2 inch diagonal slips when tightened

[djpaul]

Hi

 

Just bought a william optics 73 zenithstar

When i attach my televue 2 inch diagonal it goes tight and sometimes i hear a click and it goes loose.

Could it be to do with the saftey lug on the diagonal not lining up with the compression ring on the focuser?

If so would i be better off buying a new diagonal without the saftey lug for use with this scope?

Paul

 

[knobby]

Is the thumbscrew lined up with the compression ring, sometimes they slip through the gap where the expansion is allowed for ?

[RayD]

6 minutes ago, djpaul said:

Hi

 

Just bought a william optics 73 zenithstar

When i attach my televue 2 inch diagonal it goes tight and sometimes i hear a click and it goes loose.

Could it be to do with the saftey lug on the diagonal not lining up with the compression ring on the focuser?

If so would i be better off buying a new diagonal without the saftey lug for use with this scope?

Paul

 

Sometimes the compression ring is very close to the edge, and the diagonal nosepiece is tapered which leaves a small collar.  The compression ring just catches this collar and it can then slip off it leaving it loose.  You either have to push it hard on a tighten it good n proper, or back it out a bit and tighten it on the tiered part of the diagonal.

[Louis D]

I had to shim some 2" eyepieces in a particular 2" diagonal of mine to get the compression ring to line up with the safety undercut.  Two 4mm thick rubber O-rings did the trick for me.  You might try backing out the diagonal 4mm to 8mm and retightening to see if the compression ring gets a better grip on the barrel.  If so, get some 4mm X 50mm ID O-rings off of ebay to shim with.

[djpaul]

yes i did find that backing it off did the trick but i dont trust it lol

Better if i buy another diagonal for this scope with no tapered end i think. 

should that stop the issue?

Paul

[Louis D]

2 hours ago, djpaul said:

yes i did find that backing it off did the trick but i dont trust it lol

Better if i buy another diagonal for this scope with no tapered end i think. 

should that stop the issue?

Paul

Yes.  Alternatively, fill the undercut with 1/4" wide pinstriping tape.

[Stu]

10 hours ago, Louis D said:

Yes.  Alternatively, fill the undercut with 1/4" wide pinstriping tape.

I had a problem with the undercut on my 24mm Panoptic getting stuck when using it with the Tak prism. Same issue, and as Louis suggests, I carefully put a couple of wraps of insulating tap in the undercut to bring it near the level of the rest of the barrel and that solved the problem. Worth a try as the Televue diagonals are very nice. Is it an Everbrite one?

[djpaul]

Yes it the everbrite.

I'm looking to get another diagonal without undercut for this scope.

Obvious choice would be a william optics model I think.

Paul

[Louis D]

3 hours ago, djpaul said:

Yes it the everbrite.

I'm looking to get another diagonal without undercut for this scope.

Obvious choice would be a william optics model I think.

Paul

I really like my 2" GSO dielectric.  I'm a little disappointed with WO since my 1.25" WO dielectric has a built in field stop that vignettes the field of widest field eyepieces.  I don't know if their 2" diagonals suffer from the same problem.  However, fool me once shame on you WO, fool me twice, shame on me.  So, I'll be taking a pass on their 2" diagonals.

[djpaul]

I have found a skywatcher diagonal on abs which will do for now.

And just use the tv everbrite on my 120ed.

 

[djpaul]

Another thought I've had.

To add a baader clicklock to the focuser. And attach my televue diagonal to clicklock?

Paul

[Stu]

Why not try the tape first Paul, you might be surprised how well it works. I just cut strips of insulating tape slightly narrower than the undercut then wrapped one layer at a time until it was filled, 2 layers I think.

I wouldn't swap an Everbrite for a Skywatcher.

[djpaul]

Stu.

I'm not going to now.

I'm buying a baader clicklock to add to the back of focus tube. Then my everbrite to the clicklock.

It will add 37mm but just tested my main eyepieces and my

17mm ethos hits focus at 43mm.

26mm nagler at 55mm.

8mm ethos at 60mm.

[Merlin66]

I honestly believe those "safety undercut" features are the Devil's work!!!!! Why were they ever introduced????

There's no consistency between suppliers of groove dimensions and location, as well as the mating parts....

I drives me nuts! I have to spend unwanted time to sort which accessory/ eyepiece combo works with which focuser etc etc.

I had limited success filling these safety grooves.....