Second scope for imaging

[Pete D]

I have been looking for a new scope for astrophotography as my 200p is not the best for imaging so I was looking at the Skywatcher 80ED DS PRO or the Skywatcher Quattro f4 Imaging Newtonian. I am still going to keep my 200p but not sure whether the Quattro would be too similar to it. Anyone got any ideas on a good imaging scope between £400 - £900.

[MBJ]

the ed80 ds pro is the better choice of the 2 for imaging.

[earth titan]

the ed80 ds pro is the better choice of the 2 for imaging.

Is it? I think they are such dramatically different scopes, they cannot really be classed as better or worse. The 80mm may be simpler to set up but both have their good points. Depends what the OP wants to do.

An 80mm refractor will always some false colour - a reflector won't.

A reflector will give defraction spikes - a refractor won't.

The quatro is 200mm and will eat loads more photons. At f4 (ish off the top of my head) it is also fast and a sod to collimate.

I have similar scope to both of these and love them equally.

Sent from my X10i using Tapatalk 2

[Earl]

Before we discuss options, why is your 200p letting you down?

[sgazer]

I think knowing the problem with the 200p will also point us in the right direction.

Out of the 2 scopes, I would go with the f4 quattro due to it's faster focal ratio requiring 3.5x less exposure time than the f7.5 80mm (eg 5 mins, instead of 17.5mins). Also with a coma corrector (eg Baader MPCC), it will produce very sharp stars right to the edge. The downside is accurate collimation required.

[Pete Presland]

i would have thought the 200p at F5 would make a pretty decent imaging scope, especially for DSO'S.

[Pete D]

It`s mainly exposure times. I took a few images with my ST80 just to see and manage about 120 secs before star trailing but with the 200p 45 secs is the most I can manage. I am just starting to get into guiding so this might not be so much of a problem later on and I might be mistaken but most of the best images on here seem to be taken with refractors.

[RikM]

If you get your guiding sorted, the NEQ6 is plenty big enough to cope with s 200P and you should get some very nice images with it. The issue it has (and it's the same with my 150P) is that it is an in-between focal length. Not enough field of view for the big targets and not enough focal length for the small ones. Guiding makes a huge difference to images. Everybody says the mount is the most important component for deep sky AP, but it is autoguiding the mount that is the kicker. Get that sorted and you will be happy for ages. It opens up many new targets for you that you just wouldn't be able to get with short unguided subs.

In the future if you want something to compliment it, then an ED80 with a flatner/reducer would allow you to have a go at the big targets. Easy to set up and use, reasonable exposure times with the reducer, would be a good addition and would allow you to expand your choice of targets.

[Pete D]

Just to get this right would the 200P have the wider FOV than the ED80. I thought the the lower the focal length say F5 over F8 the larger the FOV.

[sgazer]

It`s mainly exposure times. I took a few images with my ST80 just to see and manage about 120 secs before star trailing but with the 200p 45 secs is the most I can manage. I am just starting to get into guiding so this might not be so much of a problem later on and I might be mistaken but most of the best images on here seem to be taken with refractors.

Your EQ6 is more than capable of imaging with the 200p, so the size is not the issue, the focal length is the reason you are getting shorter exposures with it. The ST80 is only 400mm focal length, the 200p is 1000mm, so you can expect less than half the time before star trailing occurs with the same setup. (Basically you are zoomed in more, so it needs better tracking). If you get the ED-80, it is 600mm, so you can expect to be able to take 1.6x longer exposures before star trailing occurs, than with the 200p on the same setup, however at f7.5, you will need double the exposure time with this scope than the 200p, so you would actually lose out.

With better alignment (eg. drift alignment), you'll get 2-3 mins with the 200p. With auto guiding, you'll get 5mins+.

I don't think refractors (in general) offer a better image quality that reflectors, but they are generally smaller, shorter focal length and easily maintainable, so put less strain on the mount and guiding and are more likely to be chosen with a CCD camera, hence more often the decent images are taken with a frac+ccd+ narrow band filters. On a budget, a newt and DSLR are generally chosen and although the images are excellent, they aren't as good as a frac+ccd+ narrow band filters.

[RikM]

Just to get this right would the 200P have the wider FOV than the ED80. I thought the the lower the focal length say F5 over F8 the larger the FOV.

You are right that focal length is what dictates field of view, but the f/5, f/8 etc. is the focal ratio (focal length / aperture). The 200P is 1000mm focal length and with a DSLR would give you a field 1.27° x 0.85°, with the same camera a native ED80 (600mm) would give you 2.12° x 1.41° and with a 0.8 reducer (480mm) 2.65° x 1.77°.

Reflectors can give very good images indeed, but they do require more maintenance and tinkering to get set up correctly. Refractors are much easier to use and generally give better results out of the box. Being easier to use, you will therefore generally see better images from refractors.

[Pete D]

Thanks for the informative comments. So the only benefit I would get with an ED80 is a slightly wider FOV and easier set up and use.

[earth titan]

But you will need to keep the shutter open for longer on the smaller scope.

Swings and roundabputs;-)

[RikM]

Thanks for the informative comments. So the only benefit I would get with an ED80 is a slightly wider FOV and easier set up and use.

More or less, yes, and Tom is right about the exposure time, but imaging is generally difficult and complex so anything that is easier to set up and use, is a big plus.

[sologuitarist61]

Has anyone got one of these Altair Astro GSO 6" F9 Ritchey Chretien Astrograph (Fully Loaded)? They look really good for imaging and get away from the problems associated with refractors. Looks a good piece of kit too (and the price ain't bad either) .