Sony A7 w Minolta MD Rokkor 50mm 1.4

Started Jul 13, 2014 | Discussions thread
ProfHankD Veteran Member • Posts: 5,909
Probably camera shake

Dkaplan74 wrote:

Has anyone used this combo and what are your conclusions. I am finding I am getting sharp images in good light (outdoor daylight), but indoors under lower light it is hard to get a sharp picture without pumping the ISO which can get a bit noisy. Is the problem that the lens just isn't that sharp? I love manual focusing. Would I have better results w a Voigtlander or Zeiss M mount? Thanks!!

Obviously, lenses don't get more or less sharp when you change ISO. Remember the 1/FocalLength seconds slowest shutter speed rule? I suspect that you're using too slow a shutter speed and getting a tiny bit of camera shake. Note that the 1/FocalLength rule was back in the days of film, and film didn't resolve 24MP like your A7 does, so you probably need a little higher speed to make the shake go away. 50mm would say 1/50s, and Sony cameras tend to use 1/60s for many things, but a little faster speed would be wise. For the A7R's higher resolution, or if you've been operating a vibrating power tool recently (not kidding; this can cause measurably more shake for a day or longer), push the shutter speed higher still. Alternatively, if you don't mind JPEG capture, use one of the multi-shot modes -- they aren't quite as good at removing camera shake as the sensor-movement in A-mount bodies, but they definitely help (and can help remove subject motion too, which sensor movement can't).

One more note: comparably fast lenses with shorter focal lengths don't need as high a shutter speed. Neither do lenses with OSS. The speed difference between even an f/1 and f/1.4 is just one stop, so the exotic ultra-fast lenses would only make a difference in borderline cases... and maybe not even then, because there are other issues that make the exposure difference between f/1 and f/1.4 less than you'd expect. In fact, in terms of minimizing camera shake in poor light, the 50mm f/1.8 with OSS is really hard to beat... probably need an f/0.6 or so to match it without OSS. (Although OSS does nothing to reduce subject motion blur.)

There's also the issue that with avery thin DoF, if you're slow focusing, by the time you actually click the shutter the subject may have moved just enough to be a touch out of focus. The only fixes are practice, AF, or stop down a little. Actually, a trick called "trap focus" can solve this too, but Sony E-mount bodies don't directly support trap focus.

Anyway, I find my Rokkor 50mm f/1.4 to be sharp enough wide open on my A7. Heck, it's even ok on my NEX-7. Yes, it has some glow -- most fast 50s do wide open, because they deliberately undercorrected SA a bit to improve bokeh rendering. The glow doesn't really hurt resolution, but does lower contrast, so boosting contrast a little is a reasonable fix if you see that as a problem.

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