finder alignment problem

[Andrew*]

I don't get it. Last time I had the scope out (can barely remember it ) I am certain my optical finder was perfectly aligned with the scope. This time, nowhere near. It's a 9x50 on the standard Synta spring-loaded brackets with two adjustment screws at 90°.

So I get the moon centred in my 31mm and look in the finder. I screw out the correct adjustment bolt and I watch as the moon closes in on the crosshairs. But then it comes to the end of travel within the bracket and the moon is not over the crosshairs.

I have used an elastic band to ensure a snug fit on the sky end of the finder bracket, because I lost the original black band. There is about 0.5mm of play in the band, but this does not make up for the discrepancy.

I check the optical line. It's reasonably well collimated but there's a bit of play between the focuser and adaptor, so I correct that. Still not enough.

I check the fit of the finder bracket on the OTA. Fine.

What is going on? Any ideas?

cheers

Andrew

[steppenwolf]

The guide 'scope mount is held to the tube with two bolts, these are often supplied not fully tightened - I suspect that the mounting block has move a fraction.

[Andrew*]

Exactly! That's just what it was. I've corrected it now and fully tightened it.

Thanks!

Andrew

[steppenwolf]

Excellent news!