Mamiya Super 23 with 100/3.5 lens way out of focus, need advice

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setyotomo

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Hi guys,

After looking for a while, finally I bought a Super 23 with 65/6.3 lens, multi format back, a ground glass. Everything seems ok, focus is accurate , RF well alligned. It's a user wear working setup.

and then i decided to get the 100/3.5 from the bay (from high reputation seller) with almost mint condition. But i just realized, after 2 rolls in 2-3 months (yes, 98% i shoot with my M2) the negative looks waay out of focus :bang:, just 1 frame survived, and that frame is using my 65mm lens.

So last night i slap the ground glass, and :bang: it's way out of focus...(yes i put it on normal - not collapsed) so i retract the bellow to the max, and it's still need about 1cm more to get it right.

After do some reading, i believe this 100/3.5 lens do not have "cam adjustment" because it fixed.

so does anyone have any ideas?

my lens looks like this one:
http://members.cox.net/gmhsint/images/100mm405lensside.jpg
Source : http://members.cox.net/gmhsint/100mm405lens.html
 
So far as I know, the only lens not RF coupled, is the 250mm f/8. It must be scale focused. The 100mm f/3.5 is RF coupled. I would guess someone has changed the cam for adjustment. I only learned recently that was possible. There are screws on the cam that allow that. That is assuming you have the cam and it wasn't removed by someone and never replaced.
 
The bellows should pretty much cover the missing extension when the lens is collapsed, so that you can use rear tilt at infinity. Which makes your dimension of misfocus rather worse than explainable by the amounts of extension available on camera and lens. The adjustment range for the cam can hardly be big enough to compensate for all the cumulative extension of uncollapsed lens plus bellows plus fully extended helicoid.

That is, the lens seems to have a wrong focal length. Is it missing its rear cell? Or is the cell spacing/order mixed up?
 
@oftheherd: thanks, which screws that adjust the cam? I think I have the guts to do it, just wanted to make sure which one. Is it the red or the green one? If not to difficult I'll try it myself.



Uploaded with ImageShack.us

Please note this picture is not my actual lens..i just do not have any digital laying around right now.
 
sevo said:
The adjustment range for the cam can hardly be big enough to compensate for all the cumulative extension of uncollapsed lens plus bellows plus fully extended helicoid.

That is, the lens seems to have a wrong focal length. Is it missing its rear cell? Or is the cell spacing/order mixed up?
Click to expand...
comparing to a "normal" lens i just attached above, it seems not missing anything.. I will try to take a picture of it once i have my digicam near me

thank you again for your advice,

Edit: here is the picture of my lens (i scanned it, so this is the best angle i got right now)


Uploaded with ImageShack.us
 
Last edited:
Well, I couldn't find what I was looking for, but I a sure I am right, it is the red. There was a thread a few months back that mentioned that and showed the proper screws. I don't recall that it gave any instructions though. I guess you would just have to use a ground glass or wax paper, to check each minor adjustment.

I do wonder if sevo is right about that being too much out of focus for the adjustments. Have you looked for signs of scratched screws that might indicate someone has already been in the lens and put an element in backwards? I don't know if that would account for it or not. You might ask Brian Sweeny if that is possible from a reversed lens. Are the bellows all the way closed?

As long as your 65mm is working correctly, I would guess the RF system and rest of the camera is working, so it has to be the 100mm lens. I am not familiar with that lens, since I have the latter black 55mm filter ring model.
 
oftheherd said:
I do wonder if sevo is right about that being too much out of focus for the adjustments. Have you looked for signs of scratched screws that might indicate someone has already been in the lens and put an element in backwards?
Click to expand...
as from my 2nd picture above (my real lens), you can see the "red" spot screws has been painted in black, so i believe that is the sign that someone has opened the lens. I suspected also someone make a "mistake" when put it all together. If this is true, I will go to repairman.

oftheherd said:
I don't know if that would account for it or not. You might ask Brian Sweeny if that is possible from a reversed lens. Are the bellows all the way closed?
Click to expand...
Yes i all the way closed, and it works perfectly with my 65mm lens.

Thank you for your input, it helps 🙂
 
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