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Looking for advice to improve images

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#1 adamsdp

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Posted 06 December 2021 - 01:10 PM

I am a beginner who is interested in taking the next steps to improve upon the images I have been getting with my EAA setup - C6/f6.7 reducer/ZWO filter wheel/ASI 533 camera/ASIAir pro/Celestron Evolution mount.  I took the image below recently.   10 sec subs, 20 frames, gain 100, Optolong UHC filter, Bortle 7 skies

 

It was hazy with a thin cloud layer but even without the clouds, there is a lot of room for improvement compared to images I have seen with similar or same equipment and conditions.  I am planning to incorporate dark and flat frames and wanted to ask which of the non-light frames make the biggest gains in image quality in case I incorporate one type at a time.  Are some types of non-light frames that with my equipment would make only a small improvement and might not be worth doing?  Any general advice will also be greatly appreciated.  Thank you!

 

 

M31

IMG_0803.JPG


Edited by adamsdp, 07 December 2021 - 10:27 AM.


#2 John Miele

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Posted 06 December 2021 - 01:47 PM

Do you mean you want better real time views on your laptop or do you want better images to post and share?

 

If you are after the latter, I would advise you to move to the AP side of the house and start learning in the BDSI forum. It looks like you have the gear to produce some very nice AP.

 

Apologies if I have your intent wrong...

 

cs...John


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#3 alphatripleplus

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Posted 06 December 2021 - 01:48 PM

I don't have a 533MC, but from what I understand if you are using the camera cooled the sensor is very clean with little or no amp glow and few hot pixels. If that is the case, dark frames may not help much with that camera. If you have vignetting with your set-up, flat frames will help to remove it. 


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#4 Medic002

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Posted 06 December 2021 - 01:50 PM

Hi Adam with the 533 u can go without calibration frames if imaged properly but most use it anyway. I would start with the flat frames if ur going to start with only one to get rid of dust motes. Darks and bias are easier to do and reduce noise and so forth so make sure to watch plenty of youtube videos of how to make these. The 533mc-p cooled camera if this is the one ur using standard unity gain setting is 100 and what I normally use. I would try taking longer exposures also maybe 120-180 seconds and try shooting for at least an hour or two minimum to get enough data to help reduce the noise to image ratio. The more lights u can stack into the final image the less noise you have usually but not always. Some pictures are just not going to always work everytime. A uv/ir filter is a good start also. I am not sure if the optolong uhc has that or not but if it does not make sure u get one because the 533 does not have one built in. I bought a fairly inexpensive one for less than 50 bucks and works great for me on galaxies and globular clusters. An easy way to process final image once stacked is lightroom but the more experienced imagers use several more complicated and pricey programs.


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#5 alphatripleplus

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Posted 06 December 2021 - 01:53 PM

 An easy way to process final image once stacked is lightroom but the more experienced imagers use several more complicated and pricey programs.

Yes, if the OP is going to do AP that is fine. However, for EAA,  post-processing with LightRoom is beyond the scope of this forum.


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#6 adamsdp

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Posted 06 December 2021 - 02:33 PM

Thanks for the replies and I am interested in near real time views on an Ipad.  I do have the 533mc-p so sounds like I won't get huge gains from the calibration frames.  The image I posted is so much dimmer than what I see others posting using EAA setups.  I have the Evolution alt-az mount so not sure how much this will limit my sub frame exposure time.  I tried going to 30 seconds but the stars were elongated in a curved fashion so I was thinking it was too long for an alt-az setup.  I built the system with the Starizona night owl f/4 reducer in place of the C f/6.7 reducer but it has been on backorder so still waiting for it to come in.  Maybe the f/4 reducer would help but still not sure why the image of m31 is so dim relative to others I have seen.  I have the Optolong uv/ir filter and use that on star fields.  For the image posted, I had the Optolong UHC in place.  



#7 bips3453

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Posted 06 December 2021 - 03:06 PM

How are the images stacked? Is the stacked image stretched? i.e. Did you adjust black level point and mid level points in the histogram? 


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#8 jcheak

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Posted 06 December 2021 - 03:10 PM

Open the histogram with the plus symbol to the right of the chart, Play with the sliders to stretch the image more. Typically move the left most slidder to the top of the curve then slide the mid to the left to get more detail. As always play around with them to get the best picture.


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#9 nic35

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Posted 06 December 2021 - 03:12 PM

Dave  

 

I'm not an asiair user, so I'm not sure how to do the following on that system (I use sharpcap).  But I would

 

Crank the gain up to around 350.  Low level gain is most commonly used for conventional AP.  For EAA, much higher gains get used. Play around with the gain.

 

Stretch the histogram.  By playing with the black, white and intermediate levels you can fine tune the image to get a better balance between dark background, detail in faint fuzzies, etc.  Again, I'm not sure how to do on the ASIair - and the manual makes no mention of a histogram.

 

Try it without the UHC filter.  I'm in between Bortle 6 and 7 and sometimes use it, sometimes do not. 

 

A UV/IR will lessen star bloat. People are undecided if they are useful for SCT scopes.  Not needed for newtonians and other pure reflectors.

   

Do you have something besides the tiny thumbnail like image you posted ?  You can try stretching the image histogram in GIMP.  The freeware version of photoshop.

 

john


Edited by nic35, 06 December 2021 - 03:16 PM.

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#10 GaryShaw

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Posted 06 December 2021 - 03:43 PM

Hi

If you’re drawn to the long exposure approach mentioned in Post 4 above, then you should probably consider moving to AP and focus on building your photographic skills. AP is all about the images whereas EAA is all about ‘real time’, ‘live’ observing and learning about the object. When you get into individual exposures longer than15-20 seconds, you’re entering AP territory in my view. 
 

I’ll often observe and/or sketch an object for 20-30 minutes while watching its details build up gradually with each 8-15 second exposure adding to the stack. I often open a browser and read about the object as the stacking is going on as well. In a way, the camera is just replacing the eyepiece to allow us to see what light pollution increasingly hides from us when observing visually. Darks are super easy to do - especially if you use an opaque filter in your filter wheel. Flats are more of a pain but might help your images more since you seem to have a lower noise camera. Good luck and enjoy!
Gary


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#11 BrentKnight

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Posted 06 December 2021 - 03:59 PM

I have the 533MCP and I found with my refractor that I still needed darks.  There were way too many hot pixels for my liking.  And often if I didn't dither I got a lot of walking noise.  Both of these will really mess up an otherwise nice image.  Using the same camera on my C8, I found I got a lot of vignetting and so flats and dark-flats were the way to go.  Once I learned how to do flats for the C8, it was pretty easy to add that step to the refractor setup.

 

If all you are interested in though is short exposures and just detecting the target, then these may not be necessary.  I do longer live stacks because I like a better image and so these extra steps are worth the effort for me...


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#12 adamsdp

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Posted 06 December 2021 - 04:05 PM

I stacked the images in the live option of the Asiair app.  I adjusted the black and mid levels in the histogram to get the best image and the result is what is in the original post.  I will try adjusting the gain and see if that helps.  I did a preview of one frame, with the gain set to high=350 and the image looked like it had a lot of noise?  Maybe this would be averaged out in the stacking process.  I am not drawn to long exposures and want to keep it as close to "live" as possible.  I have imaged with no filter, uv/ir and uhc without noticing huge differences yet.  Thanks for the help!



#13 steveincolo

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Posted 06 December 2021 - 04:16 PM

I have the 533MCP and I found with my refractor that I still needed darks.  There were way too many hot pixels for my liking.  And often if I didn't dither I got a lot of walking noise.  Both of these will really mess up an otherwise nice image.  Using the same camera on my C8, I found I got a lot of vignetting and so flats and dark-flats were the way to go.  Once I learned how to do flats for the C8, it was pretty easy to add that step to the refractor setup.

 

If all you are interested in though is short exposures and just detecting the target, then these may not be necessary.  I do longer live stacks because I like a better image and so these extra steps are worth the effort for me...

Same experience here with hot pixels and darks on the ASI533MC.  Flats aren’t too hard to do on the ASIAIR.  Scroll down through all the exposure times until you get to “Auto.”  You can park the scope using the ASIAIR as well for flats without losing position info.  


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#14 aiken999

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Posted 06 December 2021 - 04:44 PM

I would agree with Nic35 crank up the gain and try longer exposures stretch the image. The evolution mount can probably do 30 seconds depending on sky location, not much more. If you can give Sharpcap a try You can really work the histogram to get a viewable image. I have the asiair and find the images softer than using Sharpcap. I have trouble getting an equivalent image with asiair. Love the convenience and features of the ASIair. Not AP quality of course but thats not the purpose of EAA. Just my opinion. 


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#15 azcubs76

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Posted 06 December 2021 - 06:39 PM

I was having similar issues with a C8 @ F6.3 although with an asi294mc. In my case everything got a million times better when I started taking flats. Gain 100 is probably too low for EAA, I mostly use 300-500 with 4-12sec subs. The initial sub will look really noisy but the noise will go away as you stack. I always do darks as well as it's so easy and I get quite a few colored "streaks" if I don't. 

 

I will also say that I've never gotten a great Andromeda pic with EAA although more detail than what you are showing here. I think we've all been biased by the multitude of awesome pics you see of it that you expect more. If you look at the details though most of the nice pics are on a RASA/Hyperstar or have an hour or more total exposure time.

 

I find the Orion Nebula to be a great target for getting things dialed in as it's big, bright and colorful.


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#16 roelb

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Posted 06 December 2021 - 08:51 PM

Forget about darks/flats

Forget about filters

use higher gain: 350

use SharpCap



#17 dswtan

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Posted 06 December 2021 - 09:59 PM

This has been mentioned above, but I believe the OP is simply showing an image that has not been stretched. It’s critical to stretch! 
 

I haven’t used ASIAIR in a while, but I believe the auto stretch is the big green “Auto” button at bottom left of the histogram screen - see towards the end of the screenshots (with other useful tips) here: https://astronomy-im...avid-parks.html



#18 steveincolo

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Posted 06 December 2021 - 11:22 PM

This has been mentioned above, but I believe the OP is simply showing an image that has not been stretched. It’s critical to stretch! 
 

I haven’t used ASIAIR in a while, but I believe the auto stretch is the big green “Auto” button at bottom left of the histogram screen - see towards the end of the screenshots (with other useful tips) here: https://astronomy-im...avid-parks.html

The OP said he stretched the image.  But you could still be on to something.  The “save” button in ASIAIR Live view saves a JPEG that’s been stretched, but it also saves a FIT that hasn’t been.  So we could be seeing the FIT. 


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#19 Noah4x4

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Posted 07 December 2021 - 04:56 AM

+1 for John and Roelbs advice.

 

I could never get my head around appropriate Gain and Exposure levels until I discovered the Brain and Smart Histogram features in SharpCap. I realise ASIAir doesn’t have these features, so crank up the Gain until you get it right by trial and error, but others with this same camera should offer some clues. 350 Gain is probably about right. 



#20 alphatripleplus

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Posted 07 December 2021 - 08:10 AM

  I took the image below recently.   10 sec subs, 20 frames, gain 100, Optolong UHC filter, Bortle 7 skies

 

 

What is the target in the image? 

 

Edit: Thanks I see it is M31.


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#21 adamsdp

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Posted 07 December 2021 - 09:19 AM

I will try cranking up the gain and longer exposures as suggested to brighten the image.  I may give Sharpcap a try down the road after learning how to better use the ASIAir.  I had a phone consult with one of the tech reps from where I bought the camera and he also suggested increasing the gain to 350 and increasing the exposure time to as long as the mount will handle without the stars getting out of round.  He also thought adding darks may be helpful since the higher gain setting will have more noise as well as adding a dew shield to limit stray light from street lights, etc.  The night I took the posted image, I did a preview of m31 at the high gain setting and the image didn't look as good as the individual frame at 100 gain, but now realize that after stacking the higher gain frames would have the noise averaged out so likely would have had a better final image.  Looking forward to trying these ideas out.  Thanks!


Edited by adamsdp, 07 December 2021 - 09:25 AM.

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#22 GoFish

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Posted 07 December 2021 - 09:36 AM

I rarely use flats for EAA (I find them to be a PITA), and I’m mostly content with my images.

 

But vignetting and dust become very distracting when doing heavy stretches on dim targets, especially in LP skies. My suggestion, if better images is the goal, is to use flats and do more aggressive stretching. 

 

I also use a cooled camera and am not too bothered by a few hot pixels and a little amp glow. So even though darks are really simple to incorporate, I usually don’t bother. 


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#23 BrentKnight

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Posted 07 December 2021 - 10:11 AM

I will try cranking up the gain and longer exposures as suggested to brighten the image.  I may give Sharpcap a try down the road after learning how to better use the ASIAir.  I had a phone consult with one of the tech reps from where I bought the camera and he also suggested increasing the gain to 350 and increasing the exposure time to as long as the mount will handle without the stars getting out of round.  He also thought adding darks may be helpful since the higher gain setting will have more noise as well as adding a dew shield to limit stray light from street lights, etc.  The night I took the posted image, I did a preview of m31 at the high gain setting and the image didn't look as good as the individual frame at 100 gain, but now realize that after stacking the higher gain frames would have the noise averaged out so likely would have had a better final image.  Looking forward to trying these ideas out.  Thanks!

If you are using the ASIair, then the gain that people mention for SharpCap is not the same gain given by the AA.  I'm not at my setup, but I believe the scale goes from "0" to "400" for the 533MCP (please correct me if I'm off on these numbers).  Gain "0" should be unity which equals "100" in SharpCap, so 100 - 200 on the AA is higher.  I don't know of a calibration scale that equates these gains to each other...you may just need to play around with them.  I usually use 100 to 200, but I'll try bumping it even higher next time I get a session.


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#24 BrentKnight

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Posted 07 December 2021 - 10:16 AM

I rarely use flats for EAA (I find them to be a PITA), and I’m mostly content with my images.

 

But vignetting and dust become very distracting when doing heavy stretches on dim targets, especially in LP skies. My suggestion, if better images is the goal, is to use flats and do more aggressive stretching. 

 

I also use a cooled camera and am not too bothered by a few hot pixels and a little amp glow. So even though darks are really simple to incorporate, I usually don’t bother. 

I guess it really matters where the hot pixels show up in the image.  When I did an image of Stephan's Quintet, I got about 10 little red dots right in the middle of the group.  Had they been farther away, it probably wouldn't have bothered me much either...


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#25 GoFish

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Posted 07 December 2021 - 10:29 AM

I guess it really matters where the hot pixels show up in the image.  When I did an image of Stephan's Quintet, I got about 10 little red dots right in the middle of the group.  Had they been farther away, it probably wouldn't have bothered me much either...

Where I grew up they’d call that “buzzard’s luck” lol.gif


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