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Any recommendations my CG4 could carry?

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#1 Yourjones

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Posted 13 March 2020 - 08:26 AM

Hello

 

I am lately considering having only a refractor OTA to use on my Celestron CG4 (aka EQ3) mount that came with my Celestron Omni XLT 150 reflector. I understand the mount can carry no more than the allowed load. Then, what can be some good options to consider? But first and foremost, the CG4 mount can be used for other OTAs than my 150 reflector, can't it?

 

I would highly appreciate if a range of costs could be considered in your recommendations - high, medium and budget, perhaps?

 

Thank you so much!

 

Regards



#2 petert913

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Posted 13 March 2020 - 08:50 AM

I believe Celestron puts a 102mm refractor on that mount in one of their packages.

 

https://tinyurl.com/wpp4phu


Edited by petert913, 13 March 2020 - 08:51 AM.

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#3 Ihtegla Sar

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Posted 13 March 2020 - 09:29 AM

A five inch will probably be too much, but some people report using a GC4 with a five inch. I'd probably stick with four inches, or else get a bigger mount. Most four inch refractors of reasonable length and weight should be fine. At the higher end, the CG4 could easily carry an FC100DF or a DL. I have a DF and a DL and I typically run them on my LX70, which is equivalent to a CG5. But I also own a CG4 and have run my DL on it without issues. The DF (or DC) being shorter would work better on a CG4 than the DL. So if I were looking to match scope to mount, I'd suggest a DF or DC as being the ideal high end refractor for a CG4. Or maybe the new DZ.

Toward the lower end cost wise (compared to the Tak), but still a very good refractor, you might look at the AT102ED.

Keep in mind that for best performance you want to stay below about half of the allowed load, and even less than that for longer telescopes. Things will get quite jiggly as you approach maximum allowed load.

Edited by Ihtegla Sar, 13 March 2020 - 09:48 AM.

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#4 Binojunky

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Posted 13 March 2020 - 10:04 AM

OTA length comes into the equation as well, my CG4 would just about handle a 102 mmF9.8 but not a similar 120 mmF9.8, however it would handle my Orion ST120 F5, D.


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#5 MalVeauX

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Posted 13 March 2020 - 10:04 AM

Heya,

 

You could get away with a 4~4.7" refractor, depending on how long it is (102~120mm). Those F8 ones are likely going to be at the limits of the mount. But something around F7 or so, would be  more manageable. Otherwise, you could get a lot more aperture on there with a Mak, such as a 150mm Maksutov or even a 180mm Maksutov and you could even go as far as a C8 SCT on the CG4 visually too, if you want more aperture.

 

Very best,


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#6 Hesiod

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Posted 13 March 2020 - 10:16 AM

Why want to swap the optical tube? A 6" f/5 reflector is a fine and versatile telescope.

If having issues with ergonomics, and are not especially fond of widefield observations, I would rather replace your reflector with a C6 SCT (or even a C8, especially if your mount is equipped with the clock drive).

 

As for refractors, the 100/1000 achromat is a rather inexpensive but nice option, even if I fail to see it as an improvement over your reflector (less resolution, narrower fov, and still troublesome ergonomics); owning already a fast Newtonian I do not see the point for fast achros.

 

Among "apos", those around f/7 could provide you with the same fov as your Newtonian, even if at the expense of a noticeably smaller exit pupil, so probably will need to replace some eyepieces as well; depending on the relative optical prowess, these may, or may not, outperform your reflector in some circumstances (especially low-contrast features observed at high power).

If like widefield observations the NP101 (or one of its previous incarnations) could make more sense than most other alternatives


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#7 gene 4181

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Posted 13 March 2020 - 10:36 AM

 While I agree with  Hesiod on the capabilities of the 6in f5   , theres a used Celestron 102  F 9.8 at Cloudbreak Optics  ,  west  coast for decent price (150$)  .


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#8 aa6ww

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Posted 13 March 2020 - 10:43 AM

I have a Cg-4 and use it with Vixen Hal-150 legs which makes the mount very lightweight. Its a very light weight grab and go mount, even with counterweights attached.

I use to use my AT-102 on it. That was an excellent combination. I've sense sold the AT-102, and use the CG-4 mount with my FC-60, AT-92 and C6SCT. All are excellent scopes for the CG-4.

Ive added a simple 9V battery motor drive to run the RA gear. Its excellent, can be dialed in just where you want the speed, and the battery seems to last forever:

https://www.cloudyni...motor-for-cg-4/

A C8SCT is too much weight for the CG-4. The mount is just too unstable for that much weight. I tried it for 5 minutes once and said, no way, no thanks.

The C6 SCT is really excellent on a CG-4. Its so much more potent then a 4" refractor or smaller, in backyard suburban skies. In the C6 SCT, Messier objects look like the messier objects they are suppose to look like, not just little smears of light or fuzz. If you want more field of view use a simple 0.63 focal reducer. The focal length then reduces down to about 900mm which isn't bad for wide field views. The C6SCT works best with quality 1.25" eyepieces.


...Ralph

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Edited by aa6ww, 14 March 2020 - 04:08 AM.

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#9 Paul Skee

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Posted 13 March 2020 - 10:47 AM

The CG-4 mount uses a "vixen" style dovetail, a very common method for mounting. Celestron shows the mount's capacity to be 20 lbs. I believe this spec is generally considered to be optimistic. My experience with this mount is limited to the XLT 150R, (6" f/5 refractor) that came with the mount. This OTA weight is listed at 16 lbs. By the time I added a 2" diagonal and eyepieces, it was probably getting close to the mount's capacity. It performed well enough for my expectations, (I'm visual use only), marginal if any wind were present. I traded it in and got an AVX, the increased stability and GOTO features were, (for me) desirable. BTW, the AVX is currently on sale.

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Edited by Paul Skee, 13 March 2020 - 10:52 AM.

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#10 t.r.

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Posted 13 March 2020 - 11:35 AM

I use a 120mm f 8.5 on mine...no issues. Recommended.
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#11 Riccardo_italy

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Posted 14 March 2020 - 02:45 AM

I had an EQ3.2 with a wood tripod, should be very similar to a CG-4 (the main weakness of the EQ3.2 is the alluminium tripod, but the CG-4 has a steel one).

 

I could carry a TAL100RS. A 4" refractor, but heavier than the normal ones. It was marginal, and at the very limit of the mount capability (vibrations when you focus settled in about 2 seconds).


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#12 Yourjones

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Posted 14 March 2020 - 12:01 PM

Why want to swap the optical tube? A 6" f/5 reflector is a fine and versatile telescope.

 

Hi

 

I understand that refractors are better at resolving close pairs of double stars than Newtonians. I tried hard to do so with targets such as Wasat, Algieba and 54 Leo using my 750/150 Newtonian without ever succeeding. 



#13 Hesiod

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Posted 14 March 2020 - 02:40 PM

While it is true that in a few cases the spikes may be rather nasty, IMHO you should not focus so much on the design as on the optical prowess.
Your reflector should split those stars: before opening the wallet I suggest to perform a star test and try to understand the issue.
If the issue can not be solved then, and only then, would make sense to replace the reflector

Edited by Hesiod, 14 March 2020 - 02:41 PM.

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#14 Riccardo_italy

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Posted 15 March 2020 - 02:57 AM

If you want to observe double stars, factor in a drive clock.


Edited by Riccardo_italy, 15 March 2020 - 02:57 AM.


#15 Gary Riley

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Posted 15 March 2020 - 11:46 PM

I have a SW 120 ED Pro mounted on mine.  Does just fine for visual observing IMO.

 

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