Thalestris24

Yeah, I'll need the RSpec for that. As I mentioned, though, it's very difficult to get sharp focus on anything here

ps thinking about it, trying to tweak the focus is probably a waste of time since it's never steady here in the first place. I'll probably have to just try and see what I can get...

Yeah, as I say, I'll to download it and have a go. It can't need much of a tweak at such a short focal length (384mm). I might switch over to my 115mm frac which has an Ascom focuser, so easier to adjust remotely.

Hi Andrew Thanks. I can use the SharpCap FX box to aid focus on a particular star (via the SA100) but not really sure how to 'tweak' it.... I'll have to download RSpec tomorrow and maybe see how to do it on the live spectrum. Still too cloudy here at the moment.. It might clear later. Fingers crossed. Louise

I'm a bit limited with choice of stars as I have a very restricted view of the sky - can only see to the East and whatever is passing my small window... I'll just have to see what I can do in SharpCap Louise

Ok, it's just that unbinned the qhy183m pixels are only 2.4um but I'll try it out when I can - maybe tonight! Louise

Ok, thanks Robin! I was hoping to capture some images separate from RSpec (which I don't have yet) and to keep things simple anyway. I get the impression I have to be careful not to let the star get saturated... Focussing is always difficult here - almost impossible to get sharp focus because of turbulence. I'll just have to try my best! I'm expecting to keep exposure times down to <30sec, obviously depending on the star. I've never done any planetary imaging.... Louise

Hi all Thought I'd try and rekindle my spectroscopy mojo! I've been ploughing through the video tutorials but it all morphs into a blur after a while... Was wondering if there was a workflow/crib sheet I could print out somewhere? I'm thinking of just the data acquisition part in the first instance. Like how do I get the exposure right for a given star plus all the other things I need to think of and do. I get that it's a good idea to go for an A-type star but not sure about how best to do the exposure. Is it better to take an avi or individual fits subs? Should I stack them or let RSpec do that? I'll be using my 80mm APO at f4.8 with a SA-100 and qhy183m, probably bin 2x2 with SharpCap Pro for acquisition. That gives me a dispersion of 11.2 and coverage of 0-30,943A assuming a grating to sensor distance of 43mm (it's hard to measure exactly). Thanks for any help/advice Louise

Hiya Sorry, I just saw the 'without wedge' in your OP - I must be more attentive! Having a wedge will help a lot. Is there a reason why it has to be a 'big' scope? Obviously anything with a long focal length could have the same problem as the big Meade in terms of fov and speed. I suppose it all depends on what you want to achieve? I do all my live stacking with an 80mm APO + 0.8x reducer + qhy183m. I have terrible skies though - very bad lp, poor transparency, not much fun... The combination of scope plus small pixel imx183m (5544x3694) lets me bin 2x2 to get a reasonable sized image (2772 x 1847) on an otherwise smallish chip. As I said before, maybe the best thing is to try out various scope/camera combinations via a fov calculator to see a ) what suits and b ) what will practically work. For live viewing / live stacking you ideally want a fast-ish combination - sensitive camera and low focal ratio (via a reducer if necessary). Louise

Hi again Thinking a bit left field, an alternative might be to skip the big Meade itself and just attach a small, lightweight, fast F4 scope e.g something like the Altair 60mm, in place of the finder - I'm not sure what's possible here? If you could do that, you could image with a high qe guidecam e.g. gpcam2 or something like a 183 sensor with SharpCap Pro live stacking. Or even a Revolution 2 video imager (see on YouTube, e.g. Without a wedge, though, you will be limited in terms of exposure times but I think the above should enable you to get some ok images. Dark skies always helpful... Louise

Hiya What scope/mount exactly? Do you have a focal reducer? Is a Starizona Hyperstar an option? You want to plug in your scope data and camera ideas into a fov calculator to see what might work. Louise

Can you not just use a dslr+lens+adapter as per the web page? https://www.rspec-astro.com/star-analyser/ Louise

It looks like the SA100 and RSpec pages may have been updated since I was having a go several years ago. I was just using the trial version of RSpec and I expect the trial period ran out though it's not overly expensive to buy. The video tutorials on the above link are quite good. I think there are alternatives to RSpec but I never looked into it. Robin on here knows lots! Louise

I meant the calibration and processing you have to do after you've got you star diffraction grating image. You have to use the calculator on their page and read the guidance re the right focal length etc. I think it works quite well with a camera + lens + adapter as per their example on the web page. I'm keeping mine for now Louise

Hi Um, I'm afraid I never really did much with it. You have to spend some time doing the calibration/post-processing (https://www.rspec-astro.com/more-videos/ ) and I didn't really have the patience. Plus I so rarely get clear skies. I've tended towards imaging via mono live stacking with the qhy183m instead. Maybe I'll go back and look at the sa100 again one day. Good luck if you have a go! Louise

Yes, you can have worm engagement problems but it's the motors which drive the axes. Being unbalanced doesn't help the worm engagement but you can adjust that. The worm gears have very small teeth compared to the non-belt driven motor gears. In my own experience with an heq5 with belt drive, I get the best results when my scope is accurately balanced in all 3 axes. https://www.cloudynights.com/topic/484545-whats-the-advantage-of-belt-drive/ Louise

Physics and maths!

This is quite good https://blog.longnow.org/02019/09/12/short-film-of-comet-67p-made-from-400000-rosetta-images-is-released/?fbclid=IwAR1YCd-z8rsgC7SpPi3HMvCx-ioZbQ5MPsdEvIbfKexoB7YlXg9JdXHiCMk

Thanks for the compliments, Jim! I can't see me travelling anywhere with my kit. If I can't even get it down the stairs... TBH, I've been losing my imaging mojo this year. I get so few opportunities cos of the weather and it's only certain times of the year that there are any interesting targets in sight (of my windows). It's demoralising. I've thought about selling all my gear but it would be buyer collect from Glasgow... I'll be back to evening classes and studying soon too so even less time available. Oh well. Louise

I'm a masochist ha ha! No, no filters used - just stretching. I so wish I had a car or something so that I had a means to get my kit outside but, being on my own, it's too difficult to move everything downstairs otherwise. I'll just have to soldier on, sigh. Thanks for the kind words Louise

Using the trusty TS APO 80mm on the Heq5 + Belt Drive through a small window Camera was the QHY183 Mono at -10 deg. Capture / Live Stacking with SharpCap Pro. Sky was initially fairly clear (for here) but transparency dropped. M45: 4 x 16 x 60s A bit overstretched but at least shows some of the nebulosity NGC 1746: 4 x 16 x 60s M35: 4 x16 x 60s All a bit flawed in one way or another but I'm pleased I got something. The more-often-than-not clouds mean imaging opportunities are very few and far between here in Glasgow. At least it's darker again now, and some targets have come into view. I tried to grab M31 but it was too high and the window frame got caught in the subs I did. Maybe I'll have a change around and put the heq5/80mm in front of the bigger window. That will give me more scope, so to speak . Also, no LP filters were used in the making of the above images so they are affected by LP and IR. I'll have to extract the IDAS from the inside of the medium format Pentax 300mm. Louise

So you need to be in perfect balance. No concern about engaging motor gears. The bullseye target will show you if you have a balance-related drift.

I thought you had a belt drive?

Hi You should show your star profile and bullseye target from the view menu. The calibration doesn't look too good for a belt drive. Maybe guide scope flex or a balance issue. Louise

https://www.greenandblacks.co.uk/