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I am trying to determine why my images are "soft". I've never been able to finish with a nice clear and sharp image. It's either one or a combination of seeing, equipment, processing. I'm leaning more towards equipment, telescope specifically. Considering a .8 flatenner reducer, down to f/4.8.  The Wizard Nebula SH2-142 Bortle 7-8 Astrotech 60ed 360x60mm f/6 doublet zwo 533mc pro 100 gain 35 offset 180 sec total of 9.5 hours L extreme filter Dark,flat,bias Processed in Siril (based off of Deep Space Astro yourube) Graxpert for background extraction and noise reduction Starnet ++ star processing |
7.22
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IMO, that sharpness looks normal for processing with Siril you need BlurXterminator, but it's a tool you can only get for Pixinisight also, if you're not already using it, an EAF would (generally) give you better focus than a bahtinov mask, so make sure you use one |
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Have not pulled the trigger on PI yet. An AEF is one of my next purchaspurchases. thanks |
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7.22
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Keith Belzner: you wont regret it it was one of the best astro purchases I made in the last 2 years CS |
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Agree with all of the previous posts. An EAF outperforms a B Mask. I tested when I went from a B Mask to an EAF. A software like NINA, SGP, Sharpcap that will autofocus will be first on the list. I image at 384mm an use a autoguider. A small 30mm SBony and a 120mini would do the trick with PHD2 What mount? Nina is Free, PHD2 is free, Eqmod, ascom, all free. You have to pay for your hardware on your Rig. But image processing is as important to making your data look good as in focus, round stars are for integration. PI with the BXT, SXT, NXT with Photoshop can and will get you further along your journey to an image result that meets your expectations. Sorry in advance if I sounded "preachy". I hate giving advice on telling good people how and what to spend money on… CS Tim |
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There is another alternative to an EAF or a Bahtinov mask and that is to focus using HFR measurements from looped short focus exposures. That is essentially what an EAF will also do, now you just do it manually. HFR measurement focus is in my opinion much better than a B.mask focus, since nothing is open to interpretation unlike with the diffraction pattern of the mask. I focus manually like this with NINA and 3s exposures. Takes a bit of practice but you will get to the best focus point like this and can save some money on not getting the EAF. |
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Agree with the other comments. BXT is going to be the best solution here if that is in your budget. And an EAF if you don't already have one. Otherwise, this really isn't bad. If you have Photoshop, you can look into the APF-R plugin (https://www.youtube.com/watch?v=3sG_aJo-Ww8) I usually run my EAF to refocus every hour in normal conditions (I'm in the southeastern US, so temperatures don't usually drop quickly). If it's dry and the temperature is going to drop faster, I'll run it every 30 min. Another thing to keep in mind is you're using a short focal length scope with a small aperture. This is going to ultimately limit your resolution, so there is a little bit of managing expectations as well. |
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Tim Ray: I'm using the Skywatcher star adventurer, ra guiding only. I use Sharpcap for polar alignment, Nina for image capture/ plate solving / target acquisition and phd2 for guiding with 120mm guide cam. |
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Oskari Nikkinen: I did look at it before but I wasn't sure how to use it. I might look into it again. |
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IMO, that sharpness looks normal for processing with Siril I think that you need some level of oversampling to get the best out of Blur Exterminator-- the sampling looks too low here and the image scale too great with 6 arcsec/ pixel to get sharp detail? The key problem may be that the image is undersampled ? If seeing is 'normal' at say 3 arc sec then at least 2 arc/ pixel would be needed to sample it near adequately. The 360 mm f and ASI 533 setup should deliver that but the picture posted here is apparently at 6?! Was that because of binning? Even at 2 arcsec/pixel there would surely be too little information for BlurXt to be able to provide much sharpening ? If you integer downscale a fairly sharp image of the wizard at 0.9 arcsec/ pixel to about 6 it starts to look really quite soft as here   |
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Keith Belzner:Oskari Nikkinen: You only need to toggle on the star detection and analysis thing in the image capture screen. With that on NINA will measure the HFR of your stars, and your goal with focusing is to get the value as low as possible. When you reach the lowest value, you're in focus. The thing that requires a bit of practice is just knowing what kind of HFR to expect with your kit. Use your kit enough and you have a pretty good idea, and know what kind of value to target so there is less guesswork involved. Seeing will effect this quite heavily, but the goal is always the same: The lowest value that night can give. NINA will also draw a nice plot of your subs, so you can monitor your focus. If you see the HFR of your subs increase after some time its time to re-focus, you should expect to do this at least a couple of times in the first one or two hours of imaging just due to temperature changes. |
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Your pixel scale is horrendously undersampled at 6 arcseconds per pixel. The reason for that is that you are using 3xbinning. That makes your pixel size effectively 11.28 micrometers and divides your resolution by three. I'm sure you've done it by accident. My advice would be to immediately turn it off. |
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Nooa Jutila: I have gone through all of my settings and I don't see where the issue is. Running Nina, it's set on bin 1x1. I've never made any changes to the camera side, that I know of. do you know of a setting in siril that may be doing something on the processing end? Edit: I figured it out, I had reduced the image size when i downloaded it to my cellphone then to Astrobin. The original image is 2447x2447 @ 2.92 MP |
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The answer is everything! The atmosphere, optical quality, sampling, focus, guiding, exposure time, stacking and processing. That perfect image in the sky has to go through a stack of low pass filters, all stealing the high frequency detail you are looking for so the answer is, you need to optimize all of these filters as much as you can to get as much sharpness as possible. In most setups, there isn't a single answer but a lot of little ones that will solve your problem. PLEASE don't try to spend your way out of it because until you are confident that you have tuned everything as best you can, it probably won't make any difference. |
