Letus Extreme Grain?

Okay, so at f/5.6 or wider, the ground glass pattern is okay. I can live with that. The infinity focus is off though. The ground glass needs to be closer to the mount. I've taken it apart and the way the rubber rings hold the ground glass in place, I don't see an easy way to adjust it forward. It would be easier to shave a couple of mm of the mount, but I don't have the tools to do that.
 
You've hit the weakness of the Extreme - apparently you're just supposed to push the dxxn xxxing pins in by hand hoping you keep them equidistant and measuring them if you can find a way. Its an abominable system. You could also send it back for an adjustment or maybe buy the Zacuto collimation fix if that will allow you to get closer.
The nikon ring they have works Ok to adjust in the other direction but you are screwed if you need to get closer. I did do mine successfully so its not impossible, but I think I was lucky.

Lenny Levy
 
Hi guys, I sell my own brand of adapters and I have helped a letus extreme user fix this grain problem. PM me and I think I could also help you. I know what the problem is. No advertising is allowed here so I cant put any links here.
 
Adjusting the GG distance is actually pretty easy. You just need some vernier calipers, and a tiny screwdriver or any other thin flat ended instrument. Fixing the GG vibration pattern is also an easy fix. All I had to do is call Hien & he told me how.
 
Adjusting the GG distance is actually pretty easy. You just need some vernier calipers, and a tiny screwdriver or any other thin flat ended instrument. Fixing the GG vibration pattern is also an easy fix. All I had to do is call Hien & he told me how.
Can you share what Hien told you about changing the GG pattern?
 
Yeah no prob. Take off the front tube, which will reveal the gg and 3 posts. Get a single strand of copper wire and wrap around the top of the post so it sits between the little rubber tyre and the post. That's how Letus calibrate the vibration. Hien told me most of the time they don't need to use this technique, but with my Elite I did. I'm not sure if it will be the same post in every case. I just went for the one with the most play between the rubber and the post.

wire.jpg
 
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