120mm vs 150mm on tech camera

[Kevin Sink]

I need a longer focal length lens for my ARCA Rm3di, and am requesting a recommendation for the 120 to 150mm range.  Any feedback on the sharpest lens in this category?

[dchew]

I tried both SK versions and went with the 150mm.  I could not tell the difference in sharpness with the copies I had; more variability in minute focus variations than anything else.  I believe it is simply a focal length decision.  I already had the 100 HR so for me it was an easy decision.

The MTF's are very similar.  Image circles are 120mm/120mm vs. 110mm/150mm I think.

Dave

[gazwas]

Did you know that on the Rm3di from a 120mm lens and up they require the use of the spacer/extension box mounted on the rear of the camera between camera camera body and digital back?

[Kevin Sink]

Thanks for the feedback.  I think I'll go with the 120mm; I used a 120mm extensively on my Contax system and found it to be one of my most used lenses.  Thanks for the heads up on the extension that needs to be used with that focal length.  Shouldn't be too much of a hassle.  Would really like to have camera movements for that focal length!