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mAnKiNd

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About mAnKiNd

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  1. Here's another one using the above methods: http://www.astrobin.com/306296/
  2. "High-Speed, Dithered, Dual-Shot Astrophotography" By Minos K Image: http://www.astrobin.com/306255/ | Introduction | Messier’s celestial object #16 and ‘The Eagle Nebula’, a place of star-forming clouds and ever expanding molecular dust. In its core, three dark and gaseous pillars, of creation and stars. Emerging like the ‘Hand of God’, these pillars of creation point towards the open cluster M16, a swirling array of huge balls of fire. Both are situated in the next inner spiral arm towards the center of our Galaxy, 7,000 light-years away from Earth. | Methods | Location: Sia Space Observatory, Cyprus | Latitude: 34° 57' 2.32" North | Longitude: 33° 24' 23.71" East | Altitude 300 meters. -Each night, I aimed to capture these ancient photons with 1000 exposures (what I'm going to call a 'KiloStack'), 4 seconds each exposure, with the camera set to a high gain (84%). I used the fantastic Sharpcap 3.0 program to do my initial polar alignment with and then into a straight capture and calibrated each light frame with matched dark frames (acquired immediately after kilostack) in DeepSkyStacker to reduce amplifier glow noise. -Polar alignment confirmation and guiding was performed within PHD2 and dithering was set on a timer for every 2 minutes (approximately every 30 frames) with PhD2 Dither App (as Sharpcap does not currently have built-in dithering functionality and the ASCOM camera driver has no black point offset to use effectively for proper histogram conformation with short exposures in other software that does i.e. APT). Dithering scale was set at 12-pixels minimum (two-star-widths, spiral formation). I would then reject 33% of exposures in the Kilostack that would mostly contain star trails due to dithering commands. -Framing and focus was done by manual camera rotation and adjustment in a 1.25" compression ring fixed in a dual speed R&P focuser. Target centrality confirmed using Astrotortilla. -Rather than approaching this image from a traditional perspective, where one shoots LRGB channels, or narrowband channels using a single monochrome camera sensor, I took a different approach, thinking outside the box - but with a twist. Instead, I employed two identical cameras - the excellent Altair Hypercam IMX178 - one in mono and the other a one-shot colour (OSC). By doing this, I could save heaps of time by acquiring all three colour channels in one-shot instead of independently, and then by using the super-sensitive mono version to acquire the Luminance channel, I could ultimately boost the colour signal and sharpness in the final image. -Filters were a very important choice, and this is were the twist comes in. After much experimentation and deliberation, I decided to use the Baader Moon & Skyglow for the Altair 178C, as this is a wonderful filter for good white balance (tames the green Hulk in OSC's) and good skyglow reduction (although I may need to purchase a Baader Semi-Apo next time to reduce the purple fringing inherent in my doublet) and for the Altair 178M and Luminance channel, I decided to go with a more aggressive filter, the Altair CLS-CCD, which is a very interesting and effective dual-band filter that manages to isolate all of the desirable narrowband emmissions of Hydrogen-Alpha & Beta, Sulphur-II and Oxygen-III in one-shot instead of independently, whilst blocking absolutely everything else. I decided that this filter would offer me these important celestial wavelengths of light in one-shot, again saving time and effort in their acquisition. -Stacking was performed in the super user-friendly and powerful-when-setup-correctly DeepSkyStacker program: -> Stacking mode: Intersection Standard -> Alignment method: Automatic -> RGB Channels Background Calibration: No -> Per Channel Background Calibration: No -> Method: Median Kappa-Sigma (Kappa = 2.00, Iterations = 5) for both Lights and Darks -> No Offset -> Dark: 1 frames (single master average obtained from 23 dark exposures acquired after a Kilostack in Sharpcap) with no Hot Pixels Detection and Removal (dithering and sigma-stacking takes care of this) -> No Flats -> No Cosmetic Correction -> FITS DDP Settings - Generic RGGB with AHD interpolation -> All kilostacks were registered and then filtered at 67% of best frames (to eliminate dithers) with frame #1 used as the reference frame (thanks to Astrotortilla) -Processing was performed exclusively in Pixinsight and involved the following workflow: -> StarAlignment of Kilostacks -> DynamicCrop -> Image integration of Kilostacks -> RGB extraction from OSC integration -> AutomaticBackgroundExtraction on LRGB channels -> LinearFit of all channels to strongest signal - Red -> ChannelCombination for RGB -> LRGBcombination for Luminance -> BackgroundNeutralisation -> ColourCalibration -> Deconvolution -> MultiscaleLinearTransform on Luminance and ChrominanceRestore -> HistogramTransformation x 3 -> LocalHistogramEqualisation -> MorphologicalTransformation -> CurvesTransformation - Colour Saturation and Luminance -> SCNR - Taming the "Green Hulk" -> Masked LocalHistogramTransormation -> DynamicCrop for framing -> Annotation | Discussion | Acquiring colour from a OSC with a Bayer matrix/CFA might not be as good as using individual interferometric colour filters with only a mono sensor, but at the resolution I'm sampling (best @1.9"/pixel), you'd be hard-pressed to tell the difference and it only took me a fraction of the time. If you're thinking of employing this technique on high-resolution, high-focal lengths, you might wanna stick to traditional LRGB methods where quality expensive filters can shine through. 84% gain on the camera was selected as the estimated lowest read gain (calculations beyond the scope of this report), but I was not happy with the banding and noise in the CMOS sensor. Although most of this noise got clipped when sigma stacked, experimentation with lower gain settings around 30% produced a much, much visibly cleaner signal with a lower noisebed. Further investigation is required, but I propose to use lower gain settings in the future with this sensor, not only with regards to lower noise, but also to boost dynamic range. As for the argument of high-speed vs long-exposure deep-sky astrophotography, consider the following logic; In a single 300 second exposure, one can capture X amount of astrophotons. In comparison, if one were to shoot 300 x 1 second exposures, then by subtracting a given amount of sensor downtime between exposures, say for the sake of argument - 10 seconds in total from 300, then one can acquire for example 290 seconds worth of X astrophotons in 300 frames. Now, why would one want to do high-speed imaging instead of the classical long-exposure? -Well, for starters, the starlight signal will not saturate anywere near as much as it would clip in a long-exposure. -Second, noise reduction with sigma-clipping (standard-deviation outlier rejection) will be much more effective with hundreds or thousands of frames versus a few tens of frames. -Thirdly, capturing so-called "faint-photons" has nothing to do with long-exposure photography, as those photons are travelling to Earth irregardless of whether you acquire them in a single 300 second exposure or 300 - 1 second exposures (one can argue though that if the frequency of these faint photons is indeed very, very low, they will get sigma-clipped when stacked in the multi-exposure approach). Indeed, I believe I've captured "enough" faint nebulosity above using the high-speed approach. -Fourth, super-accurate guiding for long-exposure is no longer a issue. -Fifth, one can dither less sparsely rather than every frame or every other frame, as one is acquiring hundreds to thousands of exposures in total. | Conclusion | To summarise, this is a multi-frame (>6000 selected from >9000 ~67%), multi-night (9-nights - 6 for luminance, 3 for RGB), high-speed (4 seconds exposures), two-camera (Altair Hypercam 178M & 178C) and two-filter (Baader Moon&Skyglow, Altair CLS-CCD) approach. I very much like this method I've come up with, and apologies to anyone who might have done this before, but I believe I'm the first to try this specific amalgamation of approaches with the above logic in mind. Therefore in that respect, I would like to coin this method, my method, as "High-Speed, Dithered, Dual-Shot Astrophotography". Dual-Shot was conceived on the premise that one-shot is for all the RGB signal to be used for Colour, and the other one-shot is for all the desirable narrowband emmissions to be used as Luminance. Finally, I would like to dedicate this photo to my daughter Gia, who turns 1 year-old today. Little girl, you are made of starstuff, that has floated around the cosmos for eons, only to recombine into a living human here on Earth, that has given me more joy and love than anything else has ever done in this life. Live long and prosper baby, love, your Dad x
  3. Nikon D40 DSLR

    I know im resurrecting an almost decade long post, but I'm about to get a D40 and cannot find the source for this very important statement. I'm sure Rawhead is correct, but can anyone confirm this or provide the source, or is this simply a personal observation? TIA Minos
  4. QHY168C very first light

    Wonderful pictures, truly! I'm thinking of buying this camera and I was hoping someone could help with regards to where in the spectrum the IR glass in front of the sensor cuts off. Basically, is it above Ha (656nm); which judging from another awesome Ha picture you posted with this camera and the fact that it's an astronomical camera, it is. I have searched the internet high and low for this value and cannot find any info and would very much like to confirm this. Many thanks and clear skies to you all 😊 P.S. does it also cut UV? EDIT: my apologies, I confused the model number of the camera, I'm referring to the QHY163C.. EDIT2: FWIW, I found out from QHY that the IR cutoff for the QHY163C is 680nm and you can order it with an AR glass aswell...
  5. Imaging with the 130pds

    Another small step towards maximising the 130pds! Thanks for sharing 🍻 Do you find you gain backfocus with the Lacerta rather than the stock clamp?
  6. Imaging with the 130pds

    Indeed..I often get carried away by the details, but it's too much fun and I learn a lot, like the fact that I don't want to spend time erasing bad data from bright stars in PI. I'd rather go down to the nitty gritty road and effectively plan the time I invest with my imaging equipment to get the best data possible. I mean, what if I wish to keep the stars & detail et al., in the reflection that your editing out? I'd need as precise a configuration as possible, as ive learned with my refractor and to do that sometimes i need to get carried away with how many mm's are left in an M48 thread. Nevertheless, thank you all so far, sincerely, I have learned so much and I'm enjoying it in good spirits too 😊 can't wait for my 130pds 🚀🍻
  7. Imaging with the 130pds

    The only reason i mentioned the custom adapter, is that it would have more M48 thread available in comparison to the FUFMPCC, which eats up about 2mm
  8. Imaging with the 130pds

    One could order a custom M54x1mm male to M50x0.75mm female adapter and thread it to the synta drawtube, leaving the GPU CC's M48 thread fully exposed..
  9. Imaging with the 130pds

    http://www.teleskop-express.de/shop/product_info.php/language/en/info/p5836_GPU-Aplanatic-Koma-Korrector-4-element-fuer-Newton-Teleskope-ab-f-4.html In the technical specifications for this product, it specifies an M50 connection behind the M48 thread, see it in the picture. The SW seems to have a ring in place on the M50 thread, so I presume it unscrews.. EDIT: i meant this product, which is essentially the same as the above without the ring. http://www.teleskop-express.de/shop/product_info.php/info/p6706_TS-Optics-GPU-superflat-2--Coma-Correktor-for-Newtonian-telescopes--4-element.html
  10. Imaging with the 130pds

    You are correct, in that you wouldn't be able to rotate the camera and live with it's final position, which I do with my short refractor as I prefer the threaded connection to clamping but with rotation ability.
  11. Imaging with the 130pds

    The ring on the SW equivalent of the GPU CC is an M50 thread and should screw off.
  12. Imaging with the 130pds

    There seems to be many M54x1mm male to T2 adapters on sale, but I have only found the Lacerta adapter provides an M54x1mm to M48x0.75mm female thread, but that adapter sounds like it has issues with its rotating functionality. Baader makes these adapters but the M54 side has a 0.75mm pitch (for filters) not the 1mm needed for the Synta drawtube. Perhaps the FLO bespoke adapter service is still in effect and people can order a straight-up M54x1mm male to M48x0.75mm female adapter (with no rotation functionality like the Lacerta adapter) for using M48 threaded CC's on synta focusers, like the one on the 130PDS. There should be enough market for this i presume, considering synta scopes are so widespread in the imaging world, and of which many imagers use M48 threaded CC's.
  13. Imaging with the 130pds

    Thanks Rich for taking the time to reply. Vignetting with T2 did cross my mind when I was thinking of this adapter in use with the MPCC, as that's the connecting thread it uses. However, i'll be using the adapter with the GPU aplanatic CC, which has the wider M48 and would therefore avoid possible vignetting on APS-C sensor. This gave me hope that perhaps this Lacerta adapter is actually better suited for the GPU CC rather than it's advertised use with the MPCC. My concern is whether or not this adapter combination will give a secure enough connection to the DSLR flange ring, being that a 4mm long M48 male thread on the coma corrector hides approximately 2mm's inside the adapter. I think 2mm left over is sufficient to lock into the DSLR flange ring, but I don't think it will hold a lot of weight. Nevertheless, as soon as it arrives, i'll be using my 130PDS with DSLR + CC only, so not too much weight. Thanks again
  14. Imaging with the 130pds

    How so?
  15. Imaging with the 130pds

    Hi AdamJ, FWIW, when I image with my unmodded 450D on my short refractor, i use a CC <70mm> CMOS spacing for good correction, but with my full spectrum 1200D, I use a CC <65.3mm> CMOS spacing. I believe the reason for this reduction, is as you've described it, in that all glass filters inside the full spectrum camera are removed, which reduces the effective focal length required. Therefore, if you minimise your spacing as you say, would probably work better. Try it and see On a different note, a threaded connection to the focuser is assuredly always more likely to be optically aligned with the collimation than a clamped connection, with less flexure and more stability. I wonder if many of the aforementioned chromatic aberrations and bloating reported in certain CC's where also in part, due to being clamped in the focuser rather than threaded.. I understand that the drawtubes in Synta focusers found on the common newtonians utilise an M54x1mm female thread that usually houses the removable 2" clamp. Furthermore, all previously discussed CC's such as the SW 0.9x, MPCC, GPU aplanatic etc.. utilise a male M48x0.75mm to connect with a DSLR. Therefore, one would require an M54x1mm Male to M48x0.75mm female adapter, and they could adapt the Drawtube + CC + Spacer + DSLR combo in a threaded fashion. Uranium has successfully demonstrate this concept after loads of DIY with the SW0.9X CC. Such an adapter would not only ensure an improved connection, but also would provide a little more backfocus, allowing the drawtube to be racked out further, thereby minimising the intrusion that causes D-shapes on bright stars and negating the need to trim it down. Fortunately for us, the Hungarians at Lacerta make such an adapter (I've ordered one!) and there is also a T2 version (though it looks less secure). Food for thought.. EDIT: I saw on another thread here that the good folk at FLO used to do a bespoke adapter service. Maybe that's still on?
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