Manual lens adapters with correction lenses
It is a widely known fact meanwhile that it's pretty easy to adapt some older manual lenses to modern EOS digital reflex cams. The moderate register distance of the EOS system allows it to mount Nikon-F-, Zuiko-OM-, M42- or Leica-R-lenses and several other types.
Owners of Nikon DSLRs have more difficulties, because the Nikon register distance is much longer and thus most manual lenses can only be used for close-up shots. Some vendors offer a special adapter with corrective lenses inside that enable the user to focus on infinity again.
Many users claim that these lenses deteriorate the lens performance and so image quality. This is an understandable thought, since every glass element that is not part of the original calculation influences the performance of a lens desing.
I was thinking about how I could test this. Comparing the same lens on an EOS and a Nikkor DSLR didn't seem to make a lot of sense, because the sensors are just too different to draw conclusions about the lens performance. The way I have found to still compare a corrective adapter to a non-lens adapter was the following:
Owners of Nikon DSLRs have more difficulties, because the Nikon register distance is much longer and thus most manual lenses can only be used for close-up shots. Some vendors offer a special adapter with corrective lenses inside that enable the user to focus on infinity again.
Many users claim that these lenses deteriorate the lens performance and so image quality. This is an understandable thought, since every glass element that is not part of the original calculation influences the performance of a lens desing.
I was thinking about how I could test this. Comparing the same lens on an EOS and a Nikkor DSLR didn't seem to make a lot of sense, because the sensors are just too different to draw conclusions about the lens performance. The way I have found to still compare a corrective adapter to a non-lens adapter was the following:
I have chosen a decent M42-50mm lens, the Mamiya/Sekor Auto 1.8/55 (as shown in the picture on the left) and adapted it to my Canon EOS 40D using first a regular, non-corrective M42-EOS-adapter and second a corrective M42-Nikon adapter mounted to a Nikon-EOS-adapter, in order to simulate the adaptation to a Nikon DSLR.
Then I have shot the same subject with similar settings (ISO400, manual white balance, tripod, LiveView manual focus, aperture f4).
Move on to the results...
Then I have shot the same subject with similar settings (ISO400, manual white balance, tripod, LiveView manual focus, aperture f4).
Move on to the results...