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ST80 mods.

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#1 rogan

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Posted 15 January 2020 - 09:50 PM

Having some fun with an ST80. This project has been ongoing for a number of years.

I am a big fan of the Orion ST80 when used for exactly what it is made for expecting nothing further (but often surprised). I have other wide field fracs that are better in most ways, but, there is just something about the ST80.  That’s how I ended up with two of them. 

One occasionally rides with a GSO two speed Crayford but currently is stock other than a SV Nighthawk R&P focuser.  The other one, which also occasionally used the GSO Crayford, I decided to have some fun with.  After tweaking the optics the first change was purely cosmetic with painting the tube.  I tried various shades of blue but finally settled on a light sage green. Kind of a Tak thing but not really.  It pleases my eyes.

 

Next an opportunity arose to go from the stock Synta 1.25” focuser to a 2”.  I had replaced the single speed Crayford on a Yuzhong Aquila 80mm with a same brand two speed. This left me an extra Crayford that just happened to fit perfectly onto the ST80 tube. It’s not my favorite Crayford but it’s superior to the R&P and it gets me to 2”. The focuser is shorter so it also gives me more in-travel.  The opposite is an easy fix with an extension if necessary but with inadequate in-travel you are out of luck. 

One of my overall goals was to get the length of the scope down as much as possible for travel preferably fitting in a relatively small Pelican case. I kept eyeing that dew shield.  I find that with my scopes with retractable dew shields I tend to leave the shield retracted.  My usual viewing conditions negate the necessity. I cut down the shield considerably. Should the need arise I will have a dew shield extension that folds flat.

 

The final modification was necessary as the focuser isn’t rotatable. This ST80 was the variant with the dovetail plate that attaches directly to the tube.  The plate was removed and rings that I had on hand did the trick.

 

I think it’s now a neat little scope that has been improved in both form and function. Barely recognizable.

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#2 PXR-5

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Posted 15 January 2020 - 10:00 PM

I love my ST80, it’s my favourite scope flowerred.gif

That paint job on yours it’s pretty cool :) waytogo.gif



#3 Old Man

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Posted 15 January 2020 - 10:01 PM

I like the color. Looks great.

 

     Mike



#4 MartinPond

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Posted 16 January 2020 - 12:52 AM

I loves me a 2" Crayford on the 80x400.   Indeed.



#5 mikerepp

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Posted 16 January 2020 - 07:27 AM

I like it, nice color and it fits your needs, that's the important thing.



#6 rogan

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Posted 16 January 2020 - 07:29 AM

I wish that it was a two speed with the steep shallow light cone of the ST80 but so be it, that’s what I had on hand. The main goal was to get to 2” and a Crayford to boot. To be candid I don’t know how much the increased in-focus will be but I suppose it could be a benefit with some EP/Barlow combinations. Can’t really say that I have any plans to use a Barlow with that scope. For photography it could come into play. I am going to take measurements compared to a GSO Crayford.
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#7 Jon Isaacs

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Posted 16 January 2020 - 08:14 AM

Ah... The ST-80.. You've done some interesting stuff with yours..  I like ST-80s with 2 inch focusers.. the can provide some wide fields of view.  6.6 degrees with a 41mm Panoptic, 6.0 degrees with the 31mm Nagler.  A few thoughts.. 

 

First, one thing I keep in mind is the drawtube length.  Slower scopes can use longer drawtubes so a bit of care is needed if using a focuser from slower scope.  A 2 inch diagonal generally has about a 4 inch path length so at F/5, a drawtube 6 inches long with a 2 inch focuser will start to clip the on-axis light cone. 

 

I've owned a number of ST-80s, they're fun and they're kind of a half binocular-half telescope so they make good scopes for beginners.  I buy them used and then find someone who can use it. But currently I have the keeper.  

 

It's a Celestron that came as the First Scope 80 EQ.  I have had them before but this one is different.  It has a metal objective cell that threads to the tube rather than a plastic cell and the dew shield is metal and threads on to cell. 

 

Celestron ST-80 Lens Cell and scope.jpg

 

I added a GSO two speed that came with another ST-80 and I use a single heavy ring as a mounting, similar to a clamshell.  

 

Celestron ST-80.jpg

 

Not many mods, I like the Celestron black.. 

 

Jon

 

 


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#8 rogan

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Posted 16 January 2020 - 10:16 AM

Jon, that is an important consideration. Fortunately my focuser came off of an F5.5 scope. After measuring the Yuzhong focuser is approximately 2.75” long (less the 1.25” adapter). A GSO is according to Agena Astro is 4.25” to the same point. That is 1.5” shorter. Could be significant. The draw tubes have pretty much the same travel.

I agree about classic black (or white) scopes. My other ST80 remains stock white. It can also be changed over to a two speed GSO in a matter of moments. That said Stellarvue did some very nice tweaks to the stock focuser now on the scope.

#9 lakland5

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Posted 16 January 2020 - 10:23 AM

Cool mods.  I'd love to hear how that shorter dewshield works for you!

RicA



#10 Jon Isaacs

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Posted 16 January 2020 - 10:24 AM

Rogan:

 

The important thing is the draw tube length.

 

Jon



#11 rogan

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Posted 16 January 2020 - 11:05 AM

Rogan:

 

The important thing is the draw tube length.

 

Jon

Absolutely.  In this case about 1/4” shorter than the GSO. 
 

setting this up as a straight through spitting scope does require a good amount of extension shown here with a 14mm Meade UWA.  With a diagonal no extension needed. 
 

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Edited by rogan, 16 January 2020 - 11:11 AM.

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#12 rogan

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Posted 16 January 2020 - 11:41 AM

Cool mods.  I'd love to hear how that shorter dewshield works for you!

RicA

When I’m using a scope with a retractable dew shield at the end of a viewing session I often find that I have forgotten to extend it. Even though we get a lot of humidity here in north Georgia I haven’t found dew to be an issue. Maybe I’m not staying out late enough.  Despite this the final phase of this project will be to get the thin sheet of black foam and Velcro out to make a foldable dew shield extension in case dew does become an issue. This scope will be made for travel (unless my SV60EDS gets the call) so I have to assume that it will be an issue in other locations especially since I am drawn to the Caribbean. 


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#13 sickfish

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Posted 16 January 2020 - 12:03 PM

I put a GSO 2 speed focuser on it and painted the inside a flat black.

The tube itself has been painted 3 times, white.



#14 kfiscus

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Posted 17 January 2020 - 11:01 AM

I upgraded to a 2" focuser and built a modular tray for the rig.  It fits in my Z12 dob mounts.

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Edited by kfiscus, 17 January 2020 - 07:00 PM.

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#15 rogan

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Posted 17 January 2020 - 04:42 PM

In the event of dew I have this to do the trick besides a travel shield. The joy of spare parts. 
 

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Edited by rogan, 17 January 2020 - 04:48 PM.


#16 Benach

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Posted 17 January 2020 - 06:04 PM

Okay, here's my modded ST80. Has to be built, but it gives an idea at least. Am still doubting if I shall not use a 80mm f/5 triplet apo for this purpose, but okay...

 

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#17 Tim Hager

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Posted 18 January 2020 - 11:24 AM

Question for the guys who put 2" focusers on their ST80's:  Does the ST80 not have tube baffles?  I would think that if the baffles were originally optimized for a 1.25" focuser, you would get vignetting on a wide field 2" eyepiece.

 

....Tim



#18 rogan

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Posted 18 January 2020 - 12:10 PM

Question for the guys who put 2" focusers on their ST80's:  Does the ST80 not have tube baffles?  I would think that if the baffles were originally optimized for a 1.25" focuser, you would get vignetting on a wide field 2" eyepiece.

 

....Tim

It’s never been an issue and I’ve used numerous focal length eyepieces.  



#19 rogan

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Posted 18 January 2020 - 12:13 PM

I put a GSO 2 speed focuser on it and painted the inside a flat black.

The tube itself has been painted 3 times, white.

This was actually the third time I had painted it.  The first two times were medium blue and dark blue and out of boredom.  These other mods are a matter of function rather than aesthetics. 



#20 Jon Isaacs

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Posted 19 January 2020 - 05:27 AM

Question for the guys who put 2" focusers on their ST80's:  Does the ST80 not have tube baffles?  I would think that if the baffles were originally optimized for a 1.25" focuser, you would get vignetting on a wide field 2" eyepiece.

 

....Tim

 

I've done a number of ST-80s with 2 inch Focusers.  I've had to remove baffles, I just flock the tube like TeleVue.

 

I measure the effective aperture with a laser collimator in a jig using a 4.8 mm Nagler..

 

6316192-Eyepiece and laser on floor cropped.jpg

 

Jon


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