The Admiral

Thank you Nige. What, a reflector! Not a chance. But with your larger aperture I guess you might see a bit more resolution, unless you're looking through cloud, in which case it doesn't make a whole lot of difference . Whatever happened to you using your 200P? Or was that someone else? Ian

Very nice Nige, the extra data certainly helps. Ian

Okay, okay . But seriously Nige, I do like that mosaic very much. Ian

Certainly the Christmas Tree cluster/Cone nebula is within your 'scope's reach, but if you are planning on capturing other things? A quick Google reveals many images with differing fields of view, and it almost seems that the nebula never really stops! It just depends on how far back you want to view it from. Now's your chance for a mosaic! Your 'scope has a rather wider FoV than mine. Incidentally, what software are you using for the above? Ian

Yes, you can see the green crescents in the stars that I was referring to. I might have a re-process; I software binned 33%, which isn't a nice round figure, so I might try a different binning. It's also in the tif so it shouldn't be a compression artefact. Ian

Hmm, not sure about that, on my screen. If anything, I'd say a reddish cast. What does appear to be the case though is that some of the stars aren't uniform and there appears to be a coloured crescent to them, perhaps greenish. I've racked down the saturation of the greens in LR. It's over-sharpened in ST though. Ian

Thanks Ken, I'll have a look at that. Yes, I found framing difficult because I wasn't able to work out exactly where I was (or even which way up!) from one of the subs. I relied totally on my mount for putting me in the right spot to start with. And again, I wasn't sure of the extent of the nebula, and given that with the extended observation period I envisaged quite a bit of cropping too. Luckily, it just about worked out OK. Ian

Well, well, well! Two clear nights on the trot . Couldn't let that pass! The previous night I topped up my Rosette Nebula image but I'm still processing that, and last night I had a go at the Cone Nebula. I wasn't sure quite what to expect with this, as I don't recall seeing any Alt-Az images of it. I took 240 x 30s subs at ISO1600, but whittled those down to 170 before stacking in AstroArt. I took 60 flats but no darks, instead I used a generic ISO1600 bias stack. The red channel is very noisy, but I was pleased to see the Cone making a distinct appearance and the brighter parts of the nebula shows a surprising amount of fine detail. I think this target needs a lot more data, which means field rotation is going to be a problem unless one is able to image on several nights with prior alignment. Anyway, here's what I managed to squeeze out of this data set, using StarTools with the colour module, and polishing in Lightroom. Equipment: Fuji X-T1 through an Altair 102mm f/7 Super ED with a TS Photoline 2" 0.79x reducer/flattener. Mounted on a Nexstar 6/8SE Alt-Az mount. Ian

Welcome to the Forum MZ and to the wonders (and frustrations!) of astro-imaging. That said, Alt-Az imaging gives a great introduction to the art, for modest outlay. You've made a good start, presumably attaching your Pentax with lens to the mount, rather than attaching to the 'scope? But +1 to all of Nige's suggestions. Looking forward to seeing more of your images. Ian

That's rather nice Shaun and shows a lot of promise. Nice and sharp and I'm sure that there's rather more detail hidden in there, especially for 7m exposure, but I agree with Nige, the sky is so black that you may be clipping off some detail hidden in the shadows. And a bit more stretching would help I think, don't worry too much about the noise, you can deal with that later. I always think that a lot depends on processing, self-evident really I suppose, but so often one sees images that have potential which hasn't been fully exploited. Once fully exploited, it can be most encouraging I find. Don't expect pin-point stars on all your subs. Some nights the mount may seem to perform brilliantly, and at other time rubbish. In an attempt to image the Rosette nebula the other night I ended up ditching about 50% of my subs, though to be fair I was being ruthless. By the time that 'slightly off' stars are stacked they'll more than likely appear round, though perhaps not 'pin-sharp'. But there are tools in, say StarTools, which can help with that. For anyone just starting out on this 'game', have a read of 'Astro-photography on the Go' by Joseph Ashley (one of the Patrick Moore Paractical Astronomy series of books). We are not alone in using Alt-Az mounts to do imaging! Ian

Hi Ken, I'm just in the middle of processing my Rosette from last night and I used 30s subs even as it went through South. Can't say it has affected it (but with my images you probably wouldn't notice anyway ), and of course with the large amount of field rotation a lot of the edges (where it would be more noticeable) are cropped off. Good luck with your Ha filter. Why do you want a greater sub length for Ha? Is the transmission at Ha lower than for your red filter? Ian

Cracking shots there Shaun, especially as you were somewhat hampered along the way. Nice crisp stars. Personally, I wouldn't worry too much about the stated mount limit. Alt-Az mounts tend not to be like EQ mounts where one would reckon to load up to only 50% of the stated limit. Provided you are in reasonable balance the mount should give a good account of itself even if overloaded a bit. The main detriment is likely to be slightly increased wear rather than unacceptable performance. Certainly, that is what I read regarding my Nexstar mount. Ian

Looks reasonable from this review http://www.lenstip.com/380.1-Lens_review-Samyang_16_mm_f_2.0_ED_AS_UMC_CS_Introduction.html , but you might want to stop down to say f/4 to sharpen up the edge resolution. It'll be pretty wide field. A quick Google for "Samyang 16mm astrophotography" I found http://www.astropix.com/HTML/I_ASTROP/EQ_TESTS/rokinon_16mm_lens_test.html and it looks promising. Looking forward to your results. Ian

Tell me about it! I've had one good night after Christmas and another early in the New Year, and that's it, else the Moon's in the way. Even then, I almost put off imaging the Orion region, thinking I might wait until it appeared at a more sociable hour! Glad I didn't now. I think in the UK at least, you've got to grab any opportunity when it appears. That's something Ken and Nige seem up to doing. Ian

I agree Nige, it is quite a challenge to decipher what the 'correct' colours should be, but according to Ivo the core is meant to be green, one of the few occasions such a colour appears in the universe. Strangely, even my subs of 2s don't reveal any green, even though they are not overexposed. Go figure! Anyway, a nice rendition Nige, even if the colour scheme isn't quite my taste . I'm leaning towards calling the ST colour module the 'gaudiness control', although 'control' might be a misnomer! Ian

That's showing significant improvement, and with only 24 minutes total exposure. I managed to stack just over an hour's worth on my M45, but I had discarded about a half-hour's worth to get that. Call me picky! There's a bit of structure there though. My tired old eyes aren't as all-seeing as Ken's, and I didn't spot any gradients, but it is worth noting that the nebulosity extends out quite a way and I'd be uncertain whether any gradient is down to that rather than processing. See Rogelio Bernal Andrea's superb image, which can be found here. You might find the following thread informative re. sub length and sub number. https://stargazerslounge.com/topic/245183-to-stack-or-not-to-stack-30-x-1s-1-x-30s/#comment-2664662 . As for field rotation, here is a chart plotting the sub-duration for a 0.1° rotation with direction, if you are not already aware of it. Cheers, Ian

Forecast here is for clearing late tonight, but 'when?' is a matter of conjecture as the weather sites differ. But the Moon is getting on for full, in my preferred direction (and near to M1, Ken), so I don't think I'll be trying. Ian

Now if I remember correctly, that's your wife's camera Ian

Did you get that from trial and error Nige? Ian

Hi and welcome to the thread. Yes, I think Ken has summed it up very succinctly. I would certainly commend you to try astrophotography with what you already have, as it is certainly possible. It can be a long journey and sometimes a frustrating one, so it's best to see how you get on with it before splashing the cash on all the fancy gizmos oft recommended. Don't get the impression that all DSLRs are inherently bad at capturing the deep reds of H-alpha, some are better than others in this regard. That response is not a priority for manufacturers so it's not a given. And DSLRs can be modified if that becomes a priority, though as Ken says, when you need to start spending serious cash it's best to be clear on what you plan on imaging. Looking forward to seeing the results of your endeavours, and feel free to ask any questions along the way. Ian

OK, after a few more hours of messing about, I cannot fathom what deconvolution is doing in ST. ST seems to mask stars with a rounded square and as the centre of M42 is 'busy' there is a collection of star squares there. That means that part of the nebula is affected by decon, and an adjacent part not, and this shows up as a clear demarcation. I tried painting over the mask in this region to get decon to work on it, but it wasn't successful. I gave up on decon and continued as before (which is a bit of a shame really as decon did bring out detail in the nebula, where it worked!), but hopefully better refining the image compared to last time. So I've finally got to the image below which I think is an improvement on the previous one; it's hard to be objective after sitting in front of the PC for hours . Anyway, that's it for a while, time to give the bum a rest! I've got colour (aka gaudy) versions still to blend, but that will keep. I think I'm just about satisfied with this one (law of diminishing returns here). Ian

Hi rotatux, welcome to the forum and SGL. Nothing wrong with that image, and you should be pleased with that. It's good to see that you've resolved the Trapezium too. Looking forward to seeing more of your work on the forum. Ian

Thanks guys. In the main image I've dropped the decon stage to avoid the blemishes. Ha ha, I think I actually pushed the magentas more towards the red in Lightroom! The reason for the stars having haloes is because the 2s subs give small stars and the 30s subs the larger disks. I didn't do any masking when I blended them, but I could either leave them just large and fuzzy, or try the opposite. ST offers to make a star mask automatically before deconvolution, and I've not fiddled with that. As to the blocky stars, I noticed that when I looked at an enlarged image on my tablet; I don't know if that is the case with the source image. Or for that matter, whether it's from the 2s or 30s subs. I only binned 50%. Ian

Here you are guys, my first attempt at trying to blend short and long subs on M42, and me 'ead's spinning. It's taken many hours and I'm not quite there yet. But I'm packing it in for now . This is a first acceptable image. I tried to use layers in ST, but first off the pics weren't the same sizes because of cropping. And then when I sorted that, the result gave a very poor blend. Anyway, I next tried using my photo software to composite the two images and I thought I'd succeeded but having taken it into LR to polish off I noticed some rectangular shapes which turn out to be caused by deconvolution. So, back the the drawing board again. So this is 103 x 30s subs with 192 x 2s subs. No colour module, so I might try that, but even a quick check on the 2s subs I didn't get any green! Here are the shapes generated by decon. Any ideas? I tried the various pre-sets but it didn't make any difference. Ian