Fujinon 4.5cm f1.9 on a 58mm diameter focus helicoid
I opted not to use the build-in focus mechanism on this lens, and instead, use my newly acquired, though shoddy made focus helicoid with a 58mm opening. The large diameter allows the lens to go inside the helicoid so that it's close enough to the sensor for the lens to focus to infinity. The added bonus is that infinity focus does not need to be precise, as long as it can be be focused to infinity. This is not true when using the built-in focus mechanism. It must be exact, or either you can't focus to infinity, or it focuses pass infinity and causes its already long minimum focus distance to increase further.
When used with a 17-32mm focus helicoid, very close focusing is possible. Click for larger.
Like many rangefinder cameras from the 60s, the lens was designed and made as a premium product, but the lens optical formula is relatively simple compared to today's lenses. This may not be a bad thing, as fewer elements usually means more pronounced characters and better looking bokeh. Highly corrected lenses of today produce pictures that look similar to each other.
Very sharp wide open. Click on picture for a larger version.
The Fuji 4.5cm f1.9 produces very fine pictures. It's very sharp in the middle of the frame wide open, and it has a very pleasing rendering characteristic; sharp but without the hint of harshness. I like the bokeh too; nothing distracting or extreme. When stopped down to around f11, sharpness shows itself across the whole frame. I would say very good performance from a lens designed and made more than 50 years ago.