mount for C9.25
Posted 12 November 2012 - 02:19 AM
What mount is the minimum for a C9.25? Will my CG-5 be enough? Visual observing.
/Magnus 57 N.
Posted 12 November 2012 - 02:34 AM
Posted 12 November 2012 - 07:13 AM
If you weren't all the way in sweden, I would try to sell you mine, but Jim, you looking for an upgrade? =)
Posted 12 November 2012 - 09:52 AM
There are a couple of issues though. First, not all C9s come with the right dovetail, though just about all of them have the holes needed if you want to change the dovetail. Many came with the CGE dovetail though, and this won't work on the CG5.
Next, you may need some extra counterweight. The C9 is quite a bit heavier than the C8. Closer to the C11 than the C8. The C9 weighs in at about 20 lbs.
This is near the limit of the CG5 (oh, you can go over the limit of course, but the more you put on it, the less satisfying it will be to use), so you will want to keep your load light. As little extra weight as possible (focusers, finders, etc).
You'll want to add vibration suppression pads if you use high powers.
You may find an adjustable seat observer's chair to be desirable. The weak point on most mounts is the tripod, and if you have to extend the tripod to get the eyepeice to a comfortable height, you loose stability quickly.
A better alternative is to keep the legs short and lower yourself down to the eyepiece. This keeps the mount much more stable. A good observer's chair makes this quick and easy.
Celestron sold these on CG5 for years, so it works well enough that it will get you by I suppose, but it may not be ideal.
So this it simply becomes a personal issua as to whether you can live with it. Many people do, and my guess will be that much has to do with how much planetar observing you do. The more you do, the less happy you will be with the CG5.
But for all around observing, I think you can get by with this.
Posted 12 November 2012 - 01:26 PM
I have vibration suppression pads, but never bother using them.
You *will* need a 2nd counterweight and an observing chair (I use a Televue Air-chair) is highly recommended.
If you are visual only, I'd strongly advise you to *not* look for a heavier mount.
Posted 13 November 2012 - 04:23 PM
Keith if you were not as far away as US I would consider your Losmandy;-)
Eddgie: Yes my CG-5:s have (actually I have two, one GT and one non GT)2" steel legs.
The dovtail is not an issue for me as I can choose to buy CGE dovtail or Vixen dito.
I have three counterwights.
My CG-5:s handle my old orange C8 extremely well; a knock on the ota at 480X and vibrations dies within 1". They also do a decent job with my 8" f/6 Orion Optics UK Newt. (7 kg, 14 lbs)as long as it is not too much wind.
I always use the mount legs as little extended as possible. With the Newt they are not extended at all.
I have a very nice observingchair, which I can vary from very low to rather high. Can`t live without that!
I am not a particular planetaryobserver, my observingintressts are rather general with possibly a preferation to binaries and globular clusters.
Stelios: Yes, indeed, I am visual only and I agree with you I won`t look for a heavier mount, like EQ6. Glad you have been happy with CG-5 + C925 for almost 10 years!
Seems like it all "boils" down to the question: Is the C925 with a bit unstability worth the extra 1.25" over C8 which is rocksolid on CG-5?
My 8" Newt. is optically better than my C8 *but* the C8 is so much easier to use and compact in size so it almost comensate for less optical quality. The eypiece is always easy to reach. In the Newt. it often ends up in crazy positions. When rotating the ota I often lose the object and when using go-to I lose alignment when trying to reset the object. That`s my experience anyway.
Maybe I should also mentione that I always use my celstron f/6.3 FR. I don`t like the SCT f/10 tunnelvision. So using a focalreducer with a possible C925 is a must for me.
This won`t be my 1:a scope in life it will probably be my last. I am 60 this year so I don`t expect, or want, to by any more scopes. So I am extra carefull with this purchase.
I also consider a refractor instead. A S-W 120ED or APM 107 APO but that belongs to another forum.
Thanks for reading ny unsorted thoughts!!
Astro Gemini Alt-Az
And a number of diagonals and eypieces
Posted 13 November 2012 - 05:02 PM
The C9.25 is about 23lbs heavier due to the 2nd counterweight, which makes the same lift (at least for me) more than problematical. In practice I usually need three trips--scope, mount and counterweights, although I suppose I could reduce that to two.
I think those factors are much more important that the fear of instability which won't materialize.
Still, for globular clusters in particular the C9.25 will satisfy more. Both scopes are under-powered for galaxies. It's a tough decision. If you think you'd observe very often if it weren't for the hassle, then get/keep the C-8.If you pick and choose your nights, or they involve trips to a dark site, then the C9.25 becomes the lead candidate.
Posted 13 November 2012 - 05:10 PM