rotatux
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Everything posted by rotatux
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From the album: Moon, planets and single stars
My main observatory being east-oriented I have few occasions to shot the Q1 side of the moon so this is it. I also tried to shot with a barlow but it showed severe CA on such a bright subject, so gave up. Next time I try to do it with a Mak to be sharper and get more resolution. Capture: Skywatcher 130PDS on Celestron Nexstar SLT© Fabien COUTANT
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From the album: Moon, planets and single stars
Taken soon after sunset so earth still lights the moon, and over exposed to show earthshine. Interestingly, Tycho's rays are more visible this way (relatively), just like full moon. Capture: Skywatcher 130PDS on Celestron Nexstar SLT© Fabien COUTANT
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From the album: Equipment and sites
This is a compact camera shot of the view through my Omegon Polar Finder for the EQ-300 of the same manufacturer. (taken with Canon Powershot SX110 IS) It shows the reticle, which is not especially practical, since there's no mark facing years and no angular distance scale. So I used direct shots at the background scene with known focal and FoV to calibrate the finder resolution, then used it to mark the 2018 distance for Polaris-NCP.© Fabien COUTANT
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my DIY: Opened a cereal box flat, black felt stuck on inside, adhesive velcro bands on outside, et Hop ? Goes around my 130PDS as well as MAK127.
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A very nice one. I think it *is* very red actually (and confirmed by my first try at it last year). But your stars are all white or reddish so it might be too red and need a bit of color rebalancing. Depending on the software you use, it may have the option to auto-calibrate colors based on known star colors (use it with high-depth image so ≥ 16-bit). Otherwise have a play with manual white balance, maybe after subtracting a bit of red channel.
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@Manners2020 I find your Orion quite good. Comparing with unprocessed, I think you may have stripped too much of the background, hence loosing some details of the nebula you had captured. Now if this is a single sub, imagine what you will have with stacking several subs BTW what mount was your 102 lunt on ? Keep up trying, have good skies.
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Hello smisy and welcome to the hobby For a beginner IMO you actually happen to start with one the most difficult configurations: long focal, high focal ratio, ridiculously small sensor, and ocular projection which magnifies again the already long focal... and of couse Alt-Az mount. So getting any images is an achievement it itself, and yours are quite decent. Good luck and skies ! PS: your M42 looks mirrored left-right to me :-P
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Your rig seems to have great potential : at first I thought "both overexposed and not stretched enough in the darks" then I reread "220s single at 400iso". Nearly 4 minutes is a great result for a wedged Alt-Az tracking, as I can't see any obvious bad tracking artefacts in your image. That leaves you with plenty room for improvement, both for capture such as stacking many shorter exp + higher iso subs, and for processing such as non-linear stretching or black point management or color balancing. Good luck ! BTW, I find your setup is pretty unusual for A.P. -> is it a DIY wedge ? would you post some images of it somewhere ?
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Your colors are lovely, especially the nebula. If I was picky I would say too strongly blue stars and missing gradation in red/orange stars, but the subject is the nebula and it has IMO nice red-orange-grey-blue variations so nothing to complain Wish I had an occasion to get that one but weather decided otherwise and it's now probably off for me til next year.
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M38, the Starfish cluster, and its nice little friend NGC1907. Which is the full size for image posted in my gallery here:
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From the album: Alt-Az / NoEQ DSO challenge
M38 - The starfish cluster Initially taken as a check to see what I could have from Paris' suburbs heavy LP skies for a star cluster, considering that kind of object should be easier than nebula or galaxies in that kind of sky. Turned OK but I still have difficulty recognizing the starfish shape when zoomed in, I need to zoom out quite a lot for the shape to become obvious. Gear: Olympus E-PL6 on Skywatcher 130PDS 632mm/4.86 at F/4.55 with SW Coma corrector and Didymium filter on Celestron Nexstar SLT. Capture: 12 lights x 20s x 1600iso, master bias and (synthetic) flat. Software: Regim 3.4, Fotoxx 12.01+ Site: 20km from Paris France; Clear sky, relatively good seeing, SQM 16..17© Fabien COUTANT
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Hi Nigel As you tried 1:1 and 1:2 Ha/O3 ratios and I somewhat liked aspects of both but not fully, I wanted to try 1:1.5 ratio by averaging the first two jpegs in Gimp; Unfortunately they are neither aligned nor same scale. FWIW it would give something like that -- whould be nice too.
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I do use darks, which dates back to my old hybrid E-PM1 camera having strong and regular (from shot to shot) thermal noise. YMMV, as the correction brought by darks varies heavily from cam to cam : IIRC most Canon owners here don't do darks. My new E-PL6 has very low thermal and read noise, so I'm in the process of testing the replacement of darks by flats+bias.
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From the album: Equipment and sites
I took this while waiting for some clouds to roll out. As you can see I literally face some severe light pollution, though that night it quite didn't reflect in the sky, which was near crystal clear This is my Olympus E-PL6 hybrid camera attached to Skywatcher 130PDS newtonian on Celestron Nexstar SLT alt-az mount.© Fabien COUTANT
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Not a focus problem, it was dead on as far as I can tell. Such saturated / somewhat wrong colors come from applying a star-based B-V color calibration on an image with stars bloated by halos of aberrant colors. Colors and halos are exactly the same without didymium filter, but the filter allows me longer subs without saturating the background. IMO my lens model is of the poorly-coated variant (Oly made another variant of same 200/4 but with MC). Hence CA produces strong halos of different size for blue (bigger) and red (smaller). The end result depends on original star colors, but typically shows outer blue then inner red or purple. I hope to try a technique based on star filters to remove the halos someday... -
From the album: Alt-Az / NoEQ DSO challenge
First successful try at 1mn subs with my Alt-Az mount. This is full width frame, and cropped a little vertically for 3:2 DSLR-like ratio and avoiding some artifacts. Looking at the result I regret I didn't let the lens wide open, but I had to try closing it to check whether CA was going away (it's not). Equipment: Olympus E-PL6 with OM-Zuiko 200mm/4 at F/5.4 (ring filter step-down adapters) and TS-Didymium filter on Celestron Nexstar SLT. Capture: 12 lights (/90% keep) x 60s x 3200 ISO, 17 darks + 20 x 20s x 3200iso (for HDR mixin, in a faint tentative to reduce stars) Processing: Regim 3.4, Fotoxx 12.01+ Sky: near country 50km from Paris, no moon but otherwise poor (moisty) conditions© Fabien COUTANT
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Beware that if you use a fixed delay in the sleep, this kind of loop has inherent timeshifting builtin because of various lags in execution. Unless it's already the case, you should aim for fixed average frequency, by using the builtin clock to compute the next delay each cycle. I mean something like: avgPeriod = CONSTANT target = clock() + avgPeriod while (tracking) : step() sleep(target - clock()) target += avgPeriod NB: BTW, this kind of code works very well even without any interrupt handling, it will absorb and correct minor local variations of time and execution as long as your clock is stable enough.
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Nice M1... I personally struggled to frame it (too weak and too small) last year in my H-LP sky and abandonned, so that's some achievement Oh and question about your HH+Flame: what filter did you use ? your colors look like what I get with my UHC...
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You definitively have some valuable data in that sub : Some nebulosity and nice colors. Your sub is not that much overexposed, I would say it's reasonnable, so that was your stretching. You will do better focus / tracking next time, learning one step after the other (live view focus, exposure settings, stacking, etc.).
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I wish I had my first at it that good Though that's strange all your stars are already burnt at such low ISO, did you use RAW or a cam-produced JPEG ?
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While zooming you even get the start of a hint of the Flaming Star Nebula. I like this subject, already had a go at it with an old 135 last year, but being a smaller frame it was more on the center part and only catched the top cluster. Not sure I will have the night to retry it this year :-/ You say 75mm and F4.5... is it a prime or a zoom ?
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Do you mean you're tracking by hand, following a star in the cam ? I know this can be done in theory, but achieving it... wow I find the image does not reward your efforts as it should, maybe using shorter subs (and 16bits!) in live stacking could help avoiding trails and enhance final quality. (just a wild guess)
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I'm about to flock my tube too, but just a question BTW: is there any risk the flocking material could accumulate water / humidity, and raise condensation, during moisty nights ? or do you combine it with some heating device to avoid it ? PS: what I actually have for flocking is a somewhat thick felt (I mean maybe equivalent to ±15 sheets of paper)
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Perseus Double Cluster and Stock 2
rotatux commented on SteveNickolls's gallery image in Member's Album
very nice FoV and colors! Is it cropped? -
I don't know your equipment and capture settings (how many subs / overall minutes etc), but it's beautiful. Sadly my FoV is even narrower with the MFT sensor, but I'm planning to take about the same framing (which should just fit in the diagonal) with the help of my now stabilized mount and CC-reducer.
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