So my c5 came with the stock visual back (93653-A) and few times after mounting heavy eyepiece in the diagonal it keeps slipping/rotating due to the tiny screws unable to hold the contraption in place. At first I I think it was the problem with the diagonal's front part getting unscrewed, but tightening it doesn't help either. So the problem is the screws.
Placing the eyepiece directly into visual back creates no problem however with other setups it's just not strong enough. Especially when doing the eyepiece projection method or using the diagonal with a combination of Barlow with heavier eyepieces.
There are a few options that came to mind:
1.Creating a hole and replacing the screws with bigger ones
2.Placing a rubber ring on the edge of diagonal to create more friction
3.Upgrading the visual back using 2" visual back with compression ring (not sure if it connects trough) and using 1.25" adapter
4.Buying a 1.25" Baader Clicklock
Has anyone encountered a similar problem, how do you manage with it?
There is a cheap way, but only works if you use the scope in Alt-az mode.
Remove the screw in the visual back
Position the diagonal in exactly the position you want (usually vertical for Alt-az)
Use the tip of a marker inserted in the hole to make a small mark on the nose of the diagonal
Remove the diagonal, mark the spot with a punch, and using a drill, make a small depression in the diagonal nose at the mark
If you don't want to drill it, just use a file and make a small flat spot on wall of the tube. These are usually soft metal
Now many would balk at doing such a thing, but a Baader Twist Lock will cost you more than the diagonal costs, and the cosmetic damage is pretty negligible because 1.25" diagonals have pitiful resale value.
The only time I would recommend the Baader is if the scope is mounted on a GEM and it is necessary to change the angle a lot, but it is a hugely expensive solution.
A less expensive solution that will work pretty much as well is something like this:
Last, you can try to find a thumb screw of the same thread pitch so that you can simply get more purchase on the screw to tighten it. I realize that you are not in the US, but this is just included to show you that there is a huge variety of thumb screws out there. Maybe McMaster would ship to you.
If Alt-az mounted though, the free way is probably the best way.
The Baader though is just very expensive and it is a total one-use piece of gear.
Edited by Eddgie, 26 June 2019 - 08:34 AM.