Filroden
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Everything posted by Filroden
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Mixing subs from 2 cameras shouldn't have that impact. Are you stacking all the subs together or stacking subs from different cameras then restacking the results? The latter is prone to degrading the image. But if you throw it all into the same stack and use an algorythm that weights by SNR and uses a good rejection technique then it should improve the image.
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I'm not much more of an expert but open both images. On the image you want to use as base, create a new layer and make sure that layer is highlighted. Go to other image and copy it. The I think its as simple as pasting it in the other image. I'm assuming both images are identical in scale, etc. If not, they need to be aligned first.
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Can you extract the luminance from the middle and the colour from the right and recombine?
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Lovely images. And 8 min exposures Another advantage of the no darks strategy...I’d have spent 4 more hours collecting darks before I could even process.
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Nice round stars from edge to edge so I guess the tracking is good You just need to tame the stars a little during processing to keep them smaller. Otherwise a great capture!
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That makes perfect sense. What a horrible combination to have to navigate through - the periodic tracking issue wants you to point to areas of the sky not liked for field rotation. I guess the one advantage you can take from lots of 5 second exposures is it really helps the S/N ratio And with so many subs, throwing away even 10% is not much of an issue.
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First, what a great Ring Nebula and looks like you caught quite a nice spiral galaxy to the right. IC1296 maybe? Dare I say a little noisy and you may need a few more subs Just kidding. You're now facing that same dilemma anyone taking short exposures faces, whether to archive all those subs so you can add more at a later date! This surprised me. I always thought it was easier to push longer subs the closer you image to the horizon (though this is counterbalanced by atmospheric disturbance) and the closer you image to east and west. Imaging at the zenith is all but impossible and imaging to the north or south difficult other than at very short exposures. I found my ideal targets were usually crossing east or west between 30 and 60 degrees above the horizon. These allowed me to consistently achieve longer exposures.
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Have you found an alternative that gets you closer?
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![[WIP] NGC7000 North American Nebula and Pelican](//content.invisioncic.com/g327141/monthly_2017_09/small.NGC7000_H_HT_LHT.jpg.93c78b3f175f41ef126c79a3d1c54458.jpg)
From the album: Ken's images
After a long summer then a poor combination of either full moon or cloud, I finally got to set up last night. It probably took me over 2 hours to get everything set up. Even a few months break meant I'd forgotten almost everything (to be fair, I didn't have the new mount for long before the summer started). For whatever reason, I could not get drift aligning to work in PHD2. Entirely user problem through lack of use. I think I had SGPro and PHD2 fighting to control the mount so I need to update my workflow to only use one or the other at a time. It was the same for guiding. PHD2 seemed to be having fits until I realised SGPro had parked the scope and would not release control to PHD2 to guide. Once I realised, and managed PHD2 from within SGPro everything started to work for a while. I only managed 6x240s Ha images at unity gain with the ZWO ASI1600M as guiding went crazy again and would not settle. As there was starting to be a heavy dew and clouds were forecast for within the hour I called it a night and treated this as a test run So, with only minimal processing, no flat calibration (will do that once I have collected more subs) and a test of some localised contrast enhancement (still not sure I like it) here's the start of what hopefully will be a productive autumn imaging. -
As Nigel says, you'll find that imaging on a mount designed for visual and a scope with a long focal length is a ... shall we say painful experience. I've tried it and whilst I was pleasantly surprised that I got an image, it's an experience I would never repeat. Here's my take on M1 with a 9.25 SCT. It's worth noting I used a very fast/sensitive camera so the limited and short exposures sort of worked. I don't think it would have been possible with my Canon 60D. I now image with a 500mm focal length scope and it's a breeze in comparison. Give it a go but be prepared to switch to a camera/lens combo
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Thoughts on which imaging rigs to concentrate on
Filroden replied to Gina's topic in Imaging - Discussion
Ah, different types of stars! -
Hold out. I think the ZWO filters are narrower. There's plenty of other things to do while you wait
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I also prefer the first image. There are noticeably more gradients in the second image caused by the moon which would be difficult to remove in their entirety. The first image also has a warmer feel and the stars look delicious. I guess its also down to target selection. With a bright moon, it may be better to stick to clusters where you can attack the gradients a little harder; something that you cannot do well with nebula or galaxies.
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Thoughts on which imaging rigs to concentrate on
Filroden replied to Gina's topic in Imaging - Discussion
If it was I think it would be time to move planet! Good to see you back to imaging Gina. You're taking on another great project and I can't wait to follow your progress. -
Make sure you get a really good initial alignment, adding additional alignment points close to the area you want to image. This might help improve tracking. You have a nice short focal length so as Ian says above, you should be able to get reasonable length shorts which can be integrated to improve their quality.
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Those are lovely. There sure are some nice advantages to a fast wide aperture! Though there are probably just as many disadvantages
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You can apply almost all processing techniques to a jpg...you just shouldn't! Jpgs are 8 bit and compressed so they destroy data which means tools like curves can have terrible results, making them look very 'stepped'. You're always better working in at least 16 bits and uncompressed (e.g. TIFF or FITS) so you can work over a better range and not have the steps seen in a jpg. PixInisght comes with a long free trial but it requires it. I needed lots of tutorials and ultimately a guide book to really start to use it well. You can achieve the same results in Photoshop if you know how. I can do a little in Photoshop, such as level and curve adjustments, but I find the tools in PixInsight more in tune with the way I think. As I said above, I only applied some crude adjustements to see what was under the colour cast. You will be able to achieve far more using the original data and taking a little more time than I did
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Really nice first attempt. There's a lot of data hidden behind that blue cast. I don't know how to fix it in Photoshop but a quick pass through PixInsight's ColourCalibration and some crude curve adjustments shows you this. I've broken the stars (they are all showing orange) but there is a lot of colour in the nebula that you could bring out.
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Same. I set up tonight with the intention of getting 3 hours of Ha. I failed to switch on DST so my first StarSense align failed. When I did get aligned and switched on the camera it showed a massive smear somewhere. So I stripped it down and cleaned it. Realigned and now the sensor was covered in dust. I would still have to do two more aligns and it was getting so late I was concerned about waking the neighbours so I've just packed up. I think I'm going to have to wait until August.
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Competition details: Forum to post images: https://stargazerslounge.com/forum/226-imaging-challenge-3-30-second-exposures/
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I liked the first version but this is amazing! And only 16 minutes? We're your subs 30s or less? If so I'd put that into the competition.
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That's a nice result. Lovely star colours and you're just picking up the reds in the outer parts of the nebula. Do you take new flats after every session. Whilst you can re-use flats if you're certain camera and scope remain oriented, this usually applies if you're using a fixed set-up. If you're tearing down the equipment each session i would recommend trying with fresh flats. You're showing some trailing. What exposure length are you using? You may be able to take shorter exposures and integrate more of them to get the same total integration time. This might help reduce trailing and loss of exposures. I would never use an exposure that gave less than 80% results. We have far too few clear nights to be throwing away subs!
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Now you're using an EQ mount and have PHD working I would recommend trialling SGPro. It will platesolve out of the box allowing you to precisely centre on a frame taken on a previous night. It will also work if you move to a mono camera with filter wheel. It also will manage focusing if you ever decide to automate. Its interface and terminology can take a while to figure out but there is logic in its apparent madness! It's definitely made imaging easier. I fire up SGPro, connect camera, filter wheel, focused and mount. Fire up PHD and connect guide camera. Then I'm ready to start. i previously used BackyardEOS which was easier to use but is Canon specific. The only free capture software I've used were Sharpcap and Firecapture but these were more designed for short exposures. PixInsight is starting to implement image capture but I don't think it will ever catch up with dedicated capture software.
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Congratulations on your big day! I think the stars shine on your wedding
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Read noise reduces with increasing gain (you're amplifying the signal so the fixed read noise represents a smaller percentage) and dynamic range also reduces with increasing gain, so you're always is a trade-off. Jon Rista on cloudynights has put up a lot of information about CMOS chips (using the ZWO ASI1600) on read noise, gain, etc. I suspect the principles will apply to any CMOS though the read noise will be different.
![[WIP] NGC7000 North American Nebula and Pelican](http://content.invisioncic.com/g327141/monthly_2017_09/small.NGC7000_H_HT_LHT.jpg.93c78b3f175f41ef126c79a3d1c54458.jpg)
