Hello,
I just bought a B+W filter for my 21mm lens. It says on the filter the filter factor is 4x which i understood to be +2 stops. I've just checked this out and found something strange.
Without the filter, I get a "correct" exposure reading of f8 and 1/2 second.
When I put the filter on the lens, I get a "correct" exposure reading of f5.6 and 1/2 second.
(by "correct" I mean the two triangles appear in the viewfinder)
I would have thought that leaving the shutter speed at 1/2 second, I would need to change the aperture to f4.
Or am I being stupid and not realising f5.6 IS 2 stops away from f8.
Any suggestions would be greatly appreciated.
Stuart
I just bought a B+W filter for my 21mm lens. It says on the filter the filter factor is 4x which i understood to be +2 stops. I've just checked this out and found something strange.
Without the filter, I get a "correct" exposure reading of f8 and 1/2 second.
When I put the filter on the lens, I get a "correct" exposure reading of f5.6 and 1/2 second.
(by "correct" I mean the two triangles appear in the viewfinder)
I would have thought that leaving the shutter speed at 1/2 second, I would need to change the aperture to f4.
Or am I being stupid and not realising f5.6 IS 2 stops away from f8.
Any suggestions would be greatly appreciated.
Stuart