16 replies to this topic

[hurj]

Hello folks

 

this is my 1st attemt on a galaxy, the M96, maybe I not chosed the easiest one:

 

 

(other than that my skills and experience on deep sky are very limited and for sure I don't have the right best equipment)

 

Capture equipment:

Celestron C6 + 0.63 FR

ASI585MC

ZWO UV/IR cut

SW EQ6R-Pro

 

Capture software:

PHD2: for guiding

ASI Studio: for capture images

 

Camera settings:

Bit depth: 16bit

Gain: 252

Exp: 120sec

108: lights

20: darks

100: bias

50: flats

 

Processing:

DeepSkyStacker: for staccking

Siril: for color and histogram

Gimp: for some denoise and color corrections

 

 

The result I obtained was very noisy, specially on blue channel, and the sky background was very bright  (I live in a Bortle 6 area, other than that I was on my backyard whrere I have some LED city lights at 30/40 meters from the scope).

 

Do u have some suggestions to improve the capture?

Wich kind of pollution filter is better to use?

About exposure time and gain: is better to have short exposure and higher gain or lower the gain and longer exposure?

 

 

please be kind

 

 

 

 

Edited by hurj, 16 January 2023 - 10:04 AM.

[hyiger]

Good first effort! I think the focus looks a little soft and there may be some over-sampling and guiding issues.

 

1. Do you have a Bahtinov mask? For a manual focuser this will be a big help.
2. Make sure to check collimation from time to time and adjust if needed but unless your scope gets banged around a lot it not really something you need to do frequently. On my SCT I always do a quick check before I start an imaging run. 
3. What camera did you use for guiding and how were your guiding numbers? With your setup the resolution per pixel is around 0.63". That means you need to be guiding below that which is not at all easy even on an well tuned and aligned EQ6. Try using 2x2 binning instead which will give you 1.26"/pixel and is much more forgiving in terms of guiding. 
4. Your focal length (with reducer) is around 945mm which is reasonably easy to work with but close to the limit where guide scopes get in your way and OAG's offer a better alternative. 
5. What did you use for polar alignment? The polar scope or an app? It's good to learn how to polar align with the polar scope. However, like driving a manual transmission, once you learn it you don't need it anymore (unless you enjoy it). My advice is to polar align with your camera and plate solve with NINA, Sharpcap or the ASIAir for example. Plate solving is much more accurate than manual alignment (my experience but others might disagree). 
6. Your camera is a great camera but is more appropriate for Solar System lucky image videos (planets, Moon, Sun etc) or doing EAA with live stacking. If you get into DSO seriously then you'll want to get a cooled camera with a larger sensor (budget permitting). 
7. For emission nebula you will greatly benefit from any of the various dual narrow-band filters. I really like the l-Ultimate. For broadband targets like galaxies and globulars the only filter you can really use with a color camera is an IR/UV filter which will cut down on star bloat (since your camera is sensitive to those wavelengths and thus they won't be in focus) The various light pollution filters really don't work in my opinion since most light sources these days are broadband LED and are not possible to filter out (as opposed to low pressure sodium or mercury vapor)
8. Take shorter subs (like 30-60s) in a light polluted environment. 
9. You can cut down on light pollution gradients in post processing. I'm not familiar with Siril but this is easy to do with AstroPixelProcessor or PixInsight. 
10. Light pollution can be mitigated somewhat by switching to mono but this can get expensive since you'll need at least 7 filters if you want to shoot the greatest range of targets. 

 

TL;DR; version:

1. Better focus
2. Check collimation
3. Use 2x2 binning for more accurate guiding, less oversampling and shorter subs
4. Use plate solving for polar alignment
5. Take shorter subs
6. Remove light pollution gradients in post-processing

Edited by hyiger, 16 January 2023 - 11:07 AM.

[hyiger]

If you haven't tried already, you can work with a larger broadband target like M33. With your setup it looks like you can just squeeze it in if you rotate the camera: https://astronomy.to...|1|0&messier=33

 

Edited by hyiger, 16 January 2023 - 11:27 AM.

[smiller]

Nice first Attempt at a galaxy.

 

Bortle six is actually dark enough to capture most galaxies.  You are using good settings from what I can tell.  Your gain is in the low read noise region and you don’t seem to be blowing out the stars so it seems like you’re doing OK there.

 

With such little read noise you can afford to take shorter exposures if you want depending on guiding accuracy so if you find you are getting sharper stars with 60 sec exposures or even 30 sec exposures, that would be fine with your camera at gain 252 in Bortle 6.

 

As has been already noted, not all galaxies are the same, some are actually quite a bit brighter and larger.  
 

M33 is huge but surface is not overly bright.

M81 is also fairly big and I think could be a larger and brighter target for you.

Later in the Spring M51 is very bright.

 

And finally a lot of the magic of getting a good galaxy, or any target, is in the processing. Consider getting a noise reduction algorithm such as NoiseXterminator.  This allows you to take out some of the remaining noise without losing details. You need an application that uses NoiseXterminator though.  Affinity Photo would be the cheapest option in that regard.

Edited by smiller, 16 January 2023 - 10:54 AM.

[hurj]

 

Good first effort! I think the focus looks a little soft and there may be some over-sampling and guiding issues.

 

1. Do you have a Bahtinov mask? For a manual focuser this will be a big help.
2. Make sure to check collimation from time to time and adjust if needed but unless your scope gets banged around a lot it not really something you need to do frequently. On my SCT I always do a quick check before I start an imaging run. 
3. What camera did you use for guiding and how were your guiding numbers? With your setup the resolution per pixel is around 0.63". That means you need to be guiding below that which is not at all easy even on an well tuned and aligned EQ6. Try using 2x2 binning instead which will give you 1.26"/pixel and is much more forgiving in terms of guiding. 
4. Your focal length (with reducer) is around 945mm which is reasonably easy to work with but close to the limit where guide scopes get in your way and OAG's offer a better alternative. 
5. What did you use for polar alignment? The polar scope or an app? It's good to learn how to polar align with the polar scope. However, like driving a manual transmission, once you learn it you don't need it anymore (unless you enjoy it). My advice is to polar align with your camera and plate solve with NINA, Sharpcap or the ASIAir for example. Plate solving is much more accurate than manual alignment (my experience but others might disagree). 
6. Your camera is a great camera but is more appropriate for Solar System lucky image videos (planets, Moon, Sun etc) or doing EAA with live stacking. If you get into DSO seriously then you'll want to get a cooled camera with a larger sensor (budget permitting). 
7. For emission nebula you will greatly benefit from any of the various dual narrow-band filters. I really like the l-Ultimate. For broadband targets like galaxies and globulars then the only filter you can really use with a color camera is an IR/UV filter which will cut down on star bloat (since your camera is sensitive to those wavelengths and thus they won't be in focus) The various light pollution filters really don't work in my opinion since most light sources these days are broadband LED and are not possible to filter out (as opposed to low pressure sodium or mercury vapor)
8. Take shorter subs (like 30-60s) in a light polluted environment. 
9. You can cut down on light pollution gradients in post processing. I'm not familiar with Siril but this is easy to do with AstroPixelProcessor or PixInsight. 

 

 

Thanks @hyiger

1. Yes i have it, but my mistake was to no check the focus time to time within the 4 hours

2. Collimation is quite accurate, I collimate in focus using metaguide.

3. The camera is an ASI120MC on a 60/240 (f4) SVBony guidescope, guiding nubers was not so great variing within 0.55 and 0.85 rms, dont know if because of ugly seeing, (then sonsider I have the EQ6-R from less than a moth, I was used to use an alt-az mount with wedge)

I will try your suggestion 2x2 binning or to add a barlow a 2x to the guidescope

4. yes, I'm considering an OAG, but will see in coming months, but I'm considering also to buy a scope more suited for DSO

5. Polar alignement done with TPPA plugin of Nina, but need to improve something as I never get consistent values, I means if I repeat the process azimut is quite stable (±10 arcsecs within the two attempts), altitude instead is always quite off (some times by ±1 / 2 arcminutes).

6. Yes, a cooled camera in in the list...  need to define the bujet ( ), in the meatime I will try to improve my-self with the DSLR for larger targets

7. 1st thing to do is to move to countryside location, to avoid at least very near light sources

8. Yes try to use short exposures will be my next attmpts

[hurj]

As has been already noted, not all galaxies are the same, some are actually quite a bit brighter and larger.  

 

M33 is huge but surface is not overly bright.

M81 is also fairly big and I think could be a larger and brighter target for you.

Later in the Spring M51 is very bright.

 

And finally a lot of the magic of getting a good galaxy, or any target, is in the processing. Consider getting a noise reduction algorithm such as NoiseXterminator.  This allows you to take out some of the remaining noise without losing details. You need an application that uses NoiseXterminator though.  Affinity Photo would be the cheapest option in that regard.

M33 is too low for me @this time of year, as i come back home very late, will try to do something on M81/51 on week end.

 

Thanks for suggesting me some filters/software  .

 

 

I feel it will take weeks/months of dedition to get something "decent"

[hyiger]

 

4. yes, I'm considering an OAG, but will see in coming months, but I'm considering also to buy a scope more suited for DSO

 

That's a good plan (scope more suited for DSO). I would recommend an 80mm class refractor or lower (if you want something portable). 

[hyiger]

M33 is too low for me @this time of year, as i come back home very late, will try to do something on M81/51 on week end.

 

Thanks for suggesting me some filters/software  .

 

 

I feel it will take weeks/months of dedition to get something "decent"

I've been doing it for a couple of years now and I'm still learning. I suppose it wouldn't have been as fun if it were too easy? Moving off of a SCT an onto a short focal length refractor made a huge improvement. Once I got comfortable with the refractor it was much easier later on to take I what I learned and use the much longer focal length (and less forgiving) SCT. 

[Sheridan]

Affinity photo is currently on sale for 40.99,  I purchased it this morning

[hurj]

I tried several approaches to improve the opening picture, but at the end the posted one is the better I can get with the data I collected.

 

I tried also PixInsight following some guide found here and there, obtaining some sharper results but at the cost to add a lot of noise.

 

 

If someone want, attached there's the stakked (as generated with DSS), i will appreciate to see how much better an experienced imager (not to hard to have more experience than me)

is able to extract from my data.

 

 

77megabytes file:

https://drive.google...?usp=share_link

 

 

thanks to everyone want try it

[revans]

Hello folks

 

this is my 1st attemt on a galaxy, the M96, maybe I not chosed the easiest one:

 

M96_PNG_FHD_JPG_rx.jpg

 

(other than that my skills and experience on deep sky are very limited and for sure I don't have the right best equipment)

 

Capture equipment:

Celestron C6 + 0.63 FR

ASI585MC

ZWO UV/IR cut

SW EQ6R-Pro

 

Capture software:

PHD2: for guiding

ASI Studio: for capture images

 

Camera settings:

Bit depth: 16bit

Gain: 252

Exp: 120sec

108: lights

20: darks

100: bias

50: flats

 

Processing:

DeepSkyStacker: for staccking

Siril: for color and histogram

Gimp: for some denoise and color corrections

 

 

The result I obtained was very noisy, specially on blue channel, and the sky background was very bright  (I live in a Bortle 6 area, other than that I was on my backyard whrere I have some LED city lights at 30/40 meters from the scope).

 

Do u have some suggestions to improve the capture?

Wich kind of pollution filter is better to use?

About exposure time and gain: is better to have short exposure and higher gain or lower the gain and longer exposure?

 

 

please be kind

Your focus is just a little bit soft.  I don't have an EAF so this also happens to me fairly often.  Lately I look at the stars magnified 3x or 5x in APT (Astrophotography Tools) to be very sure of my focus and even then it can drift off during a long imaging run, so frequent checking is needed if the temperature changes.  

 

But I think you have collected more data than your image shows.  I think you could get more detail in post-processing.  Siril has some good tools you can try, especially contrast-adaptive histogram equalization and wavelets.  Also, Asinh transformation.  Of these I find contrast-adaptive histogram equalization to be most useful, followed by wavelets.  I usually use 4 wavelets and it is surprising what adjusting the 4th one can produce for a result.

 

Rick

[rj144]

Super-quick edit:

 

 

I couldn't even finish... I need to use my computer to do some emergency work.

[rj144]

Nevermind... got a few more minutes on it:

 

[hurj]

Your focus is just a little bit soft.  I don't have an EAF so this also happens to me fairly often.  Lately I look at the stars magnified 3x or 5x in APT (Astrophotography Tools) to be very sure of my focus and even then it can drift off during a long imaging run, so frequent checking is needed if the temperature changes.  

 

But I think you have collected more data than your image shows.  I think you could get more detail in post-processing.  Siril has some good tools you can try, especially contrast-adaptive histogram equalization and wavelets.  Also, Asinh transformation.  Of these I find contrast-adaptive histogram equalization to be most useful, followed by wavelets.  I usually use 4 wavelets and it is surprising what adjusting the 4th one can produce for a result.

 

Rick

Thanks for your suggestions, I will try them on coming days.

 

 

Here below the result I got using PI, need to find a way to enhance the outer part of the spiral and reduce noise background

[VincenzoZito]

Hi,

Tips?
Check the focus every hour (two if the temperature variations are not high) and take more subs (unfortunately a SCT and very slow).

[hurj]

And this is probably the last attempt I'll try with this data:

 

 

 

Done with PixInsight: follwing this Guide from Alex McConahay as reference

[mayhem13]

Given your gear and exposure time, I think you did a fantastic job! I don’t see anything that indicates poor guiding or polar alignment. M96 is a pretty dim target so all I would suggest is more subs and more frequent confirmation and adjustment of focus.

 

There are some great threads here on SCT acclimation and cool down to review as well so you can be sure your c6 is ready when the shutter stars rolling.

 

You can also add a dew shield which will help with the lights close by……a rolled up black poster board and some rubber bands will do the trick.