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C5 Visual back screws issue

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#1 Bowlerhat

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Posted 26 June 2019 - 04:11 AM

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?



#2 markb

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Posted 26 June 2019 - 07:36 AM

Baader Clicklock!

 

Once I got my first one, I got a thread-on one for every focuser that would take one. Only one scope refused to let me, so I added a slip in 2" barrel Clicklock. No regrets, only positives. No more dropped or wobbly eyepieces.

 

Very well made, fairly priced and affordable.


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#3 Eddgie

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Posted 26 June 2019 - 08:26 AM

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:

 

https://agenaastro.c...SRoCl8sQAvD_BwE

 

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.

 

https://www.mcmaster.com/thumb-screws

 

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.

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#4 Bowlerhat

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Posted 26 June 2019 - 10:26 AM

That's true, the cost is quite high. Recently there's 10% additional tax import charge as well. I think using thumb screws could be a good idea, gonna have to check the warehouse tomorrow.

 

I've been trying to find something similar to clicklock as alternatives, but only came across the rotolock. Shipment from taiwan would cost less, however, still not so cheap either.



#5 markb

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Posted 26 June 2019 - 12:46 PM

The Clicklock is worth every penny. And I am pretty economical in my astro expenditures. You will likely get it from a US dealer like Highpoint or B&H, so any trade war stuff is built in.

 

But wallets vary! 

 

A Want ad can cut the cost about a third, they are out there from folks that have moved on to other scope types.

 

I do recommend AgenaAstro's Bluefireball compression ring eyepiece holder as a MASSIVE improvement over the Celestron single screw if you are saving a bit now.

 

Even if you upgrade later, the compression ring holders always seem to reemerge for some project or another, never money wasted.

 

I cannot believe they still ship scopes with those old single screw eyepiece droppers (and barrel scratchers) that you were given!

 

The two-screw brass compression ring works very well, you will be very happy with one, I was for many years.

 

Good luck!



#6 epee

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Posted 26 June 2019 - 01:43 PM

https://agenaastro.c...-back-e-15.html



#7 Ford Prefect

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Posted 27 June 2019 - 01:17 PM

That's true, the cost is quite high. Recently there's 10% additional tax import charge as well. I think using thumb screws could be a good idea, gonna have to check the warehouse tomorrow.

 

I've been trying to find something similar to clicklock as alternatives, but only came across the rotolock. Shipment from taiwan would cost less, however, still not so cheap either.

I do not use a Click Lock but I use a different contraction, that will work only if you use a diagonal with a T2 thread at the nose.

 

Since I use a Baader T2/32 prism diagonal, I unscrewed the nose of the diagonal to have a T2 thread; then replaced the stock visual back with a SC-to-T2 adapter and screwed the T2 diagonal directly on the adaptor. It is rock solid this way.

I use the C5 on an Alt/Az mount, so I usually do not rotate the diagonal, but if needed, there is only a collar to be slightly unscrewed, then I rotate the diagonal and screw again the collar.

 

The SC-to-T2 adapter is cheaper than the Click-Lock, but works only if you have a T2 diagonal.



#8 barbarosa

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Posted 27 June 2019 - 05:33 PM

The cheap but effective solution is to use a self taping bolt (M4 to M6?) and a matching nylon screw (thumb, hex or slotted). Drill a hole through the VB. Drive in the self tapping bolt to cut the threads.  Remove it and clean up the exit hole if needed the thread in the nylon bolt.

 

If you want to ensure that the bolt will be at a right angle to the optical axis you can use a drill press/vice or jig. Functionally however it won't matter. If you do it by eye the nylon screw may have a slight tilt.

 

I've used this expedient method with 1/4 x 20 bolts because that was the size I had on hand.



#9 Bowlerhat

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Posted 28 June 2019 - 08:59 AM

Claudio, I tried that before, however, I couldn't change the camera angle due to the angle when it's fastened. so sit stuck in a weird angle. I use a t adapter with the filter screwed in at the front, so I prefer the DSLR to be still disconnected to the tube. My camera is not full frame so I can't use the clip filter.

 

David, I think the original bolt is m3, it's pretty tiny. I'm thinking of some kind of bob knobs to use, I think the problem is the tiny grip of the screw bolt head. I'll consider this.



#10 Bowlerhat

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Posted 29 June 2019 - 04:09 AM

Update: Went to a DIY shop and got some screws. Ends up replacing the short bolt with a longer one, with nut wings. The grip is much better, no more sliding, and much easier to turn. The m3 screws fit the holes perfectly. I'll stick with this at least for now.

 

12

Edited by Bowlerhat, 29 June 2019 - 04:11 AM.

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