[RCC] M81 - first Image ever Requests for constructive critique · Hermann Pais · ... · 10 · 328 · 1

hpais 0.90
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Hi,

I am a beginner, and this is the first image I was able to collect, process and I'd like to hear your feedback.

Location: Issaquah, WA, USA - Bottle 6 sky - front porch of my house.
Lights - 30 images @ 120 sec
Flats - 10 @ 0.8 sec
Flat Darks - 10 @ 120 sec 

Main Camera: ASI533MC (no filters)
Scope: Askar FRA300 [300mm f5]

Guide Camera: ASI715MC

Guidescope: ZWO 120mm
Mount: Skywatcher Adventurer GTi
Power: ELB500W
ASIAIR Plus 256GB 

Processed 100% with PixInsight using Lukomatico's Workflow for beginners... https://youtu.be/YcR...iZPGRCYLpnafMQ6

1. Weighted Batch Preprocessing
2. STF stretch
3. Blur Xterminator - correct only
4. SPCC with all defaults
5. Blur Xterminator - reset tool and apply defaults (=Sharpen)
6. GradientCorrection
7. Star Xterminator 

Starless processing:
8. Background Neutralization
9. Noise Xterminator
10. Stretch - used STF to feed Histogram Tool. Then used Curves Transformation to fine tune RGB, then Saturation, then Hue (shifted towards red) 

Stars processing:
10. Stretch - used only the Curves transformation to get some natural colors and limit number of stars 

11. combine ( M81, M81_stars, op_screen())M81_processed_small.jpg
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dkamen 6.89
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Looks a bit on the green side of things and your focusing could be a little tighter, otherwise pretty neat for this amount of data.
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Zeb 0.00
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The .JPG is compressing too much and artefacting too much for me to give feedback on your process - can't see any detail! Try and save the picture at ~97% quality in GIMP or something of equal result.

The picture looks like it has nice quality underneath all that JPG'ing, though!
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siovene
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Zeb Németh:
The .JPG is compressing too much and artefacting too much for me to give feedback on your process


If only there was a website that allowed uploading astrophotographs without compression 😉
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AstroDan500 4.67
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For 1 hour it looks fine. You need about 10 times that much at least.
It's hard to shoot without a filter in Bortle 6,  you did pretty well getting what you did.
Spend some money and get a filter and put in more time and you are on your way.
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skybob727 6.08
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Considering this is your very first image ever taken and processed, I think it's pretty darn good. Wait tell you get the hang of processing
and getting use to what exposures you can get and need for the object you go for.
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ntphey 1.81
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Congratulations on your first image and welcome down the rabbit hole! 

I haven't seen the link provided, but I would suggest changing the sequence of your processing, based on RCAstro's documentation and that of some PI processes.  My recommendations would be to do GradientCorrection, followed by SPCC, then BXT, then SXT if used, instead of the sequence you have. Also, given that you have done SPCC, you shouldn't need to repeat a background neutralization on your starless image, I would't think. 

It is my understanding that the 533MC needs a uv-ir filter to work best--prevents bloating of star images. You can spend money on all kinds of other filters, but good luck finding one that will cut down on light you don't want and not the light you do want! The best way to combat light pollution is collecting more total photons and then correcting the gradients. Save the money for something else is my advice and that of many others. Maybe spend it on a dual band filter and shoot emission nebulae with it, or use it as a source of H-alpha data to merge with your RGB data. Use only one filter at a time, depending on your target and intentions. 

There are two books well worth having. Warren Keller's Inside PixInsight and Charles Brcken's Deep Sky Imaging Primer.  Free help on YouTube is great, but you know, sometimes you get what you pay for. In the case of these books, you get far more than what they cost.
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AstroTrucker 6.05
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Much better than my first image! Congradulations!

CC:
after WBPP and STF, do a crop of your master image. WBPP in stacking and aligning your subs to each other has to slightly move each one to align with the rest. In doing that the edges of your final "MasterLight..." image will have edges that need to be trimmed off. Use the expanded STF to bring this out and help with the crop... After that do your GC or DBE to remove gradients. Then pickup your work-flow at BTX (Correct only), SPCC. (After SPCC hit the lock on STF and reapply STF), BTX, 
Find EZ Processing Suite for PI on the Internet. Perform a "Soft Stretch" converting linear to non-linear
NXT
SXT
on the starless image: add a little saturation to bring out the colors - if you have a green tint to your image do a scnr to remove it, curves, sharpen to taste
I sometimes add a little saturation on the stars image but that is to personal taste...

Recombine stars and starless image in Pixel Math with the following ~((~stars)*(~starless)), uncheck rescale and use create new image.

You always want to remove the gradients early in your work-flow
This is just a few tweaks to yours. 

CS Tim
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AstroTrucker 6.05
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Also forgot to mention your calibration frames.  

Dim your light source and increase your flats to 3 to 5 sec. each. I do 25 flats
Flat-Darks should be exactly the same as your flats (3 to 5sec each). I do 25 flat-darks
Since you are capturing flat-darks, do not use Bias frames when you use a CMOS camera... Use Bias Frames if not doing Flat-Darks. If you use Flat-Darks and Bias Frames you are basically subtracting the Bias Frame twice in the calibration process.
Darks frames should be the same as your Light subs in length. in your example 120secs each (I do 25 Darks - A pre-taken MasterDark from my MasterDark Library)

I made a Master Dark Frame Library for each of my cameras. I image at 0 or -10 degrees C. I took 25 darks at 30,60,90,120... to 300sec. Then made a MasterDark for each set of 25 Darks Frames for each exposure and temp and gain setting.  I image with the camera at gains 0, unity gain or 200 for NB imaging. I just grab one of these files for WBPP and don't take Dark frames as part of my sequence. Do take Flat-Darks. your flat frames vary in duration and the really don't take to long to capture...

CS

Tim
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hpais 0.90
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Wow. This is awesome feedback. 

thank you so much for taking the time to review my image and write your feedback. 

Norman, I have one of the books (Primer) and I’ll get the second one this week. 

Tim, thanks for the detailed response on flats and darks. I confess I’m confused by the nomenclature and your detailed answer helped bring clarity to this. I really need to make a table for my self of all the calibration images, times and settings to build my master calibration library. That’s a great idea. 

Bib, Dan, Salvatore, Dkamen thank you as well. This is great feedback and ill
indeed upgrade to where I can upload uncompressed images. 

thank you for the words of encouragement. Have an awesome Sunday. 

equinox is in two days.
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AstroTrucker 6.05
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Just a little clarification.

My MasterDark library only has MasterDarks.  All Flat Frames, and Flat-Dark Frames are taken in real-time with the Light Frames. The MasterDark Frame basically calibrates the "Noise" from the sensor created during the Light Frame capture. The Flat Frames calibrate out the effects of the telescope and optical system... (Vignetting, dust moats, etc..) The Flat-Darks calibrate out the sensor noise of the Flat Frame since your Flat Frame is technically a "Light" frame.

So always capture Flats and Flat-Darks each night or after rotating the camera or a filter change....  Basically any time you change something. I take these frames every session I image and I have an Observatory where nothing changes from night to night except the Date...

A good recipe for success in this hobby is to have a detailed and consistent  work-flow on data-acquisition. I just published a revision to an image I collected data on  and posted the original 4 years ago. The workflow in image processing has changed tremendously during that time. However, A well calibrated MasterLight frame with in-focus, round stars never goes out of fashion...

CS Tim
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