trittium
Well-known
What is the Proper Method for Calibrating a RF?
My M2 has become misaligned, and I have a conundrum. I have no money to get it properly aligned; and want it done asap. I know aligning the rangefinder is a pretty simple process. I technically know how to do it (i.e. I know where the screws are, and how to turn a screw driver), but I am unsure of the process. I hiked to a cliff to get an infinity focus, but it is still slightly off. So here are my question...
Should I calibrate to infinity, then calibrate a close focus reference, or visa versa?
At what distance should I do a close focus calibration?
How do I set up the close focus set up? Tripod & measuring tape?
Do I measure to the front of the lens, flange, or film plane?
Thanks. I think this information would help the RFF community greatly.
My M2 has become misaligned, and I have a conundrum. I have no money to get it properly aligned; and want it done asap. I know aligning the rangefinder is a pretty simple process. I technically know how to do it (i.e. I know where the screws are, and how to turn a screw driver), but I am unsure of the process. I hiked to a cliff to get an infinity focus, but it is still slightly off. So here are my question...
Should I calibrate to infinity, then calibrate a close focus reference, or visa versa?
At what distance should I do a close focus calibration?
How do I set up the close focus set up? Tripod & measuring tape?
Do I measure to the front of the lens, flange, or film plane?
Thanks. I think this information would help the RFF community greatly.
ferider
Veteran
Matt,
I usually do vertical first, then infinity horizontal (with a star, and magnifier),
then check close up with tripod, long throw trusted lens
(Nikkor 50/1.4), measuring tape and 3-4 ft. I never had to change
the close focus on my Leica bodies,
they were always on (.25-.5 inch in either direction is OK, from the film plane). if this
ever happens I'll send the camera in.
Bessas are a different matter.
Roland.
I usually do vertical first, then infinity horizontal (with a star, and magnifier),
then check close up with tripod, long throw trusted lens
(Nikkor 50/1.4), measuring tape and 3-4 ft. I never had to change
the close focus on my Leica bodies,
they were always on (.25-.5 inch in either direction is OK, from the film plane). if this
ever happens I'll send the camera in.
Bessas are a different matter.
Roland.
ferider
Veteran
I'm mentioning long throw, since the lens throw should be accuracte
enough for what you want to measure. The Nikkor has a DOF of about 3cm wide open and f1.4 DOF marks.
Roland.
enough for what you want to measure. The Nikkor has a DOF of about 3cm wide open and f1.4 DOF marks.
Roland.
R
ruben
Guest
Hi Matt,
First I don't own any leica, which is already a good start
But I would like to deal with the basic concepts.
There are three things that should go in harmony
a) The real distance vis a vis film plane sharpness.
For this you use a metering tape for let's say one meter, and infinity. And a ground glass or an slr split image screen, with it matted side pointed to the lens, plus a magnifier that can be a 50mm lens, reversed.
b) The Yellow Patch coincidence vis a vis the film plane.
Whenever you have coincidence of yellow patch, you must have sharpness at film plane. Here you deal with the controls moving the yellow patch.
c) The lens (or in other models the camera's) distance scale vis a vis the real distance, comfirmed by sharpness at film plane.
This last alignment has been subject to many controversies in the past, but in my opinion it is necessary for making sure that 1) the lens you are using is correctly aligned, and 2) that the camera mount is at its right place. Otherwise you will not have sharpness with other lenses.
Cheers,
Ruben
First I don't own any leica, which is already a good start
But I would like to deal with the basic concepts.
There are three things that should go in harmony
a) The real distance vis a vis film plane sharpness.
For this you use a metering tape for let's say one meter, and infinity. And a ground glass or an slr split image screen, with it matted side pointed to the lens, plus a magnifier that can be a 50mm lens, reversed.
b) The Yellow Patch coincidence vis a vis the film plane.
Whenever you have coincidence of yellow patch, you must have sharpness at film plane. Here you deal with the controls moving the yellow patch.
c) The lens (or in other models the camera's) distance scale vis a vis the real distance, comfirmed by sharpness at film plane.
This last alignment has been subject to many controversies in the past, but in my opinion it is necessary for making sure that 1) the lens you are using is correctly aligned, and 2) that the camera mount is at its right place. Otherwise you will not have sharpness with other lenses.
Cheers,
Ruben
trittium
Well-known
this helps
since I have no way of telling if the lenses are correct, I guess I should use a leica lens with a long throw that has worked in the past.
Another problem I have is that the horizontal rf screw has been painted over. EEK! Should I use turpentine to remove it? Nail polish remover isn't working.
since I have no way of telling if the lenses are correct, I guess I should use a leica lens with a long throw that has worked in the past.
Another problem I have is that the horizontal rf screw has been painted over. EEK! Should I use turpentine to remove it? Nail polish remover isn't working.
trittium
Well-known
ferider said:
Roland, What's a star and magnifier?
ferider
Veteran
trittium said:
Oh, sorry, "star" like "Northern Star, etc.", at night.
Magnifier, I use a 1.25x magnifier as the ones you get from Hong Kong or
Leitz. Helps a little but is not necessary.
WRT horizontal screw being overpainted - that's bad. Be very careful with
the RF arm - not too much pressure of course. Also, the slit on the screw
is convace, deepest in the middle. Not sure what it was painted with.
If acetone doesn't work, that's weird. Maybe try to scratch it free ?
trittium said:
Your 90/2 sounds perfect for the job.
Roland.
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R
ruben
Guest
trittium said:
If you have performed stage a) and then b) according to my post, and the lens distance scale agree, then the lens is correct.
Now, for the very short distance at the scale on the lens you don't have to be extremely fanatic, and can forgive some two milimeters to each direction from the mark "1m". But at infinity, no mercy at all. This is my approach at least.
Cheers,
Ruben
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ferider
Veteran
ruben said:
Depends on the lens. Check the error that you can make using the DOF
scale. For example on a CV 40/1.4, with 2mm, you would be safely above
f2.8 already, which would not be acceptable for me.
Roland.
R
ruben
Guest
Quote:
Originally Posted by ruben
Now, for the very short distance scale on the lens you don't have to be extremely fanatic, and forgive some two milimeters to each direction from the mark "1m".
Depends on the lens. Check the error that you can make using the DOF scale. For example on a CV 40/1.4, with 2mm, you would be safely above f2.8 already, which would not be acceptable for me.
Roland.
Roland, My Friend,
How can it took you so long
I was starting to think you are not talking with me
Cheers,
Ruben
Matt: Roland is much more experienced than me, no doubt at all. And I remind you I do not own any leica. But I was just basing myself in my limited general knowledge, by which obtaining absolute accuracy both at infinity and at 1m is a matter for Hell. Perhaps with leica models it is a piece of cake, I don't know.
If it is not, then it is more an issue of approach. How much will you be shooting subjects at 1m ?
Provided your infinity setting is absolutely sharp, those 2mm at 1m will be progressively dissolving at 1,5m etc.
Originally Posted by ruben
Now, for the very short distance scale on the lens you don't have to be extremely fanatic, and forgive some two milimeters to each direction from the mark "1m".
Depends on the lens. Check the error that you can make using the DOF scale. For example on a CV 40/1.4, with 2mm, you would be safely above f2.8 already, which would not be acceptable for me.
Roland.
Roland, My Friend,
How can it took you so long
I was starting to think you are not talking with me
Cheers,
Ruben
Matt: Roland is much more experienced than me, no doubt at all. And I remind you I do not own any leica. But I was just basing myself in my limited general knowledge, by which obtaining absolute accuracy both at infinity and at 1m is a matter for Hell. Perhaps with leica models it is a piece of cake, I don't know.
If it is not, then it is more an issue of approach. How much will you be shooting subjects at 1m ?
Provided your infinity setting is absolutely sharp, those 2mm at 1m will be progressively dissolving at 1,5m etc.
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ferider
Veteran
ruben said:Roland, My Friend,
How can it took you so long
I was starting to think you are not talking with me
Cheers,
Ruben
SLRs are so much easier, my friend.... you know I'm a sucker for close up shallow DOF !
trittium
Well-known
ferider said:
I am a sucker for close up shallow DOF too, I never thought to use a magnifying glass, that might be where I went wrong. I like the star idea also. This way I don't have to hike to the top of a mountain with screw drivers and worry about loosing the tiny screws in the dirt.
trittium
Well-known
no fighting you two, lets keep it friendly
I am going to go try the "star" technique
I am going to go try the "star" technique
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ferider
Veteran
Ruben and me are buddies (no sarcasm) ....
Yeah schlepping the 90/2 up the mountain only works if you
also carry a few beers up
Yeah schlepping the 90/2 up the mountain only works if you
also carry a few beers up
trittium
Well-known
ferider said:Ruben and me are buddies (no sarcasm) ....
Yeah schlepping the 90/2 up the mountain only works if you
also carry a few beers up
Definately,
That paint is still giving me a problem. It started to dissolve with the acetone, and I chipped the rest off, but the screw still won't turn. Arg. I am going to keep applying acetone and scraping. Hopefully it will be free soon.
FallisPhoto
Veteran
trittium said:
It isn't enamel. Try lacquer thinner.
Ronald M
Veteran
Set the vertical.
I use a star at night or better yet a bright planet if available.
The close calibration is set at 1 meter from film plane. All leica 50mm lenses are marked with the one meter calibration. This will probably be ok and not need adjustment. If it does, repeat the star, then the close.
Best if you take the bottom inside off and remove the plug so you can access screw properly. The infinity one is easier. Do not put pressure on the arm.
I use a star at night or better yet a bright planet if available.
The close calibration is set at 1 meter from film plane. All leica 50mm lenses are marked with the one meter calibration. This will probably be ok and not need adjustment. If it does, repeat the star, then the close.
Best if you take the bottom inside off and remove the plug so you can access screw properly. The infinity one is easier. Do not put pressure on the arm.