360mm Symmar-S

I am starting to learn to use the 360mm Symmar-S lens (what a heavy beast it is too!) on my 8x10 camera (an old Ansco) and need some advice on a couple of things:

What would be the optimum aperature for this lens - is the same prinicple as with 35mm lenses and you should stop down atleast two stops from wide open?

And what is the smallest workable aperature to maximise depth of field before diffraction problems kick in?

Any advice most gratefully received - thank you!

(also, on a tagent - I am the only person who feels a bit self conscious getting the 8x10 camera in public? I don't have problems with my little 35mm cameras but so far with the 8x10 I have only plucked up the courage to use it in my mother-in-law's garden!! Hope this changes with experience)

Paul, the handy-dandy generally accepted rule of thumb is that diffraction limits resolution in line pairs/mm on film to 1500/n, where n is the f/number. 5.6, 8, ... f/number to get at least resolution r on film is then n = 1500/r.

To get a good print you'll need 8 lp/mm on print. So if you know how much you're going to enlarge your 8x10 negative, you can easily work out the smallest aperture you can use without losing image quality to diffraction. If all you'll do is contact print, you'll need 8 lp/mm on film and want to use an aperture no smaller than 1500/8 = f/180 or so. At that small an aperture, though, you may lose image quality to movement, camera or subject. There are always compromises ...

Hello Paul,

I have the 360 Symmar-S, too, and have found f/16 to f/45 to be its sweet spot. That said, though, for 8x10 I've never worried about sharpness loss from diffraction limits or the like. If I need to stop down to f/64 to get the DOF I want, I won't hesitate to use it.

Yes, the 360 SS is heavy--front element about the size of a small dinner plate--but IMO few lenses match it for the type of image it draws on the film. And, no, I don't feel self conscious using this large camera in public. On the contrary, I've had many people approach me asking questions about this "old" camera I use; even back about 25 years ago when my 8x10 camera was brand spanking new!

My advice: just get out and make some images...don't worry about others, except to keep your wits about you, of course.

Thank you Dan and Alan, very useful information. Now to get shooting in the great outdoors!!