Rodenstock APO Sironar digital vs. Apo-Sironar digital HR.

[jerry2]

I am trying to figure out the difference between the above two

lenses. From the Rodenstock site....

 

The Rodenstock Apo-Sironar digital HR was developed for special

applications with extremely high resolution CCD chip cameras and CCD

line scanner cameras with pixel sizes of < 10 ìm such as can only be

realized with smaller digital camera formats.

 

So does this mean the HR will produce sharper images using

film vs. the non HR digital lenses? How much sharper are these

lenses on film vs. modern non digital LF lenses?

[per_volquartz1]

My guess (and thats all it is) would be that these lenses are extremely sharp. My second guess would be that they have a much smaller angle of coverage as digital chips (even for large format photography) are still quite small!

[kelly_flanigan1]

The digital lenses are good for film and digital sensors. <BR><BR>When TV video cameras evolved; it was found that some movie camera lenses were better than others on the "new" video cameras; even when both lenses tested high on 1951 USAF resolution charts. Electronic Engineers at the pre IEEE society started developing MTF testing; which now is used on still camera lenses also. A sensor has a certain physical size to its elements; unlike film that accepts a wide range of spacial frequencies. Video camera lenses were developed to have high contrast at for video camera sensors. <BR><BR>Today with the new digital craze; lenses are now designed specifically for digital sensors. Here is some more <a href="http://www.phootos.com/dig_lens.htm">info/</a> .

[kelly_flanigan1]

The "color fringe" that happens with a digital camera system is greatly reduced by a "digital lens". A standard lens may or may not work well; the sensor element pitch varies; plus the subject matter. Some combinations of lens/sensor/subject produce horrid results; the digital lens is a good attempt to greatly reduce these weird effects. I saw a digital back in use on a process camera in 1996; they used a APO Ronar. I saw no weird "color fringes" with their settup; maybe the sensor pitch was huge and it masked the effect.

[pete_andrews]

A cynic might say that adding the 'digital' tag to a lens is simply a ploy by an old established company to try and break new markets, when their traditional ones are dying, and in the face of stiff competition. That's what a cynic might say.<br>BTW a 10 micron 'pixel' size is NOT high resolution. It's only equivalent to 50 lppm, which ain't exactly breaking a sweat for any decent lens.<p>As Kelly has said, the real difference is in the MTF characteristic of these lenses, which is tailored to the contrast demands of digital sensors, rather than to sheer resolution figures.

[bob_salomon]

The HR lenses cover a 70mm circle and are for cameras with very small pixel

sizes or ones that do micro scanning.

 

The Apo Sironar Digital have image circles at least twice as large - depending

on the focal length.

There are only 3 HR lenses 35, 60, 100mm. There are many more in the Apo

Digital series from 35 to 180mm and a macro.

 

As for use with film the HR series uses the glass plate that covers a digital

sensor as part of the optical system. Film does not have this glass plate so the

image would not be as sharp as on digital devices unles you add a 0.5mm

thick corrector plate to the rear element of the HR series. At this time

Rodenstock has not released this corrector plate.

[kelly_flanigan1]

Bob; is the glass plate to keep the sensor nice and tidy; to keep dust off the sensor elements?

[bob_salomon]

Digital sensors have a glass plate on them. Film does not. Without the added

glass plate the image will not lie on the film plane when using film.

 

The glass plate is the final element in the lens design