Lense Differences

[A Brown]

Can someone please clarify for me the differences between the Schneider APO Symmar and APO Digitar lenses?

Likewise, what are the differences between the Rodenstock APO Sironar lenses (N Series and/or S Series) and the APO Sironar Digital lenses?

We will be moving to a digital scanning back setup (Betterlight or Phase One) for copywork and artwork reproduction and I am trying to determine the differences between these lenses and which one would best meet our needs

[Mike Chini]

Be careful when using the Rodenstock Sironar digital lenses. They can get very soft from f16 down. The Schneider digital lenses are much better at stopping down. As far as I know, the digital lenses were designed to be used in new digital shutters so they can be controlled using specialized software from Leaf, Jenoptik etc. but can do so at the expense of DOF. I'd suggest staying with the regular lenses.

[Ole Tjugen]

Digitar lenses were made for digital recording technology, which has very different needs compared to film. While both types of lenses can be used for both purposes, the optimum specificatoins are different enough that most major manufacturers have found it worthwhile making special lenses for digital photography.

[paulr]

"They can get very soft from f16 down"

I'd be curious to hear an explanation for this ... how one lens can experience more diffraction than another. or if there's something very odd going on.

[Mike Chini]

Paul-

I know this only from experience. I've been working with medium format digital backs on view cameras for almost 2 years and anything past f16 on the Rodenstock digital lenses is soft. I can't offer you a technical reason for this but ask any Phase One, Leaf, Eyelike (etc.) rep and they might know why. Most people I know that use the high end backs now simply use a traditional camera set-up and simply control everything manually because of this.

[paulr]

Mike,
have you tried the same backs with regular lenses (ones made for film)?
It makes me wonder if the phenomenon has to do with the lens, or with something about the angle of light hitting the ccds at different apertures (not that I have any idea what would be about, exactly).

[Emmanuel BIGLER]

anything past f16 on the Rodenstock digital lenses is soft.

Which focal length did you use with those 'digital' lenses ? Which enlargement ratio with respect to the initial "silicon" image ?

I ask the question because if the lenses were of short focal length designed for a small one-shot sensor of size, say 4.5x6 cm, stopping down at f/16 delivers the same visual diffraction softening effect, when enlarged 2X than a conventional lens of twice the focal length and stopped at f/32 but with 1X view.

Now if side by side, two lenses, a conventional 'film' one and a 'digital' of exactly same focal length used on the same sensor exhibit very different image quality at f/16, then we have to look for another phenomenon.

[Bob Salomon]

Rodenstock makes two series of digital lenses:

The Apo Sironar Digital from 35mm up to 180mm.

The Apo Sironar Digital HR from 35mm to 100 mm.

Which series was Mike using?

Every piece of literature published about these lenses from t factory states clearly that the best performance is at f8 to f11. These type of lenses are clearly in diffraction at f16.

To use the HR series with a film camera a very thin corrector plate must be attached to the rear element as the glass cover of the sensor on digital backs is part of the lens formula on the HR. This is not so on the non HR digital Rodenstock lenses.

[Mike Chini]

The lenses we used were the 55 and 105 (non-HR). Both performed almost identically and we had the proper mounting plates for the backs we were using. They were wonderful lenses but just couldn't be used for commercial still-life work past 16 and as Bob stated, they performed best around f11. I could not tell you much about comparisons since we never made any but we've gotten MUCH sharper results with the new Canon 1Ds mk 2 lenses although the overall quality is obviously much better with the 22MP backs.