Is there a filter to avoid glass reflection??

[Tasiamay]

I have a Canon Rebel XT with a kit lense. I just purchased the EF 70-300mm f/4-5.6 IS USM. Is there a filter that I can get that will avoid the reflection off of the glass (for instance in full tank shots)? I've tried several methods - no flash, flash, covering the light with a towel, straight on pics, pics at an angle, etc. I don't have an external flash & unfortunately don't have the cash to get one now. This is the best picture I've got, but there's still that nasty reflection.

 

[sven]

polarizer

 

[sven]

since your camera autofocuses through the lens make sure it is a circular polarizer

 

[BlueCorn]

Polarizer's really only work well when the light source is 90 degrees from the focal plane. One should help with what you're dealing with but you'll still need to play with the angle of your shot.

Cheers