The Hoodman HoodEYE eyecup is a great way to prevent excessive ambient light from entering your viewfinder. By removing your camera's eyepiece and substituting the HoodEYE, you can improve your viewfinder clarity.
HoodEYE/SLR Camera Model Compatibility Chart
H-EYEN22R
H-EYEN22S
H-EYEC18
H-EYEC22
H-EYEC18L
NIKON ROUND
NIKON SQUARE
CANON STANDARD
CANON LARGER
CANON LONG
EYEPIECE
EYEPIECE
EYEPIECE
EYEPIECE
EYEPIECE
5D
D3
D300, D300s
10D
1D MARK III
5D MARKII
D3x
D200
20D
1Ds...