Graflex.org

worldphoto · Posted: Wed Feb 19, 2003 7:29 pm Post subject:

Hi
After several tries I've finally won a lensboard to mount my 127mm f/4.7 Kodak Ektar lens for my 4x5 Crown. My camera already came with stops for 135mm and 152mm lenses. I realize there isn't room to add stops for the 127mm but I do need to determine the infinity stop location on the camera's rail. Any ideas?
P.S. I already have the 127mm cam and mask for my top mounted rengefinder.

[ This Message was edited by: worldphoto on 2003-02-19 11:33 ]

45PSS · Posted: Wed Feb 19, 2003 11:27 pm Post subject:

Simple,
Mount the camera with lens on a sturdy tripod, open the bed to 90⁰, turn the focus knob counter clock wise to run the rails all the way into the camera body then clockwise to extend the rails 1/8 inch, point the camera at an object with sharp verticle lines that is at least 1/2 mile away, and move the front standard only until the image is sharp on the ground glass with the standard locked in place. Slide infinity stops up to touch the standard or mark the rails.
The rail starting position is Graflex's starting position for calibrating the range finder.
Use a loupe to get the verticle lines sharp.
Charles

_________________
While a picture may be worth a thousand words, a quality photograph is worth a million.

[ This Message was edited by: 45PSS on 2003-02-19 15:29 ]

worldphoto · Posted: Thu Feb 20, 2003 12:00 am Post subject:

That's great Charles, your directions are very clear and easy to follow.
Harry

Les · Joined: 09 May 2001 Posts: 2682 Location: Detroit, MI

Another trick, if you have the tools is to make a spacer. Follow the above directions, then measure with a pair of dial calipers the exact distance the standard is away from the 135mm or even the other infinity stops. Make a block of hard wood, plastic or aluminum this lenght and the width of the rails. Now when you want to use the 127 you can drop this in front of the standard and run it up against the stops for the other lens.

Les

_________________
"In order to invent, you need a good imagination and a lot of junk" Thomas Edison

worldphoto · Posted: Fri Feb 21, 2003 4:36 am Post subject:

Thanks Les, I will make a spacer as you say.
I've never been shy about exposing my ignorance.... So I had the bright idea that once one infinity stop for a particular lens such as my 152mm was set that all I would have to do was add or subtract the different length lens to set its' infinity stop. The difference between my 152 and 135 is 17mm but the actual different set is nearly 20mm. Don't figure?
Any ideas why?
Harry

45PSS · Posted: Fri Feb 21, 2003 5:09 am Post subject:

Production varrances results in lens being +/- 2 to 3 mm in focal length. Look at the different cams for varrious lens here http://www.graflex.org/speed-graphic/top-rangefinder-cams.html and here http://www.graflex.org/speed-graphic/super-graphic-cams.html . Focal lengths were determined with optical measureing equipement. One may be able to approximate the exact focal length of their lens by carefully focusing on infinity, measure from the film plane to the center of the lens board (lens optical axis prefered) and subtract any pre calibration rail extension of the camera.
Charles

_________________
While a picture may be worth a thousand words, a quality photograph is worth a million.

[ This Message was edited by: 45PSS on 2003-02-20 21:17 ]

worldphoto · Posted: Fri Feb 21, 2003 3:56 pm Post subject:

Thanks again Charles, that clears it up for me. I have always gotten sharp images with those two lens infinity settings using my rangefinder. Now I know why!
Harry