EOS 300D Exposure problems ??

[petrus]

Until recently my Rebel has worked very well, but when I purchesed the 28-135 IS lens, the automatic exposures are completely out of line. It seems the camera tries to use largest possible aperture and slowest possible time as soon as there is a lot of sunshine. The target is just la´ndscape, so no moving target. If anyone is interested to give me expert's advice, I can email two pictures taken within one minute - the other is reasonable, the other is completely overexposed. The reasonable one was with 28mm (1/125 F7.1), the overexposed with 70mm (1/80 F5). I have a Hoya polarizer filter attached as well.
What's the problem - me, camera or lens?
:cry: :cry: :cry:

[Guillermo Freige]

Probably the polarizer. I've read somewhere the polarizers can turn AE crazy.
I'm using a 28-135IS too, and exposures are ok, and totally consistent between them. I've even taken a large series of pictures, at all lens apertures, and all the exposures (from the same subject) were between 1/3 stop.
The problem only happened once, or is consistent?. Sometimes I push AE lock by accident (I noticed it when flash is used because the flash fires), and when that happens and the camera is not aimed to the scene, the exposure is locked to a different scene with probably a very different light level (as the ground, for example), so the picture can turn over or underexposed easily. The * sign in the viewfinder will alert you about an AE lock situation.

[robertwgross]

Petrus, you will get better advice if you can furnish more information. For example, what mode was the camera in? Shutter speed and aperture? ISO setting?

All of that stuff should be included in the EXIF data, which should be attached to the image file.

That gives others a better place to start from in guessing the problem.

---Bob Gross---

[Cadwell]

Try some shots without the polarizer and see what happens.

[scottbergerphoto]

Four possibilities come to mind:
1. You are using a Linear Polarizer instead of a Circular Polarizer.
2. You are shooting a highly backlit scene where small changes in where the lense is pointed have big changes in metering results.
3. You are using partial metering and there are objects of widely varying reflectibity (black/white) and the metering point moves from one shot to the next. (similiar to #2)
4. If you use a tripod, you are not covering the viewfinder on some shots and allowing extraneous light into the camera.
Regards,
Scott

[petrus]

Guillermo,
I was using "creative zone", automatic program "P" no settings canged. In my two reference pictures the data is as follows;
28mm 1/125 F7.1 and the result is acceptable
70mm 1/80 F5 and the result is a catastrophically overexposed picture.
Both shots ar the same landscape, some trees in the foreground (dark) and the open sea in the background (not against the sun). In the 70mm shot, the trees in the foreground are not visible, practically only the sea and the sky! I have several pictures showing the same effect!
I never had such problems with any other lens than this 28-135IS lens (I was using the dedicated Rebel lens 18-55 and a 75-300 Canon before), and I was using circular polarizer before as well!
Any help from this explanation?[/img]

[mttmrphy]

Any chance you could post these photos?

[robertwgross]

Years ago, when I was a non-Canon film camera user, my camera suddenly started giving me shots that were about 5 stops operexposed. I studied all of my shots until I saw the pattern. Everything shot with the 50mm lens were that way, and everything shot with other lenses were normal. So, it was a problem of the lens rather than the camera. To be more specific, it was the coupling of that lens to the camera body. Since it was a 15-year-old camera, and lenses were hard to find, I took that moment to bail out from that camera and buy my first Canon. The rest, as they say, is history.

Make sure you don't have one lens that is screwing you up.

---Bob Gross---

[petrus]

mttmrphy,
find my pictures on the
www.fager.cc
chose English and they are at the bottom of the page.

[scottbergerphoto]

I just looked at the two pictures at the bottom of your homepage. That is a very tricky situation, and that is backlighting. If your camera meters the trees, the picture gets blown out, if it meters the sky, it gets underexposed. It all depends on where the exposure is biased. I suggest you retake the pictures using manual exposure and partial metering. Try to meter off something midway between the bright sky and the dark trees.
Regards,
Scott

[petrus]

Yes, I am aware of that now, but the original question remain - why is this 28 - 135 mm lens performing differently when it comes to light metering than the bundled 18 - 55mm? Today I have made several te4st shots under conditions where half the picture is bright white wall and half is dark window. The 28-135mm lens (using 28mm) is doing worse with automatic settings, while the other (at about the same focal length) is much more forgiving.
It seems I am in for a lot of learning!

[Tom W]

Just an idea, but you may want to try and clean the electical contacts on the lens to make sure that it is communicating properly with the camera. It may have an intermittent connection from a dirty contact that is passing erronious aperture information between the camera and the lens.

[scottbergerphoto]

As an additional check, measure an 18% Grey Card in the same lighting with both lenses. Make sure that the Grey Card fills the viewfinder in both shots. Check to see that the meter readings are the same. If they are different, then there is a mechanical problem somewhere.
Scott

[petrus]

Hi and thank you,
I will get the grey card and check.
Additionally I have done other tests and found, that the meter reading can be very different by just shifting the camera a few degrees only. Somehow it seems the 28-135 lens is much more critical than the 18-55, and probably also a lot better and therefore more demanding.

[petrus]

Hi again,

should anyone of you who tried to help me out on the exposure problem happen to see this post, it is just to let you know that I took the camera to the Canon repair shop and got it back again in perfect working condition. The verdict was: measruing recalibrated (software only), I was told the measuring system was completely out of order. Unfortunately nobody could explain why - so I never got to know what to avoid in future.....

[robertwgross]

In a technical repair shop like that, it is best for the shop if they write a simple report:

"Found the problem. Replaced the part. Tested it. OK now."

The more detail they provide, the more leverage it gives to the customer on future problems that may or may not be related.

---Bob Gross---