or that of the Sironar S at larger frequencies. The sure difference remains the higher degree of correction of the Digitars, which from centre to edge is remarkably high and more consistent. Additionally, the Digitarís performance at 40 lines/mm is quite high and about par with the better 50mm lenses, which of course have more limited coverage. I do not know of course how the Sironar would perform at 40 or 60 lines/mm, for which there is data available for the Digitar.

Film flatness is indeed an issue with LF as with MF. Additionally, groundglass calibration, which many photographers seem to take for granted from what I have read, would be also paramount to attaining the full excellence of Digitars. Of course, focusing accuracy and film flatness are issues with film, nor with digital film backs. Incidentally, and I am a little puzzled as to how you intend to do a controlled test, which presumably would have to include control of film flatness. Perhaps you are aware that Zeiss has recently carried out a lengthy study involving specialized instrumentation for measuring and determining factors contributing to film flatness. As I recall, their work indicated that camera back brands and types had some bearing, and that 220 roll film was the definitive choice over 120. Finally, yes, there is the money issue. Are these things really worth 60% more than a Sironar S? I am waiting for your tests; do tell us.

-- Julio Fernandez (gluemax@ora.auracom.com), December 16, 2000.


Julio: Yes, I saw the Zeiss results on 120 vs. 220, although I noted that they felt that the differences were gone by f/8 or f/11, so typical view camera work, it's not clear if the hassles of 220 (limited availability and more prone to edge fogging) are worth it. What I hope to do is shoot a Digitar and Apo-Symmar side by side. I will have to rely on shooting several frames of each (skipping frames to prevent film bulge!) and see if there are any systematic differences. Since my question is whether there are systematic differences in real world conditions, the test should be valid for that question (not whether in an absolute optical sense the Digitars are better).

-- Glenn Kroeger (gkroeger@trinity.edu), December 16, 2000.

Hello All. For those interested, Zeiss has an interesting article on digital lenses in their Camera Lens News, No 9, 200 Edition. this is available from http://www.zeiss.de

-- Julio Fernandez (gluemax@ora.auracom.com), December 17, 2000.

Julio, thanks for suggesting this article on the film flatness test. I had realized my 6x12 were sharper on 220 than on 120 but when I mentioned it, feedback came that it should be otherwise. Nevertheless, I have used almost exclusively 220 film in my rollfilm backs for years and the results are excellent. I know there are or have been fogging problems with the Kodak films, as Glen suggests, but the Fuji's are perfectly light proof. The weak point with 220 is that some processing laboratories are not equipped to process them properly. Instead, they have to make extra loops on standard 120 equippment. I had many 220 misprocessed until my lab finally decided to invest in the proper equippment. Since, everything is well.

Here is the link to Zeiss page: http://www.zeiss.de/de/photo/home_e.nsf/allBySubject/Launch+-+Zeiss-engl+NotesTemplate

-- Paul Schilliger (pschilliger@smile.ch), December 17, 2000.


Paul,

Which roll film back do you use for 6x12? I thought that 6x12 backs did not work with 220 roll film.

Thanks.

-- Mike Foster (mike567@acgecorp.com), December 17, 2000.



Mike, I use to have a Calumet C12, awful with 120 but alright with 220 (the back had mechanical flaws as well). I have now two Sinar backs. They all take both 120 and 220. Thinking of what has been said before on constraints and bend, the Calumet had rollers of only about 6 mm in diameter but the Sinar rollers are about 15. Unfortunately the Sinar backs are expensive. I bought first one used and after using it for a while decided it was worth investing in a new one too. So I have a medium and a high contrast film at hand. I don't know if the Horseman and Linhof take both formats or not.

-- Paul Schilliger (pschilliger@smile.ch), December 17, 2000.

Paul,

Since you are in Switzerland (I presume) the Sinar backs must have been cheap for you. How much are they over there? It is the "Zoom 2" you have? That seems like the untilmate back but its like $3000 over here!

Which films do you use? I am curious, which is the low constrast and the high contrast???

Thanks.

-- Mike Foster (mike567@acgecorp.com), December 17, 2000.


Mike, I received some precisions from Bob Salomon on Linhof rollfilm backs:

"Linhof panoramic cameras in 612 and 617 as well as the Linhof techno Rolex 612 back shoot 220 film. The back requires a different film holder. Unlike Sinar and others Linhof's 612 is 56 x120mm rather then 56x111 or 112 like Sinar's."

Everything made by Linhof is highly dependable. The Rapid Rollex insert backs are only available as 6x7 and 6x9. The Techno Rollex 6x12 requires unmounting the spring back. The Sinar backs are of course cheaper by some 40% here, but the best prices, I have been told, are from Robert White in England. The Zoom 2 is the best back available. I would not recommend the Zoom 1 but the previous Vario in it's latest design was fine too.

I think there is also a Toyo 6x12 that some photographers use successfully. I am not sure but I think it can be inserted in some spring backs.

-- Paul Schilliger (pschilliger@smile.ch), December 18, 2000.


Forgot: I use mostly Velvia and a lower contrast film (has been Astia but I now might use Provia 3F more and more).

-- Paul Schilliger (pschilliger@smile.ch), December 18, 2000.

Just to clarify Paul's post, which could possibly confuse someone about Linhof 617 film choices. He references this information:

"Linhof panoramic cameras in 612 and 617 as well as the Linhof techno Rolex 612 back shoot 220 film. The back requires a different film holder. Unlike Sinar and others Linhof's 612 is 56 x120mm rather then 56x111 or 112 like Sinar's."

I have a Linhof Technorama 617 S III, and it shoots 120 OR 220 film by rotating a pressure plate for the film type. The actual on-film image is 56 X 171 millimeters, as measured by a ruler. I've onlyl shot 120 with it however.

-- lloyd chambers (photo@llc4.com), December 18, 2000.



Thanks Lloyd! I just passed the information through without thinking too much at it.

-- Paul Schilliger (pschilliger@smile.ch), December 18, 2000.

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