Some help with processing(Andromeda)

[wimvb]

Here's my attempt. All 87 good lights were used, no darks. Processed in PixInsight.

Edited August 3, 2019 by wimvb

[Scooot]

9 hours ago, wimvb said:

Here's my attempt. All 87 good lights were used, no darks. Processed in PixInsight.

Good one Wim, did you rotate it & use canonbanding to remove the vertical noise?

[wimvb]

9 hours ago, Scooot said:

Good one Wim, did you rotate it & use canonbanding to remove the vertical noise?

Yes.

Started with cropping stacking edges off, then two passes of DBE. CanonBanding reduction (with rotations) followed by one more pass of DBE. CBR sometime creates an uneven background. An extra pass of DBE to flatten that out. Background Neutralisation and Photometric Colour Calibration. Noise reduction, then stretching.

[Scooot]

1 hour ago, wimvb said:

Yes.

Started with cropping stacking edges off, then two passes of DBE. CanonBanding reduction (with rotations) followed by one more pass of DBE. CBR sometime creates an uneven background. An extra pass of DBE to flatten that out. Background Neutralisation and Photometric Colour Calibration. Noise reduction, then stretching.

Thanks Win, I’m curious to know what settings you used for photometric colour calibration as I couldn’t get that to work , although I didn’t do background neutralisation first, I planned on letting PCC do it as well. 

Edited August 4, 2019 by Scooot

[wimvb]

Default settings. Did the process find an astrometric solution? You need to give it correct values for pixel size and focal length. I used a small preview near the bottom edge as background reference.

[Scooot]

1 minute ago, wimvb said:

Default settings. Did the process find an astrometric solution? You need to give it correct values for pixel size and focal length. I used a small preview near the bottom edge as background reference.

I didn’t know the correct focal length at the time but guessed 1000mm from the openers kit. I used astrometry.net for pixel size and coordinates so they should have been correct.

[wimvb]

I used astronomy tools from FLO's website. Canon 6D and sw 200p scope.

[Scooot]

1 hour ago, wimvb said:

I used astronomy tools from FLO's website. Canon 6D and sw 200p scope.

Strange that generates the same result as astrometry.net so it should have worked.

[msacco]

On 03/08/2019 at 09:56, wimvb said:

Regarding the banding:

They are a result of the camera read noise showing through, and indicate under exposure. If they also show in your calibrated darks, you could test stacking without darks altogether. Use cosmetic correction to remove excessive hot pixels. 

The CBR script will only remove horizontal bands. Quick rotate your image 90 degrees, use the script, turn back. If the bands aren't exactly horizontal, the script won't work properly. 

 

On 03/08/2019 at 21:59, wimvb said:

I've also downloaded your data set and am playing around with your image. Impressions so far:

• You have a full fram camera, and I'm not sure that the scope will illuminate the whole chip.
• Do you use a coma corrector? Even that would need to illuminate the whole chip. Vignetting can only be corrected up to a certain level.
• Calibration frames (darks, bias, flats) can never decrease the random noise in images. Only averaging during stacking can do that.
• The integration process is so slow because you have such large images (20 Mp). You can try increasing the memory settings in PI, but in all honestly, I don't think that will improve things much.
• Your unstretched master doesn't show any stars. This and the vertical banding are tell tale signs of under exposure. The bands are the read pattern of the sensor.

If you want to fully utilise the dynamic range of the camera, you need to increase the exposure time. At a dark site, even at ISO 1000, you should be able to use an exposure time of several minutes. A general rule for DSLR imaging is to have the peak of the histogram at 1/4 to 1/3 from the left edge of the display. But at a truly dark site, that may be impossible. You should at least have the brightest stars at full intensity. If you want to keep star colour even in the brightest stars, you can decrease the exposure somewhat once you've determined which exposure starts to blow out star cores.

Calibration images should be gray scale. Bias, darks and flats are never deBayered, because they correct the light frames pixel by pixel. If these calibration images were deBayered, their pixel values would change.

Thanks for the tips!

I'll reply to a few of the notes here:

I'm not using a coma corrector, thought about buying one, but I might be upgrading my gear in the following 2-3 months, so I'm not sure it's worth spending money on that.

You're saying that my images are large, is that not common for AP? Usually the average image size is smaller?

The issue with having longer exposure for me is that my gear is really far from being suitable for AP, I have skywatcher 200p with EQ5 goto, that is not an equipment that's used for AP usually, the DSLR gives more weight into the equation.

I believe the limited time I can use exposure for without my image being ruined is around 30 seconds~.

Maybe with my new gear there will be some improvements, I also need to invest into some kind of guidescope/something else that will help me get better tracking, but until then, I probably won't be able to use more than 30 seconds

Hopefully the new gear will give me the ability to get much better photos :]

Thanks.

 

On 04/08/2019 at 02:16, wimvb said:

Here's my attempt. All 87 good lights were used, no darks. Processed in PixInsight.

Wow! These are some amazing results! Can you try explaining a bit more about the CanonBanding reduction (with rotations)? The image looks really nice! And also there is so much less noise.

I'm so curious now  Also, you said that you didn't use the darks, did you use the bias or you used only the lights?

Edited August 5, 2019 by msacco

[wimvb]

You should definitely invest in a guide scope and camera. A finder guider with an ASI120 (mini) isn't that expensive, and should get you subs with more than a minute exposure time. Regardless which gear you have (other than very short fl camera lenses), guiding will allow you to gather more data / sub.

Yours is a 20 Mpixel camera with a 36 x24 mm sensor. Many dslrs have aps-c size sensors, and dedicated astro cameras may even have smaller (mine is 2.3 Mpixels). Smaller images (file size) means faster stacking.

4 hours ago, msacco said:

Maybe with my new gear there will be some improvements

What gear are you looking at? If it's another Newtonian, you will need a coma corrector. Especially with your large dslr sensor.

4 hours ago, msacco said:

Can you try explaining a bit more about the CanonBanding reduction (with rotations)? The image looks really nice! And also there is so much less noise.

CBR is really simple. The script was developed to remove read noise bands from Canon images. But it can clean up any image that has horizontal lines or bands. I use it at default settings with highlight protection activated. But it only works when the lines or bands are truly horizontal. If they are vertical you have to rotate the image (process>geometry>fastrotation) before you apply the script.

For noise reduction I used multiscale linear transforms kappa-sigma noise thresholding, with its built in linear mask (amplification 750). Use it before stretching, first on a preview to test it. I adjusted the kappa value such that the diffraction spikes in the very brightest star of your image kept their sharpness.

4 hours ago, msacco said:

I'm so curious now  Also, you said that you didn't use the darks, did you use the bias or you used only the lights?

Only lights and bias. I used the cosmetic correction function in batch preprocessor in stead of darks (with automatic detection activated).

[msacco]

21 hours ago, wimvb said:

You should definitely invest in a guide scope and camera. A finder guider with an ASI120 (mini) isn't that expensive, and should get you subs with more than a minute exposure time. Regardless which gear you have (other than very short fl camera lenses), guiding will allow you to gather more data / sub.

Yours is a 20 Mpixel camera with a 36 x24 mm sensor. Many dslrs have aps-c size sensors, and dedicated astro cameras may even have smaller (mine is 2.3 Mpixels). Smaller images (file size) means faster stacking.

What gear are you looking at? If it's another Newtonian, you will need a coma corrector. Especially with your large dslr sensor.

CBR is really simple. The script was developed to remove read noise bands from Canon images. But it can clean up any image that has horizontal lines or bands. I use it at default settings with highlight protection activated. But it only works when the lines or bands are truly horizontal. If they are vertical you have to rotate the image (process>geometry>fastrotation) before you apply the script.

For noise reduction I used multiscale linear transforms kappa-sigma noise thresholding, with its built in linear mask (amplification 750). Use it before stretching, first on a preview to test it. I adjusted the kappa value such that the diffraction spikes in the very brightest star of your image kept their sharpness.

Only lights and bias. I used the cosmetic correction function in batch preprocessor in stead of darks (with automatic detection activated).

I'm currently considering which camera for guiding I should get, the thing is I'm not really familiar with how good some equipment will be, and I don't really like buying something that I'll need to replace a few months later.

So the question is, will the ASI120 be sufficient as a guide camera? Obviously, the more I invest, I'll get a better camera, which will result in better tracking, but I'm not really into going too crazy as I have other things as well to consider.

Also, is there any way to install the camera onto the skywatcher 9x50 finderscope?

As for the image size, how much difference does the image size makes? Would scaling down the images harm the quality by much? Would you recommend doing that?

I'll probably get in 2-4 months a second hand CPC1100 + wedge + hyperstar, this will be used for both visually and astrophotography, so a coma corrector is not necessary here, and I'm not sure it's worth investing in that for only a few months, I might be thinking of getting a new AP camera later on, the color and cooled ASI294 seems like a decent choice between getting something decent and not spending fortunes on it I believe.

As for the CBR, I tried that, and that really did an amazing job! But I didn't manage to really get it through the whole image, I tried rotating, but left pretty much with a cross which received the CBR, and the rest of the image which remained the same.

Is there anything else I'm missing here?

Thanks a lot for the explanations!

[Danjc]

13 minutes ago, msacco said:

So the question is, will the ASI120 be sufficient as a guide camera?

 

13 minutes ago, msacco said:

Also, is there any way to install the camera onto the skywatcher 9x50 finderscope?

I’m guessing you are referring to the ASI120 Mini if so I find it fine and have managed 600s subs with that and the SW 9x50 finder. 

Im sure This is the adapter you require. It’s a tight fit so patience is key. 

[msacco]

4 minutes ago, Danjc said:

 

I’m guessing you are referring to the ASI120 Mini if so I find it fine and have managed 600s subs with that and the SW 9x50 finder. 

Im sure This is the adapter you require. It’s a tight fit so patience is key. 

Thanks! Since The shipping from that site is rather expensive, do you know where I can get it from aliexpress/ebay maybe?

Is this the correct item? https://www.aliexpress.com/item/32675339177.html?spm=a2g0o.productlist.0.0.153d484fd43Wle&algo_pvid=936beef2-28d0-495c-a204-bac8c7b6d42f&algo_expid=936beef2-28d0-495c-a204-bac8c7b6d42f-2&btsid=a05aacdc-3bb9-4682-87de-e81aeedebcd6&ws_ab_test=searchweb0_0,searchweb201602_7,searchweb201603_52

Maybe I'll get something a bit more reliable, but is this the correct direction?

Thanks

[Danjc]

4 minutes ago, msacco said:

Is this the correct

No it looks totally different !

[Danjc]

7 minutes ago, msacco said:

The shipping from that site is rather expensive

To be fair mate the P&P from FLO for that single item is only £1.95 so cheap as chips 👍🏻

[msacco]

3 minutes ago, Danjc said:

To be fair mate the P&P from FLO for that single item is only £1.95 so cheap as chips 👍🏻

Are you shipping to the correct place? It says £10 when I'm trying..

[Danjc]

Just now, msacco said:

Are you shipping to the correct place? It says £10 when I'm trying..

I’m assuming you are uk mainland ? If not then that’s probably why it’s more expensive. 

[msacco]

Just now, Danjc said:

I’m assuming you are uk mainland ? If not then that’s probably why it’s more expensive. 

I'm from Israel, that's why I said the shipping is really expensive 😕

Do you know if it's possible to find it any aliexpress/ebay?

[Danjc]

Ah fair enough.......I’m not sure mate I would just have a good old internet search. 

[msacco]

26 minutes ago, Danjc said:

Ah fair enough.......I’m not sure mate I would just have a good old internet search. 

Yeah tried that, but I can't really find anything related to "Sky-Watcher 9x50 Finder to C Adapter" on either aliexpress/ebay/amazon.

Guess I'll keep trying, or maybe look into a diy adapter.

Edited August 6, 2019 by msacco

[wimvb]

2 hours ago, msacco said:

So the question is, will the ASI120 be sufficient as a guide camera?

Many people use it as a guide camera. Either the standard, wide body version, or the new mini.

Do you have a local skywatcher representative? Maybe they can help with a camera adapter.

For a cpc1100 you should also consider an off axis guider. But beware of the hyperstar. From what I've heard and read, they can be a real challenge to set up. Any telescope system that is fast (lower F-number) will also be difficult to manage. Focus, squareness and collimation become much more critical if the system is faster.

2 hours ago, msacco said:

how much difference does the image size makes? Would scaling down the images harm the quality by much? Would you recommend doing that?

What is important is pixel scale; how large area of the sky falls on each pixel. For that you muliply pixel size in micrometer with 206 and divide by focal length in mm. For your current setup

6.54x206/1000 =1.35 arcseconds per pixel. If you decrease the "image size" by resampling, you will end up with a pixel scale of 2.7 arcsecs/pixel (combining 2x2 pixels into 1). You may start to lose detail in your image. If you want to have smaller files, but keep the level of detail, you need fewer pixels, or a smaller sensor. Eg, my camera has 1900x1200 pixels, 5.86 micrometer in size. The sensor is only about 11.6x7 mm, and file size is 4.6 Mbyte. But it also covers a much smaller area of the sky, while each pixel covers 1.17 arcsec, at 100 mm focal length. This means that the level of detail for your and my camera is almost the same, but my smaller sensor covers less area, and results in smaller files. Having a large sensor costs.

2 hours ago, msacco said:

But I didn't manage to really get it through the whole image, I tried rotating, but left pretty much with a cross which received the CBR, and the rest of the image which remained the same

That's strange, because the script  works on the entire image. I can post the Pixinsight  process container tomorrow, so you can have a look at how I did it.

[msacco]

4 hours ago, wimvb said:

Many people use it as a guide camera. Either the standard, wide body version, or the new mini.

Do you have a local skywatcher representative? Maybe they can help with a camera adapter.

For a cpc1100 you should also consider an off axis guider. But beware of the hyperstar. From what I've heard and read, they can be a real challenge to set up. Any telescope system that is fast (lower F-number) will also be difficult to manage. Focus, squareness and collimation become much more critical if the system is faster.

What is important is pixel scale; how large area of the sky falls on each pixel. For that you muliply pixel size in micrometer with 206 and divide by focal length in mm. For your current setup

6.54x206/1000 =1.35 arcseconds per pixel. If you decrease the "image size" by resampling, you will end up with a pixel scale of 2.7 arcsecs/pixel (combining 2x2 pixels into 1). You may start to lose detail in your image. If you want to have smaller files, but keep the level of detail, you need fewer pixels, or a smaller sensor. Eg, my camera has 1900x1200 pixels, 5.86 micrometer in size. The sensor is only about 11.6x7 mm, and file size is 4.6 Mbyte. But it also covers a much smaller area of the sky, while each pixel covers 1.17 arcsec, at 100 mm focal length. This means that the level of detail for your and my camera is almost the same, but my smaller sensor covers less area, and results in smaller files. Having a large sensor costs.

That's strange, because the script  works on the entire image. I can post the Pixinsight  process container tomorrow, so you can have a look at how I did it.

There are only 2 telescope shops total, and they're both extremely expensive, so they probably won't be able to help me, I'm still thinking between a guidescope and an OAG. With my current set up I don't think getting an OAG is even possible because of the extra weight, but with the CPC1100 and wedge I could probably easily achieve that, so maybe it's worth investing into that, on the one hand I want to get as much things as I can that will also be relevant to the new gear, so I will be able to take it up to its full potential, but on the other hand I'm still not 100% sure exactly what I'd need etc until I actually receive it, kinda confusing.

I believe the CPC1100 will be very challenging for me at the beginning, and I might get frustrated at first. But I know that I'll be able to learn and overcome it with time

If you could post the process container that would be really useful, as for me that didn't really go well for a reason, at least not to the whole image. ^^

Thanks!

[wimvb]

Here is the PixInsight process container

msacco_m31.xpsm

[msacco]

10 hours ago, wimvb said:

Here is the PixInsight process container

msacco_m31.xpsm 242.28 kB · 1 download

When I'm trying to open it I'm getting this:

What does that mean exactly?

[wimvb]

It means that you haven't installed the arcsinh stretch module. I can repost the prkcess without it. But you should consider installing arcsinh stretch, it's really great.

https://www.cloudynights.com/topic/569440-pixinsight-arcsinh-stretch/

Or the pixinsight forum