Thank you for your explanation, but I know very well how the autofocus system works. I understand that the adaptor is not responsible for the focus, but the camera is. I just thought I'd share my appreciation of it as it was the kind of information I was looking for to help me make up my mind on buying one or not, but never found.
Yes, like I said, I thought you might "be tired of knowing all this" , I took the time to write it thinking maybe it will be usefull for someone in the future...
On thing that I find strange is that I seem to get over exposed image (one stop) with the chipped adaptor compared to a non chipped adaptor, regardless of focus or aperture setting (f2, 5.6 and 16) . I tried on a real life contrasty scene and on a gray card. Any clue as to why? The only difference between the two is that one of them is black... I doubt that this could affect metering.
Well, AFAIK, with a regular (chipless) adapter, the camera will default at center-weight metering, and that is not as acurate as matrix (especially if you're not expecting it). I supose it happens the same with a chipped adapter, as there is no info regarding lens focal length being provided to the camera (is there?), nor about focus distance (Nikon at least take this info into consideration for the exposure calculations, not sure if Canon do so, too ).
Anyway, Canon users here at the forum state that more recent Canon cameras are pretty messed up as far as metering with old glass goes (as surely you have already found out ). My experience with Pentax is the same, pre-A-series lenses usually meter poorly at smaller-than-full apeture, wich is actually strange, as M-series and adapted lenses measure in stop-down mode (wich is supposed to be the most acurate way of measuring ). So far, I've had no real problem with A-series and newer lenses...
As for the adapter being black or metal finish, I'd say it MIGHT have an efect in the photo (i.e., if there are metal parts exposed to the light path, wich may cause internal reflections), but I don't think it would affect the meter readings (surely not more than 1 stop).
Could the chip it self have an effect?
I once read that Canon was compensating on some very fast primes by over exposing the pictures, for not being able to pickup all the light from the lens because of the micro lenses on the sensor:
http://www.luminous-landscape.com/essay … rers.shtml
On the 7D their is almost 1 EV compensation with lenses with 1.2 openings! I programed my chip with a F2 max aperture so I doubt that this is the reason.
Anybody with a clue? Thanks!
Sorry, can't say I have info on the subject .
Part of the argument seems to me to be flawed. The reason the Leica's sensors are engineered diferently, is not because of the large aperture lenses, it's due to the small register distance. This in fact may be an interesting point to put in another thread here in the forum, about the Sony NEX cameras (not sure you read it, it's pretty interesting, and the discussion has diverted a bit to its use with old, fast primes, namely rangefinder lenses). But I'm drifting...
Is it possible to use your chips without programing lens info? I mean, just using the AF confirm feature, and finding the exposure "the hard way"?
I never had any kind of metering with my D40 (with manual glass ), and always did alright ("guestimating" shutter speeds and adjusting if necessary). Also, never noticed any of the problems mentioned in that article, even with my f-1.2 Rokkor (never realy compared, tough ).
Anyway, long answer, hope this helps. Cheers!
Nikon: D7000; F2; F4; FA. RMC Tokina 17/3,5; Ensinor 24/2,8 Macro; Nikkor: S.C. 50/1,4; AI-s 28/2,8; Micro 55/2,8; 80-200/4; S. E: 35/2,5; 100/2,8; Viv. S. 1 105/2,5 Macro (Kiron); MC Rokkor PG 58/1,2; Canon FD 300/4; Pentacon 135/2,8.
Pentax: K20D; CZJ Flek 20/4; SMC Pentax: A 28/2,8; 50/1,7; M 50/1,4; Tak. 50/1,4; Tamron Adall 2: SP 90/2,5 Macro; SP 60-300; 35-70/3,5 CF; .
And some others...