5x7 facts considering Super-Symmar 80XL

[Paul Schilliger]

I wonder what the "real" image circle for this lens is and if it can be used with 5x7 cameras with minimum shift possibility. The published image circle for this lens is 210mm at f22, which barely covers, but knowing that there is sometimes a margin of possible image but with poorer performance before the dark corners hit, I thought I would ask if someone knows. Has someone experimented? I actually have the Super-Angulon, a fine lens and perhaps better for me by it's focal too, but I'm still considering replacing it to make room in my pack for another lens...

[Eric Woodbury]

I use 57 and although I'm not familiar with the 80xl, I do have a SA 72 xl. It covers 57 with room to spare and there isn't anything wider. Then the next lens up that I have is the SS 110mm.

As far as covering 57, unless you're 'weird' about using the whole negative, printing the notches and all, then use as the image circle as is and crop if need be.

[Julio Fernandez]

Paul: At a 212 mm image circle and 20 L/mm the MTFs for this lens are only 20 and 5, quite low to resolve well 20 L/mm detail in the subject. This is the point where according to Schneider, the IC has reached its limit, i.e. 212 mm. (106 mm from center). If on the other hand the photographer is willing to make compromises and settle for a spatial frequency of only 5 L/mm, an IC of 230 mm appears reasonable as can be seen by extrapolating by eye the 5 L/mm curves to 120% of image height. Thus, at 230 mm the MTFs for the 5 L/mm detail are about 40 and 60 quite enough contrast to resolve 5L/mm detail. If you are happy with resolving only 5 L/mm, yes you have a little extra leeway and 230 mm is then a reasonable IC.

It is obvious from the data that Schneider calculated the IC for this lens from the MTFs. Their definition being that at the the IC is reached when one of the MTFs approaches zero for the 20 L/mm spatial frequency. At that point, the lens can barely render any detail at that spatial frequency. Obviously, reducing the spatial frequency requirement from 20L/mm to only 5 results in a larger IC but the question then is if the imaging quality of the lens at the edges will be acceptable. On 5X7, 230 mm may be a reasonable IC since for this format the spatial frequency requirements are only about 1/2 thus for 4X5, so , 5L/mm in 5X7 will be equivalent to 10 L/mm in 4X5. Even this more liberal interpretation of the IC will give you only very little room for movements but yes, it should be possible to do 5X7 with this lens given the stated limitations.

[heidis]

Paul - I haven't used the 80XL with 5x7, but I would be very hesitant to try it. My 4x5 has 42mm rise capability, and the 80XL is the only lens with which I regularly run out of image circle before I run out of physical rise capability when shooting verticals. It will produce very noticeable dark corners (i.e. solid black, not just a bit dark) if I give it too much rise. I suspect that you'd get little if any room for movements with 5x7.

I'd strongly suggest a 72XL instead; yes, it's much larger and requires 95mm filters, but it has room for lots of movement and covers 5x7 with ease.

Regards,

[Paul Schilliger]

Julio, I see what you mean. I just have to think of what the corners of my 65mm look like on 4x5 with some movement.

As for the 72XL, I'm sure it would be a better choice. But then, maybe I should just stick to the 90mm, already a very wide lens on 5x7, forget the smaller lens and place the money in the box for the Ultrachrome printer! Thanks!