graybeard

I have a Canon T3 which I use with several Canon and Tamron automatic lenses, all of which work fine in all modes. I also use a few old film lenses and have spotty performance based on my camera's light meter not seeming to work right. When I am in M or AV modes, and mount, for example, my Mamiya/Sekor F1.4 lens (via a programmable M42/EOS adapter) the meter will work fine when the camera's aperture is set to 1.4 and the lens aperture ring is set to 1.4. Just like a film camera I can adjust my shutter speed and/or ISO and the light meter will respond correctly, as proved by a properly exposed image. But if I set the aperture on the camera to anything other than 1.4 and adjust the SS/ISO to center the light meter, I end up with an overexposure, of slight to extreme, based on how much off 1.4 it is. By ignoring the light meter and guessing, I can get a good exposure after enough trial and error. I realize that the same amount of light is entering the lens regardless of the camera setting, but shouldn't the meter be measuring this accurately? Also, all my manual lenses have this problem, and one of the ways I can get a good exposure is to use the aperture ring on the lens, but again it is without any help whatever from the meter. 40 years I used film SLRs and never had trouble with the meter (unless the battery was dead). Anybody else have this problem, or am I missing something here ??

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

If I understand your situation correctly, there is no way that the camera can stop down the lens - no mechanical linkage and no electronics in the lens. Metering can only function accurately in stop down mode / manual mode. It works fine for me with adapted older lenses, so I think the T3 will do the same. You can focus with the lens open, but must meter and make the exposure with lens stopped down.

oldtigger Loc: Roanoke Virginia-USA

sounds as though the lens is not closing down at the moment of exposure.
set it for a 1 second exposure, look into the lens front and see what the iris does.

JPL

Yes I think you are missing something here, like Petereff said, you always have to set the aperture manually on your old lenses, the adapter will not do that for you. And like you have already found out one of the ways to get good exposure is to use the aperture ring on the lens. That is because it is the only way to do this correctly. After all the lenses are manual lenses because you have to do this and the focusing with your own hands. That is what is called manual

speters Loc: Grangeville/Idaho

That is just the way it works in manual, you have to set the aperture manually (in modern optics it's done through the camera using its power)!!!

graybeard

I certainly did not expect the camera to physically adjust the lens aperture ring !! What I meant was that the camera, when set to a given aperture, like say F16, should compensate and make the meter react as if the ring was set to 16. What I did not mention is that even if I set the aperture ring to the same F setting of the camera, that when the meter is centered I still get an over exposure, in the case of 16 I would get total white out.

graybeard

As I mentioned before, even when I set the aperture ring down to match the camera setting, I get overexposure.

graybeard

OK for clarity's sake, these are the steps I take: Set camera F setting to 16, set lens aperture to 16, set ISO to 100, press shutter half down to get a meter reading, adjust shutter speed to center the meter, take the picture. It will be badly overexposed. If I adjust the shutter speed to very high, so the meter needle is way down to underexposed reading and take the picture, it will be ok (if I have guessed right on the shutter speed). My point is I have no meter to help me unless I am all the way down to F1.4 on lens and camera.

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

Then there is something going on that we don't understand here. Can you be much more explicit about the lenses and adapters that you are using as well as what you are doing. It appears that many of us are doing similar things with similar or equivalent cameras/lenses and do not find a problem. The camera cannot compensate if there is not communication between then camera and the lens. You must meter with the lens manually set at the aperture you wish to use and then adjust shutter speed or ISO until "the needle" is in the middle or equivalent.

graybeard

Please check my generic reply of a few minutes ago. Thanks for your consideration.

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

I did, and I responded. Unless your camera is faulty then you are doing something wrong, and most of us do not seem to have a problem. It is simply old school stopped down metering.

graybeard

I agree. Other than setting the camera to an aperture, it is the same procedure as that followed in a film camera. Set either the aperture or the shutter speed to a given setting, then adjust the other until you get a good meter reading. Exactly the same. I keep my ISO set to 100, so it is precisely as in film days. Maybe it has something to do with the adapter ring, but I have tried both programmable (set to 1.4 & 50mm) and autofocus confirm types, and both seem to not be a part of the problem. I can live with this, but it is an annoyance, and I thought someone on the forum might point out my error. I guess that is not going to happen. Thanks anyway.

BebuLamar

I guess that the camera can not stop the lens down for the exposure and open the lens up for viewing. I don't think the Canon EOS has the mechanism to do so on old non Canon lens. So the lens either doesn't stop down during exposure or more likely that it stops down to actual aperture as soon as you set the aperture without taking any picture. With that case, I think you can stop the lens down and set the camera to the f/1.4 always and follow the the meter to set the shutter speed. I think that would work.

blackest Loc: Ireland

I think you're on to something here, the camera thinks it is metering at f1.4 so now you tell it you are going to shoot at say f2.8 it changes the shutter speed to suit f2.8 but then the lens doesn't stop down. so you're going to be 2 stops overexposed.

The adapter i use always says f1.4 i can't change it, the camera's happy with that it thinks , dark out isn't it. :) and happily takes the photo with the right exposure for the amount of available light. I kind of wish i'd read this earlier having ordered a programmable m42 eos adapter it is highly likely that it could have the same issue. On the plus side it could have a real focal length.

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

Whatever the type of lens, old Canon R/FL/FD/FDn, Contax, Nikkor, m42 (Helios), manual Rokinon (Samsung) there is no communication between the lens and the camera for the actual aperture value being used, so the camera must be set to 'stop down' or actual aperture value to meter. If the aperture is opened wide to focus, where a chipped adapter may allow for focus confirmation, the lens still needs to be manually set the the desired aperture for the exposure.

Personally, I don't have a problem with that, it's simply a part of using old or manual lenses. It does require a little thinking, but that's how I learned with my Zenit E. My Canon AE-1 and T90 had a mechanical linkage to allow for open aperture metering but then stop down 'automatically' for the exposure. Modified or adapted lenses can't normally do that.

What I get from my adapters, so long as I dedicate an adapter to a specific lens in the focal length (or range for a zoom), the max aperture, and focus confirmation. For myself, focus confirmation is the most useful.