Saturday, December 28, 2013

Checking focuser slip

There were many reports around that the focuser that comes with Takahashi scopes isn't great and slips. I asked Richard Crisp how to measure it. He recommended to put the scope in focus, point the scope up and then move the focuser all the way out and back to the focus position and check if the scope is still in focus.
For this, I could use the Bahtinov mask and Bhatinov Grabber to measure exact focus. Luckily Capella was almost in the Zenith which made a clear Bahtinov pattern.
Here are the results (I moved the focuser several times to check if there would be small slippage over time):

1.0.10
2.-0.10
3.0.03
4.0.03
5.-0.08
6.-0.04
7.0.01
8.0.06
9.0.00
10.-0.31
11.-0.10
12.-0.06

Looks as if there isn't any noticeable slippage. Good!