PDA

View Full Version : Apo Sironar N 240 mm

giorgio.lanz
2-Apr-2007, 15:07
I plan to use may Apo – Sironar N 240 mm that normally I use for the 4 x 5 on a 8 x 10 camera.
From the technical spec. I know that the 240 mm cover just the 8 x 10 with more o less half a inch for movement at f : 22 and is not Recommended for the 8 x 10. But was happen at f : 45 ad example and for distance less of infinity ? Any experience ?

Thanks

Giorgio

Ron Marshall
2-Apr-2007, 15:13
The 240mm APO Sironar N covers 350mm at f22, enough for some movements.

If you stop down more and focus closer than infinity you will increase that a bit.

giorgio.lanz
3-Apr-2007, 00:08
Thanks a lot for the help!

Is it possible to calculate the image circle at the different f stop and focus distance knowing the Angle of view and the image circle at f : 22 ? In other word is simple a matter of some math. or is a matter of how the lens is built.

Sorry for may English.

Giorgio

Bob Salomon
3-Apr-2007, 06:15
The image circle as someone else stated for this lens at infinity at f22 is 350mm. This is not "some movement" It is 28mm of rise and 23 mm of shift when the back is in portrait or horizontal position. Both are well over a half inch which is 12.52mm.

Bob Salomon
3-Apr-2007, 06:16
The image circle as someone else stated for this lens at infinity at f22 is 350mm. This is not "some movement" It is 28mm of rise and 23 mm of shift when the back is in portrait or horizontal position. Both are well over a half inch which is 12.52mm.

It looks like your half inch figure is from the 210N when used with 18 x 24cm film.

giorgio.lanz
3-Apr-2007, 09:07
Bob you are right.

It was may mistake . I read right the technical specification but I do a mistake in the translation from mm to inch.

I was really concern about a “reduction” in the image circle stopping dawn or focusing at short distance.

Thanks

JJ Viau
3-Apr-2007, 09:13
Hello Giorgio,
I planned to use this lens with 8x10" but the image circle proved to narrow for me in most conditions (you have some amount of rise but rise and swing at some distance for example is critical)...but I do use movements quite a bit, I consider the N 300mm being the minimum and cannot live with a 75&#176; 150mm lens on 4x5" for example.