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Penguin

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Everything posted by Penguin

  1. Interesting idea. Does the extension tube go before the barlow or between the barlow and the camera?
  2. My birthday is coming up and I am thinking of asking for this: https://www.tringastro.co.uk/celestron-x-cel-lx-3x-barlow-612-p.asp It would mainly be to get closer in to the planets for webcam imaging and visual. I currently have a Skywatcher Explorer 150p (which I gather is not great for planets), a Philips SP900 and an x-cel 2X barlow but this combination does not get as close in as I used to get with my old TAL-1 and its stock 2X barlow. Would this 3X barlow help or would it be too much for the scope? What would you recommend, without buying a different scope: I'm working on a budget!
  3. Hmm, I have created an image container and added all my raw images but when I go to scripts->utilities->CanonBandingReduction, it says "No active window. Terminating script". So how do I apply the script to the images in the image container?
  4. Interesting, I tried the CBR script in PixInsight on my stacked image and it has significantly improved the banding, but of course that has then allowed other problems to show through, notably some linear diagonal noise and also a little vertical banding. I wonder of running CBR on the individual subs prior to stacking might help further. As to the diagonal noise, would dithering reduce that? I've noticed some people saying that the 3 minute exposure might be causing more banding than shorter subs and that the warm nights might also be a factor, both of which make sense as I normally only do 2 minute subs for fear of star trailing, and I have only really noticed bad banding recently and not so much on the colder nights earlier in the year. Also, would taking many more subs also help? I tend to only take an hour or two of lights and then only stack around 2/3 of those after discarding ones with planes, satellites and star trails. Maybe I will have another go at this target on the next few opportunities. Anyway, here's what CBR did (unstretched tif and a quickly stretched jpeg) M106 flats darks-CBR.tif
  5. Thanks for these suggestions, I will definitely try the Canon Banding Reduction in PI on that image. I don't have Photoshop at the moment, so those plugins are a backup option. Will they work with PS Elements or would I need to subscribe to the full Creative Cloud? I have had a quick look at the dithering options in an APT manual and that does indeed look very do-able. I like a setting that you can configure once and then forget. Not knowing much about ASCOM though, will it work alongside my current use with Stellarium through StellariumScope? I guess I will just try it and see what happens. A quick Google for "canon banding reduction" has bought up loads of interesting links. That's my lunchtime sorted then!
  6. I have noticed some annoying horizontal banding that is totally ruining my shots and was wondering if any one could diagnose it. It's not an artifact of the stacking, I can see it in the raw subs and stacking just makes it worse even though it is also visible in the darks: surely subtracting the darks should then remove it? I have seen it before but its not normally got in the way, the last few sessions it has really dominated my images. Last night, I took 1.5 hours of 3 minute subs of M106 at ISO800 and the stacked result looks awful, as you can see from the PI screenshot! I am taking lights, darks and flats (one of each attached and also in the screenshot). I have not grabbed any bias frames for ISO800 or I would have used those as well. I am stacking with DSS, following all its recommendations blindly, and then doing further processing in PixInsight. Someone on SGL recently pointed me at a tutorial for stacking in PI instead of DSS which was interesting and very long but didn't seem to resolve this issue and the process took too long to be worth it for the improvement it gave in the image. I have seen a couple of other threads talking about banding. Some explicitly mentioned Canon SLRs but none actually resolved the issue. There was mention of dithering, which looks like an absolute ball-ache to do but if it is likely to fix my issue I would give it a go. I am using an unmodified 450D through a Skywatcher 150P on an HEQ5-Pro, unguided. I am using Stellariumscope/ASCOM to control the mount and APT for the camera. Really, I want to understand why it happens in the first place, how to prevent it happening if that is possible, and/or how to remove it in processing. If anyone can help, I'd be hugely grateful. Many thanks, --- Alistair. L_0467_ISO800_180s__20C.CR2 D_0434_ISO800_180s__24C.CR2 F_0482_ISO100_0-3s__20C.CR2
  7. I think something like that must have happened. I never move anything between taking lights and flats but maybe the camera got knocked slightly. Thanks for playing with it.
  8. I spent several hours running through the stunning lighvortex preprocessing tutorial. Unfortunately, I realise now that I should have adjusted the numbers in the weighting expression, and also, because I had not yet upgraded to 1.8.5, could not use the 'local normalisation' section. Anyway, the result is shown below and is still full of noise and banding, both of which I think must be the result various issues at the scope. I think I need to re-check my alignment and gather new data, rather than continue with this image.
  9. The ISO and sub lengths are as in the example shots, it's no typo. Again on this forum, I have been told that the ISO for flats does not need to match the other frames since their purpose is the removal of dust bunnies etc and the measurement of vignetting and other effects of the optics rather than anything to do with the sensor. So I have gone to ISO 100 since that evens out the flat field: the LED lighting panel I am using to generate my flats refreshes at something like 50 or 60Hz (mains frequency?) so I need to expose for significantly longer than that to get an even flat image and the easiest way to do that is by lowering the ISO. However, maybe my flats are causing some of these problems? I will have another look at stacking in PixInsight, I have got used to DSS, where I pretty much just accept the suggestions that it offers. PI seems to demand a bit more knowledge of what is actually happening, which can only be a good thing in the long run! Thanks for the help thus far.
  10. So over the weekend I had a few goes at imaging objects in the Virgo Cluster, and I can't get anything good out of the results. This is using an unmodified EOS450D through a SkyWatcher 150P on an NEQ5-Pro without guiding. There seem to be two main problems. 1. After stacking in DSS, the resulting image has obvious horizontal banding. I use Darks and Flats taken on the night, with Bias frames that I took a few months ago. I tried stacking with none of these calibration frames and the stack came out much better (with regard to the banding anyway. 2. When I pull these into PixInsight, crop them and then do a DBE with settings I have been advised to use on here and that have worked nicely in the past, they don't do anywhere near as good a job: the extracted background is solid red (I am not used to my initial stacked images being this red either) and the only improvement to the image is the lack of that redness. I have attached examples of the dark, flat and light frames, along with the final stacks (with and without the calibration frames) and a screenshot from PixInsight showing the full horror that I am trying to work with. Any advice would be hugely appreciated. --- Alistair. D_0155_ISO1600_120s__20C.CR2 F_0199_ISO100_1-5s__18C.CR2 L_0182_ISO1600_120s__20C.CR2 stacked-with-calibration.TIF stacked-no-callibration.TIF
  11. Thanks for those suggestions guys, I have plumped for this StarTech one: https://www.amazon.co.uk/gp/product/B00SCE4E0I/ref=od_aui_detailpages00?ie=UTF8&psc=1 I am considering keeping it indoors between sessions, like I do with the observatory laptop after everyone's comments about the environment. Also, this ACF50 stuff sounds quite miraculous, do you recommend spraying the mount and other components as well? When I get to guiding, I fully expect the observatory laptop to need replacing, at least with something that has USB3 and maybe at that point I will also consider a 2nd hub. At the moment I am only really using 2 or 3 ports (mount, camera and a games controller) so the 7-port hub I have ordered is probably a bit of overkill but does look more rugged than the 4-port ones I have seen.
  12. I currently have a laptop in my roll-away observatory, connected to a powered USB2 hub on the pier, from which I then power and control the various bits and bobs on the rig. This is now the 2nd USB hub that has stopped working. Can anyone recommend a reliable one? I have seen a few threads mentioning USB hubs but none actually recommending a reliable one. The laptop only has 2 USB sockets so although my cables will reach it, without the hub I can only connect 2 things at once, one of which has to be the mount. All the stuff in the observatory is powered via an extension cable from the house.
  13. It now leaks to the point that I have covered it in a tarpaulin. Luckily, I am still able to use it. We're moving house in the summer so the scope will be back on a tripod for a while and that will give me a chance to fibreglass it before returning it to its observatory function.
  14. Oh yeah, it leaks, but only in a couple of places. I plan to fibreglass the roof soon in the hopes of fixing that.
  15. Here's mine, inspired by @lukebl's. Built over the summer by your's truly:
  16. Thank you so much guys, I am learning again! I took a load of bias frames at ISO 1600 (matching the lights/darks) and 400 (matching the flats) and re-stacked the HH image in DSS, which warned about differing ISO settings but seemed to apply them correctly. Then I applied Wim's workflow which was a slight re-ordering of steps and very different with DBE: I had previously been told to use 30 samples per row, which often seems to extract a very mottled background and I suspect may be a major cause of the problems I have been having. For colour calibration, I have never previously used the entire image for white reference, nor used structure detection. Here are the results, it's much cleaner but has also lost dome detail and definition, particularly noticeable in the Horsehead itself. Possibly some aspects of my previous processing were better than this attempt:
  17. Thanks guys, there's a lot to think about here, I shall take it away and cogitate.
  18. Hi Michael, that would be fabulous to save time or get an extra few lights. Can you explain how using bias as dark frames works? I thought a primary purpose of darks was to get the thermal signal with the light-frame exposure at the temperature the lights were taken at so that it could be subtracted from the lights. How do we achieve that without darks? Also, DSS complains if the darks are not the same exposure as the lights. Will it still work? Also, what do you mean by "you must Dither between shots"?
  19. Thanks Alan, there's some useful (and free!) things I can look into there. I have not tried TGVDenoise so I will investigate that. I normally do SCNR Green as the last step in my workflow but having just tried it on the Flame/Horsehead image, I can see that it is reducing the green so maybe I had missed that step. In terms of calibration frames I normally take 15 darks at the end of my session. It's a bit annoying having to spend another 1/2 hour taking 'blank' shots before packing up when its already 12:30am but I do understand the benefit. Is 15 frames/30 minutes long enough for the darks? I also take around 15 flats at the end of the session using this panel, which has several sheets of photo paper in front of it to allow the camera to take a long enough exposure that the LED refresh doesn't mess up the image, and is housed in a makeshift frame. I have also attached a single flat from the most recent session. Again, is 15 enough? Is there a better way to take them? Bias is easy and I gather I can prepare a set once and use them multiple times, I have just been lazy. I will prepare a set now and might try reprocessing a few of my existing images.
  20. Yes, I focus with a bahtinov mask, but I always end up with one of the axis spikes diverging into two, as can be seen with Alnitak on the Horsehead/Flame image and I don't understand what is causing that. I tend to focus at the scope since I don't have an auto-focuser so would have to keep going back and forth between scope and computer. Otherwise, I would post the focusing images for you.
  21. Hi Guys, just looking for some general help with improving my images I'm not sure what to concentrate on to get the best bang for my buck. Here are my latest couple of images: Both of these are taken with an unmodified Canon 450D through a Skywatcher Explorer 150P on an HEQ5 Pro which is on a permanent pier. I have no guide-scope or filters and just take colour subs. I am stacking in DSS and processing in PixInsight, blindly following a workflow I was shown a couple of years ago. The PixInsight workflow goes: Background Neutralisation DBE Colour Calibration Histogram Transformation HDR Multiscale Transform ACDNR, followed by another bit of histogram transformation Curves Transformation (I possibly overdo this a bit but I like the colours!) SCNR Both these images were with 2 minute subs. The Flame/Horsehead was 2 hours-worth (with 15 darks and no flats) and M81/M82 was 4 hours (with 15 darks and 15 flats). What do you think are my worst offences? I can think of lots of things I could improve but I don't know what to attack first: Better polar alignment Guiding (I do have an 80mm Skywatcher refractor that I can piggy-back but I don't have a guide camera) Bias frames (I believe I could just take one master set rather than taking them every session. Would they have much of an effect?) Using filters (maybe a light pollution filter?) Coma Corrector Better use of DSS Better use of PixInsight
  22. Cheers, so in summary, that heater is suitable but any dehumidifier would need to be a desiccant type, preferably with a drain hose. That's really helpful, thanks guys --- Alistair
  23. That is a really neat and compact observatory and a gorgeous first-light image!
  24. I am looking to protect the gear I have in the roll-away Tardis observatory I built this year (see this thread on the build if you are interested: A dehumidifier: https://www.appliancesdirect.co.uk/p/md400/electriq-md400-dehumidifier) A greenhouse heater: https://www.greenhousepeople.co.uk/products/3872/slimline-eco-heater-55w-tube-heater-with-thermostat/ The observatory itself is around 1 meter square and 2 meters tall. Ventilation is currently provided by the gap in the base around the pillar, a large vent behind one of the 'Police Box' signs at the top, and the gaps around the door caused by my general bad workmanship! Do these seem suitable for my needs? Is there anything else I should consider?
  25. Thanks Bob, and I'm also very interested in your home-brew guide camera article. Definitely something to look into once I am happy with the alignment. I'm planning on following this guide to get the alignment sorted: Drift Alignment by Robert Vice since it should be easy and quick to verify if the adjustments I make are correct.
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