Olympus E500 Over-Exposing?

[Harlequin565]

Hi there,

It's a bit of a long shot.... but I'm hoping someone will think of something I missed here. One of my students has an Olympus E-500 and it's massively over-exposing in Av mode (I'd guess 3-4 stops). I only got a chance to have a brief look, but I...

Metered the shot (it was roughly ISO 200, f8, 1/50sec).
Program, Manual and Tv/S all correctly exposed. Av was exposing by using the same aperture/shutter but pushing the ISO to 1600. Manually set the ISO to 200, and it dropped the shutter speed to 1/2sec(ish) and still over-exposed.

Exposure compensation was at 0 (was my first thought)

I can't think of an explanation other than the camera's broke, but it's really weird that the other modes are fine.

So what have I missed? Any bright ideas?
Thanks in advance! Ian.

 

[StewartR]

Are you sure that all the correctly-exposed shots were taken at f/8? It sounds to me like a sticky iris on the lens that prevents it stopping down. So when you're in Av and you insist it stops down, it can't and the shot is over-exposed. But maybe in other modes it's not selecting parameters that require the lens to be stopped down...

 

[Harlequin565]

Are you sure that all the correctly-exposed shots were taken at f/8? It sounds to me like a sticky iris on the lens that prevents it stopping down. So when you're in Av and you insist it stops down, it can't and the shot is over-exposed. But maybe in other modes it's not selecting parameters that require the lens to be stopped down...

Thanks for replying Stewart.

Yes. In Manual, I set ISO 200, f8, 1/50 sec and it took the photo fine.
In Tv I set ISO 200 and 1/50 and it took a correct exposure at f8
In Av, I set ISO 200 and f8. It told me the shot would be 1/50sec and then promptly did a half second exposure, over exposing.

 

[StewartR]

OK, let's try an experiment.

Your initial report was that the camera was over-exposing by 3-4 stops when in Av mode. Is it always 3-4 stops, or is it aperture-dependent? I still think it's the iris not stopping down. So if the lens is, say, f/2.8, then it should be OK when you select f/2.8 in Av mode, 1 stop over-exposed when you select f/4, 2 stops over-exposed when you select f/5.6, 3 stops over-exposed when you select f/8, and so on...

 

[Harlequin565]

OK, let's try an experiment.

Your initial report was that the camera was over-exposing by 3-4 stops when in Av mode. Is it always 3-4 stops, or is it aperture-dependent? I still think it's the iris not stopping down. So if the lens is, say, f/2.8, then it should be OK when you select f/2.8 in Av mode, 1 stop over-exposed when you select f/4, 2 stops over-exposed when you select f/5.6, 3 stops over-exposed when you select f/8, and so on...

Ah I get you now. Sorry. Will ask to test and get back to you.
Thanks!