Photography is all about light and controlling the light between the lens and the sensor is very important. The black paint keeps stray and unwanted light from reaching the sensor or bouncing around inside the mirror box.
This lens originally had black paint in the same place, but had dried out and flaked off. I’m just repainting it.
I have been shooting with mine (I’m using an adapter with my Fuji X-E2) despite having very large flakes of what I assume to be large flecks of paint. The images show no trace of the loose paint affecting the image however it does annoy me to see it floating around in there. Thanks for the quick response! I wonder if the paint will improve the contrast of the photos at all…
The wider the aperture the more likely stray light will affect the image. It’s difficult to see as it generally causes a loss of contrast and washes out the image.
The loose flakes won’t hurt anything unless they really jam up the aperture blades. If you’re adventuresome and have the tools, the instructions to open it up are right here.
Mark O'Russa 
Curious what purpose the black paint serves? Is it just for cosmetics? Thanks!
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Photography is all about light and controlling the light between the lens and the sensor is very important. The black paint keeps stray and unwanted light from reaching the sensor or bouncing around inside the mirror box.
This lens originally had black paint in the same place, but had dried out and flaked off. I’m just repainting it.
LikeLike
I have been shooting with mine (I’m using an adapter with my Fuji X-E2) despite having very large flakes of what I assume to be large flecks of paint. The images show no trace of the loose paint affecting the image however it does annoy me to see it floating around in there. Thanks for the quick response! I wonder if the paint will improve the contrast of the photos at all…
LikeLike
The wider the aperture the more likely stray light will affect the image. It’s difficult to see as it generally causes a loss of contrast and washes out the image.
The loose flakes won’t hurt anything unless they really jam up the aperture blades. If you’re adventuresome and have the tools, the instructions to open it up are right here.
LikeLike