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How to calibrate a Richter R2 AutoCollimator? ..& collimating collimator lenses?!


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Hello all,

I have recently moved to the other side of the world and upon unpacking my things and setting up my Richter test bench - I noticed the small screw holding the reticle of my R2 autocollimator had loosened and that the reticle had slid out the barrel where it usually is. I put the reticle back in its place but am not sure of its exact positioning? moving it forward or backwards must obviously affect infinity. ..so basically - how do you calibrate an r2 autocollimator?

I also recently purchased two richter lenses to add to my kit - obviously i am having issues with the reticle (see above) - but assuming i get the issue resolved soon - can the collimator lenses be in need of collimation themselves? ..and if so, after checking how compensate for any discrepancy? do you need to move the lenses only glass forward or back? or do you simply have to mark how far down the thread you have to screw them into their respective c-mount?

I appreciate any feedback and help as to how to resolve this issue. Thanks in advance.

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The quick and dirty way to check if the reticle is in its place is to mount one of the collimator objectives on the eyepiece and point it at a mirror while looking through (as though collimating a lens). Assuming the objective is properly calibrated, the reticle should look sharp in the eyepiece. If it isn't, then you have to determine whether the other objectives have the same problem. If they all look soft, then the reticle probably needs to be adjusted. If some are sharp and others aren't, then you need to decide which variables to start eliminating.

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Hey Alex,

Thanks for the reply. ..mount a collimator objective on the eyepiece? ..Do you mean to connect the eyepiece to the back (light source) of the R2 and mount the objective in its regular lens port? ..and then look into a mirror. (think i've either read or heard that before)


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I apologize, my original instructions were not terribly clear. I have an LED flashlight on my Richter, so I was envisioning taking the whole autocollimator assembly (light source, eyepiece, and objective) into, say, a bathroom and pointing the whole thing at a mirror. The more reasonable method would be to just get a small hand mirror and place it in front of the objective without taking the whole thing off the rails. The rest of the process is the same.

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Hey again Alex,

Thanks a lot for that. Am away on shoots these next few days. Sure to try this as soon as I get back.
..as I, kind of' alluded too above; I have also heard something about mounting the eyepiece to the light source "socket" and looking at the moon or something as such - know anything about that?

Thanks again. Will post back with what happens.

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Pointing the eyepiece assembly at something like the moon will tell you if the objective/eyepiece are properly calibrated, but placing a mirror in front of the whole thing with the light source turned on will also tell you if your reticle is calibrated as well.

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  • 3 years later...

 

Nicolas,

 

I’m sorry I didn’t notice this when you posted it. Also it was just before I began working in this problem.

Over the last four years, I’ve spent a lot of time on this issue. I’ve discovered that the Richter collimators tend to go out of calibration.

Whether it is due to time, mishandling or users tampering with the components is not clear. The most recent Richter Cine products are already over 20 years old.

There is no way for a user to get an accurate do-it-yourself calibration, at least not to today’s standards. For this reason I started to offer a calibration service in late 2017.

One day in 2018, back when I was based in Burbank, CA, I tested 20 Richter Cine collimator objectives on the same day. The test was done using my Moeller-Wedel collimator.

Alex Nelson was present for some of this testing and we calibrated his objectives. The result was surprising: ALL 20 objectives tested at a different back focus!

I was able to determine the correct focus setting and began calibrating objectives to a standard.

Calibrating the R-2 Collimator Block is complicated by the very poor quality eyepiece and the fact that the reticle is held in a smooth sided tube with a single set screw holding it. Also you have to calibrate the grid reticle as well.

Currently I calibrate the R-2 Blocks on my Moeller collimator, using a procedure I have developed over time. The procedure I use does not involve looking through the Richter collimator itself.

I am now able to get focus accuracy of 0.002mm or better on the Richter Collimator systems after calibration.

There is more information about this on my website: cinematechnic.com

Hope this helps. I know its a big problem shipping things in-out of South America. If you’re still in Peru perhaps the people at ESO can help you.

 

 

 

 

 

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