Industar 61 focus off by feet

[Robmtdew]

I recently picked up an Industar 61. I shot a roll through my M3 and the majority of the images were badly out of focus. In one image it looks like things are somewhat sharp about 20 feet behind the object that I was focusing on. Today while looking at the lens, I discovered that the rear retaining ring was very loose (close to 3 complete turns). Would this most likely be the reason why things are so out of focus?

Rob

 

[former member]

Loose rings are bad things.

But- if the focus is 20ft behind the subject, the optics are sitting too close to the film by a few millimeters. That is hard to do with an I-61, it does not use a regular shim.When focus is off by this much, something was misassembled such as the helical, or something missing.

This thread might help:

http://rangefinderforum.com/forums/showthread.php?t=91163&highlight=industar

 

[Robmtdew]

Thanks Brian. I was hoping that it was just the retaining ring but suspected that the helical was started at the wrong thread. There's a lot of evidence of prior tinkering. I guess at this point it's a matter of identifying the correct starting point on the helical via trial and error and then using a ground glass at the film gate. Thanks again.

Rob

 

[former member]

At 3ft, close focus, the RF cam should be about flush with the mount. That is how I determine when I get the correct starting thread.

Good luck.

 

[Chinasaur]

Brian, do you work on Industar-61's as well as Jupiters?

 

[former member]

I posted a DIY thread for the Industar-61, here:

http://rangefinderforum.com/forums/showthread.php?t=91163&highlight=industar

I do not work on them, except for these project threads.

 

[John Shriver]

Other check is that the RF ring should protrude 7.5mm from the lens mounting plane when focused at infinity.

 

[Chinasaur]

I'm not a DIY'r and don't have the tools or dexterity even if I did want to do the work myself.

So who DOES work on these lenses? 😕

 

[brachal]

I'm not a DIY'r and don't have the tools or dexterity even if I did want to do the work myself.

So who DOES work on these lenses? 😕

I like Industars, but it's usually cheaper to just get a new one than to have one repaired. You could try the repair service at fedka.com.