| Author |
Message |
    
Bill
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 26, 2004 - 12:57 pm: | 
|
Hello.
Cameras in question: Konica T-4, Konica TC, any SLR manual focus camera body with TTL pentaprism viewer.
I'm slightly confused as to setting/checking the infinity setting on any camera lens if you can't be sure that the perfectly corrected & focused image in the viewfinder is what is also in perfect focus on the film plane.
How do you check that the focusing screen is correct with the film plane, never mind the lens being correctly set.
In what order does one proceed?
It seems to me that you would need a perfectly calibrated, interchangable lens FIRST, then proceed to test the film plane focus with some method that I don't yet know.
How do I do this correctly??
Thanks for any help. -Bill |
Jan Dvorak
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 26, 2004 - 01:46 pm: |
|
Bill,
Without having special equipment (collimator), proceed as follows:
1) Mount your camera on a tripod, open the back and using a cable relase, lock the shutter open at the 'B' setting.
2) Use a ground glass, positioned on the film plane rails to check your infinity focus. Use a magnifier to check the image on the ground glass.
3) When your lens is set to infinity, the film plane image shoud be sharp.
4) If the film plane ground glass image is sharp at infinity when your lens is set to infinity, check the finder image. If it also indicates correct focus, all is well.
If the finder image disagrees with your film plane, problem could be either a finder screen or your mirror out of alignment.
If both the screen at film plane and the focusing screen agree at infinity while your lens is not at infinity, problem would be with the lens.
I hope all this makes sense...
Good luck,
Jan |
Peter Wallage
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 26, 2004 - 02:01 pm: |
|
I know lots of people use a screen in the film plane, and focus on a distant object, but IMHO the best, and easiest, way to set a lens at infinity is to use a second camera (an SLR), and the 'backsighting' method. It has to be spot on because you are in effect using the two cameras as a collimator.
There was, I thought, a feature about this method in Favorite Classics somewhere, with Kar Yan Mak holding the camera, but I can't find it. Where is it, Henry?
Peter |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 26, 2004 - 02:27 pm: |
|
On many, if not all, SLRs the focussing screen is adjustable, too. Since correct focus in the film plane is most important, this must be adjusted first. |
Henry
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 26, 2004 - 06:08 pm: |
|
https://kyp.hauslendale.com/classics/collimator.html
In this article we show a couple ways to go about it.
Henry |
Matt Denton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 27, 2004 - 10:07 am: |
|
Additional note -- many SLR viewfinder screens I've taken off have a shim of some kind, sometimes it's part of the meter display, sometimes it's not. It just occurred to me that if one has been taken apart before the shim could be missing and the viewfinder could indeed register an out of focus image. So I agree with the check against film plane focus as a way of verifying this.
Note that the shims in question are amazingly thin....and probably only replaced from a junk camera if missing.
Matt |
|
