Jump to content

30sec_exposures_2021.jpg.48851b1871a4bf9500ebd53c3e790d81.jpg

 

 

Delboy_Hog

Members
  • Posts

    441
  • Joined

  • Last visited

Everything posted by Delboy_Hog

  1. Absolutely, I've had so much fun trying to image with the Skywatcher Mak 127 (which I see in your signature too!) on its alt-az mount. Granted I'll never win any awards for the resulting images, and at 1,500mm focal length you have to be prepared to ditch 95% of your 30s frames, but it's still fun - and very rewarding too! That said, I've hugely enjoyed having an HEQ5 and small refractor for those occasions where I need a slightly higher success rate!! And yes, on the dither, any direction at random is good. Although be aware that your mount might take more time to settle down when you nudge it in certain directions. It might not of course, but where mine will settle almost immediately in two directions (apologies, I can't remember which), it will continue to move slowly in the others for 10 - 20 seconds after I've stopped pushing the button! The dithering and settling process eats into your total imaging time, so I mean to experiment with how many frames I can get away with taking between dithers. There's a skill in getting the size of dither right. Small is fine, I gather it only needs to be a couple of pixels. I went too large to start off with and the stacking software rejected a few batches of images, though using the long focal length Mak there weren't many stars in the field of view to align - with the ED72 I think you'll be fine....good luck!
  2. Hey LeeHore7, that's a nice looking image you've got there! Yes, as Michael says, I think it's walking noise - on an equatorial mount that doesn't have the field rotation, it appears in straight lines (I encountered this a while back, see: I scratched my Soul (nebula) - but don't know how? - Imaging - Image Processing, Help and Techniques - Stargazers Lounge Dithering has indeed helped, and having also tried this on my Alt-Az mount where I don't guide or dither, I have tried moving the mount a tiny bit between frames. Time consuming (can take a few seconds for the mount to settle afterwards), but definitely worth it. Doesn't need to be a big movement, and you can get away with doing it once every few frames if you're taking lots of them (e.g. one dither every 3-5 frames). Be prepared for having to do a fair crop of corners / edges afterwards, to account for field rotation and moving the mount to dither, especially if you're taking lots of exposures over a long period of time, but otherwise it should work fine! On a separate note (I also have a 600d), you might not need the dark frames for 30s exposures if you're dithering, especially if you're stacking 100+ frames as you did here. While the 600d is a bit of a noisy beast if you start pushing it to 2+ minutes (especially on warmer nights!), I haven't noticed much of a difference with or without darks on shorter exposures - though I should stress I am no expert, so others may disagree! Maybe have a look at the master-dark file and see how yours looks?
  3. I didn't figure it out I'm afraid @JemC, I found the "save files simultaneously to DSLR" option on the ASIair, so have gone back to using RAW files from the camera's memory card, rather than the FIT files from the ASIair, though would still like to know what's going on here! Because I have to break up and pack away my kit after every night, the approach I have now means I can stick the intervalomter in the camera and start taking darks while I strip down the rest of the kit, rather than having to keep the ASIair plugged and powered. Though having learned the hard way that you can't stack a combination of FIT lights and RAW calibration frames in DSS, I decided to go back to all RAW stacking. Like you @Eddie Jones, I wondered if you could just crop and process the quarter that had data in. That might still be the answer, I'm not sure, but since it didn't seem right, I was worried that some of the data might be missing / have been compressed in some way etc etc.
  4. I've had a similar issue on a couple of different occasions (albeit with the older version of the ASIair. How far (if at all) did the mount move within the 60 steps? Yours sounds weird if things had all worked previously, although I've found some settings reset following an update to the app etc, so worth double-checking the settings are still the same as you remember. And just in case helpful, some things I got wrong at various points were: - Tried to calibrate guiding on Polaris - Plugged the ST4 cable into the ASIair rather than the camera - Hadn't given a big enough figure for the calibration steps in the guiding menu - Not provided enough power (either to the ASIair or to the mount I was trying to guide) Hopefully something helpful there. Good luck!
  5. The other thing I'm learning is how different images look on different screens - it's very strange! I've just looked through the images on this thread again, and they look so different from my phone to the laptop, and different again on my work laptop...how on earth do you know what your image really looks like if it's different to everyone depending on their screen!?
  6. Holy Moly, that's a lovely version - lots of faint stuff, detail in the dust lanes, and I love the colour you've got in the stars - that's something else I need to work on - it's white blobs only for me at the moment! I really must check out this Startools! What's the secondary point spread thingy?! Thanks for that - it's comforting to know that there's good stuff in the data. Like many of us, I've got a lot of projects in mind, but I've taken a number of images where I did something wrong and something doesn't work for some reason, it can get disheartening. I'm finally getting to the point where I can take a reasonable set of images....I've just got to learn what to do with them!
  7. Many thanks for that, that's hugely helpful to hear the similarities / differences with Pixinsight. The masking is probably next on my list to learn, I think. It's a helpful one for night-landscape shots too. And yes, I definitely agree that there's a fine line on how far to push it - and it seems very easy to go that one stretch too far! I think what I've learned most from this thread is that there are other tools that I'm not yet using that can get my data a bit further in the right direction before it starts to come apart - I just need to get some experience of using those tools. The big problem I have (like everyone) is the weather. I learn new skills, but then not get the astro kit out for 2 months and have forgotten it all next time around! (Shakes fist at clouds!) Thanks again for your thoughts on the processing!
  8. Lovely! So many good processes - I really like these - the faint stuff around the edge of the galaxy is there (that I didn't manage to bring out), but in a way that makes it distinct from the background sky. That seems to be quite an art (or science?!) - my version (albeit riddled with gradients) just seems to merge indistinctly with the background sky. That's definitely on my list of things to correct. And some people seem to be managing to bring out the dust lanes more clearly, and get some detail of a swirl in the core too - that's barely visible in my go at this - presumably that's controlling the brightness and boosting contrast, some how? I guess more data would help with that too. Thanks for taking the time to play with the data. I'm still trying to master consistently some of the steps that Vlaiv and others have kindly set out, but if anyone has any techniques they've used for galaxy processing on their own data, I'd be fascinated to hear them!
  9. Thanks all, I'm intrigued by the different approaches, software, brightness, contrasts etc. Makes me realise just how much I've got to learn! Will definitely try again / add more data on this (preferably moonless!), and as discussed in other threads recently, I definitely still need to master flat frames! The 6d is a great camera, but certainly comes with some challenges! Hoping to get to some darker skies once we're out of lockdown too!
  10. Thanks David, yes I suspected it wasn't the darks - and as you say, I rarely use darks with the 6d unless my exposures are 10+mins - a good dither between frames more or less does the trick there, especially in this cold weather! I would agree with you that the flip shouldn't affect the flats - it hasn't for me in the past. But this time there are artefacts that seem to be generated through the flat frames (i.e. they're not there when I just stack the lights) that are being repeated across the frame (e.g. see the light and dark smudges in the top right and bottom left of the full frame). I'm not sure if there's a light frame that the flats are correlating to that isn't stacking in the same orientation, or what's going on... The only things I can think of that would make the flats not correlate to the lights is that the white t-shirt flats technique either added some dust to the front of the scope lens (which must have blown away when I took the t-shirt off, as the lights I took after that point don't work with the flats either!) or possibly that there was some crinkle or mark on the t-shirt, or an issue with the even lighting of the screen I was using. Looking back over the frames, I also wonder if I didn't help myself by not re-framing precisely enough after I'd moved away to a brighter star to check focus. There's also some shift in the orientation (field rotation?) in the stacked frames, which you can see in the full field image above, which may not have helped my cause, though again, neither of those have been a problem for DSS before...
  11. Hmmm, no, I'm having no luck with this.... The artefacts seem to be coming from the flats, and the issue is being compounded by the flip, duplicating some of the artifacts. I take two sets of flats at different exposures in case one of them doesn't work...and this time neither does, regardless of whether I apply them to the pre or post-meridian flip light frames, or the whole stack. I just don't understand how these flats can seemingly generate distinct artifacts? It's a shame because I think there's some reasonable data here, and about 3 hours of it. Unfortunately one of the perils of working with a 6d on an ED80 is that if your flats don't work, you're left with a largely unworkable light drop-off. The good thing about working with a 6d is that it's a reasonable camera, so the data that falls right in the center of the image isn't awful, even if your heart is breaking at having to crop off 80% of the overall image! Quick levels process in photoshop... I might try and download one of those auto flat-generator software thingies to see if that can salvage anything from the wider-field data...
  12. I'm really struggling here, and hoping you can help! In the past I've not had any trouble with DSS coping with the meridian flip and calibration frames, but something's gone very wrong this time, and you'll see from the image I've got weird artifacts appearing all over the image (I've circled a few of the weirder ones). On this occasion, I took about 40 light frames (M81 / M82 with ED80 and Canon 6d), then as the forecasted cloud rolled in for an hour or so, I took my flats and a few darks, then as the cloud had cleared, did the Meridian flip and took another 40 or so light frames, then took the bulk of the darks. Is it because I took flat frames before flipping, rather than at the end of the session? Or because some of my darks were before and some were after the flip (but I wouldn't have thought darks could be responsible for these artifacts)? Or has something else crept in here that I haven't thought about? My bias frames are from another evening, but they worked fine last time (or at least, didn't cause any obvious issues), so can't believe they're responsible. I tried rotating the RAW files, but have just learned you cannot apparently do this without converting the file type to something else. I'm about to spend the next few hours (or days, with the speed of my computer!) trying to re-stack various combinations of files to try and route out the problem, but thought I'd see if anyone here knew what might be going on. I'd be very grateful for your thoughts! Image straight out of DSS...
  13. Hi Laurieast, thanks for that - I definitely need to look up Gradient Exterminator! And I haven't used (or even seen!) that feature in photoshop, so I'll be googling that one too, thank you!
  14. Thanks Almcl, it is different isn't it? It stands out much brighter than the background sky on this version - it has a punch to it! I'd be curious to know how you brightened the galaxy specifically and not the background, is that something you've done through curves etc, or is it layer masks and things - not sure if StarTools has those specifically? It's a trick I need to learn for the fainter objects in the night sky, I think. Thanks for taking the time to use the data - it fascinates me how everybody has slightly different approaches and different outcomes!
  15. Many thanks for that Vlaiv, that's really helpful to see - I have much to learn! Very much appreciated - I'll go and have another tinker with the data and see what I can do! Thanks again!
  16. Thanks for the kind words, and I most certainly do like it! That's fabulous, thank you so much for taking the time. You seem to have shifted the gradient entirely, and found some additional faint stuff that I had not! It looks a much more complete image. May I ask what approach you took? I've followed the discussion on the colours that our deep sky objects should have with interest. Being significantly colourblind, I tend to rely on photoshop to tell me when my background is reasonably neutral, and tend just to pray that the main object isn't abnormally coloured as a result. I feel like that's a processing step I've been putting off learning for a while, but think I'm going to have to get into it! Many thanks again for your efforts, Vlaiv, it's really helpful for me to see what others can do.
  17. Hi All, I wonder if anyone might see what they can do with this Andromeda data from last night? The kit is an Evostar ED80 with stock ff/fr, on an HEQ5, taken with a Canon 6d. The stack is 70 x 2min guided, dithered light frames, calibrated with 20 - 30 each of bias, darks and flats. Taken from light polluted Bristol, with a large moon not that far away (both of which contribute to the beastly gradients, I suspect!), I didn't expect the results to blow me away, but I'm curious to see what you expert image processors might be able to do with it.....Dropbox link below - if anyone is tempted I'd be hugely grateful! https://www.dropbox.com/s/g94yazgu045kwi9/M31_2min_Autosave.tif?dl=0 For context, I'd attempted a batch of 1min subs a couple of nights before, sticking to the one-third histogram 'rule', but the results were disappointing, so I risked going quite a bit over 50% on the histogram to see if I could find anything more in the data...think it's worked, though there's a weird light band on the bottom of the frame, and I need to look at how I'm taking flats, as they don't seemed to have reduced the light drop-off on the right side all that well. My (limited) processing is simply DSS for stacking, followed by levels and curves in Photoshop. Any thoughts would be much appreciated, and I hope you're all keeping safe and well, Derek
  18. Ha ha, I love that feeling when you get a clear night and the views are good! Glad you had a good one - the Skywatcher 127 is an absolute beauty on the moon (and planets). On those occasions where the seeing is good, the views look like you could be in orbit around the moon, looking down over the lunar craters and mountains! Here's hoping for more clear skies soon!
  19. Hey Ande, Sorry to hear of the frustrations, but nicely done on pushing through. I've had to accept that (for now at least) astrophotography is a journey more of constant learning than of capturing stunning photos! EVERY night something new seems to crop up (and my experiences of the ASIair suggest you'll have more learning soon!)...if it's not some tiny, seemingly insignificant setting in some menu on the technology, it's the slightly heavy-handed adjustment of the kit post-polar alignment, or the seeing / temperature change that means you need to restart, refocus, then reframe, then change the battery again, then find a new target because yours is now in the light pollution, then adjust the guiding settings because you're looking at a different part of the sky, then re-polar align because you knocked something etc etc... As you say, keep sticking with it and trying to figure things out. I've recently been more determined not to pack it in when things that appear to be showstoppers that make no sense show up. Even last night I was out cursing the kit and being tempted to throw the whole lot over the neighbours fence and be done with it! And while I have very few decent images to show for my efforts over the last few months, I'm now at a point where I think I've seen and googled how to resolve almost any issue that crops up, have established a routine for setting things up accurately, and am on the cusp of producing a reasonable image! On those (for me) rare nights where everything comes together and works well, it is a truly wonderful hobby and the rewards are amazing. But by god do you have to work for it! All the best and look forward to seeing how you get on over the coming days / weeks!
  20. Looking for the older, white version of the ASI-air. If anyone is thinking of moving onto another system, or upgrading to the newer, red ASIair, I'd love to hear from you regarding your old one! Many thanks, Derek
  21. Yes, unmodified camera, and yes, with the field flattener / focal reducer that's specifically recommended for the Skywatcher ED80... I think the approach you suggest is right - taking different exposure lengths to cater for the bright star and the faint nebulosity, and combine them in processing? I guess though that the reflection would still be there in the longer subs, so perhaps Pete's suggested approach of attacking it in photoshop might be the way forwards? I've also wondered whether having Alnitak absolutely central in the subs would help prevent light bouncing around at strange angles...some testing required, I guess!
  22. Following this one with interest - I've encountered a similar thing in my last attempt at the Alnitak area, though my blueish blob appeared in a slightly different place. 5 min subs, ED80 and Canon 1100d. I'd assumed it was a reflection, but wasn't sure what to do about it. Is your image above cropped at all? If not, both our bluish blobs appear to be roughly equally distant from the centre (or edges) of the frame from Alnitak, so I'm guessing that's the culprit, but which piece of glass is doing the bouncing was beyond me. Given its location I'd struggle to process it out convincingly... Like you MylesGibson, I was pushing the exposure length to give me a sporting chance of catching the nebulae...and similarly , ran short on total number of subs, and had no calibration files. I guess a greater number of shorter exposures might help, and I gather that you can use star masks and the suchlike to 'contain' Alnitak, though those are processing skills well above my current skill level! How long an exposure is too long, for a bright star like Alnitak?
  23. Picture above wasn't hugely clear, so here's another - If there are any DSS experts out there, I'd be extremely grateful for any advice on what I might have done wrong here. Stacking FIT files - you can see the DSS output below (I've tinkered with the histogram so you can see the image properly - although I'm not sure what the X-shaped histogram is about??) - I've never seen this before. It's always placed the data across the full screen, rather than cramming it all into just one quarter of it? Any thoughts?
  24. Hi all, Attempting to stack and process a bunch of files in DSS, but the file that's churned out only seems to have data in the top left quarter...... Taken with a modified canon 600d with an Ha filter, but captured by an ASI-air as FIT files, rather than the usual RAW files I'm used to using straight from the DSLR (I haven't yet figured out how to save the images as RAW files to the DSLR at the same time as the ASI-air saves the files as FIT on its micro-SD card). The tiny JPG file that the ASI-air produces of each photo suggests there's data registering across the sensor, so I'm hopeful I've just missed a step in the stacking process..............? It's M33 in Ha, and on a slightly hazy night, so whatever's there is pretty faint! Anyone seen this before, or know of a potential fix? I'd be very grateful for any advice! I didn't know if DSS had issues stacking FIT files so I even attempted to convert them to TIFF files first...still no luck...although I might have done it wrong! Image below straight out of DSS....
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.