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First light with Ha 7nm with qhy8l

Thalestris24

By Thalestris24
in Imaging - Discussion

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Thalestris24

Thalestris24

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Hi all

After being inspired by our russellhq and being frustrated by lp, I decided to quickly shove a H-alpha filter on to see what difference it made. I only did single 1200s subs but was quite pleased to actually see some nebulas! (with some stretching, lol)  :)

First was California Nebula:

post-33532-0-89505300-1409158445_thumb.j

Next was Flaming Heart Nebula:

post-33532-0-55218200-1409158523_thumb.j

Poor star shapes with the latter - think my guiding went a bit screwy... Also picked up a satellite trail - tut!

Still they've given me an idea of what can be done. I couldn't use Astrotortilla because of the long exposures needed though apparently it can be done with bin 4x4 so might try that another time. A filter wheel would be good if I can get one to fit behind the coma corrector. Of course an 80mm (or 70mm) frac would be better for the bigger nebs.

Oh, it was the Baader 7nm filter. Next time I'll aim to stack numerous shorter subs :p

Anyway, thought I'd share :)

Louise

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Thalestris24

Thalestris24

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Hi Olly

They were just a quick try-out last night and obviously a colour camera isn't ideal, I know. I've been trying to image M33 (see Imaging - Deep Sky tdnicholls thread) and have been getting frustrated indeed! However, for that I'm going to try many shorter exposures (~300s) rather than the longer ones (900s and 1200s) that I've been using - not very successfully! If I can get a suitable filter wheel then I'll have more goes at nebulae :)

Thanks

Louise

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lensman57

lensman57

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Heh heh - I couldn't ever afford a WO71Star! Maybe an Evostar ED80 at some point :) I only have a state pension...

Louise

Hi Louise,

Last May I found a WO 72 Megrez F6 on the UK Astro Buy and Sell, it is the FD-DDG version which I believe uses The FPL53  glass rather than the 51 in doublet and has the beefed up focuser to cope with heavy CCD and FF/FR . I have been very impressed with it and I intend to use it with the Star 71 as a double set up if I ever getthe chance to sort it out . If my memory serves me right I paid around £270.00 for it and I think it is worth keeping an eye out for one of these if you look around. I did this version of the Eastern Veil in  NB Bi Colour with this scope on the 5th of August and I think that it performed well. http://www.astrobin.com/111545/B/

Regards,

A.G

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lensman57

lensman57

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Hiya

Nice image, as usual! I'll bear it in mind  though I'm not really confident enough to buy second-hand. At the moment, my priorities are a second guide camera and a filter wheel. Together, they will use a lot of funds!

Thanks

Louise

Hi Louise,

I understand what you are saying. The filter wheel is convinient but not essential, also so long as you can mark the position of the camera relative to the scope there is nothing stopping you from using the filters on the nose piece and changing them as required. In my experience ( limited as it is ) unless the filters are truly parfocal, the filter wheel mechanics 100% accurate and the scope highly corrected  ( Tak FSQs or other exotic brands ) then a refocus between filter changes is essential so this negates the role of a filter wheel. You should also consider the use of an OAG if you are to stick with the 150PDS as the OAG will greatly reduce the effects of the primary mirror sagging or flexure of the tube due to the weight of the guide scope and camera. Your QHY5 LII is designed in a similar manner to a LodeStar so it will work better with an OAG than my ASI 120.

A.G

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Thalestris24

Thalestris24

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Hiya

Yeah, I did that when I tried out the Ha the other night but it's not at all convenient. I fitted the 7nm to the thread on the scope end of the MPCC. I think taking the camera and MPCC out to put the filter on caused the camera driver to crash - must have caused a movement of the camera cooler cable or something. That necessitated powering everything off - including the computer, in order to get it running again :( That worries me - never good to suddenly switch the cooler off. So I don't want to risk that happening again. It may have just been a glitch but I don't want to experiment to find out! Plus having the 7nm in place made it very difficult to focus. Add to that, not getting the camera back in exactly the same place could result in needing to take a new set of flats or inadvertently introducing tilt.  

The Baaders are supposed to be very nearly parfocal - I had the idea of using a 35nm Ha to focus with (and maybe also use AT with) then switching to the 7nm to image with :), then switching to clear filter for normal colour imaging. I maybe crazy in my expectations! I would also want to combine the Ha with my normal colour image. So imaging time is always important! I mean, the amount of time I have to image through the window is limited so I don't want to lose any swapping filters on and off.

My guide scope is bolted to the tube rings and seems to be quite rigid. I don't think I want to fiddle about with an oag but I'm not writing off the possibility in the future! I have been getting 1200s subs but find they are too long with the lp so now it seems I need to limit exposures to more like 300s. It's a game isn't it??

Anyway, I have to find a filter wheel that will fit behind the MPCC... Modern Astro sell the Brightside one for £99 but I'm not certain if it will fit. If not, I'll have to search for a slimmer one!

Cheers

Louise

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Thalestris24

Thalestris24

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Thanks Alex Louise!

Hehe. They were just a quick try out - a first go. The images seem quite noisy - I think maybe some lp was showing through with the relatively long exposures? But also they are only single subs. My filter wheel arrived today :) Who knows when the weather will give me an opportunity to try it out...

Louise

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