IQ of digitar lenses on 6x7 film back versus film lenses

[Weihan]

Has anyone ever compared the IQ of shots taken with a view camera + a 6x7 / 6x9 FILM back using a Schneider or Rodenstock digital lens versus a 4x5 film image shot with a traditional analog lens? I'd be interested in seeing the results or in reading about the assessment of the differences. I'm sure the digital lens will have a much higher resolution on the film, but does this result in an overall better IQ when compared to the overall better tonality of a 4x5 image? I imagine film flatness might play a significant role. Please note: I'm not interested in the result of a digital image on a digital back but rather solely in the film results. THANKS!

[paulr]

I haven't. We can assume the lenses are in a whole other category of sharpness and resolution ... you just have to compare the same manufacturer's MTF curves between the product lines. It should make a big difference at big enlargements, if you can manage focus accuracy, etc. etc..

But!! I don't know if any of these lenses will even cover 6x7. Many of them won't. It's a big butt.

[Bob Salomon]

I haven't. We can assume the lenses are in a whole other category of sharpness and resolution ... you just have to compare the same manufacturer's MTF curves between the product lines. It should make a big difference at big enlargements, if you can manage focus accuracy, etc. etc..

But!! I don't know if any of these lenses will even cover 6x7. Many of them won't. It's a big butt.

Most of the Rodenstock ones have image circles of 120 to 150mm so they will cover most roll formats with no problem.
But be aware, The Rodenstock HR Digaron-S series and the former Rodenstock Apo Sironar Digital HR lenses require a correction plate mounted to the rear of the lens if these lenses are used with film. This is because the last element in the formula of these lenses is the cover glass over the sensor on digital backs. If the corrector plate is not used then the image will be slightly out of focus on film.

The Rodenstock HR Digaron-W and the Rodenstock Apo Sironar Digital and the Apo Macro Sironar Digital lenses do not need a corrector plate for use with film.

The new Rodenstock 90mm HR Digaron SW will probably not require a corrector plate and one has not been announced yet. This lens replaced the 90mm HR Digaron-W which is no longer manufactured.

[Weihan]

This is very helpful info. Do you know if there is any feedback on the IQ from users who've actually employed the lenses with rollfilm backs and how the IQ might compare with 4x5 film + analog lens? Schneider also offers the Schneider 120mm f/5.6 Apo Digitar N Lens w/ Copal #0 Shutter with a state 120mm i.c. that will cover up to 6x9 if I'm not mistaken.

[Bob Salomon]

This is very helpful info. Do you know if there is any feedback on the IQ from users who've actually employed the lenses with rollfilm backs and how the IQ might compare with 4x5 film + analog lens? Schneider also offers the Schneider 120mm f/5.6 Apo Digitar N Lens w/ Copal #0 Shutter with a state 120mm i.c. that will cover up to 6x9 if I'm not mistaken.

Not really. We do know that MIT bought the HR Digaron S Rodenstock for a film project but they have never told us if they had any problems with it for this purpose. I am sure that we would have heard if they did have a problem or if it was not performing to stated specs.

Since we are the distributor for Rodenstock and not a retailer for Rodenstock (we sell them to camera stores) we do not always know what purpose the retail purchasor bought the lenses for.

[Weihan]

This sounds very exciting. Thanks a million for all the information. If you do eventually get feedback from the MIT project, it would be great to hear about it second-hand, assuming there's no breach in confidentiality.

[Weihan]

For Paulr: Some of these newer Rodenstock and Schneider digital lenses will cover up to 6x9 film (see Bob Salomon's information above), so my guess that the most critical component would be actual film flatness. One would need to do the utmost possible to achieve that, so my guess that a great deal would really depend on the quality of the rollfilm back being used.

[paulr]

Bob, I'm looking at my Rodenstock datasheet for Digaron S and W lenses. Have the lenses been updated? The diagonal for 6x7 is 92mm. The only lenses listed that will cover that (with minimal movements) are the 70 and 90 HR Diraraon Ws. The sheet I have is called e_Rodenstock_Digital_Lenses_3-26__8236.pdf

What does the corrector plate correct for?

[Nathan Potter]

I'm also interested in the answer to Pauls question and additionally; where exactly in the image side of the lens does the corrector need to be. In other words does it need to be located directly in front of the film as it is on most sensors or can it be close to the rear element?

Nate Potter, Austin TX.

[Bob Salomon]

I'm also interested in the answer to Pauls question and additionally; where exactly in the image side of the lens does the corrector need to be. In other words does it need to be located directly in front of the film as it is on most sensors or can it be close to the rear element?

Nate Potter, Austin TX.

It screws into the rear of the lens.