Canon 50f1.4 overexposes

How can a lense overexpose? Isn't it just the meter on the camera not working properly? I mean, if it overexposes just use a higher shutter speed or nd filter if low shutter speeds are wanted.

^^

Put all the lenses which you have on the camera in turn. Aim at a plain colored uniformly lit wall. Put the camera in Av mode, and take a shot with each. If all the shots come out the same tone (brightness) you can then conclude that no lenses 'overexpose'.

macroimage wrote in post #11961746
I've noticed that there is something different with the exposure from the EF 50/1.4 too. At first I thought it was due to greater light falloff wide open since metering is done wide open. I thought that the darker corners would cause the meter to indicate longer exposure.

I just tried it with filling the frame on an 18% grey card, ISO 100, f/2.5 selected in Av mode, cloudy white balance and infinity focus using the EF 50/1.4. I took the pictures and compared them first with the 7D. Matrix and center weighted averaging gave the same 1/8s exposure while partial metering gave 1/10s exposure and a 1/3 stop darker image. Then I put on the EF 50mm f/2.5 CM lens on and tried it again. This time the meter indicated the same 1/8s but the resulting picture was closer to 2/3 stops darker. It wasn't due to loss of light from high magnifications as the lens was at infinity focus. Strange.

Then I tried the same test with a Rebel XT. This time the EF 50/1.4 metered 1/10 second and made the same brightness as on the 7D at 1/8s. The EF 50/2.5 metered at 1/8s, the same as on the 7D but the image was only 1/3 stop darker than the 50/1.4 and 1/3 stop brighter than on the 7D for the same settings.

Could it be related to this?:
http://www.luminous-landscape.com …amera_manufactu​rers.shtml

I looked at the article and it might explain what is going on. I took another look at my outside photos, and all but one was slightly over exposed. I am going to do a more formal check later on today. There are no problems with my camera bodies. It may be an electronic issue with f1.4 lenses. All my other lenses are slower (all of them are f1.8 or slower).

Bang Bang Boy wrote in post #11963406
How can a lense overexpose? Isn't it just the meter on the camera not working properly?

The camera meters and focuses with the aperture wide open, then stops down for the exposure. If the stopping-down isn't exactly as expected, it's too late and the mis-exposed image is recorded.

Here are two photos from different lenses and different bodies. The 35f2 was on the XS at 1/200 and f2. It missed focus here by a little, but it shows the point I wanted to make. The 50f1.4 was on the T2i at 1/200 and f2 (top photo). The exposure of the 35f2 was more typical of what I normally see in the world. Exposure is generally right on. Most of the 50 shots are about 1/3 stop overexposed.
I realize that two variables were changed here, camera bodies and lenses (and angle of view was not identical), but they show what I have been seeing from the 50 compared to my other lenses.

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Either the test is controlled or it's not. This is not. If you want us to see the real problem, why not just show the problem without other variables?

Put a camera on a tripod. Shoot with one lens. Shoot with the other.

AntonLargiader wrote in post #11967221
Either the test is controlled or it's not. This is not. If you want us to see the real problem, why not just show the problem without other variables?

Put a camera on a tripod. Shoot with one lens. Shoot with the other.

Yup.

And I should have added:
- at the same shutterspeed, aperture and ISO
- at the same framing
- at the same time, within the lens changing time
- at the same ambient light
- at the same EVERYTHING except the lens

ISO was the same (800), as was shutter speed and f stop. but I would have to move the camera to reproduce the framing. The only other 50 I have is slower, and I wanted to use a faster F stop. It is difficult to reproduce the same framing without using the identical focal length - perhaps that is next.

Here you go. Both lenses were on the same body, ISO 1600, 1/125@f2.8. The first shot is from the Sigma 50f2.8, the second from the Canon 50f1.4. The difference in exposure is small, but real. It is easier to see in the originals and on my screen.

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I think I need to start a new thread soon about how my battery over exposes some shots....

On the originals, the Sigma at f2.8 is a bit sharper than the Canon at f2.8.
I was looking for constructive comments, and wondered if the lens was OK. I think it is OK, but I will need some care in using it at larger apertures.
Try not to overcharge your battery.

If these were at 2.8 sigma vs. 1.4 for the canon, per the examples above, it would be safe to say that the canon is underexposing rather than overexposing...right? NV...I just saw they both were at 2.8...
They both seem fine to me....I say stop examining and go shoot...
Ron

Yeah, I thought the second one (Canon) was a bit darker also. The focus or DOF is also a bit different, looking at the light switches on the left edge; the middle switch is much sharper in the 2nd shot. BTW it seems the camera was not on a tripod for these anyway; the framing is slightly different.

This difference in exposure isn't anything I would worry about. Heck, I don't think I'd notice. I get more shot-to-shot exposure variation without even changing lenses.

I suspect that I was confusing some flare in some of the shots I took with overexposure. I'll know more when I work with a hood.