p.1 #2 · How accurate AF Confirm C/Y to EOS adapter from eBay
I wouldn't recommend AF chip, because it's almost useless on fast primes. You should get Eg-s focus screen. And, don't get the split or prism screen either.
p.1 #3 · How accurate AF Confirm C/Y to EOS adapter from eBay
I used af confirm cy-eos adapters on few lenses couple of years and it worked pretty nicely on situations where liveview was not possible. However with fast lenses like zeiss 50/1.7 the range where the af chip claims the area to be in focus is actually much smaller. But with bit of practice (focusing backward-forward and approximating the center of the "sharp" area) I learned how to get almost same keeper rate than with autofocus lenses. So: the af chip can be helpful in some situations but you should not trust it blindly.
p.1 #4 · How accurate AF Confirm C/Y to EOS adapter from eBay
The accuracy of focus confirmation is determined by the camera, not the chip. The chip simply makes the camera think that there's an AF lens attached, and so the camera evaluates focus.
p.1 #5 · How accurate AF Confirm C/Y to EOS adapter from eBay
I have ZE50MP on my 5DII which works perfectly. If the chip on the ring does not control AF, in theory, my C/Y lenses (I have 28/2.8, 35/2.8, 50/1.4, 85/2.8 and 135/2.8) should work as ZE50MP. I will buy one from eBay and give a try.
I hesitate to use Eg-s because I heard it makes the screen darker.
BTW, I also use C/Y to NEX on my 5N and it works so well
p.1 #6 · How accurate AF Confirm C/Y to EOS adapter from eBay
A true electronic lens does not only communicate focal length and aperture to the camera body. It also conveys information about certain parameters pertinent to its optical formula to the camera body. Some of these parameters are important to AF accuracy. In the case of a zoom lens these parameters change as focal length changes.
When you buy a ZE50MP, Zeiss already programmed these parameters correctly into the lens, because Zeiss knows its optical design and they have done research on how to communicate that information properly to a Canon body.
A glued-on 'chip' does not know about the optical formula of the manual focus lens. It returns random data, probably copied from a Canon lens of a completely different optical design.
A very common misconception is that Canon deliberately disabled AF confirmation for manual focus lenses and a 'chip' is required to bring that functionality back. Nothing can be further away from truth. The real reason Canon disabled AF confirmation for manual focus lenses is because the optics for the autofocus module and the optics of the lens attached forms an integral optical system. The camera body really needs to understand the details of the lens' parameters related to its optical formula (not just focal length/aperture) before it can autofocus (or AF confirm) accurately.
As it now is, the glue-on 'chip' concept is flawed, because while we may be made to believe that the 'chip' is one-size-fits-all, in reality this is inherently not possible. Each lens has its own characteristics and every optical design would require a dedicated 'chip'.
Our Contax N lens to Canon EF mount conversion worked because the Contax N lens (or 645 lens) is an electronic lens to begin with, and it does convey the parameters pertinent to the optical formula to a Contax N camera body in a very similar manner. All we need to do is to make some calculations to convert these numbers to Canon equivalents.
p.1 #9 · How accurate AF Confirm C/Y to EOS adapter from eBay
jcolwell wrote:
The accuracy of focus confirmation is determined by the camera, not the chip. The chip simply makes the camera think that there's an AF lens attached, and so the camera evaluates focus.
Sort of. . .
I have a couple of programmable adapters and these direct the lens focusing -- notably one is on my C/Y 80-200/4 and is extremely accurate. I have one other on an alt lens that is accurate and wonderful to get focus confirmation. The other three or four would not take the programming or were simple pre-programmed models that weren't precise -- I stripped the chips off those and am much happier to manually focus with the OVF. In future, I'll not be buying the inexpensive chipped adapters and instead stay with the non-pro manual adapters from Fotodiox and HK. I recommend staying away from the cheap chipped adapters, but hey, I tried, so anyone is welcome to do the same.
Naturally, Voightlander, Zeiss ZE, ZF, etc, are perfectly fine and set up properly. I'm just referring to adapters, not independent lens makers.
p.1 #10 · How accurate AF Confirm C/Y to EOS adapter from eBay
As been said, the EG-S is superior on fast lenses. But for anything stopped down or slow a chip can be great. The trick is to learn behavior on each lens which can differ depending on how liberal that lens' focal plane is. To get a feeling for that always move the focus ring eg from smaller distance to longer and start to get a feel for when the indication comes. When you get to know that lens, you'll also know the acceptable tolerance/span and know what kind of adjustment is needed. Adjustment is perhaps a slight movement back from when focus was indicated, sometimes a bit further ahead. All depending on the lens.
For a fully manual lens such as the Samyang 14/2.8 there's no shortcut, you'll need it. At least if you're turned off by tripods/liveview shooting. And the EG-S will give you close to nothing with a lens like that. But if you learn how that lens behaves with the chip, you can start to do snapshots, and they'll be sharp. Even at infinity despite that the lens allows focusing beyond.
