A test for internal reflections
One argument against using film camera lenses for digital is the lack of modern lens coatings that made-for-digital lenses have. Light can bounce around between the sensor and the rear element and show up in your images. This is true under extreme conditions, such as when you photograph a black object on a white background at f/16.
The black object used for the test.
For this test, I used 4 manual focus film camera lenses and a Canon AF zoom lens on a tripod mounted Canon 30D. All exposures were made at f/16 with the camera set at 100 ISO. I used a 400 watt-second monolight with a softbox and a white laminate shooting table. No lens hoods or filters were used. I tried lens hoods on the lenses that performed poorly and there was no discernable improvement.
- Mamiya 45mm f/2.8 S lens for the Mamiya 645
The rear element of this lens was further from the sensor than any of the other lenses. This lens was designed for professional use with studio flash for the Mamiya 645 cameras.
45mm F/2.8 S lens for the Mamiya 645 used with an EF adapter.
- Nikon 55mm f/2.8 Micro Nikkor
The 2 reflections are the same color as the sensor and were still there when I used a lens hood.
55mm f/2.8 AI Micro Nikkor with EF adapter
- Contax 50mm f/1.4 Carl Zeiss Planar
This is from the Contax 50mm f/1.4 Planar.
Carl Zeiss 50mm f/1.4 Planar in Contax mount with EF adapter.
- Rollei HFT 50mm f/1.8 Planar
The Rollei HFT Planar in 2 pin QBM did better than the Contax Planar. The Rollei Planar was manufactured at Rollei’s Singapore plant during the early 1980s.
Rollei 50mm f/1.8 HFT Planar 2 pin QBM mount with EF adapter.
- Carl Zeiss Jena 50mm f/1.8 Pancolar M42
The 50mm f/1.8 Carl Zeiss Jena Pancolar on a Canon 30D had more internal reflections than other lenses in this test.
Carl Zeiss Jena 50mm f/1.8 Pancolar in M42 mount with EF adapter.
- Canon EF 28-70mm f/3.5-4.5 zoom lens
This is from the Canon 28-70mm f/3.5-4.5 EF lens set to 50mm.
Canon EF 28-70mm f/3.5-4.5 zoom lens
Here’s an example of an unwanted reflection created by the 55mm Micro Nikkor at f/32 on a Canon 10D under a 500 watt-second softbox.
Lens coatings under ordinary conditions
If reflections aren’t showing up under extreme conditions, you shouldn’t expect any under ordinary conditions. The rear element on the 45mm Mamiya was farther from the sensor than the rear elements of the other lenses. The Mamiya was also designed for professional use with studio strobes. Thirty years ago, a new 45mm Mamiya lens sold for $840. Now you can find one for $150-200.
Rollei had their own HFT coating on their version of the Planar which was sold minus the Zeiss name. This lens listed for $220 new in 1977 which was more than the 50mm f/1.7 Contax Planar that came out a few years later. Now you can find one for less than $80.
Here’s another look at that Carl Zeiss Jena 50mm f/1.8 Pancolar under normal lighting conditions.
50mm f/1.8 Carl Zeiss Jena Pancolar on an Olympus E-600. RAW file processed in Photoshop.