Help with Lighthing issue!! Canon D20

Hi Everyone!
I'm new to this forum ... and new to Canon too

Here is my question. I bought a Canon D2O about 2 months ago, which has worked out great. I set up a little home studio to take portraits of my kids and it went well for a while. Now I'm having HUGE problems with my pics coming out overexposed. I really don't know what I'm doing wrong.

I think it might be something to do with my lense or camera. It is a Zigma Zoom 28-300mm Aspherical IF lense. OK here is the issue: I'm in manual mode. I'm in one spot, say 7 feet in front of my subject, I have taken my light metering and it says to put it on aperture 11. I do this and the shot comes out OK (say I am at 100mm). I focus in a little (200mm) to do a close up shot and it goes COMPLETLY OVEREXPOSED ... I mean not only a little but hugely. I pull the lense all the way back to get a full (say 50 mm) shot and it is still overexposed. But then I put my lense back to the original 100mm and it is fine.
Even if I put my aperture at 32 it still comes out way over exposed if I want to do a close up. The wierd thing is two days later it'll take the close up fine and the full shots are overexposed. It is pretty frustarting.

Like I said before, this all with me staying in one spot and not moving my lights ( one main on the left, one back light on right, and one fill light over my head).

All this has happend the last 3 times I have tried to shoot , but had no problems at all when I first got the camera.

I'm I doing something obviously wrong here? Did I maybe change a setting in the camera by mistake? Could this be something wrong with the camera?

Any light you can shed on this would be a great help. Or maybe have me do clear steps to handle this issue.

Thanks so much!!

Nathalie

The Sigma 28-300 isn't a constant-aperture lens (as you zoom, the max. aperture changes from f/3.5 to f/6.3 - about 2 stops), but at f/11, it should be able to maintain your aperture.

Are these pictures in available light, or are you using a flash (and, if so, what flash)?

Can you post a couple of example photos here? One that worked and one that didn't, and include the EXIF dat, which is recorded whenever you take a picture and which most photo-editing and -viewing programs will read?

My viewfinder went dark when taking more pics and now it wont take any more pictures. Everything else seems to be working fine (battery, focusing, settings ect) , but the camera wont shoot and the viewfinder is still dark. I've cleared all settings, but nothing.

Help!
Nathalie

If your viewfinder is black then your Miror must be stuck open which is bad. It could be your shutter as well that is stuck. Take the lens off and have a look he mirror should be stairing you in the face on about a 45 degree angle if everything is OK. The only good thing is that it is still under warranty. Take it back to whare you bought it and get it repaired or repalced. Try not to get discouraged because it really is a great camera I love mine

It could be a compatability problem between your Sigma lens and your Canon camera. Do you have any Canon lenses yuo can try?

Is your viewfinder dark or completely black? If it just dark the lens has probably stopped down and not opened up again. Try turning off your camera and removing the batteries from the camera. Look through the viewfinder and see if it is lighter. It won't be in focus without a lens on the camera. Put the batteries back in and check again to see if the viewfinder is still dark. If it is your camera has to go back for service. If it is light I would put a Canon EOS lens on and check out how the camera performs. Borrow one if you don't have one. If the camera works OK with the Canon lens it must be a problem with the Sigma lens. Contact Sigma and get instructions about how to send the lens back for repairs.

Thanks so much everyone for your help and replies, it was really appreaciated.

I put a Canon lense on the camera and everything seems to working just fine

There must be something wrong with the Sigma lense. Now I wonder if it Is worth getting checked out or repaired. Anyhow I'm just happy it's not the camera.

Thanks again!
Nathalie