step down filter adaptors

[foxbat]

I'm considering getting one of these to enable fitting a 67mm polarizer to a 77mm lens but am concerned that this is going to obscure 5mm from around the perimeter of the 77mm lens. Will this be visible in shots taken with the 300D?

[thomascanty]

That's going down quite a ways, but I'd think you should still be ok, considering the 300D's 1.6x crop factor. I've stacked two 72mm ND filters on a 77-72 stepdown ring on my 10D before with no vignetting.

[mdr]

Quite easy to test. Hold the 67mm polariser in front of the lens, a couple of mm away from the lens to compensate for the stepping down ring and take a photo of a light wall.

But then again. Just buy the step down ring as most you'll loose is a couple of quid.