Loss of quality using 8x10 lenses for 6x9?

[m.bruehl]

Hi everybody,
today I'm taking pictures 4x5, and I also use roll film backs 6x9 and 6x7. As I plan to upgrade to 8x10, I am looking for replacement for my 4x5 lenses, that don't cover 8x10.
Do I have to expect a loss of quality if I use 8x10 lenses with my roll film backs?
Regards

Michael

[IanG]

That will depend entirely on the lens.

Undoubtedly older lenses designed for 10x8 won't have been built to the same tolerances as lenses for smaller formats, but with modern lenses you'd need to run a test and see.

A 240mm Symmar or Sironar would be superb on any format. But would a 165mm SA be as good as a 150mm Symmar.Sironar on smaller formats, it probably wouldn't even fit.

There will only be a few lenses you can use on 10x8, 5x4 & 6x9.

Ian

[John Berry]

If you are talking about a 90 4x5 vs 90 6x9, like quality might be hard pressed to see a difference in an 8x10 print. If you are talking about using long lenses on 6x9 remember larger circles of confusion will apply. Think along the lines of about 4x enlargement from an 8x10 neg, cut your print out of that. If you can hang with that, you in the good. I have shot my 24" red dot on 6x9 and have not been disappointed. You might give a little more thought about what the optimum stop would be before diffraction comes into play. I remember Sandy king using a program that would give the optimum f stop before diffraction, with the format, lens, and print size info entered.
It was part of the BTZS program, if I remember right. ( don't bet your retirement on my opinion though )

[Brian K]

Why not just test your lenses and see which perform well with 6x9cm film?

[Dan Fromm]

As everyone has said, it depends on the lens. FWIW, I use some process lenses (Apo Nikkors, Apo Saphir) that cover 8x10 on my 2x3 Graphics and they're fine, just fine.

[Walter Calahan]

Only you will know 'cause we can tell you how your tools will work with your personal vision.

[Ken Lee]

It has been said that the human eye can resolve around 8 lines per mm. That's when someone really strains to read a test target, I presume.

A really good Medium Format lens of modern design might get up to 80-100 lines per mm at best aperture, allowing a 10x enlargement or more. The average viewer is not going to step up to the image and count tiny lines, if you know what I mean. So larger prints are possible in many cases.

Very good lenses for 8x10 will get somewhere around 60% of that resolution in the center of the lens coverage. This suggests that you can enlarge around 6 to 8x and still retain critical sharpness. More so, if the subject is not a test target, or other finely detailed item.

I have made many lovely 11x14 prints from my 1950's Agfa 6x9 folding cameras, whose simple Tessar-style lenses are of moderate quality at their best. As long as I choose my subject-matter appropriately, the images sharp enough even for my Large Format eye. Normal people never have never complained about lack of detail in these photos. Since they are used to digital and small format quality, they marvel at the smoothness.

[Chuck Pere]

Are you planning to only use long lenses with the roll back? Not sure many 65-100mm lenses cover 8x10 except some very special ones. Also you might want to use a lens shade to cut off excess coverage to keep reflections down.

[eddie]

are you planningt o sell all your 4x5 lenses and only use 8x10 stuff? will you stop shooting 4x5? i ask becasue you could still keep your best 4x5 lenses and when you shoot roll film or 4x5 on your 8x10 camera you could just use those lenses.

personally i would keep a small 4x5 for when it is needed. it is much easier to carry around and use a 4x5....but you already knew that.

eddie

[David A. Goldfarb]

Lenses that cover 8x10" are often in larger shutters than lenses that cover 4x5", and they have lots of excess coverage, so while they can be handy for, say, architectural subjects requiring lots of front rise, they also are more prone to bellows flare on a small camera, so they are best used with a compendium shade.

I've got a few lenses that I use on both 4x5" and 8x10" (and larger), but even though I have lenses of similar focal length for both, I often stick to the 4x5" lenses for 4x5" and smaller.