Re: 1974 Minolta Rokkor 55 mm f/1.7 Lens
1
Nice photo! Very good result for that vintage lens, especially considering it was shot at ISO 1600. I can see the 'warmth' that the Minolta Rokkors have vs the slightly cooler tones of the modern Canon lenses.
How did you process the photo? What aperture was it shot at?
I have a set of Minolta SR-mount lenses. The oldest I have is an MC Rokkor-QF 200mm f3.5 'hills and valleys' lens, which is about the same age as yours and a reasonably good performer. I have some MC Rokkors from the 70s and some MDs from the 80s. See the following Minolta lens calatog:
http://minolta.eazypix.de/lenses/
I believe your lens is older than you mention: the MC Rokkor 55mm 1.7 lenses were made between 1966 and 1970, in a few different versions. After 1970 Minolta went to a newer all-black lens style, and went to the more standard 50mmm focal length.
From my experience, I'd expect that your lens to start sharpening up across the frame at around f2.8, and to give you clean, sharp images around f5.6 - f8.
I had fairly good luck sharpening my vintage Minolta lens photos using Canon DPP 4 against Raw files, but was never able to correct the chromatic aberration very well. IN particular it never did a good job with a Minolta MC Rokkor-X 28mm f2.8.
However, I found that DxO PhotoLab 4 (5 is now out) does an outstanding job with vintage lenses --- using unsharp masking with intensity around 150, Radius 0.75, Threshold 0, and edge offset 50-100 (Edge offset is how much additional sharpness 'intensity' to apply in the edges/corners over the middle of the frame, to sharpen up soft corners).
DxO really shines when correcting the chromatic aberrations of those old lenses. I usually find settings of: Lateral CA enabled, Intensity 180, size 8, Purple fringing enabled works well, but each lens is different and experimenting helps.
DxO allows you to bump up contrast and microcontrast to compensate for the lower contrast of the old lenses, and Deep prime Noise reduction will clean them up and enhance the sharpness, making the photos look very much like they were shot with modern lenses with full lens corrections.