I have never used Leica R and need a quick summery of the 'goodies' out of the following bunch. Which ones do you think will do well on a A7R?
R 35/2
R 60/2.8 macro
R 90/2.8
R 135/2.8
R 28-70/3.5-4.5
I bought the A7 specifically to use with a kit of six Leica R lenses I acquired last year with a pair of Leicaflex SL bodies. These are the ones I have:
Elmarit-R 24mm f/2.8
Summicron-R 50mm f/2
Summilux-R 50mm f/1.4
Summicron-R 90mm f/2
Elmarit-R 135mm f/2.8
Elmarit-R 180mm f/2.8
These are older generation Leica R lenses, the oldest (Summicron 50) dates from 1965 and the youngest (Elmarit 135) dates from 1981. ALL of them work beautifully on the A7; I suspect they would do the same on the A7r.
Also, testing with my four Nikkors (Micro-Nikkor 55/3.5 Pre-AI, Nikkor 50/1.2 AI-S, Nikkor-H 85/1.8 Pre-AI, and Micro-Nikkor 105/2.8 AI-S), all of them work very nicely with the A7.
Testing my M-mount lenses' performance on the A7 has not been so successful. The Color Skopar 21 and 28 do not work well, the Ultron 28/2 is *barely* acceptable at f/5.6, the Color Skopar 35 is "ok", the Nokton 50/1.5 LTM does not work well. The M-Rokkor 40/2 and Nokton 40/1.4 MC seem to perform pretty well, the M-Rokkor 90/4 and Hektor 135/4.5 work well. I suspect this performance will be exaggerated—both good and bad—with an A7r.
From that, it's pretty clear to me that the RF mount lenses present a challenge for the A7/A7r digital sensors that most SLR lenses do not. I think you will find that nearly all of the Leica R lenses, and most other SLR lenses, perform very well with both A7 and A7r where only a select few M-mount lenses can excel.
Of the lenses you listed, the one I have heard the most praise about is the Macro-Elmarit-R 60mm f/2.8. I've heard it referred to as one of the finest macro lenses ever made. I don't know if your 135/2.8 is the same as mine, but mine produces very beautiful rendering.
I love these Leica R lenses. They're big, heavy, beautifully finished examples of lens manufacturing. And even these ancient ones have that
Leica Look™ that is the work of fairy dust from the Leica logo ...
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