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ollypenrice last won the day on February 11
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M63 with tidal loops and extended spiral arms.
ollypenrice replied to ollypenrice's topic in Imaging - Deep Sky
OK, thanks for the encouragement! I tried again to exploit the TEC data in the inner galaxy and came up with the image below. To my surprise it was easy to upsample the RASA image to the scale needed for the TEC resolution to show. Full size is here: https://ollypenrice.smugmug.com/Other/Galaxies/i-psSP6gB/A Olly -
M63 with tidal loops and extended spiral arms.
ollypenrice replied to ollypenrice's topic in Imaging - Deep Sky
This is just what tried to do and have done many times before, but I haven't yet managed to make it work this time. In fact, scaled to fit the RASA image, there is not all that much more resolution in the TEC than the RASA. If I were to rescale in the other direction, making the RASA image larger, I'd be lifting the noise in the RASA and it's already on the ragged edge of the possible stretch. It doesn't help that the TEC field of view stops short of the upper spiral arm. If I can come up with any new ways of making the composite I'll give them a try. The obvious solution would be a RASA 14.... If the people would like to give Olly one, he'd be most willing to accept it! 👌 Olly Edit: there is another problem, too. The TEC's resolution requires dynamic range, ie contrasts within the central spiral arms. In the ultra-deep RASA image a lot of the lower dynamic range has been used by the faint outer streams so the dark stuff in the central spiral is brighter and can't be as contrasty. I'd be in danger of having the tidal streams brighter than the dark regions between the bright spiral and, in reality, they are not. -
You should be able to get far more of the long tidal tail to show, though it will run out of the frame on this crop, I think. It will be there in the data. If you have Photoshop, just go to Image-Adjustments-Equalize and it should leap out. You can't just use that as a processing technique but it will show what you have in the data. Olly
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Sensible stepwise approach to photography?
ollypenrice replied to Neutrinosoup's topic in Imaging - Discussion
You wouldn't go far wrong with this, on the astrophotography side. https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html Like most things in life, DSLR photography is best approached by thinking things through from the basics. There are really not so many of those and this is, for me, the big one: Understanding F stops and light cones. https://www.dpreview.com/forums/post/63155522 When a lens is wide open it lets in more light and therefore shortens exposure time, freezing fast action, but the steep light cone has a shallow depth of field meaning only selected parts of the image can be in focus. This can be good or bad, depending on the photographer's intentions. A stopped down lens has a greater depth of field but lets in less light and, therefore, needs longer exposure - which can introduce motion blur. If you were to go out with a basic DSLR and experiment with this single set of related parameters, and really get the feel for them and how they play out, you'd be self-educating very effectively, I think, and would have a grounding for further learning. For land and sky photography, check out the free Sequator software. https://www.startools.org/links--tutorials/free-image-stacking-solutions/sequator On image processing and U-tube tutorials, the instant you hear the presenter say, 'I just play with the sliders till I like what I see,' turn them off and never go back to them! Most astrophotographers are autodidacts and the best ones are the best because they seek to understand before they act. Olly -
M63 revisited with modern software...
ollypenrice replied to ollypenrice's topic in Imaging - Deep Sky
Just for info, an all-new RASA 8 image has gone much deeper than this. Olly -
A deep dive with Paul Kummer (capture and pre-processing.) This had 9 hours in the RASA 8, equivalent to about 40 hours in a fast refractor of comparable focal length. After 3 hours we were going well but 9 hours brought out more structure and, of particular interest, the uppermost spiral arm winding anticlockwise in this orientation. This arm is a new one to me and was an exciting find in the processing. Edit: please scroll down for a version using TEC140 data to enhance the core. This is a close crop and is presented at one-to-one here: https://ollypenrice.smugmug.com/Other/Galaxies/i-sgC3bGn/A Olly
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Fascinating extensions. Olly
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The spring is a lean time for short focal lengths but mosaics in the Coma-Virgo cluster can be fun. Sooo many galaxies! Once the southern Milky Way starts to come up in early summer you can't go wrong. We're at Lat 44 and you'll be south of that but, even here, we get four hours of darkness in June. You can work through the year. I'd look at the Eagle and Swan, Sagittarius triplet, The Great Sagittarius Star Cloud, Rho Ophiuchus... Olly
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I denoise in a Photoshop top layer with the original underneath. This lets me erase, wholly or partially, any areas adversely affected by the NR. Often it's only needed on the faint stuff so it's easy to select and erase the bright stuff or just erase it by eye. I sharpen in the same way, though I sharpen the bottom layer and selectively erase the unsharpened top layer. Olly
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My small object imaging was initially done with an ODK 14 (2.6M FL) and then with a TEC 140 (1M FL.) Image scales were about 0.6"PP for the ODK and 0.9"PP for the TEC. I'm pretty satisfied that both were, in truth, oversampled, the ODK massively so. Alas, the ODK's camera would not bin satisfactorily so we were stuck with the oversampling. On the whole, I preferred the TEC. https://www.astrobin.com/335042/?nc=&nce= https://www.astrobin.com/full/tak87a/0/ I would say this: don't expect any kind of radical transformation in your high res imaging over what you can do with the Esprit 100 and a modern, small pixel CMOS camera. There will be more detail to come, but it may be a lot less than you think and your guide RMS will need to be no more than half of your image scale in arcsecs per pixel. Presumably you already know your guide RMS or can easily find out what it is. Olly
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Galaxies galore below the paws of the Great Bear
ollypenrice replied to wimvb's topic in Imaging - Deep Sky
Lovely image. Olly -
A small amount of matt black paint fully covering the scratch and of a soft, rounded shape, will entirely eliminate it as a cause. No, the guide camera might be following the star perfectly but the imaging scope (or just its mirror) might be moving relative to the guidescope. An off axis guider removes this possibility by guiding on the imaging light cone itself. So called 'Mirror flop' has essentially the same consequences as flexure. However, I'd put money on tilt, in your case. (Not a lot of money but a bit... ) From what I can see, the elongations all go the same way, meaning they are parallel with each other. Optical defects rarely produce this effect but tilt does. Since you see the same thing in two cameras, it is unlikely to be a tilted chip. (These are not uncommon and some cameras have chip tilt adjustment built in.) I would look for sag or slack in the focuser. Are all your attachments screw-fit rather than push fit? Screw fit is best. Are you placing your camera in this orientation, parallel with the counterweight bar? It's the best. Tilt can spring up suddenly because some mechanical component becomes loose or a bearing breaks. Olly
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I would rather say that OIII is faint, rather than noisy. Russel Croman's Noise Xterminator is an order of magnitude better on astrophotos than any other NR routine I've tried. Because our RASA 8 data invites extreme stretching, I do often lift it well above the noise floor but StarXt sorts it out in an invisible or, in extreme cases, almost invisible manner. Here's a close crop pushed beyond its limit. Before Noise Xt... After noise Xt... Had I wanted to erase the brighter parts of the noise reduced image, feeling that the NR had damaged them, this would have been a ten second operation in Photoshop Layers but, really, are they damaged? Here I had the 'Preserve details' option in StarXt set to minimum. Alternatively, the noise reduced image could now be further sharpened. Olly