How to adjust focusing screen
Dec 21, 2008
Hello. I just learned that the ground glass focusing screen in my Olympus E-510
is out of proper position. It does not show the true focus of the camera, which
makes manual focus very difficult.
Worse yet, it turns out that this is standard for the Olympus E-volt series
of cameras. They don't adjust the focusing screens at the factory,
except for in the E-3.
So Olympus won't fix it. The focusing screen is considered fixed, and
non-adjustable. So I have to fix it myself.
The real focusing point is in front of the point where it appears to be in
the viewfinder. That is, if I lay a newspaper on the ground, and shoot
at a particular line of text from a very shallow angle, the line of text that
is clearest and in sharpest focus in the photograph is closer to me than
the target that I focused on.
So, does the focusing screen need to be moved closer to the mirror (down),
or further away (up)?
Are there any equations or approximations that could help in guessing
how much I need to shim the ground glass? How many thousandths of
an inch are we talking about, roughly, to shift the focusing distance by