Daire Quinlan
Newbie
Apologies to the mods, I posted this in the general discussion forum originally, I didn't see this repair forum. Probably a better fit for it here
Hi All, I have a Mamiya Super 23 with RF problems.
Originally I adjusted the rangefinder as recommended in countless discussions using the two screws straight/angled for infinity/close focus respectively. Still had a problem. Namely, that I've nailed the closest focus distance, that's super sharp, but then it starts to drift quite dramatically from there. At about 10 feet it's about an inch, 30 feet it looks like a couple of feet.
I then came to the conclusion from examining the mechanism that what's commonly referred to as the 'infinity adjustment screw' in most discussions doesn't actually result in any adjustment at all, it's just an infinity stop. The only adjustment screw is the angled one, and that only enables you to correct linearly for distance.
I only have the 100mm f/3.5 so It's not the lens, I have the ground glass, at the lens' infinity stop the ground glass registers the lens as being on infinity.
So I hunted around for a repair manual and someone on APUG pointed out the the Polaroid 600se repair manual is readily available. I got it, the RF mechanism is identical to the Super 23 so good to go.
So I took to it again over the weekend to try and dial in the focus at both close distance and infinity. I didn't really succeed, partly because I don't understand the function of the eccentric screw that's mentioned in the repair manual.
The repair manual says to use the RF adjustment screw (the one that's at 45', commonly referred to as the 'close focus adjustment' on most discussions that talk about this) to adjust for infinity, and then if the close focus / RF distance is outside of stated allowances (basically about 1mm on the focus ring) to use the 'eccentric screw' to compensate for this. It doesn't go into details :-D
The eccentric screw can be turned, and you can adjust for close focus distance all right, but then infinity is out of whack again, so I'd use the other adjustment screw to re-adjust for infinity, which would throw close focus out of whack again, necessitating another fractional turn of the eccentric screw, which meant the infinity needed adjustment etc etc etc
I went through a couple of iterations of this, and couldn't get both lined up perfectly, so I settled on making sure about 6 feet was dialled in properly and put the top back on again.
Anyone else any experience with this ?
Hi All, I have a Mamiya Super 23 with RF problems.
Originally I adjusted the rangefinder as recommended in countless discussions using the two screws straight/angled for infinity/close focus respectively. Still had a problem. Namely, that I've nailed the closest focus distance, that's super sharp, but then it starts to drift quite dramatically from there. At about 10 feet it's about an inch, 30 feet it looks like a couple of feet.
I then came to the conclusion from examining the mechanism that what's commonly referred to as the 'infinity adjustment screw' in most discussions doesn't actually result in any adjustment at all, it's just an infinity stop. The only adjustment screw is the angled one, and that only enables you to correct linearly for distance.
I only have the 100mm f/3.5 so It's not the lens, I have the ground glass, at the lens' infinity stop the ground glass registers the lens as being on infinity.
So I hunted around for a repair manual and someone on APUG pointed out the the Polaroid 600se repair manual is readily available. I got it, the RF mechanism is identical to the Super 23 so good to go.
So I took to it again over the weekend to try and dial in the focus at both close distance and infinity. I didn't really succeed, partly because I don't understand the function of the eccentric screw that's mentioned in the repair manual.
The repair manual says to use the RF adjustment screw (the one that's at 45', commonly referred to as the 'close focus adjustment' on most discussions that talk about this) to adjust for infinity, and then if the close focus / RF distance is outside of stated allowances (basically about 1mm on the focus ring) to use the 'eccentric screw' to compensate for this. It doesn't go into details :-D
The eccentric screw can be turned, and you can adjust for close focus distance all right, but then infinity is out of whack again, so I'd use the other adjustment screw to re-adjust for infinity, which would throw close focus out of whack again, necessitating another fractional turn of the eccentric screw, which meant the infinity needed adjustment etc etc etc
I went through a couple of iterations of this, and couldn't get both lined up perfectly, so I settled on making sure about 6 feet was dialled in properly and put the top back on again.
Anyone else any experience with this ?
mikemc_photo
Established
focus on infinity first....the stop screw will let you do this. Make sure the beam splitter mirror is square and tight
charjohncarter
Veteran
I did the same as you; it was adjust infinity an infinite number of times. I settled on 10 feet and it seems to work when viewed through the ground glass from 4 feet to 50 feet.
Daire Quinlan
Newbie
The stop screw does nothing, it's just an infinity stop for the rangefinder mechanism. There is one linear adjustment, the screw angled at 45', and apparently one adjustment which allows you to adjust the RF range, the afore mentioned elliptical screw. I'm asking if anyone has actually succeeded in using this elliptical screw to adjust a rangefinder in which a simple linear adjustment did no good.
There is also a brass ring at the back of the lens which makes contact with the rangefinder pin, which is held on by 3 screws, suggesting that perhaps it's amenable to being shimmed selectively which would also adjust the RF range. I may try this if my current adjustment doesn't work out. At the moment It's spot on at 2 metres and out at either end of the scale by an amount on the focus ring less than the marked DOF at f/5.6 so I should be good to go as long as I don't shoot wide open ...