The Admiral

Very nice image that, Nige. 3-4 hours to stack! That's torture, blessing in disguise that it failed I should imagine! Ian

Forgive my ignorance Nigel, are you saying change 'scopes after first aligning? Why do you need to do that? Is that the 150 on the mount? Ian

It's always worth a try Neil. I would imagine that even an EQ mount that isn't perfect at tracking will give you an advantage over an Alt-Az mount. I'm not so experienced at astrophotography that I fully understand the benefit of a 2 minute sub compared to a 1 minute one, but I presume that skyshine will limit you eventually. I'm always reassured by the following thread: "To Stack or Not To Stack: 30x 1s = 1x30s?" (https://stargazerslounge.com/topic/245183-to-stack-or-not-to-stack-30-x-1s-1-x-30s/?page=1) by Martin Meredith. I've seen Olly Penrice commenting that he finds darks to be a waste of time, particularly with dslrs, and uses dithering and bias frames as darks instead. I need to explore that further, but the lack of precise tracking with Alt-Az mounts and presumably a less-than-perfectly tracking EQ mount would do much the same thing as dither. So all is not lost! Ian

That's kind of you to say so Carsten. It's taken us a while to get this far, but it is all achievable with our modest gear, and you should be no different. I've said it before, if you take lots of subs, then processing can make or break an image. Get that right and your image can zing. Personally, I've found the processing part the much more challenging and difficult to get right. I suppose that goes for any astrophotography, EQ or Alt-Az. That's why I think by starting with modest gear one can develop ones processing skills, and then later decide whether to get into the full works with all the fancy and expensive gear. It's not time wasted. I use Star Tools, and it does have its quirks and I wouldn't say I've got it tamed by any means, but it can (can, not always!) produce some decent results without a great deal of effort. I dabbled with PixInsight on a trial, and although I can see it gives one great control, it does require a deep multi-stage process so far as I can see. Keep at it! Ian

I think that's likely to be the problem Nigel, it's just recording the variation of the light it's seeing in the field of view. I understand that whilst the 'scope needs to use the same focus position as when imaging, you need to present it with a uniform source of light, but this doesn't itself have to be in focus. Hence the use of diffusers at the end of the OTA. I've not seen any consistency on exposure levels, some say 1/3, others 1/2 of max. If you do as Steve does the camera should record it as mid-grey. I guess the main thing is that you accommodate the full range of light variation. Ian

I presume you were using the tea-towel over the end? If you were, I imagine the light presented to the OG would have been uniform, in which case the distribution should reflect the sensitivity across the field. I have read that the histogram peak should be about 1/3rd of max. Clearly, one needs to avoid any chance of saturation. I did mine with a laptop screen and a sheet of opal perspex in front of the OTA. If anything, you'd expect the image to be brighter in the centre and darkening towards the corners. Ian

I'm guessing but probably processing clusters is less troublesome because the stars are significantly brighter than background, and you can adjust the black point. With nebulae I find it's often a fine line between faint nebulosity and noise. It'll be interesting to process such an image with and without. As I say, this is the first time I've used flats, so I've nothing to go on.

Thanks Steve, difficult to say as I haven't tried stacking without. Ian

Nice images Steve. I particularly like the ring Neb, very colourful, something I'd like to capture when it becomes favourably positioned. Ian

Here's a couple of Altazographs from last night (19 April 2016). I'm struggling to think of new targets, as with a southerly aspect and the raging moon (though I did image that ) I'm confined largely to the south-west, east and north-east (above the houses). I stuck to starry objects, and went with M67 and M13. All imaged using Altair Wave 102mm f7 SuperED APO, Fuji X-T1, Nexstar 6/8SE Alt-Az mount. Used flats for the first time too. For M67 I used about 50 frames each of lights (30s), darks, flats and bias, stacked in DSS, processed in Star Tools, and tweaked in Lightroom. For M13 I used the same flats, darks and bias frames as in M67. The lights were a bit of a problem, because after the first 50 I realised that the field tracked through some overhead power wires, so I had to do another 50 frames. Checking through them I ended up with only 26 x 30s lights to stack! Stacked in DSS, processed in Star Tools, and tweaked in Lightroom. Thanks for looking, and I hope you like. Ian

+1 to that Steve. Considering the state of the moon it looks surprisingly contrasty. Fingers crossed for tonight! Ian

That's a lovely image Nige, I'm quite envious. Mind you, 2am, that's suffering for your art in my book! And the total exposure isn't that long either, which I guess is a result of a decent aperture. Ian

Light pollution or not, you picked up a lot of the nebula and the Running Man. What did you use to process it, because dedicated astro packages can help clean up any background light pollution? Ian

I had another go to improve the image in Star Tools, but I just can't seem to find the right formula, even assuming it is possible. However, I did import it into Lightroom and did a bit of light tweaking there, and I think it is improved. It's an extra step but I think it worth doing. Ian PS. Actually, to be perfectly honest, I find it extremely difficult to get anywhere near the same output from ST by re-doing the processing, unless I use the ST log and enter the same parameters as I did before!

Hi Nige No that's OK. Does it automatically optimise the image, or do you manually select operations? If so, which ones did you use? I've a variety of photo manipulation software, but I didn't post-process the ST processed image. I tend to be PC based only and wouldn't want to swap the image from one to t'other. I'd like to think that you should be able to get the same using ST, but I'm a long way from taming it! Ian

Thanks Nigel. Yup, good luck, there is an infinity of options Ian

Well I had another go at processing M64, spending a bit more time on it and using bias frames instead of darks as Olly Penrose has suggested, but of course DSS won't let you add the same files for the bias frames as well, so I left it at that. So whether I'm doing it right goodness knows. Still, I think this is about the best I'm going to get with this limited data set. There's no substitute for photons! Ian

Thank you Nige. My mount limits the altitude of my refractor to less than 60 degrees, but I'm generally happy with that to keep rotation within limits. Ian

Here's a quick and dirty look at M64, the Black Eye Galaxy. I was out taking some images of the Moon and Jupiter, testing a newly acquired x2 focal extender. After I'd finished that I reverted to my usual set-up and as there was a bit of time I turned the 'scope towards M64. I set the camera going for the first batch of 50 frames, but when I returned to the camera it was completely dead. Not knowing how many frames it had managed and as it was getting a bit late I decided to throw in the towel. In the end I did get about 50 frames, but no flats, darks or bias frames. Not really enough, but this is the result. Not great. I'll need to have another go when the skies clear again. When! Usual set up, Altair Wave 102mm f7 SuperED APO, Fuji X-T1, Nexstar 6/8SE alt-az mount. 12th April 2016. Stacked in DSS and processed in Star Tools. Ian

You are not alone! I did the self-same thing yesterday. Despite setting up on the RDF, I still couldn't see it on the LCD screen. I spent an age slewing back and forth until I realised I hadn't turned the wick up Your sky background is very black. I wonder if some fainter details are being clipped?

You deserve to be well chuffed with those Nigel . I've said it before, the post processing can make or break an image, it seems so much more critical with astro images than conventional images. I think a lot of folk try to take pictures with relatively modest gear, and because the results are disappointing they think they need all the fancy bits and bobs and give up. But quite often, there's so much that could still be teased out with the right processing. Star Tools has its own quirks, but it looks like you're managing to tame it. I still don't feel I've mastered it. Ian Ian