Got the mount now for the tube...

[stormin63]

Hi,

I've just returned to this forum so forgive me if this question has been asked many times before and feel free to redirect me to the relevant thread elsewhere if you wish.

Ok, a couple of years ago I purchased my son a small (76mm) cheap telescope and mount from a local superstore (ALDI's if you're interested!) for Christmas. I was aware of the quality considerations, although it's actually pretty good for the money, but although he has always been interested in the subject you know what teenagers are like and I didn't want to pay lots for a system that would get used for a month or so and then be forgotten about!

However, his interest has continued and as I have always been interested we decided to join our local astronomy club to gain some more practical knowledge and meet like minded people. Following this it was clear that amater astronomy had moved on a lot since I last looked, particularly with regard to imaging. As a result we bought a webcam (SPC900NC) and adapter for our camera (Nikon D3100) and obtained some free software (Registax) and started taking some pictures. The results were pretty good for the initial outlay and we picked up a lot of good tips. So I decided the next step was to start building a system that would allow us to take things to the next level, taking into account economic considerations of course!

We were advised that a good principle to follow was to spend a third of your budget on the mount, a third on the OTA and a third on the eyepieces. So after some research and seeing what other members of the club had I started this process by purchasing a Skywatcher EQ5 with GOTO. That was a year or so ago and now I'm ready to take the next step of buying a new OTA.

So the usual question is what do we want to do with this scope? And probably the equally usual response is a bit of everything!! I'd say we'd like to spend perhaps 70% of our time doing imaging work and again the same percentage of this doing lunar and planetary work with the remainder looking at DSO's. I'm basically looking for a good all rounder - if our interest continues and we want to specialise further that would be great but that's for another day.

Considerations that I'm aware of include:

o Weight issues, I believe the weight limit of the EQ5 is 9kg (not including counter weights) but that for DSO imaging you should try to keep to about half that (is that true if it's well balanced?).

o Large f numbers (say above 10) are better for planetary work while smaller are better for DSO's. These can be extended using focal reducers and Barlows.

o Getting as big a bang for my buck as far as aperture size is concerned (8" or above if possible)

o Ease of use, set up and maintenance.

o Connection issues - what dovetail do I need?

o Available accessories etc.

For convenience and cost I'm thinking of a SCT or Mak rather than a Newtonian or refractor and my current thinking is something like a Celestron C8 (which gives you an idea of my budget) but I'm open to all suggestions. Also I'm happy to buy second hand if it's in good condition although I'm prepared to buy new.

Mmmm that's a lot of text, if you've got this far thanks for reading and thank you in advance for any advice you might give.

Cheers,

Paul

[ronin]

If you go for a Mak or SCT then you may be disappointed if you go for deep sky imaging, and it sounds as if you will.

In AP forget the idea of a big aperture being better, an 8" on an EQ5 is as big as makes sense with visual not really AP.

The AP route would be something like an 80mm ED on the mount.

That would be reasonable for visual but not great, depends on the darkness of the skies. Not sure what 90mm and 100mm ED's are around that might be usable, check the Telescope Service site as they seem to have a fairly wide selection of various makes.

Best all round I would have said a 102ED refractor, but weight and cost would be the negatives, the WO Megrez 90 being another but they are not produced any longer.

Check the used market such as UKAB&S

[Catweazel]

In many ways, you seem to have a good idea of what you are looking for, which is good I would say that the C8 is a good scope for AP, although it may be adviseable to factor in a Focal Reducer if you want to take wide field exposures. The other thing is that the C8 weighs about 5.5 kilos, so long exposures might be a problem on a EQ5.

[ollypenrice]

In my view a C8 on an EQ5 would be a disaster for DS imaging. The accuracy of the mount, even autoguided, would be nowhere near good enough for the focal length even at F6.3.

DS imaging on an EQ5 will have to be at very short focal lengths. The HEQ5 is far more accurate and also more stable. The distinction is important. On the EQ5 keep it short. OTA weight gets far, far too much air time in these discussions. Focal length asks a lot of a mount since it 'magnifies' the errors. Think of trying to pick up a pea with two metre long chopsticks. It doesn't matter how light the chpsticks are, you'll still struggle!

The Do It All scope simply doesn't exist. DS imaging, planetary imaging and visual observing have mutually exclusive requirements. That's why we're all broke!!

Olly

[stormin63]

Thanks for your prompt responses which give me plenty to think about. Olly I take your point about there not being a Do It All telescope and the resulting effect on your wallet! I guess we really need to sit and think about what we want to see and how we are going to use it. I plan to chat to the guys at our local club who do AP to get their advice and I'll do my best to check out images produced by potential solutions to see if we'd be happy with those results.......after a bit of practise! I'll keep you updated with developments.

Cheers,

Paul

[Spanishfly]

Best all round I would have said a 102ED refractor, but weight and cost would be the negatives, the WO Megrez 90 being another but they are not produced any longer.

When I finally get into imaging I will be using my Stellarvue 102ED, a brilliant scope both mechanically and optically, with its Feathertouch focuser. That is my keeper, the one I will never sell (famous last words?), for a number of reasons, it is a rare beast this side of the pond, and they don´t make this one any more.