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 MARK III
D3s
D100
30D
7D
D700
D90
40D
1D MARK 4
D2
D80
50D
D1
D70, D70s
1D
D60
1D...