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Telescope maker needed for WO 80mm alterations.

RobH

By RobH
in Discussions - Scopes / Whole setups

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RobH

RobH

Posted
Posted

OK....I've had it with my short tube WOZS80!!!

I love the lens, but when imaging, and this is an imaging only scope for me, I have to use 2 x 2 inch extensions. When you hang a camera and motorised filter wheel off the back of it, it sags.

I added another guidescope ring to support it nearer the FW, but when you tighten it, focus shifts slightly.

I've been struggling with this for 18 months now and I've had enough.

Can anyone suggest a professional telescope maker who can either take my lens and focuser, and either replace the tube with a longer one, or make a tube extension, so that I don't have to use the extensions, and can thus support the whole thing better?

Cheers

Rob

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Whippy

Whippy

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I feel your pain Rob. I had this with my old ZS110 where I had to use 50mm and 80mm extention tubes together to achieve focus. My thoughts were that not only the sagging is an issue, but it can't be doing the focuser much good either. I ended up selling it to get the FLT.

Tony..

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Merlin66

Merlin66

Posted
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I feel your pain!

I have the same problem hanging a 2Kg+ spectroscope ( which is about 230mm long) on the focuser...

In your case a dedicated OTA tube spacer between the OTA and the focuser would be the way to go ( this can then be removed if you ever want to revert to the orginal tube length), this would have minimum impact and maximum rigidity. There must be a small machining shop out there somewhere.

For me the solution was to fit a bracket between the spectroscope and a piggy back bracket on the tube; I could then firmly bolt the bits together- no movement- no sag.

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Merlin66

Merlin66

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Don't know about the WO. On my ED80 I machined a threaded adaptor to fit the draw tube thread ( M55 I think) and a T thead at the other works well. I also made one to go to the 2"SCT thread so I could use the Meade flip mirror etc from the LX200.

There may be a similar adaptor in the Baader collection over at TS..

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RobH

RobH

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Thanks for the ideas all :D

I think I'll give Beacon hill a call...if they can't do it, I bet they know someone who can.

A spacer would be the best solution I think, although I'm intrigued by Peter's 'cunning plan'!

How about a helical at the camera end...?

The problem there is that you end up with problems with framing using a Helical focuser.

As for replacement focusers....expense!

If I can do it with the bits I've got, this would be much better as the coffers are bare at the moment.

Merlin, the problem with adapters of any variety is that you still end up with a huge lever arm with a big weight on the end of it which could easily give rise to flexure, and puts a big strain on the focuser.

Ideally, a scope with the right length tube would be good.

I wonder why so many manufacturers make shorty scopes? Surely thay have done some research into how the scopes are used.....I fly a heck of a lot but have yet to see anyone putting a short tube frac into an overhead locker :)

Cheers

Rob

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Psychobilly

Psychobilly

Posted
Posted

The cunning plan involve the use of a guide ring but instead of standard bolts it will use 3 with ball bearing ends that will run a parallel section of the last extender... these would be individually adjustable to Centre the far end of the tube...

I am trying to source some micro Ball transfer units...

The smallest ones I can find at the moment are 1/2" ...

These are typically used in material handling applications and I use the cup mounted ones to allow my dome to rotate...

I was in the process of trying to solve my own "slop" problem with the Megrez 72.. it doesn't need a lot of extension (none infact) with the FF III fitted but the focuser is racked out far enough for some "drop" to be detected when i analyse the images in CCDInspector...

Do the Borg style focusers cause rotation?

Peter...

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daz

daz

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I had an idea about making a tube with a rigid back-end and a focuser that moved the lens cell instead - but a tube that was designed as an astrograph, so it didn't to be racked 4 feet to achieve focus!!

I claim copyright if anyone thinks about becoming a millionaire!! :D

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Merlin66

Merlin66

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I was originally advocating ( message #5 above) an extension of the main OTA ie between the end of the existing tube and the focuser - about 150mm long x internal diameter to suit OTA ( 85mm?)

This would allow the normal FW and camera connections to the focuser draw tube but at a minimal extension.

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steve51450

steve51450

Posted
Posted
I had an idea about making a tube with a rigid back-end and a focuser that moved the lens cell instead - but a tube that was designed as an astrograph, so it didn't to be racked 4 feet to achieve focus!!

I claim copyright if anyone thinks about becoming a millionaire!! :D

sounds like a mini borg 60mm astrograph to me............i wont tell them if you don't :)

but i have to say the principal also works in practice as my camera, wheel etc are as rigid as hell while the front helical focuser does all the work

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RobH

RobH

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I use this arrangement

Yes, that's the same as I currently do, however, in my case the lever arm is much longer, and tightening up the third ring after focussing shift the focus slightly, even with the focus lock on. :D

Cheers

Rob

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Ibbo!

Ibbo!

Posted
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I use a separate motor focuser I think the jmi is on at the mo

my problem is not so much focus

more focuser sag esp with the 132 which gives me differential flex and really messes up my images

i have seen some quite interesting and substantial solutions posted unfortunately my mere njp would not take the load

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RobH

RobH

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Hi Ibbo,

I also have the differential flexure problem with the WO scope, and I find, as you probably have, that the ring near the camera helps a lot.

I'm going to phone Barry Watts at Beacon Hill on Monday and have a chat about a tube extension, but perhaps a motorised focuser might not be a bad idea at some stage, but then I'd have to put one on my TMB too, and we're back to spending lots of money :D

Cheers

Rob

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ollypenrice

ollypenrice

Posted
Posted

This is an interesting one. WO and others are a darned nuisance making three quarters of the ruddy telescope in the form of a draw tube. It obviously doesn't work and they need to be told not to do it!

I have flown with my old f5 Genesis in the locker and my regular guest Tom O'Donoghue carries his 106FSQ that way on his visits. Customs are sometimes suspicious; if it's a telescope why can't we see through it? Why is it so heavy? etc!

Wasn't there a regular ad in Astronomy Now for years, a guy who specialized in makeng brass refractors. Wouldn't that be nice, a brass long-tube WO. Lovely!

Olly

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