Is A7R better for legacy manual focus lenses than A7?

Started Dec 11, 2013 | Questions thread
blue_skies Forum Pro • Posts: 11,473
Re: Is A7R better for legacy manual focus lenses than A7?

I am completely lost by your comments, and I do not subscribe to your findings, based on my own experiments to date.

Older lenses can be more prone to flare (e.g. SC lenses), but a sharp legacy lens is still a sharp lens on a digital sensor.

The Nex/Alpha cameras were not the first to adapt legacy SLR lenses - you could already adapt e.g. OM lenses on Canon EOS cameras in the past.

Given that the A7 has a lower sensor resolution than the A7r, it should be a better match for older lenses than the A7r, not the other way around.

Aperture control on an MF lens is no different that using the camera in A-mode. Instead of dialing a button on the rear, you are dialing the aperture ring on the lens - the camera handles everything else.

Thus far, the wider angle RF lenses are prone to vignetting and possible color shift and corner smear, and this puts a damper on adapting the wide angle RF lenses. RF lenses got popular as they are very compact and very high quality (they are expensive lenses). But if you use SLR lenses, you are not necessarily looking at much bigger setups - e.g. the OM 24/28/35/50 lenses are all quite compact with a stellar image.

The most impressive FF images tend to come from a fast FF lens with high contrast used wide open. This was typically done with RF lenses - and in  the 35mm to 50mm you can get many very high IQ RF lenses that work well on either A7 or A7r.

If you get a fast SLR lens instead, you may not get the same micro-contrast - in the SLR lens days, it was more common to make the lens perform best when stopped down a bit. On the other hand, SLR lenses have no trouble with the corners - for the better ones (and if stopped down) - whereas RF lenses deal with more acute ray angles for wide-angle lenses.

Again, as I pointed out earlier - the Nex-7 has the highest pixel density, followed by the Nex-6 and the A7r and then the A7. If you pixel peep, you will see most detail with a Nex-7, which then leads to disappointment with the A7. But this is only if not understanding the crop - the A7 is full frame, the Nex-7 is APS-C. Look at the entire image to get a better appreciation of the IQ.

As to the FE lenses - they are designed with the sensor in mind, so you will see the best of what technology can bring to bear. Are they better than adapting legacy lenses? Yes, if AF and OSS come into play, but not necessarily if you just want IQ. E.g. take a Contax-G 45/2 lens next to the FE55 and I expect to see a very similar IQ. Less so for a ZM35/2 next to the FE35, as the M lens may vignet at 35mm - but then, I'd take f/2.0 over f/2.8...

Lastly, the 36Mp A7r and 24Mp A7 FF cameras are really much closer than the 24Mp Nex-7 and the 16Mp Nex-6 APS-C cameras are in terms of image IQ (not croppability) - meaning, it is a bigger step from 16Mp to 24Mp than from 24Mp to 36Mp.

UnderDriven wrote:

In the end, there will be a lot of disappointed people who imagine their old MF SLR lenses can be revived by the A7/A7R. I love the solidity and smooth focusing of my old MF lenses (and the long focus throws), but most of them really don't do very well on modern digital cameras. They tend to be soft and low contrast wide open, or have poor edge performance compared to more modern designs (probably made much worse when using a FF sensor). Add to that the lack of aperture control, and many people will gladly pay for new FE lenses after a few months of experimentation with legacy MF lenses...

In reality, only the best MF lenses are worth using on a modern FF DSLR, and they are still expensive (Contax, Leica, Zeiss, and possibly Voigtlander). Macro lenses may be the exception--they were designed to be very sharp, have minimal distortion, and have a flat field. This is where you can find bargain lenses which will still perform well on a FF DSLR. The problem is that macro lenses are usually 50mm and up. In the end, I predict that most people will buy whatever Zeiss wideangle zoom Sony produces, and forget about trying to use legacy MF lenses for anything below 35mm...

If you are really interested in using legacy MF lenses, then the A7R is better--primarily because you can crop to APS-C and still get 16MP. Or do a 1.2 crop and still get 24MP--this will probably eliminate the worst of the edge degradation on most lenses (other than wideangles). I would buy an A7R right now if it was cheaper--I'll have to wait for a year until the price comes down a bit...

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