Contax and Yashica and Contax/Yashica fit lense with Sony A7

I've used the cheap stuff to test new legacy glass on digital with an NEX F-3, which uses the same e-mount plates that the A7 series does. It allows me to evaluate a new-to-me lens or 'family' type without sinking big cash into the high-end adapters. I don't mind the outlay for good gear, but I'll stay low for just testing. I certainly would not want to depend on the cheapos for daily use when I was a pro, nor would I expect them to perform well enough (or safely locked-in enough) to risk my Yashica/Zeiss glass on any extended field trips as the amateur I am now.

Having said that... I too have had better luck using the K&F adapters. The versions with the extra tripod foot have been helpful with the really heavy stuff that I dare not expect the e-mount setup alone to handle. The v1 Zeiss 300mm f/4 weighs 2.6 pounds and the v2 200mm f/3.5 is a bit less, at 1.7 - and they do NOT have a collar and foot of their own. K&F adapters also seem to be closer in tolerance for ifinity focus than the others. They've all been anywhere from .05mm to .085mm too short from what I remember in measuring, so you'll usually go past infinity with most if not all of them - no matter who makes them. Not necessarily horrible, but your keeper rate can go down when you forget it's out of whack.

I can't say I've had quite the same experience with overly misaligned adapters as described, but I have found lenses that were modified into something beyond their original design. The only mount type that I've had big problems with are those for M42 to Sony E. They have set screws to adjust the threaded section for positioning, and it's orientation can be different depending on which lens you adapt. I ended up getting quite a few of them and keep them adjusted and attached and not having to fiddle with alignments when mounted on-camera. The one M42 Yashinon I have uses an M42 to C/Y plate to adapt it with - to exact tolerance - so no whacky positioning.

I've never had hood issues with C/Y lenses that I can remember. They don't use a bayonet system like Nikkors or Canon FD's, etc., so they've always been able to be realigned when they're the clamp-on types - or it's a non-issue for the round screw-ins.

(Jasee replied) Thanks, but I don't quite understand this, C/Y lens DO have a bayonet mount, not a screw, I think you're misremembering 

Ah yes, sorry, my mistake. I do have hood issues, I have rubber Contax lense hoods for my Contax lenses and anyway my smallest Contax focal length is 35mm. But I've got 16mm Sigma fisheye with a fixed hood and a couple of 21 to something zooms with fixed hoods, all of these don't align with the Sony Alpha 7 through the cheap mount. They do no Contax cameras of course. Hopefully they will (and lock) to the mount suggested.

Thanks all, the K&F Concept C/Y Adapter is the answer. The lenses all lock in correctly in the correct place and the don't fall out! In answer to lumiworx, all my lenses are one owner so I know they haven't been tampered with. I only paid about 18ukp for the adapter, it seems to be available at a range of prices, but seems to be a snug fit. So I'm now looking forward to many happy hours of photography. Thanks again

+1 for the K&F Concept adaptors. I tried some cheaper ones to start with but then bought a K&F one and have been happy ever since.

One thing to look for is whether the adaptor uses proper springs, or not, to hold the lens against the flange. Some of the cheaper ones use, what amounts to, a bent bit of metal. Look at the picture below to see what I mean.



There's a split in the metal that gets opened out. The first time you mount a lens, the metal gets set into position (sorry, my description probably isn't very good). That's OK if you only mount one lens to it but if you continually remove and fit other lenses it doesn't work well and can become loose as there's no spring in the metal.

Compare it to the K&F one where there's a proper spring.



What is surprising is that even the very expensive adaptors use the cheap method. See this Novoflex



The other issue I've had with all the adaptors, including the K&F one, is light leaks and internal reflections so I've fitted flocking to the inside of mine.

Since my last post I've finally upgraded my adapters, and now have a single (used) Novoflex C/Y to Sony E adapter. It's the early version with a traditional round push-button and not the circular 'disk' shaped lens-lock, but it's otherwise the same internally, as best I can tell. It works perfectly - with no slop at all - and is within .003mm in tolerance with its flange distance at any point along the barrel. That's the major difference to most of the cheaper ones I've used, and I appreciated that detail enough to pay a premium to get it. I'd still recommend the K&F adapters as a best-in-class though.

Following soon after the Novoflex adapter, came a Novoflex ASTAT foot bracket to fit it. I had customized an after-market Mengs tripod mount ring with some cork and leather sheeting to use on the Novoflex adapter, but the clearance was far too close in getting to the release button. It worked and was solid enough, but it was difficult to swap lenses. The new foot is far slimmer and presents no issues at all, for doing lens swaps or quickly reorienting the mount to 90 degrees (or whatever angle is needed).

I've gotten to the point where I've acquired all the lenses I really want for now (at least in C/Y mount), and it's time to upgrade what's behind the adapter to full frame, so having a quality adapter was the last part of that process. It seems like I've spent more time in acquiring, collecting, and getting ready - than actually shooting with what I have. It's time to flip that ratio around.

@peterr ... You mentioned the questionable use of split or 'bent' metal versus using springs to lock lenses - even when done on high-end adapters. Although that might seem reasonable in theory, the mechanism's design isn't the only part of the equation on how well the lock holds. The quality of the base material, and the strength given to it by hardening processes and base composition properties take precedence over the design alone. Metal can be incredibly strong even when paper thin, or it can still be brittle even if it's 25mm thick. I think you'll find there's no flimsiness in the Novoflex at all, and likely it would be the same for MetaBones, Kindai/Rayqual, Leitax, Conrus, and the other pricier brands that use better base materials than their cheap Chinese counterparts do. There's a reason those are as cheap as they are.