one90guy
Well-known
Been trying to adjust focus on a C-3 that I rebuilt. Would reindexing lens change focus? So far thats all I have not done, had a hard time with lens to start with. All thought and suggestions welcome
David
David
L David Tomei
Well-known
I'm always learning something new here, so pardon my ignorance. What kind of indexing are you referring to?
farlymac
PF McFarland
First, one would need to know just how drastic you were with the rebuild. In other words, just what did you do to it in the first place to throw the focus off? Or is it just the lens you are using? I've never taken a C-3 that far apart to know what the lens flange looks like on the inside, but I'm kind of sceptical about it being able to be indexed wrong.
Most manufacturers put some kind of flat spot in the flange that will only alllow it to be placed on the camera in the proper indexing position. Did you get all shims back in properly? You would need a depth gauge to measure the distance from the flange to the film plane at all points around the diameter of the flange to see if the shims are correct.
After all that, then you need to look at the lens, to see if it was reassembled correctly. You might find some good information at http://www.arguscg.org/ or at http://arguscg.tripod.com/Repairing_the_Argus_C3.htm
PF
Most manufacturers put some kind of flat spot in the flange that will only alllow it to be placed on the camera in the proper indexing position. Did you get all shims back in properly? You would need a depth gauge to measure the distance from the flange to the film plane at all points around the diameter of the flange to see if the shims are correct.
After all that, then you need to look at the lens, to see if it was reassembled correctly. You might find some good information at http://www.arguscg.org/ or at http://arguscg.tripod.com/Repairing_the_Argus_C3.htm
PF
farlymac
PF McFarland
Lenses are indexed so that when they are fully seated on the flange at the proper distance from the film plane, the center mark on the lens should be at top-dead-center (the first landing on the M42 mount thread is always in the same place). Problems arise when newer lenses are placed on cameras that used the original Practika indexing, instead of the Pentax indexing, such as Yashica did with their M42 mount cameras. The lens will still focus correctly, it just doesn't line up when you look down on the top of the camera, usually by around 10 degrees past vertical.
Some Argus Sandmar 100mm lenses have center mark alignment problems that can be adjusted by loosening a couple of screws, and turning the barrel until it's properly lined up. This does not affect the focusing of the lens, from what I have read. I'll find out when I adjust mine.
PF
L David Tomei
Well-known
Thank you, Farlymac. After 25 years I had never used the word "indexing" like that... I would have referred to registration and collimation. Now I know that it refers to "index" marks. "Too soon old, too late schmart", as my aunt used to tell me.
Ciao
Ciao
greyelm
Malcolm
Sorry if I've misunderstood your problem but page 20 pf the C3 manual describes how to reset the rangefinder when replacing a lens. Is this what you meant?
http://www.cameramanuals.org/argus/argus_c-3.pdf
http://www.cameramanuals.org/argus/argus_c-3.pdf
J.Ed
Established
Did you disassemble the lens? The focusing helix has 8 threads. This means there are 8 places where you can start the lens sections together, only one is correct. Have you tried checking the focus with a ground glass (or equivalent) on the film plane? The Argus Collectors Group site has specifics for resetting the rangefinder, if needed.
Steve M.
Mentor
Sounds like you disassembled the lens, and started the helicoil threads at the wrong starting place. I know all about this one, as an Argus C4 was the first camera I overhauled (w/ nothing but a flat blade screwdriver). I didn't know anything was wrong until I took some photos and the focus was WAY off).
If that's possibly what you did, it's easy enough to fix. Take the back off the camera and figure out a way to strap it to a tripod and point it at something across the street. Take the lens off, then take some Scotch Magic tape and put a piece across the camera's film plane. Set the lens to infinity, and using a loupe (or a lens) see if your image on the tape is in focus. If not, and it sounds like it won't be, then take the lens apart and restart the threads at a different place. Make a little mark on the lens body w/ a pen so that you don't restart things in the same place over and over. Now, set the lens to infinity and see if you're in focus in the back. Keep doing this until you get to a point where it's sharp in the back when you have the lens at infinity.
There's a lot of info on the web if you also need to reset the rangefinder. Mine took wonderful photos once I got everything right, but the sound of the shutter finally drove me nuts and I left the camera when we moved last time.
If that's possibly what you did, it's easy enough to fix. Take the back off the camera and figure out a way to strap it to a tripod and point it at something across the street. Take the lens off, then take some Scotch Magic tape and put a piece across the camera's film plane. Set the lens to infinity, and using a loupe (or a lens) see if your image on the tape is in focus. If not, and it sounds like it won't be, then take the lens apart and restart the threads at a different place. Make a little mark on the lens body w/ a pen so that you don't restart things in the same place over and over. Now, set the lens to infinity and see if you're in focus in the back. Keep doing this until you get to a point where it's sharp in the back when you have the lens at infinity.
There's a lot of info on the web if you also need to reset the rangefinder. Mine took wonderful photos once I got everything right, but the sound of the shutter finally drove me nuts and I left the camera when we moved last time.
one90guy
Well-known
Thanks for all the replies. I did a total tear down on lens and feel confident it is reassembled correctly, in fact Ive taken it apart many times looking for a problem. I used the Argus directions for setting the focus, if I set focus for 15 feet and then set for infinity the short focus is off if short focus is set then infinity is off again. This is my first time to take a lens apart so I am out of my comfort zone.
Steve I had not consider that, I believe I have been taking to big a swing at adjusting.
Back to the bench and start over. Will post my results, been definitly a learning experience.
David
Steve I had not consider that, I believe I have been taking to big a swing at adjusting.
Back to the bench and start over. Will post my results, been definitly a learning experience.
David
one90guy
Well-known
Finally have the range finder adjusted, after several weeks cool down. Reread directions, made very small adjustments and in 10 minutes prefect. I was just way over adjusting, so easy but I had to make it so difficult.