Popular Post Dave_S Posted February 28, 2022 Popular Post Share Posted February 28, 2022 40 x 240s, 115mm APO + 0.8x Reducer (f/5.6 at 644mm FL), and 294c Pro TEC camera Captured and pre-processed with Astroart 8, tweaked in Lightroom. 11 Quote Link to comment Share on other sites More sharing options...
Dave_S Posted February 28, 2022 Author Share Posted February 28, 2022 Here's a mono version for those that prefer it. Quote Link to comment Share on other sites More sharing options...
GazAstro Posted February 28, 2022 Share Posted February 28, 2022 It really does look like a monkeys head ... when you see it ! 1 Quote Link to comment Share on other sites More sharing options...
Dave_S Posted February 28, 2022 Author Share Posted February 28, 2022 Just noticed that I had forgotten to remove the "dreaded CMOS sensor green", so here it is without the green stars 🙂 2 Quote Link to comment Share on other sites More sharing options...
P Holdsworth Posted March 1, 2022 Share Posted March 1, 2022 Really nice image Dave. You've got lots of detail and great colour. I've just posted my effort on the Monkey head from Sunday night but have to say I much prefer yours !! Cheers Paul Quote Link to comment Share on other sites More sharing options...
Astrobdlbug Posted March 1, 2022 Share Posted March 1, 2022 12 hours ago, Dave_S said: “dreaded CMOS sensor green" Hi Dave, nice Monkeyhead nebula capture and process. The green cast is due to the nature of One Shot Colour cameras as they use a Bayer matrix usually RGGB that sits above the mono sensor well and the same (green)effect was seen on CCD One shot colour cameras - to your comment it’s not specific to CMOS sensors. The Bayer matrix captures 2X green than blue and red, which was one of the arguments against using OSC as you waste time capturing more green than needed for Astro - but CMOS sensitivity largely negates that old argument and why as OSC gain popularity and as the cameras are almost exclusively CMOS based sensors why it may be thought of as a CMOS issue - but it’s not. Bryan Quote Link to comment Share on other sites More sharing options...
Dave_S Posted March 1, 2022 Author Share Posted March 1, 2022 (edited) Hi Bryan. I fully understand the green being caused by the RGGB Bayer Matrix, but in my experience of 12 years imaging with two different models of Starlight Xpress OSC ccd cameras, I saw no evidence of green colour cast. Neither did I hear any reports of it from the astro imaging community. With the SX H9c for example, which used the Sony ICX285AK CCD, although this used a RGBG Bayer Matrix, there was no green colour cast. I can only assume that White Balancing in-camera corrected this. Maybe that unlike CMOS cameras where the amplifier etc is on-chip, the CCDs amplifier is separate from the CCD 'chip'. As such in-camera white balance could be achieved, hence no colour caste. My background is in radio frequency, and electromagnetic compatibility engineering, not cmos or ccd sensor technology, so I can only summise. Edited March 1, 2022 by Dave_S Typo Quote Link to comment Share on other sites More sharing options...
Astrobdlbug Posted March 1, 2022 Share Posted March 1, 2022 Dave, thats very interesting information, never considered that the underlying sensor tech may influence how the bayer matrix is handled either by on-chip circuitry or perhaps the camera driver - I also have engineering background in semiconductors so may delve back into some old text books I have on CCD to try and understand this a bit better. Anyway - now get why you made comment about dreaded CMOS green as your previous experience with OSC CCD the green monster didn't make an appearance, I've got some reading to do. Bryan 1 Quote Link to comment Share on other sites More sharing options...
Carastro Posted March 1, 2022 Share Posted March 1, 2022 Really nice image Dave. Why are the two vertical edges darker. Carole Quote Link to comment Share on other sites More sharing options...
Dave_S Posted March 1, 2022 Author Share Posted March 1, 2022 30 minutes ago, Carastro said: Really nice image Dave. Why are the two vertical edges darker. Carole A good question Carole. I hadn't noticed that, so thank you for pointing it out. An easy fix with cropping of course, but that doesn't answer the question. It could be a problem with extreme edges of the sensor itself, or it not being fully illuminated by the incoming photons. Or, it could be something that crept in during processing, as I haven't seen it in other images. Gradients yes, but that is more than just a gradient. I will investigate 🙂 1 Quote Link to comment Share on other sites More sharing options...
Dave_S Posted March 1, 2022 Author Share Posted March 1, 2022 (edited) Just realised Carole, that I had cropped the image as it is square, whereras the 294c sensor isn't. 🤔 Edited March 1, 2022 by Dave_S Typo Quote Link to comment Share on other sites More sharing options...
Dave_S Posted March 2, 2022 Author Share Posted March 2, 2022 (edited) Is this better Carole 🙂 It was definitely introduced during processing, as it was not present at 'stacked and calibrated' image stage, but I was unable to find out where it was introduced. Re did the processing from the 'stacked and calibrated image stage, including the CMOS camera generated green stars 😉, and some star reduction, here is result. Thanks again for spotting, and pointing out the problem. Edited March 2, 2022 by Dave_S typo 1 Quote Link to comment Share on other sites More sharing options...
Dave_S Posted March 2, 2022 Author Share Posted March 2, 2022 (edited) Found the source of the problem. The dark banding at the left and right edges, which are actually the top and bottom of the image, so not included in the crop (in the full frame he is actually facing down, and I rotated the image so the he is facing to the right), is introduced by adjusting the 'clarity' in Lightroom. As you can see below, the detail is nicely improved, but the dark edging, left and right, is starting to creep in. Very subtle, but it is there. Its not a gradient, as Russell Croman's "Gradient Exterminator doesn't remove it. Edited March 2, 2022 by Dave_S 2 Quote Link to comment Share on other sites More sharing options...
Carastro Posted March 3, 2022 Share Posted March 3, 2022 (edited) Quote Is this better Carole 🙂 I am sitting in a room with too much light, so need to look at this later when it gets dark. Quote Thanks again for spotting, and pointing out the problem. Glad you managed to sort it out. So often one hesitates to say anything for fear of offending, but it can be a great help as you can easily not spot things when you spend hours looking at the processing. Glad it helped. Carole Edited March 3, 2022 by Carastro Quote Link to comment Share on other sites More sharing options...
Dave_S Posted March 3, 2022 Author Share Posted March 3, 2022 (edited) 5 hours ago, Carastro said: "Glad you managed to sort it out. So often one hesitates to say anything for fear of offending," If you can't accept constructive critique, then don't post images on forums. As Yorkshire folk would say, "there's now't as queer as folk" 🙂 There is no place for destructive critique of course, but constructive critique can, as you say, be helpful. It is certainly welcomed, and encouraged on my photography group, and was on the Progressive Astro Imaging Group (PAIG), that I and Roger used to run. And of which you were a valued member Carole. 🙂 There is one astro group, which shall remain nameless, that is so heavily censored and biased, accepting only positive comments/posts related to equipment, that I no longer bother with it. Edited March 3, 2022 by Dave_S Typo 1 Quote Link to comment Share on other sites More sharing options...
Carastro Posted March 3, 2022 Share Posted March 3, 2022 (edited) Quote If you can't accept constructive critique, then don't post images on forums. Lol, but some people just want to be told how wonderful their images are. I can see the image OK now and yes it looks much better. Carole Edited March 3, 2022 by Carastro Quote Link to comment Share on other sites More sharing options...
Carastro Posted March 3, 2022 Share Posted March 3, 2022 Quote There is one astro group, which shall remain nameless, that is so heavily censored and biased, accepting only positive comments/posts related to equipment, that I no longer bother with it. Crikey, what a carry on. Carole Quote Link to comment Share on other sites More sharing options...
Dave_S Posted March 3, 2022 Author Share Posted March 3, 2022 It's called 'social media' Carole 😅 1 Quote Link to comment Share on other sites More sharing options...
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