Re: Wista 45DX focusing problem, astigmatism? Try a bright screen?
Originally Posted by Bob Salomon - HP Marketing
To adjust the focus of your loupe properly. Turn on a light in front of the camera, remove the lens. Focus your loupe on the ground glass until the grain of the gg is in sharp focus. Now put your lens back on and shoot.
Assuming that you have a Wista gg and a Wista fresnel installed on your camera and assuming that you had not focused your loupe then when you placed your loupe on the fresnel and focused you were out of focus by the thickness of the fresnel + the thickness of the gg + any space between the 2.
If you don't have the fresnel then you would have been out of focus by the thickness of the gg.
In photographic terms those can be large errors in focus.
Great, this is helpful. When I adjust my loupe I can focus either on a sand pattern (which I assume is the grain of the glass?) or on a series of concentric thin black lines (the fresnel?). I should focus on the sand pattern, right?