What lens for a Canon EOS400D?

[johnf3f]

Because I was holding the filter whilst putting it's case back in my camera bag, looked down at the filter to check it was the right way round then noticed this effect as the camera was underneath. Quite simple really - blind chance!
The shaded pattern seen was suggestive of the LCD screen being under stress at a few points, looked at my 5d and a friends 20d at the same time and did not see this effect, so I investigated further.
Hope this clarifies.
I frequently look at the world through rose tinted glasses but rarely through polarising filters!