Posts from international forums suggest that there are severe limitations to using traditional LF lenses with Digital Backs. Have any forum participants tested different options and identified top performers for digital capture?
Posts from international forums suggest that there are severe limitations to using traditional LF lenses with Digital Backs. Have any forum participants tested different options and identified top performers for digital capture?
A guy I've assisted for has had great results with his APO-Symmar 150mm, and also with a 135mm APO-Sironar S.
Not as "sharp" as the digital-designed lenses of similar focal-length's, but the added image circle is the primary reason for using them vs the digital-designed ones.
-Dan
Thanks for the input Dan. Very helpful.
I'd be interested to know more about this. I assumed sharpness was sharpness, and that a lens would act the same regardless of what it was projecting onto. How is a lens designed differently for digital?
Garrett
flickr galleries
One can find technical information offered both by Rodenstock and Schneider. I have found two Eurozone blog sites with pros who offer made-for-digital lens suggestions, and their experience with various newer products. It appears that most of these lenses have radical reduction of lateral chromatic aberation, very strictive movements, and with maximum useful apertures of F11.
I had hoped to find a silverbullet series of well corrected traditional lenses which could serve the purpose. From what I have read, many suffer from color fringing and strange color streaking when movements are used. I am not well versed to offer any technical information.
Your assumption seems reasonable, but in fact, is very, very wrong.Originally Posted by goamules
The Rodenstock HR series of lenses, and some of the Schneider Digitar lenses are the sharpest lenses available to normal people like us, but don't expect to shoot 4x5 with them.
They make the best 4x5 lenses look like soda bottles. The APO-Symmars and Sironar-S lenses should perform okay, but the digital lenses are designed to be at their best at large apertures (f/4-f/11), which is optimum when you're shooting digital.
Shoot the film lenses wide open with digital, and you're in Chromatic Abberation city. The digital lenses have NONE.
Actually some of the Digitars will cover 4x5, like the 120mm, even though the documentation says it doesn't, but the Rodenstocks have much smaller image circles for the most part.
https://www.schneideroptics.com/pdfs/Digitar.pdf
The digital lenses are also designed to have high MTF at spatial frequencies more appropriate to digital sensors, to provide a stronger edge effect for edges that will be resolved by the sensor.
And they come in short focal lengths needed by the small sensors (small when compared with sheet film), which requires a bit of retrofocus design to for mechanical convenience and to minimize fall-off, which is a bigger problem with sensors that have deep wells for the sensor sites.
They take advantage of the low-dispersion glass and possible aspheric designs, which are common in higher-end small-format lenses but have not been common in large-format lenses. And they give up coverage.
All that said, a conventional large-format lens that will provide 8x enlargement at a given quality with film will provide 8x enlargement at the same quality with a digital back, not counting the effects of the film and the sensor. When the sensor is no bigger than 645 medium format, though, larger enlargement ratios will be needed to make prints of a given size, and thus more demands are made on the lenses. A 16x20 print that only requires a 4x enlargement with 4x5 will require an 8x enlargement with the bigger digital backs (not including the scanning backs, which are truly large format). Lens faults will get enlarged twice as much.
Also because of the greater enlargement ratios, diffraction will get enlarged twice as much, and so the lens will be used at a larger aperture, which places additional demands on lens performance.
And one final psychological difference. When making a photo on film, one views the negative on a light table with perhaps a 4x loupe, and maybe a 10x loupe to check focus. Then, one looks at the enlarged image at print size. Then, digital cameras came out and we started looking at images on computer monitors with a 1:1 relationship between sensels and pixels. That is often some significant multiple of any useful print size. Lens flaws that would never have bothered us at print size glowed in the dark at actual pixels on a computer monitor. When I bought my first digital camera, I immediately felt the need to replace my lenses. And as we demand better and better lenses (meaning we're willing to pay more and more), digital sensors get denser and denser, and so we are looking at them on the computer monitor at higher and higher enlargement ratios that are less realistic than ever of any print we might actually make. Digital cameras sell lenses.
Rick "noting the fabulously high prices of high-end small-format lenses that have had to improve greatly for all the same reasons" Denney
What about a modern apo ronar 150mm and 240mm in shutter. They are very sharp and well corrected, and seem sharp even wide open at f9. I think my 240mm ronar is sharper than my 210 sironar s, specially wide open and closer than infinity. Probably dark on a tiny groundglass though. There is a 100mm Sironar N for sale on the FS board for a very reasonable price, it should be the equal of most anything.
David Cary
www.milfordguide.nz
You'd have to do a test for yourself to find out if a Sironar N is optimum with digital, vs. digital lenses.
However, the smallest aperture I would shoot with a 645 or 36x48mm sensor is f/8. Are you telling me that a Sironar N shot wide open, or at f/8 will give me optimum sharpness and be free of chromatic abberation with an 80MP sensor with rather small pixels?
Don't think so...
You must be shooting flat test targets. The three-dimensions subjects I shoot need more depth of field than f/8 provides.
Rick "who'll take diffraction over grossly unfocused any day" Denney
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