16 replies to this topic

[HfxObserver]

There are some helpful posts here about adapting the Celestron Comet Catcher to accept 2-inch eyepieces and some on using 1.25 fine focusers. I found that most used some of the original Comet Catcher photo adaper parts which are difficult to find used while others had some custom parts. Additionally, tube rings are difficult to find for the 6-inch OD tube and there are lots of poss on making these up but I put mine in anyway as they turned out to work very well. Here is my journey.

 

I wanted a Comet Catcher, they always look so sweet with that orange peel colour and as a wide field fan I loved the idea of an almost 6-inch f3.6 scope. This meant that if it could be adapted to take 2-inch eyepieces the scope could provide 3.5-degree true fields. I have 4 & 5 inch refractors that already do this but the small light weight Comet Catcher was appealing if I could locate one here in Canada for a good price. Most good examples are from the US and between the currency conversion and often high asking prices I remained out for a long time. One appeared this spring, it was a littled dinged up but had a good focuser which I undersand is tough to find, so for $250 cdn I committed to it.

It arrived and I soon had it out under the stars to test and figued I could resell it if it wasn't good as wanted. But even on a light weight Bogen tripod it performed well enough for me to order a set of 6.3-inch Orion rings from Telescope Express in Germany and step down ring felt from ScopeStuff in Texas. I used hot glue to glue it on, they are a little tight but will compress a bit over time according to Jim at SS.

 

Rings: ORCR160 Orion Cradle Rings - Aluminium - for Tubes diameter 160mm
 

Felt: 3/16" felt is 0.188", #FL92 

 

After the ring materials arrived I found a new 22mm Naler on sale for last years price with free shipping. I had the 2-inch TPO adapter below but the 22mm Nagler would focus when the focuser was at the extreme end of inward focus. While digging around I found a T2 fine focus that would give the needed distance while also making for a better focus experience as the CC focuser is rough to use with heavy eyepieces which get pulled out of focus when the scope is pointed upwards. Here are the parts I used to convert my Comet Catcher to take  2-inch eyepieces with the ability to fine focus:

 

BA1508039 Baader Adapter M36.4 male / T2 male - adapter for Vixen
 

TS Helical Focuser with 11mm travel
 

TPO 2-inch Adapter w/ T2 Thread
 

 

Clear skies,

 

Chris

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Edited by HfxObserver, 24 July 2022 - 03:50 PM.

[HfxObserver]

I also purchased a Baader T2 Plug for travel so the eyepice holder won't damage the focuser if it knockes around in transit.

BA2904010 Baader T2 Protection cap for male T2 thread

 

My 22mm Nagler sits up high (bottoms out by 1.5mm) and is close to the focal point of my 12.5mm Docter, so I recently ordered a 2" parfoclaizing ring. from FLO as they had them for really cheap, ~5 pounds and a ~4 pounds to ship.

 

Chris

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[topomountain]

hey any reports on how this looks at the ep?

[Garyth64]

What size secondary came with the scope? Did you go to a larger secondary?

[telesonic]

hey any reports on how this looks at the ep?

 

Curious to this as well. I've only used 1.25" eps with my CC, 19mm Panoptic - but I'm setting up another Comet Catcher that I acquired. That one has a vintage 2" Novak helical focuser modification to the tube. (parts are currently at my machinist's shop - which will later be explained in a new thread here, perhaps.)

 

 

What size secondary came with the scope? Did you go to a larger secondary?

 

Gary -

The stock secondary that came with the Comet Catcher is:

55mm width on the minor axis. 78mm (give or take) on the major axis, according to my measurements.

 

It's a very large secondary mirror! I don't have any plans to change the secondary out in my other CC - the secondary has a bevel cut to fit into the cell. I've never seen a good replacement to the stock secondary, at least an off the shelf one that would work with the existing single-stalk and secondary holder.

 

If one were to adapt a more traditional spider and holder, I imagine that would solve it. I might do that on CC#2 - with the Novak Focuser. I've got two of these Comet Catchers, one was a complete basket case, stock Vixen sled (holes everywhere in the OTA) and now repaired. My second one came with the Novak focuser, so one down, one more to go.

 

Cheers,

T

[topomountain]

please keep us posted

 

 

Curious to this as well. I've only used 1.25" eps with my CC, 19mm Panoptic - but I'm setting up another Comet Catcher that I acquired. That one has a vintage 2" Novak helical focuser modification to the tube. (parts are currently at my machinist's shop - which will later be explained in a new thread here, perhaps.)

 

 

 

Gary -

The stock secondary that came with the Comet Catcher is:

55mm width on the minor axis. 78mm (give or take) on the major axis, according to my measurements.

 

It's a very large secondary mirror! I don't have any plans to change the secondary out in my other CC - the secondary has a bevel cut to fit into the cell. I've never seen a good replacement to the stock secondary, at least an off the shelf one that would work with the existing single-stalk and secondary holder.

 

If one were to adapt a more traditional spider and holder, I imagine that would solve it. I might do that on CC#2 - with the Novak Focuser. I've got two of these Comet Catchers, one was a complete basket case, stock Vixen sled (holes everywhere in the OTA) and now repaired. My second one came with the Novak focuser, so one down, one more to go.

 

Cheers,

T

[telesonic]

please keep us posted

 

Will do!

 

I do have a thread here in the classic forums - titled: Repairing Holes in OTA tube, or something to that effect. It details what I undertook on my first Comet Catcher. Once the second one gets parts made, I'll make a new thread detailing that scope as well.

 

 

Cheers,

T

[HfxObserver]

I spent much of 2022 observing with this scope and the 22mm Nagler, this gives 23x and just over 3.5 degree TFOV which is about the same as my 125mm Apo. I had it semi-permanently installed at one of the locations I was testing for an observatory and picked that spot. The observatory has been in and out of service as we work through various stages of the builds and issues that popped up. It's out of service again as I'm doing some painting so I'm back poking around the sky with smaller instruments. I'll take the Comet Catcher out again.

 

The main thing I don't like about this telescope is the reflections on the corrector and it is prong to dew, and we get very little dew here. 

 

Chris

[deSitter]

You don't really need 2" eyepieces in a f/4 scope. The maximum exit pupil is 7mm and at f/4 that is achieved with a 28mm eyepiece. A 24mm Panoptic will work well at f/4 and give a 6mm exit pupil, which is all most adults can manage anyway.

 

edit: Seems this scope is actually f/3.6 so the 24mm is all you can use. Anything longer will effectively stop down the scope. There will be coma visible at the edges in ultrawides, and likely also in superwides (e.g. the Panoptic). The Panoptic is a fine eyepiece and should work well in a fast scope.

 

-drl

Edited by deSitter, 02 October 2024 - 07:29 AM.

[telesonic]

You don't really need 2" eyepieces in a f/4 scope. The maximum exit pupil is 7mm and at f/4 that is achieved with a 28mm eyepiece. A 24mm Panoptic will work well at f/4 and give a 6mm exit pupil, which is all most adults can manage anyway.

 

edit: Seems this scope is actually f/3.6 so the 24mm is all you can use. Anything longer will effectively stop down the scope. There will be coma visible at the edges in ultrawides, and likely also in superwides (e.g. the Panoptic). The Panoptic is a fine eyepiece and should work well in a fast scope.

 

-drl

 

Good point!

 

I use a 19mm Panoptic with these scopes, almost every time one of the Comet Catcher scopes is out. It's a great EP, and works good at F/3.6... there is a bit right near the edge that is a little soft / coma, but it's nothing bad.

 

Having tested (just visually) some EP's with this scope, some work okay.... and some are terrible. Keep in mind, that I see these scopes as low power wide field sweepers... and they do that pretty well.

 

That said, it never hurts to try. I've found that in my collection, I have a few EP's that also work in this scope very well. One is an older Bausch and Lomb Pro Plossl (26mm) and a Meade 4000 5 element smoothie (26mm - though I also have a 32mm 5 element that use sometimes.)

 

I prefer the Panoptic though, it's nice. A buddy of mine has some Naglers, and a couple cases of various Televue.... I've meant to ask him if I can borrow one or two to test on this scope..... I'm curious what the 2" modified scope I have would produce visually, just hadn't gotten around to it. This one came with a 2" Novak helical, and it was set up for astrophotography.... though I did manage to get a working spider setup on it, it's just been chilling.

 

Cheers,

Temp

[upwinddan]

I am guessing that I am not the only one who has been looking for one of these interesting scopes. I enjoyed everyone’s comments. 

[telesonic]

I am guessing that I am not the only one who has been looking for one of these interesting scopes. I enjoyed everyone’s comments. 

Well, I'm not looking for another - being that I have two of 'em.     I only got lucky on those because they were not original scopes in pristine condition, so that was a gamble I had to take. Plenty of things had to be done on mine, they were both kind of a mess.... labor of love they say? Eh...

 

You just don't see these very often anywhere, let alone someone selling one... so I get where you are coming from.

 

I haven't gotten around to it this year, but I intend to use the 2" (modified focuser) scope with some 35mm film astrophotography)  - but telescope things / projects tend to go slow for me out here - I have been told that I have too many irons in the fire once in awhile. And, they'd probably be correct on that.

 

 

Cheers,

Temp

[HfxObserver]

I agree, this scope doesn't need to go for 2-inch mode but the 2-inch eyepieces provide a ~0.5° gain with the Nagler 22mm vs the Panoptic 24mm, the exit pupil is also reduced by 0.5mm, 6.1 vs. 6.6. Initially I was going to get a 24mm UFF when a retailer offered me a discount on the 22 Nagler so I thought it'd be fun to make it work.

 

Having a 3.5° field provides enough space to frame the entire Veil , North America and Pelican Nebulae, IC1396 with enough space around it, Heart and Soul in the same field, NGC 1499 with enough space for contrast, the ">" feature surrounding the M24 "Star Cloud", Lambda Orionis Nebula SH2-264 to name a handful.

 

I've thought about tracking down the slightly more rare Vixen version, seems to have a mildly pink tone to it.

 

Chris

[deSitter]

I agree, this scope doesn't need to go for 2-inch mode but the 2-inch eyepieces provide a ~0.5° gain with the Nagler 22mm vs the Panoptic 24mm, the exit pupil is also reduced by 0.5mm, 6.1 vs. 6.6. Initially I was going to get a 24mm UFF when a retailer offered me a discount on the 22 Nagler so I thought it'd be fun to make it work.

 

Having a 3.5° field provides enough space to frame the entire Veil , North America and Pelican Nebulae, IC1396 with enough space around it, Heart and Soul in the same field, NGC 1499 with enough space for contrast, the ">" feature surrounding the M24 "Star Cloud", Lambda Orionis Nebula SH2-264 to name a handful.

 

I've thought about tracking down the slightly more rare Vixen version, seems to have a mildly pink tone to it.

 

Chris

Ultrawides will show a huge amount of coma in an 82 degree eyepiece. The extra field will be a distraction rather than a bonus. This is an f/3.6 scope - even superwides are going to show flared stars at the edge. And coma cannot be magnified away - all 82 degree eyepieces, even short ones, will show the same amount of coma.

 

I just don't see the point in essentially rebuilding the scope and removing its essential character.

 

-drl

[davidmcgo]

I agree with deSitter.  Mine gives pleasing views with a 26mm Plossl, but the edge in a 16 Nagler T5 or a 19 Panoptic isn’t great enough to make me want the wider apparent field.  So I dropped any notion of killing the focuser with a 17 Ethos.

 

Maybe other folks are OK with coma and astigmatism, but even at f4.5 in my Obsession, my Paracorr never leaves the focuser.  
 

Dave

[HfxObserver]

It was just a fun project to do, plus with nebula filters help mitigate the aforementioned issues. 

 

The aim of this relatively inexpensive project was to get the largest field, not the sharpest field, for that I have other instruments. Also note, the scope lives under fairly dark skies so having the ability to take in large sky vistas is really nice, the same field of view my Pentax/Borg gives but in a package ($200 vs $$) I felt more comfortable leaving out all summer under a Telegizmos cover while I tested locations for my observatory.

 

This was a worthwhile undertaking since I already own a good handful of 2-inch filters. It would have been more costly for me to purchase a 24UFF and associated 1.25" filters to use on the targets. 

 

Chris

[Roger Belveal]

I'm enjoying reading about all the upgrades and tinkering others are doing with these Comet Catchers. I have incorporated a 1.25 helical focuser for one thats in near perfect condition. The one I'm actually using has been fitted with a 1.25 rack-n-pinion focuser. I really prefer it over the sled type it came with. I really think these scopes are under appreciated performers. Just my opinion though...