Jupiter 21M: Grinding my way to infinity

[tietze]

I've been a little disappointed with the sharpness of my Jupiter 21M, so I thought - maybe something is up with the distance between sensor and lens. So I started grinding.

My question is - should I continue to grind my adapter down until I achieve infinity or should I stop the pixel-peeking madness?

Initial position lens/adapter:


Example photo at infinity F4 (not 100% crop):


Current position lens/adapter:


Example photo at infinity F4 (not 100% crop):

[rafa1981]

In the second pic the focus is further away, so it looks like it's working. If you are interested in infinity sharpness at that aperture you should continue grinding the adapter.

You can adjust the lens infinity instead too, or meaybe it would be more time effective to just order a new adapter in case that this particular lens is correctly adjusted.

[tietze]

I think it is the lens - but still I'm using cheap adapters, so it wont be a disaster if the adapter end up being unusable or only usable for the Jupiter Lens.

Just for comparison here is an example of F4/infinity at 100% crop with my Volna-9 50mm:


I would have expected more IQ from the Jupiter, so I'll try to see how much more material is to be removed with the adapter still usable

In the first grinding cited above about 0,6mm was removed.

[Pancolart]

Something is wrong with Jupiter. Lens should be closer to infinity in original state. You can test adapter with other lenses and you show Volna combo is fine thus...