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Stub Mandrel

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Stub Mandrel last won the day on June 14

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  1. Returning, I think I do too. I did a quick experiment on a photo of a yellow flower (a dandelion relative). Strong turned it a dull orange-brown, weak it stayed yellow, but more saturated. Obviously not what it is meant for but it's clear it 'kills' more acidic yellows if you use the stronger settings - I think it can spoil stars in RGB images too.
  2. It's a tough call. I want to keep a distinction between Ha (which comes out green) and HA+Sii which comes out yellow. I don't like the bright green so try and push it using selective colour so Ha is a duller yellow and Ha+Sii is brighter yellow. If I run HLVG weak I get this, which is perhaps better: If I run strong HLVG I get: This is a 'traditional' hubble palette, but always looks a bit dull to me. The problem with HLVG is that it kills yellows stone dead. I have extremely weak Reg/green colour blindness and this may mean that I see the line between lemon yellow and a very yellow green in a slightly different place.
  3. Photoshop and Astra Image. I use Astroflat Pro (which I find only works well if the image is already pretty well balanced).
  4. According to Stellarium it's smack over the Flying Dragon! 21h22m 38"42' Somewhere roughly halfway between Deneb and Cygnus's lower wingtip.'
  5. This time at a longer focal length of 135mm using a venerable Zeiss Sonnar.
  6. It's too small and my sky background was too bright, It's here in the middle, but no detail just smudges. Perhaps one for Notgrove if the cloud gods are kind!
  7. That's lovely Carole - what focal length did you use. I didn't get very far trying to copy your success with a 135mm lens!
  8. The moon! Eagle nebula (with Ha from 2020): M4 - filling in a gap in my Messier collection: Snake Nebula:
  9. After some advice I got yesterday, last night I took new flats and let DSS stack them rather than doing it in Sharpcap. The difference is striking (not much to see in this image, due to haze):
  10. I've got an issue with over-correcting flats in Sharpcap. I'm fed up of relying on Gradient exterminator! I'm also posting this on the SHarpcap forum. I have been using Sharpcap and stacking in DSS for a couple for years but have always struggled with what appears to be a degree of residual over-correction of the flats. I use an ASI1600MM-pro and the problem is common to all my scopes/setups. Last night I accidentally had 'automatically apply flats' checked and the preview images clearly had the 'crater like' image of a dust bunny (quickly removed!) which emphasised how bad the problem is - the resulting artefact was more noticeable than the dust bunny and its complex gradients would have been harder to correct. When I stack in DSS I always use temperature matched lights, DSS master dark, Sharpcap master flat and a DSS master Dark Flat, with no bias frames. Typically, I get over corrected vignetting (brighter corners) and any gradient is reverse, although the effects aren't as severe as in the original image - see below! I am always careful to get the histogram peak near 60% and use unity gain (139 for the ASI1600). All the 'cures' I have seen involve making sure you use darks and bias/flats. Are there any suggestions? Thanks!
  11. I think Julian has it right. That's more than just a bit of backlash or lost motion, it looks like a loose connector, binding or, IMHO a loose mounting bracket.
  12. No pixel peeping! I should have stopped the lens down a bit 🙂
  13. Given the weather I'm only slightly surprised to see so few shots of the eclipse. I set up my scope and despite clear sun five minutes before and after I was never able to get it on the sensor - the sun wasn't bright or strong enough to cast a dot in my solar finder. Ironically it was so weak through the clouds it was possible to see the eclipse naked eye towards the end, so I ran and got my bridge camera and tried a few shots at focal lengths up to 1000mm equivalent F/L and 1/2500 second, using my mount as a support! Contrast was very poor, but I got about ten usable shots.
  14. Always nice to see M13 👍
  15. Having a shot at the Sadr area using my 135mm Zeiss Sonnar. Just checked it and picking up loads of Ha in 150s, but I looked closely and saw my stars were tiny doughnuts. Two tiny tweaks and getting really tight stars now 🙂
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