Mamiya Super 23 Focusing Issue

[Curtis Miller]

I'm having a problem with a Super 23 that I just bought. I shot a roll of film to find that none of the pictures were even remotely in focus. My first thought was that it might need the rangefinder adjusted. Today, I put a ground glass on the film plane (I'm waiting for an official ground glass attachment to arrive) and I found that the lens will not focus anywhere near the right minimum distance. When I am focused all the way in on a subject at about 1 meter, the image is very blurry. The subject is in focus at about 8 feet when at minimum focus on the barrel. It reaches infinity at about 4.5 feet on the lens barrel. I moved the bellows out about 1/4" and it focuses about as it should.

I can't see what could be adjusted on the lens, but maybe someone can enlighten me. Is there a way that the lens could be adjusted to change the film plane offset? Could it be put together incorrectly? Could there be something amiss at the back of the camera causing the film plane to be off? The bellows were locked all the way down tight and I have a simple 6 x 7 back on it. I also shot with a 6 x 9 back with the same results.

 

[Grim Tuesday]

What lens do you have on there? Some of them are collapsible. I assume you have un-collapsed them, right?

 

[Curtis Miller]

No, I did not know the lens was collapsible! It's the 100mm 3.5. I expanded it and I'm all set. Guess that's what these forums are for! Thanks.

 

[Mamiya_Repair]

A feature of the Mamiya Super 23 is a "lens barrel retraction warning signal". If a lens is installed that is not extended, the rangefinder patch will show a red signal. However, the lens has to be focused from around 30 feet to infinity for this feature to work. And the red signal is very faint. So not all that useful and while this warning system was used on the Mamiya Press and Super 23, it was dropped by the time the Universal came into production.
Bill

 

[Neil Poulsen]

Perhaps the range finder apparatus needs to be internally adjusted? Here's how . . .

Lifting off the aluminum colored housing on top of the camera (single screws on left and right side of housing), one can find two internal screws for adjusting the range finder. You also have to remove the knob that changes the frame lines between 100, 150, 250.

At the rear of the camera, you will find two screws that are located just to the left of center.

NEAR FOCUS: This screw is at a 45 degree angle.
INFINITY FOCUS: This screw is just to the left of the NEAR FOCUS screw.

First adjust INFINITY FOCUS. Point camera to a target at infinity with 100mm f3.5 lens attached and adjust the focus so that the lens is closest to the film. (Infinity focus.) Next, adjust the INFINITY FOCUS screw until the range finder shows this target in focus.

After completing this step, point the camera to a target that is much nearer, maybe 10 feet or a little under. Using your ground glass, adjust the lens so that this target is in focus on the ground glass. Next, adjust the NEAR FOCUS screw so that this target is shown in focus by the range finder. (Don't change the lens, just the NEAR FOCUS screw.)

Check the infinity focus again to see if the range finder is still accurate by pointing camera back to the infinity target. If not, adjust INFINITY FOCUS screw a second time as above. Then, it may be necessary to point camera again to nearer target and make a minor adjustment to the NEAR FOCUS screw.

Put housing back on top of camera.

For 150mm lens, there should be a screw on the inside of the lens itself. (Mine has one.) Point lens at a target that's 12-15 feet away and adjust the lens so this target is in focus on the ground glass. Then, adjust the internal screw until the range finder shows the camera to be in focus on this target. For the 250mm lens, pick a near target at about 20-25 feet and do the same with the internal screw in the lens. I don't believe that these adjustments affect the range finder when the camera is at infinity focus. (At least, hopefully not!)

50mm and 65mm lenses can be a problem, because they may not have these lens internal screws. Getting them "perfectly" correct can involve adding or subtracting shims using a process that I don't understand. But with their wide-angle depth of field, especially at small apertures, they maybe don't need to be perfect anyway. (Since when are range finders perfect?)

I got this focusing adjustment process from a post by Roger Krueger at 1:15pm on Feb. 6, 2002 at www.photo.net from the Medium Format Forum. (One of the sub-forums.) He wrote something a little different than the above. It's also worth reading his post. Oh, the applicable thread has a title, "Calibrating Range Finder in Mamiya Press Universal." (Process is the same for Super23.)

 

[Daire Quinlan]

Except that that post by Roger Krueger, and most other posts on the net, are actually wrong. There's a simple adjustment screw, and an elliptical cam screw that adjusts the tracking. That 45 degree 'infinity adjustment' screw that everyone talks about is just a stop screw. It has no effect on the rangefinder tracking.

Flickr discussion here https://www.flickr.com/groups/18528883@N00/discuss/72157640597185714/

Unfortunately the repair manual referenced in that post seems to have disappeared.

 

[pentaxpete]

I did a VIDEO on MY Super 23 -- you can see it here :