# Optical Forums > Optical and Ophthalmic Equipment >  Topcon LM-6E: Calibration

## Kujiradesu

Recently purchased this bonnie beauty of a manual lensometer (lensmeter?). It came with no guarantee of calibration, just that the bulb worked and the reticle is visible through the eyepiece. I have used this particular model for months at my current shop and love it to death. Accurate, reliable, and dots as straight as an arrow. I have much experience repairing and servicing the B&L style vertometers; so I figured that giving this little salaryman of a lensmeter a shine and a polish wouldnt be too difficult.

After receiving the lensmeter, I took her out for a spin and the mires seem to be straight and accurate, the reticle is focused and zeros out nicely. Axis is beautiful and ramrod straight.

My one issue is the prism compensating ring. I can zero it out, and it falls right into dead center of the reticle at 0-180, but when I move the prism axis on the prism compensating ring to 90 it wanders. Im not sure how this can be adjusted, so anyone who has done this work before please let me know how it can be done. Ive googled to no avail. Also, I have access to a Gaugemaster, if that would help in calibrating this (I dont think so, but Its worth throwing out there).

Any help the community could provide would be greatly appreciated. Thanks in advance.

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## Kujiradesu

UPDATE: So Ive been thinking about what to do about this issue since I posted this. Tonight I resolved to disassemble the prism compensation ring and the objective lens of the telescope to see what could be done. I figured, if its hooped I cant make it worse, but I might be able to figure it out. After removing the Prism compensation ring the objective lens fell right out. The wandering of the mires when using the prism compensating ring probably had to do with the fact that the objective lens was loose. There are three set screws that needed to be tightened and adjusted. I centered the objective lens and tightened the set screws, replaced the prism compensation ring and re-centered that using its two set screws, and I was in like sin. Reverified with my Gaugemaster and shes purring like a kitten.

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## Optitech USA

You sound like me. I would lie awake at night thinking about it.

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## O.GVisions

I have a Topcon LM8 and it will not zero out, it becomes clear at +0.50 can would you guys know how i can fix this issue?

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## Kujiradesu

> I have a Topcon LM8 and it will not zero out, it becomes clear at +0.50 can would you guys know how i can fix this issue?


On the B&L 70 there is a set screw on the power drum that allows you to rezero the power. However, Ive never had to make this adjustment on my LM-6E. I would call Reichert and ask them how to make the adjustment.

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## Trina

I have a Topcon LM-6E at work and recently the prism compensating device has gone out of alignment. It's sitting at about 4.5 diopters of prism to be in the center of the reticle and when I try to move it on any axis, it doesn't move completely straight. I've tried taking it apart (big mistake) and I'm unable to get the prisms inside to line up with each other and in the ring (sorry, not sure of all the exact names for the parts!). Is there an easier way to do this or do I have to send it out for repair? Thanks!

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## Trina

> UPDATE: So Ive been thinking about what to do about this issue since I posted this. Tonight I resolved to disassemble the prism compensation ring and the objective lens of the telescope to see what could be done. I figured, if its hooped I cant make it worse, but I might be able to figure it out. After removing the Prism compensation ring the objective lens fell right out. The wandering of the mires when using the prism compensating ring probably had to do with the fact that the objective lens was loose. There are three set screws that needed to be tightened and adjusted. I centered the objective lens and tightened the set screws, replaced the prism compensation ring and re-centered that using its two set screws, and I was in like sin. Reverified with my Gaugemaster and shes purring like a kitten.


I'm having this exact issue! You make it sound so easy. I can't for the life of me get everything centered properly.

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## Trina

> I'm having this exact issue! You make it sound so easy. I can't for the life of me get everything centered properly.


I fixed it! I feel like a genius. Lol. "Why, yes, I AM a lensometer repair man!" Woo hoo!  :Bounce:

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## Kujiradesu

> I fixed it! I feel like a genius. Lol. "Why, yes, I AM a lensometer repair man!" Woo hoo!


Congrats. Sorry I couldnt offer more insight, but it seems you didnt need it anyway. Great job.

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## O.GVisions

> I fixed it! I feel like a genius. Lol. "Why, yes, I AM a lensometer repair man!" Woo hoo!


Sorry im just getting back, i could have gave you some pointers but the way you handled that is actually the best way to learn. I had to dismantle the Lensometer to figure out how to calibrate the axis because mine too will wonder. now thats fixed but ive yet to figure out how to Zero out the lensometer it is still clearing up at +0.50 so im forced to send it in to get it calibrate it.

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## ESG

> Sorry im just getting back, i could have gave you some pointers but the way you handled that is actually the best way to learn. I had to dismantle the Lensometer to figure out how to calibrate the axis because mine too will wonder. now thats fixed but ive yet to figure out how to Zero out the lensometer it is still clearing up at +0.50 so im forced to send it in to get it calibrate it.


Hello O.GVisions, this post may be irrelevant, if you have already sent the unit in for repair. However, you are going to want to look for a set screw for the knobs on the side of the lensometer wheel that control the magnification. You can usually find this on the inside of the wheel, riding the shaft that goes into the lensometer. If you can find this, get the lensometer to focus clearly, as it should on 0.00, then loosen the screw for the wheel. Rotate the wheel until you are aligned on 0.00 and tighten it back up. 

Check to make sure that you are clear at 0.00 and you should be all set. Hope this helped!

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## O.GVisions

That really would of helped, i spent quite some time just trying to figure it out but i never got it. its alright though i appreciate the intel, ill use this for next time, i had to send it in thanks alot though 





> Hello O.GVisions, this post may be irrelevant, if you have already sent the unit in for repair. However, you are going to want to look for a set screw for the knobs on the side of the lensometer wheel that control the magnification. You can usually find this on the inside of the wheel, riding the shaft that goes into the lensometer. If you can find this, get the lensometer to focus clearly, as it should on 0.00, then loosen the screw for the wheel. Rotate the wheel until you are aligned on 0.00 and tighten it back up. 
> 
> Check to make sure that you are clear at 0.00 and you should be all set. Hope this helped!

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## Lado

Hi Folks, please need your help to calibrate a RM-A2000 topcon refractometer.

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