MikeODay Posted March 26, 2018 Author Share Posted March 26, 2018 Objects in image: Hypergiant, Eta Carinae ( HD 93308 ) in the centre of the Homunculus Nebula Carina Nebula ( NGC 3372 ) Keyhole Nebula Open Star Clusters: - Trumpler 14, 15, 16 - Collinder 232 Link to comment Share on other sites More sharing options...
MikeODay Posted March 26, 2018 Author Share Posted March 26, 2018 Open clusters in the Carina Nebula image above ..... Collinder 232 ..... Trumpler 14 ..... Trumpler 15 ( southern half of cluster only ) ..... Trumpler 16 Link to comment Share on other sites More sharing options...
Uranium235 Posted March 26, 2018 Share Posted March 26, 2018 Smashing stuff Mike, and with an unmodded DSLR too! Link to comment Share on other sites More sharing options...
MikeODay Posted March 27, 2018 Author Share Posted March 27, 2018 11 hours ago, Uranium235 said: Smashing stuff Mike, and with an unmodded DSLR too! Cheers, thanks for that. It helps that the nebula is so bright; it means I am not missing out too much by not capturing more of the Ha. Link to comment Share on other sites More sharing options...
MikeODay Posted March 27, 2018 Author Share Posted March 27, 2018 I am still travelling so I am limited to playing with what I have on my IPAD. I downloaded PS Express and played with it a little... the result is a little more detail in the shadows and highlights ( with a side effect that the highlights have a little more apparent colour ( not that they needed more colour ))... Tweaked version One from the top post above: What do you think, better or worse ? ... I think I might prefer the new one; the increase in shadow brightness shows up most in the top left corner and I think this might help balance the composition a little better ( before the heavy dark weighed that corner down, if you know what I mean ). Link to comment Share on other sites More sharing options...
geoflewis Posted March 27, 2018 Share Posted March 27, 2018 13 minutes ago, MikeODay said: I think I might prefer the new one I agree, the tweaked versions is better, but what a cracking image it is with loads of great features as shown in all the cropped versions. Breathtaking.... Link to comment Share on other sites More sharing options...
MikeODay Posted March 27, 2018 Author Share Posted March 27, 2018 11 hours ago, geoflewis said: I agree, the tweaked versions is better, but what a cracking image it is with loads of great features as shown in all the cropped versions. Breathtaking.... Thanks, much appreciated. I have added the new one to the top post to show it off better Link to comment Share on other sites More sharing options...
Xiga Posted March 27, 2018 Share Posted March 27, 2018 On 21/03/2018 at 14:49, MikeODay said: Thanks, much appreciated The HDR capture and processing is to keep colour and detail in the stars. The 1/8 sec exposures @ ISO 250 just manage to capture the core of the central star "Eta Carinae". The total dynamic range of the linear HDR image is 36bits ! There is no way any normal camera can record that in one exposure. My workflow ... - calibrate, debayer and alignment as a single group - Integration in sets of like exposure - in this case 12 separate integrations - remove pedestal from each integrated image ( I added this during the calibration stage to make sure that I did not clip the shadows ) - Combination in this case is by using Pixinsight's HDR tool, although I have often had trouble with it and usually I do manually using Pixinsight's pixelMath tool. - Divide each channel of the HDR image by the correct factor to achieve "daylight colour balance" ( for the D5300 that is approx.: Red/1, G/2, B/1.4 ) - DynamicBackgroundExtraction tool to remove the colour cast in the shadows caused by light pollution - MaskedStretch in multiple small steps to take the background level from around 5e-6 to around 1e-3 ( on a 0..1 scale ). I double the background level at each step and also use the histogram tool at each step to clip away zero values as the peak slowly moves away from the left with each step. - Either keep going with MaskedStretch until background level is about right or, as in this case, switch to ArcSinH for the final stretch from 1e-3 to 1.6 e-1 - Curve tool to tweak contrast - And a final tweak of colour balance using the curves tool - usually, as in this case, I apply a small green reduction only ( ~ 1 to 3 % ) I hope that helps... One day I will get around to doing a tutorial, one day ... Cheers Mike Thanks for this Mike. Very informative indeed! Even as a non-PixInsight user, i think i can follow most of the methodology. The only stumbling block would be the HDR combination bit. I know APP doesn't have this yet (it's on Mabula's to-do list), but i think DSS does contain something similar (i haven't used DSS in a while now so i can't say for sure). Something for me to play about with one (cloudy) day no doubt. Cheers! Link to comment Share on other sites More sharing options...
MikeODay Posted March 29, 2018 Author Share Posted March 29, 2018 On 28/03/2018 at 11:46, Xiga said: Thanks for this Mike. Very informative indeed! Even as a non-PixInsight user, i think i can follow most of the methodology. The only stumbling block would be the HDR combination bit. I know APP doesn't have this yet (it's on Mabula's to-do list), but i think DSS does contain something similar (i haven't used DSS in a while now so i can't say for sure). Something for me to play about with one (cloudy) day no doubt. Cheers! You are most welcome. Glad to be of help. Link to comment Share on other sites More sharing options...
MikeODay Posted March 29, 2018 Author Share Posted March 29, 2018 I have uploaded the full size image of the Carina Nebula ( 6062 x 4082 ) to my Flickr page so you can zoom in and see all the fine detail ( and imperfections ) Link to comment Share on other sites More sharing options...
MikeODay Posted March 29, 2018 Author Share Posted March 29, 2018 I quite like this little nebula and the colourful 'little' stars scattered through the image. I vaguely remember seeing this object photographed by hubble ( or some other high powered large scope ) but I can not find it now. Does anyone know if it has been given a name or designation? 100% crop ( bottom middle ) of full size image ( 6062 x 4082 ) making this image about 7' wide. Link to comment Share on other sites More sharing options...
Rodd Posted March 31, 2018 Share Posted March 31, 2018 Very impressive.....its like we are not even participating in the same hobby. I am obviously missing a great deal! Amazing images, all. Rodd Link to comment Share on other sites More sharing options...
MikeODay Posted April 1, 2018 Author Share Posted April 1, 2018 17 hours ago, Rodd said: Very impressive.....its like we are not even participating in the same hobby. I am obviously missing a great deal! Amazing images, all. Rodd Now that IS way too kind ; your image gallery on DSO-Browser is full of truely wonderful images that have inspired me to strive harder over the past four years that I have been learning this new hobby. Some of your galaxy images in particular are truly stunning. Thank you for your support and encouragement it means a lot. Cheers Mike Link to comment Share on other sites More sharing options...
lux eterna Posted April 2, 2018 Share Posted April 2, 2018 On 2018-03-21 at 12:50, MikeODay said: Capture ( 17, 18 & 19 March 2018 ): 12 sets of sub-images with exposure duration for each set doubling ( 1/8s to 240s ) all at ISO250. ( 181 x 240sec + 10 to 20 each for the other durations ) Processing: Calibration: master bias, master flat and master dark That is really wonderful images you have (all of them), I was surprised to see they were captured with a standard dslr. You mentioned that this target is pretty luminescent. I guess that is the reason for so short (max 240s) subs. How long subs would you use if you were to capture a more subtle and darker target ? I have a similar camera as yours (but only 16 MP), the D7000. Would you say I am missing something important by not using any darks, flats or bias ? /Ragnar Link to comment Share on other sites More sharing options...
astro mick Posted April 2, 2018 Share Posted April 2, 2018 They dont come much better Mike. Good job. Mick. Link to comment Share on other sites More sharing options...
MikeODay Posted April 3, 2018 Author Share Posted April 3, 2018 7 hours ago, astro mick said: They dont come much better Mike. Good job. Mick. Thanks Mick, much appreciated. Link to comment Share on other sites More sharing options...
MikeODay Posted April 3, 2018 Author Share Posted April 3, 2018 14 hours ago, lux eterna said: That is really wonderful images you have (all of them), I was surprised to see they were captured with a standard dslr. You mentioned that this target is pretty luminescent. I guess that is the reason for so short (max 240s) subs. How long subs would you use if you were to capture a more subtle and darker target ? I have a similar camera as yours (but only 16 MP), the D7000. Would you say I am missing something important by not using any darks, flats or bias ? /Ragnar Thank you Ragnar. I have over time varied the maximum exposure I use. Currently it is 240sec @ ISO250 using an f4 scope ( f4.7 effective including coma corrector ) and no filters. This choice is independent of the target object as it is an attempt to optimise the capture of the background; that is, at that exposure duration ( with my semi-polluted skies) every pixel is recording some signal so none of the background is being clipped. If my camera had significant read noise I would increase the exposure to shift the peak of the histogram ( displayed on the back of the camera ) more to the right ( from its current 5 - 10% to 20 - 33% the way across the display ). As for your D7000 ... Flats will definitely help if you have significant vignetting of the light path or some other constant gradient. It will also help if you have dust 'donuts' visible in your images. The trick is to capture high quality flats. I really struggled doing so until I invested in an LCD panel designed for taking flats; it has been one of my most successful purchases! Bias? Yes I recommend these. The are easy to take and are not significantly sensitive to temperatue so you can just create a master bias and keep reusing it. Darks? Probably yes. Unless your camera has no pattern noise then your images will be improved by subtracting a master dark. Note that by pattern noise I am not only refering to banding or amp glow ( if you have these then definitely you should use a master dark ); if you have significant numbers of stationary warm/hot pixels then these will show up as bright noise in your images if you do not dither while guiding and possibly as streaks if you do. The D5300 is a very low noise camera and for quite a while I did not think that the improvement in pattern noise reduction was worth the increase in random noise you get by subtracting a master dark. However, after running some experiments, I have found that the quality of the background noise in my final images is improved if I use a master dark. Sorry for the long reply - I hope some of that was useful Link to comment Share on other sites More sharing options...
lux eterna Posted April 3, 2018 Share Posted April 3, 2018 2 hours ago, MikeODay said: Thank you Ragnar. I have over time varied the maximum exposure I use. Currently it is 240sec @ ISO250 using an f4 scope ( f4.7 effective including coma corrector ) and no filters. This choice is independent of the target object as it is an attempt to optimise the capture of the background; that is, at that exposure duration ( with my semi-polluted skies) every pixel is recording some signal so none of the background is being clipped. If my camera had significant read noise I would increase the exposure to shift the peak of the histogram ( displayed on the back of the camera ) more to the right ( from its current 5 - 10% to 20 - 33% the way across the display ). As for your D7000 ... Flats will definitely help if you have significant vignetting of the light path or some other constant gradient. It will also help if you have dust 'donuts' visible in your images. The trick is to capture high quality flats. I really struggled doing so until I invested in an LCD panel designed for taking flats; it has been one of my most successful purchases! Bias? Yes I recommend these. The are easy to take and are not significantly sensitive to temperatue so you can just create a master bias and keep reusing it. Darks? Probably yes. Unless your camera has no pattern noise then your images will be improved by subtracting a master dark. Note that by pattern noise I am not only refering to banding or amp glow ( if you have these then definitely you should use a master dark ); if you have significant numbers of stationary warm/hot pixels then these will show up as bright noise in your images if you do not dither while guiding and possibly as streaks if you do. The D5300 is a very low noise camera and for quite a while I did not think that the improvement in pattern noise reduction was worth the increase in random noise you get by subtracting a master dark. However, after running some experiments, I have found that the quality of the background noise in my final images is improved if I use a master dark. Sorry for the long reply - I hope some of that was useful One of the things I like with this hobby is the process of improving things and getting better results - preferably without spending too much money. Climbing the learning curve, that is the most rewarding I think. So I will definitely take a closer look at my histograms and work out some standard exposure time for my equipment. And now when the astro season is almost over where I live, I have plenty of time to do some experiments with calibration frames. I have a dark utility room in my basement where I can experiment with an ordinary camera lens. I usually have very subtle vignetting and no gradients, so maybe I can get away with just bias and darks. Thank you for your very informative answer . Link to comment Share on other sites More sharing options...
Tom OD Posted April 3, 2018 Share Posted April 3, 2018 Excellent capture Mike. Tom Link to comment Share on other sites More sharing options...
Ceph Posted April 3, 2018 Share Posted April 3, 2018 I can't add more then others here, very nice job done. Link to comment Share on other sites More sharing options...
MikeODay Posted April 4, 2018 Author Share Posted April 4, 2018 On 04/04/2018 at 02:41, Tom OD said: Excellent capture Mike. Tom On 04/04/2018 at 05:24, Ceph said: I can't add more then others here, very nice job done. Thanks guys, much appreciated. Link to comment Share on other sites More sharing options...
MarsG76 Posted April 8, 2018 Share Posted April 8, 2018 I saw your pic on flickr, nice collection.. very nice... If I'm following you and you're following me, aren't we just going around in circles? HAHAHA Link to comment Share on other sites More sharing options...
MikeODay Posted April 10, 2018 Author Share Posted April 10, 2018 On 09/04/2018 at 10:49, MarsG76 said: I saw your pic on flickr, nice collection.. very nice... Much appreciated, thanks. On 09/04/2018 at 10:49, MarsG76 said: If I'm following you and you're following me, aren't we just going around in circles? HAHAHA Link to comment Share on other sites More sharing options...
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