Jump to content

sgl_imaging_challenge_2021_annual.thumb.jpg.3fc34f695a81b16210333189a3162ac7.jpg

Beginner advice for DSO imaging through refractor


Recommended Posts

Dear All,

I am looking for a cheap way to get into astrophotography of DSOs and am after some advice. I currently own an AZ tracking mount and am considering buying a Skywatcher 102mm f/5 refractor as seen here:

Sky-Watcher STARTRAVEL-102T (Tube Assembly) 102mm (4") f/500 REFRACTOR

I plan to attach Canon DSLR on the end and take some shots. As my mount is AZ, I realise I will only be able to take up to 1 min exposures (or less) before field rotation becomes an issue. With that in mind, would my idea to also buy a 2" f/6.3 reducer make sense? My plan is that this would hopefully speed the telescope up to f/3.3, so that I could capture more light. I realise I might get some vignetting but as the focal length of the scope will be reduced (to say 330mm) then I could crop anyway to resize M31, for example.

I would welcome any advice on this potential route, particularly if I have missed anything obvious that might scupper any chance of a half-decent image.

Thanks very much,

Nick

Link to comment
Share on other sites

Steve,

that's an achromatic scope, so it will suffer from chromatic abberation - violet haze on your images. You'd be better off seeing where you get using your Equinox 66 (if you haven't already done so) which I should think would give you a better corrected image.

Cheers

Alan

Link to comment
Share on other sites

Alan,

Thanks very much for reply. The reason I thought of the Startravel is that it has a larger aperture than my APO 66 and is also faster (i.e. f/5 compared to f/6). Given that the max length of my exposure will be 1 minute, my sense was this would be more important than some chromatic abb. However, do you think the APO 66 would be able to gather enough light in 1 min (perhaps with a focal reducer)?

Any more advice greatly appreciated,

Nick

Link to comment
Share on other sites

Nick, the wo will give you lovely widefield views and being a better corrected lens element will not give the halos that either need to be processed or filtered out, even filtering will not get rid of all of them on the brightest stars with the ST

If you can stretch your budget a bit, then Clearance / Pre-Owned - Celestron 80ED APO Premium Refractor is a cracking scope, same optics as the SW 80ED but a smaller tube, therefore a bit lighter. This will also work very nicely, at a later date, alongside the wo66 for guided imaging.

Link to comment
Share on other sites

Thanks again for advice everyone,

Thinking about the APO 66 route, does anyone have experience of using a reducer/flattener? If I'm correct, I can use a WO 0.8x reducer on my scope (which is Skywatcher Equinox), which will speed it up to F/4.8 and allow some half-decent images on my AZ mount?

Is there a cheaper alternative to the WO reducer or should I really pay £100+ for this model to get good quality?

Thanks,

Nick

Link to comment
Share on other sites

Nick,

I should think the WO FF II would work well with the Equinox 66 as it is designed to work with the ZS66 which is similar except it has a slightly shorter focal length. Does anybody know the Equinox 66 has a 2" sct thread on the back?

I just got a PM back fom Steve51450 who previously owned my ZS66 and WOFFII and he says you will get an image, but it will be a bit noisy using that combination and sub 1 minute exposures. I guess it would improve as the number of subframes you took increased.

I got a passable image of the ring nebula using a C80 ED using 30 second exposures (OK C80 ED has got more aperture, but it is f7.5). A good field flattener would also be useful if you went for a bigger scope in the longer term (80 or 90mm) and it would be easier to sell because you can just pop it in a jiffy bag. Maybe some more experienced imagers would have an opinion on suitability of the Meade 6.3 which seems popular...

Regards

Alan

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.