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M101 the Pinwheel Galaxy...finally.

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#1 ttnova

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Posted 01 June 2020 - 12:48 PM

I've tried to image the Pinwheel Galaxy before but never had anything worth keeping but last night with my new ZWO camera and good focus and polar alignment and light pollution filter and tracking I was finally able to get what I consider a decent image (for me). It feels so good to finally be able to get this target.

 

It was windy again but with no clouds and decent seeing I wasn't going to not pull out the scope again. I got around 30 x 300 second subs. The camera was cooled to -15C. 

 

I was hoping I could get some advice on color. With the trifid I was able to pull some red out but the pinwheel looks very monochromatic. I use photoshop (I'm an artist by trade so I'm scared of pixinsight). Do I need more time on the object to get some color out of it? Should I bin 2x2 instead of 1x1? Are the color images I see done with mono cameras and filters? I don't want anything crazy but some color/hue variation would be great. I'm posting a dropbox link to my TIF and hoping someone with more skill and experience could give me some tips or at least show me the potential or let me know that the color just isn't there. 

 

Thanks again. Clear skies. 

gallery_242599_5209_246391_mod.jpg

 

dropbox link:

https://www.dropbox....RoGjBGemTa?dl=0


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#2 Huangdi

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Posted 01 June 2020 - 01:26 PM

There definitely is some color. However there are some ugly gradients and the colors in general, are off. There also is some strong banding, not sure where that comes from.

 

I suggest you sell whatever light pollution filter you have ASAP and never touch one again. I rarely ever see people benefit from them. 

 

You also didn't take flats it seems, I recommend you do that. The image appears to have a lot of hot pixels as well.

 

I would highly recommend for you to try out AstroPixelProcessor for stacking your images and correcting for gradients/light pollution and calibrating your star colors, it makes it a lot easier.

 

I took a stab at your image and besides the deficiencies I mentioned, your image actually is nice. Stars are round and you have some great detail, just be sure to add at least 5-10 hours of exposure to it, then processing will become much easier.

 

A small note: This was a quick 5 minute process of your image, I didn't try to deliver a clean or crisp result, I merely wanted to show you that there is color in the image!

Attached Thumbnails

  • cn m101.jpg

Edited by Huangdi, 01 June 2020 - 01:27 PM.

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#3 F.Meiresonne

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Posted 01 June 2020 - 02:37 PM

Color or not, i find it a great image. Personaly i would put it a tiny bit to the blue but that is personal.

 

Myself i don't see much gradients (in my photo's there are) and banding i don't see it either...maybe my 60 year old eyes are desceiving me shrug.gif

 

see below, really should try to rework that...

Attached Thumbnails

  • M108_21 (Large).jpg

Edited by F.Meiresonne, 01 June 2020 - 03:10 PM.

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#4 ttnova

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Posted 01 June 2020 - 02:44 PM

@Huangdi thank you. That looks great! Just what I'd love to be able to achieve and amazing this was a quick job for you. It gives me hope and something to shoot for. I'm glad that the image in general seemed like it was a good start. I will begin taking flats (never had good enough data to need them). I will also look into AstroPixelProcessor. I will also try without the light pollution filter (I'm in NJ 20 miles from New York City so it can be bad). And more time imaging this target.

 

Can you explain why there might be a lot of hot pixels? Is that not having enough dark frames? Camera being bad (it's a new camera)? My dark frames look pretty dark even with 5 minute exposure so didn't think I had hot pixels.

 

Thanks again for you time and suggestions. 

 

@F.Meiresonne thank you for the kind words. I like that take on the color. It's supposed to rain the next few days so I'll have a lot to play with and try.


Edited by ttnova, 01 June 2020 - 04:13 PM.


#5 Huangdi

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Posted 01 June 2020 - 07:33 PM

@Huangdi thank you. That looks great! Just what I'd love to be able to achieve and amazing this was a quick job for you. It gives me hope and something to shoot for. I'm glad that the image in general seemed like it was a good start. I will begin taking flats (never had good enough data to need them). I will also look into AstroPixelProcessor. I will also try without the light pollution filter (I'm in NJ 20 miles from New York City so it can be bad). And more time imaging this target.

Can you explain why there might be a lot of hot pixels? Is that not having enough dark frames? Camera being bad (it's a new camera)? My dark frames look pretty dark even with 5 minute exposure so didn't think I had hot pixels.

Thanks again for you time and suggestions.

@F.Meiresonne thank you for the kind words. I like that take on the color. It's supposed to rain the next few days so I'll have a lot to play with and try.


I don't think that you necessarily have a larger amount that usual of hot/cold pixels, you simply didn't get rid of them :p

Bad Pixel maps (integrated in APP for example) are one way to do it, dithering helps as well.

You're off to a great start, I would've been in awe if my images looked like this when I was beginning.

Keep it up!
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#6 Mert

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Posted 02 June 2020 - 02:06 PM

IMHO that's a nice image, indeed you should take flats since there

is quit some dirt in the optical train aparently but that camera works fine!

What setup did you use? Exposure time, Gain/offset, scope etc.

I don't know which filter(s) you have, but I can recommend a UVIR

block filter, always good to use.

If you have strong light polution like myself when imaging from my

balcony, then an IDAS LPV4 filter might help.

Here you see my effort on your image ( I downloaded the TIF file )

and first cleaned it up in APP then into Pixinsight for stretching

and some more fiddling to bring some color into it trying not

to make it look artificial but it took me some 20 minutes to get here.

Just my personal taste!

 

Stay well,

Mert

 

 

 

 

Attached Thumbnails

  • M101_Pinwheel_Galaxy-ret-CN.jpg

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#7 ttnova

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Posted 02 June 2020 - 02:32 PM

@Mert. That looks really nice. I like the natural look. Here's the gear I used:

 

Explore Scientific 80 ED Triplet

Celestron CGEM Mount

Optolong L-Pro Filter

Zwo Asi533Mc Pro

30+- images X 300 seconds at -15C temp 

I just keep it at the Unity settings in the ZWO driver setup.

 

So you can see dirt in the image? I did think I saw a big circle (dust?) in the center left side of the image. Maybe I should break things down and check?

Thanks for the advice and help. 



#8 Mert

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Posted 02 June 2020 - 04:49 PM

Yes, in the left center part of the image, like a dark circle. I dealt with it using a tool of Pixinsight called clonestamp. Ok, that's a nice setup you used and also unity gain. Likely there is dirt on the filter.
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#9 Mert

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Posted 02 June 2020 - 04:51 PM

Maybe I would back off on exposure time, like 240 seconds maximum. Very nice data, just keep adding data :waytogo:
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#10 ttnova

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Posted 07 June 2020 - 10:56 PM

I put some more time into this target but the seeing wasn't that good and I actually think I lost some clarity and detail. I also thought I got rid of the dust but that spot showed up again. But I did play around with getting more color into the image. I need to track down that dust and also get some flats on the next target I image. Thanks again for all the advice and help.

 

gallery_242599_5209_167530.jpg



#11 niktnowy

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Posted 07 June 2020 - 11:47 PM

I like it a lot.  I was trying to get M101  last night. I've got 60 exposures of 5 min each but my results are not nice like yours. I will redo processing again. Will see.  I just have so much fun  learning.

How often did you check focus?

 

 What did you use to focus?

 

Thanks



#12 ttnova

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Posted 08 June 2020 - 06:07 AM

Thanks niktnowy. I use Apt’s focus tool. It works with the Bahtinov mask. I was eyeballing focus either a mask but the tool is much more accurate. I just set the focus once at the beginning of the night.

This video does a great job of showing how it works.
https://youtu.be/0rGDyjiffTI
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#13 niktnowy

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Posted 08 June 2020 - 01:35 PM

I do the focus the same way. I'm using Vega or Arcturus. When using mask I'm able to get focus to around 0.03-0.07. I use ZWO EAF with ZWO ASIAR but I use APT to focus. I really don't know how to focus with ZWO app.


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