What should my next steps be?

[Celestron4]

As I am now coming to the point in the year that University finished for the summer and I can finally turn my attention back to astrophotography, I figured that it might be a good time to spend some money on new equipment. 

My current equipment:

Celestron Nexstar Evolution 6 SCT (with celestron f6.3 reducer)

Celestron AVX mount

Altair 60mm guidescope and GP-CAM 130C guide camera

Canon DLSR (modified EOS 600D)

What would be best to spend some money on? My budget is limited (ideally around the £500 mark, I know this isn't very much) and I would ideally like to keep the SCT if possible but would be open to any suggestions for telescopes if the SCT is a significant limitation (I have had collimation issues earlier in the year). I have bortle 4 skies (light pollution is noticeable from nearby towns) if this is any help. I have attached an image of NGC7380 captured with my current setup. It may be slightly over processed but would be interested in any suggestions on what I need to improve it! 

 

 

[Hughsie]

Been wondering what to write here because my first thought would be to upgrade the mount as having a solid base with good tracking is essential, even more so when using a 6 inch SCT. Then I look a your image and the question that comes to mind is ‘are you happy with it?’. I ask that because its a great photo with the equipment you have so why change at this time especially when gear looks expensive and is typically hard to find. 

You may be thinking about a new scope and as you have more free time and hopefully some clear skies in the Summer then as its nebula season you my want to go down the wide field route with 50, 60 or 70 mm aperture being an option. William Optics offer a lot of good optics in this size though the 50 and 70 mm options would be outside budget plus all three may require added extras like a flattener or smaller guidescope.

Right now, I would enjoy what you have and save up for that mount. Having a good work horse in the stable that is is going to cover some future scope purchases will be a great investment.

[catburglar]

Depends what you want to achieve.

If you want a wider FoV you could go for a small refractor as suggested above, OR a SW130PDS plus coma corrector OR a Samyang 135 F2 ED lens - and carry on using your DSLR.

Also, if you’re sticking with the DSLR, you may want to try one of the dual-band or tri-band filters so you can do a bit of “narrow band” with your colour sensor.

You could also try a cooled camera - but with your budget you’d be looking at the used market - there’s an ASI533MC on astrobuysell- it’s over budget, but if you sold the DSLR it might not feel so bad. The sampling  rate is a bit high for your focal length, but you could bin to bring it back to somewhere between 1-2 arc sec per pixel.

It’s probably true that a better mount would be a good investment in the longer run, but I doubt you’d get anything much better than your current set up for your budget- and if you’re going shorter FL then tracking precision is less important.

 

[Celestron4]

I have been thinking about a wider field telescope and wondering whether it might be a good idea. The mount does the job at the moment but could a shorter focal length scope help get more out of it? Would the Optolong L- Enhance be a good option in terms of a tri-band filter? 

[Celestron4]

Also worth adding, I’m looking at automating (in a loose sense) my setup a bit to allow me to leave it running overnight. The DSLR can be powered with an AC adaptor and I might move towards using a Raspberry pie to run the imaging setup. Is there anything that stands out as potentially helpful to achieving this?

[catburglar]

If you’re not having troubles with guiding and your individual sub lengths are not limited because of tracking errors - then a shorter focal length scope won’t make a difference to your ‘image quality’. But it will give you an option to capture wider fields of view- so it’s a question of how wide you want to go? The 130pds option is about 600mm (compared to around 1000 with your current SCT & reducer), the refractors are around 400mm and the Samyang lens at 135mm is very wide. You might want to check what FoV is required for the targets that you want to shoot.

I don’t have any direct experience of the Optolong filter- but if imaging was my bag, I’d be considering that one.

It should be fairly straightforward to get some automation using a raspberry pi/Astroberry combo. I used it with a 600D and AZ-EQ5 some time ago-plate solving, guiding and image capture, but didn’t go as far as completely unattended imaging. You might need some other bits depending on how far you want to go- I’d start with an autofocuser, then you might want to get a ‘flip flat’ so you can automate taking flat images, and you might want an all sky camera or something to monitor the weather so you can shutdown safely when the clouds arrive and before the downpour.

[Celestron4]

In terms of focal length, ideally wide enough to get decent images of larger targets (M31, NGC1499, NGC7000) without having to worry about creating mosaics (I’ll have a go at some point but don’t have the time or enough clear nights at the moment). From what I’ve read refractors tend to be best for image quality but can get hugely expensive. What would be my best bet?

A focuser is a good call, I might look into that but will depend on the telescope. I’m basically aiming to get my setup in a position that I can set it up leave it running (when I have clear nights) to maximise available image time and to avoid lugging a lot of heavy equipment inside during the early hours of the morning if at all possible. 

[catburglar]

For those objects with your camera you’ll need a focal length around 430mm or less (see screenshots- The first two are 430mm, the last is the Samyang 135mm- I use Telescopius.com to estimate the FoV of different scope camera combinations). You are probably better off with something in the 3-400 mm range so you can crop any stacking artefacts at the edge. So unless you’re going for a takahashi epsilon or sharpstar 150 reflector your looking at a small refractor or camera lens WO ZS61 or Sharpstar 61EDPH or WO Redcar or Askar 180 or 200 lenses might do. For the 61mm scope you’ll probably want a flattener, you shouldn’t for the Redcar, but not sue about the others. You could always start off without and see what you think about the corner stars

Edited April 30, 2021 by catburglar
Corrected typo

[Dazzyt66]

On 29/04/2021 at 00:36, Celestron4 said:

Also worth adding, I’m looking at automating (in a loose sense) my setup a bit to allow me to leave it running overnight. The DSLR can be powered with an AC adaptor and I might move towards using a Raspberry pie to run the imaging setup. Is there anything that stands out as potentially helpful to achieving this?

I use Astroberry with an RPI4 using Ekos scheduler to perform my imaging overnight. I don’t have autofocus so I basically set it up with a Bahtinov and then schedule the target to run as many images as I can get in. I’m unguided so limit to an hour of 30s subs and then rerun the same set over again so it re-plate solves. Seems ok so far and I’ve had some good results. I do my bias and flats when I get up (the white t shirt method at dawn)