Red Robin
It Is What It Is
Do I need to shim a Jupiter 12 lens to get proper focus with a Canon III or P range finder?
J-12 Lenses with Canons
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jmcd
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Whether or not you need to shim will depend, I think, on the particular lens. My J-12 focuses fine at f2.8.
However, on the P I had, the rear element was just too wide to fit between the light baffles.
However, on the P I had, the rear element was just too wide to fit between the light baffles.
Mablo
Well-known
There seems to be at least two different varieties of J-12 in regards to the rear element. Some people say the newer variety (black) fits in the P and I can corroborate that with the 3 P bodies I had. An early chrome J-12 didn't fit in but a later black J-12 did, but only barely. Beware of the light baffles inside the P body when you screw the J-12 in place.
Cannot really comment on Canon III but I'd assume the J-12 fits in nicely.
I don't think you need to shim the J-12 for Canon bodies. A 35mm lens has enough DOF that will take care of any small focus irregularities in my opinion. Besides, J-12 fully open is pretty soft so you'd be hard pressed to see any improvement through shimming anyway. A 50mm lens like J-3 is a different matter and definitely needs shimming. J-9 is almost hopeless to get right in my opinion.
Cannot really comment on Canon III but I'd assume the J-12 fits in nicely.
I don't think you need to shim the J-12 for Canon bodies. A 35mm lens has enough DOF that will take care of any small focus irregularities in my opinion. Besides, J-12 fully open is pretty soft so you'd be hard pressed to see any improvement through shimming anyway. A 50mm lens like J-3 is a different matter and definitely needs shimming. J-9 is almost hopeless to get right in my opinion.
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