First long focal length scope

[Tom33]

I am wanting to try imaging some of the smaller deep sky objects and galaxies and would like some advice on the type of scope I should be looking at. At the moment I use a SW Esprit 100 on a pier mounted EQ6RPRO in a roll off roof observatory. I am looking at either an 8 inch Newtonian or an 8inch RC or similar Celestron Edge HD. I have read many reviews which give pros and cons for all these but would be interested to hear other people’s experiences in making this choice.

[Elp]

Before you get into it, have you looked at the resolution based on a particular scope/camera combo and the mounts tracking capability? I don't know the specifics but paired with seeing conditions there will be some sort of limit to what's achievable.

A Newtonian or RC will likely be much sharper than an SCT, I had a 130pds its a decent scope but with Newtonians in particular you may have to tinker and modify the scope a lot to get it into a prime imaging condition, you can image out of the box if you have a coma corrector though. I find having to tinker though is unacceptable, the scope should work out of the box, you usually don't need to do meddling with refractors so why should any other scope be any different.

The edge hd will also be decent, I image primarily with a C6 so expect the edge to be far better. I only chose the C6 because I use it primarily with Hyperstar, in comparison imaging at f6.3 reduced is so so much slower in comparison but you do however get much better resolution with the longer focal length.

Note longer FL will require better guiding erring towards using an off axis guider and you have to be sure the setup is well balanced in Ra and Dec.

[ollypenrice]

My small object imaging was initially done with an ODK 14 (2.6M FL) and then with a TEC 140 (1M FL.) Image scales were about 0.6"PP for the ODK and 0.9"PP for the TEC. I'm pretty satisfied that both were, in truth, oversampled, the ODK massively so. Alas, the ODK's camera would not bin satisfactorily so we were stuck with the oversampling. On the whole, I preferred the TEC.

https://www.astrobin.com/335042/?nc=&nce=

https://www.astrobin.com/full/tak87a/0/

I would say this: don't expect any kind of radical transformation in your high res imaging over what you can do with the Esprit 100 and a modern, small pixel CMOS camera. There will be more detail to come, but it may be a lot less than you think and your guide RMS will need to be no more than half of your image scale in arcsecs per pixel. Presumably you already know your guide RMS or can easily find out what it is.

Olly