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Author Topic: NGC7635 image for C & C  (Read 711 times)

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Online Annie

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NGC7635 image for C & C
« on: 12:03:59, 02 December, 2017 »
Am wanting to improve my basic imaging techniques and also my processing so wanting some constructive criticism on some recent images.  I took this one last week of the Bubble nebula when the moon was around: 21x600sec exp at ISO800 with Takahashi 106ED, crop sensor Canon 550D DSLR and Lacerta MGEN guider.  Stacked in DSS with darks and flats and processed in PS (with my usual limitations!).  The image is uncropped.

Thanks
Annie

Pulsar Observatory; NEQ6/EQ6 wedge; HEQ5 Pro; TS Star 71 Astrograph; Takahashi FSQ 106ed; Skymax 150 Pro; Nikon D600; Canon 550D modified; Canon 5D Mk11; ZWO ASI120 MM-S; Lacerta MGEN stand alone guider.

Online Nimbus

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Re: NGC7635 image for C & C
« Reply #1 on: 18:33:01, 02 December, 2017 »
Hello Annie,

Firstly, you have a pleasing image and it is always less than easy to comment on a Jpg of restricted size,  but here are some observations from me:

You mention you applied Darks and Flats - no Bias? Bias are need also.

There appears to be a dark circle at about 7 o'clock to the bubble  indicating the Flats may not have dealt with any artifacts.

Overall the image appears a little dark for my taste indicating there may be some black clipping.  Try aiming for a background of about 30-40 in the info palette.

I suspect there is more nebulosity hidden in the original image that means you can stretch things a little further.  You may wish to remove the stars first to prevent bloating.  You can layer the stars back in and tighten them up to reduce there dominance in the image.

The colour balance appears a little off, try aligning the left hand side of each of the RGB histograms to achieve the correct balance.

The good news is you have retained some colour in the stars which can easily be lost when stretching.

Have a go at adjusting your original image in line with the above and re-post and we can see where we go from there. If you are not sure how to achieve the above any of the techniques - ask away.

HTH Jim
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Online Annie

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Re: NGC7635 image for C & C
« Reply #2 on: 19:24:24, 02 December, 2017 »
Hi Jim - thanks for some helpful comments.  Firstly I just forgot to mention the bias but I did add them and you're right that the flats didn't get rid of all the artefacts.  I take my flats using a head torch with something over it to diffuse the light but my torch packed up so the flats didn't work very well! I can try most of what you suggest other than removing and layering the stars back in but I guess that would be a bit difficult to explain so am happy to try and work that out!!

Thanks again Jim

Annie
Pulsar Observatory; NEQ6/EQ6 wedge; HEQ5 Pro; TS Star 71 Astrograph; Takahashi FSQ 106ed; Skymax 150 Pro; Nikon D600; Canon 550D modified; Canon 5D Mk11; ZWO ASI120 MM-S; Lacerta MGEN stand alone guider.

Online Annie

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Re: NGC7635 image for C & C
« Reply #3 on: 14:31:12, 06 February, 2018 »
Another version of my original 'Bubble'.  First go with any image at extracting stars - via Straton software - to enable further stretching and later trying to dim and reduce the impact of the stars by using the minimum filter method in photoshop a la Adam Block tutorial.  I obviously need loads of practice as though I may have cropped too much, some of my stars, esp bottom right seem mis-shapen and the image lacks sharpness.  Before I try again can anyone see an obvious cause of this?

Thanks
Annie
Pulsar Observatory; NEQ6/EQ6 wedge; HEQ5 Pro; TS Star 71 Astrograph; Takahashi FSQ 106ed; Skymax 150 Pro; Nikon D600; Canon 550D modified; Canon 5D Mk11; ZWO ASI120 MM-S; Lacerta MGEN stand alone guider.

Online Annie

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Re: NGC7635 image for C & C
« Reply #4 on: 14:31:51, 06 February, 2018 »
Oh dear wrong image!

Annie
Pulsar Observatory; NEQ6/EQ6 wedge; HEQ5 Pro; TS Star 71 Astrograph; Takahashi FSQ 106ed; Skymax 150 Pro; Nikon D600; Canon 550D modified; Canon 5D Mk11; ZWO ASI120 MM-S; Lacerta MGEN stand alone guider.

Online Annie

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Re: NGC7635 image for C & C
« Reply #5 on: 14:38:41, 06 February, 2018 »
Hope this is the new version!

Annie
Pulsar Observatory; NEQ6/EQ6 wedge; HEQ5 Pro; TS Star 71 Astrograph; Takahashi FSQ 106ed; Skymax 150 Pro; Nikon D600; Canon 550D modified; Canon 5D Mk11; ZWO ASI120 MM-S; Lacerta MGEN stand alone guider.

Offline Carole

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Re: NGC7635 image for C & C
« Reply #6 on: 20:59:49, 06 February, 2018 »
Hi Annie, I am rather dubious about the head torch method of flats,  has it always worked for you previously?

Anyway, is there any chance of posting up the unprocessed final tiff stack so we can have a "go" at processing it and see what there is in the image, then we can tell you how we did it.  I think this would be the most useful thing to do.  You might have to link it via dropbox or something.

Big improvement between the first and 2nd processing posted up.

I thought you were getting a mono camera, or am I wrong?

Carole
Mount: NEQ6 (on pier), HEQ5 (for astrocamps),  Telescopes: SW ED120 Pro and SW Evostar ED80 pro, WO ZS71 APO, Cameras: Modified Canon EOS 450D, Atik 460EX, Atik314, DMK21, DBK, Dual rig options. Observatory: SkyPOD & PZT
https://sites.google.com/site/caroleastroimaging/home

Online Annie

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Re: NGC7635 image for C & C
« Reply #7 on: 08:00:56, 07 February, 2018 »
Thanks Carole - I'll send a link for dropbox.  I'm not sure about the head torch method either so last imaging session had a go with a light panel which I think will be much better.

Yes you're right I was thinking about a mono camera but my processing skills were so lacking I have been concentrating on improving those.  Inspite of  all the advice towards a mono ccd am still of a mind to buy a OSC camera as a first step which won't preclude me from moving to a mono ccd( when the weather and my skills improve!) - was thinking about an Atik 460ex, colour in the first instance.

It will take a bit of time to upload the image to dropbox - we have a very slow broadband speed.

Cheers
Annie
Pulsar Observatory; NEQ6/EQ6 wedge; HEQ5 Pro; TS Star 71 Astrograph; Takahashi FSQ 106ed; Skymax 150 Pro; Nikon D600; Canon 550D modified; Canon 5D Mk11; ZWO ASI120 MM-S; Lacerta MGEN stand alone guider.

Online Annie

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Re: NGC7635 image for C & C
« Reply #8 on: 09:47:38, 07 February, 2018 »
Having problems uploading the file into dropbox. Not had this problem before - after about half an hour it says an error has occurred during upload!  No idea what's causing this at the moment.  Am not exceeding my dropbox quota so wonder if it's my slow broadband speed so will try later in the day!
Pulsar Observatory; NEQ6/EQ6 wedge; HEQ5 Pro; TS Star 71 Astrograph; Takahashi FSQ 106ed; Skymax 150 Pro; Nikon D600; Canon 550D modified; Canon 5D Mk11; ZWO ASI120 MM-S; Lacerta MGEN stand alone guider.

Online Annie

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Re: NGC7635 image for C & C
« Reply #9 on: 16:02:17, 07 February, 2018 »
It's unlikely that I'll be able to provide a link to dropbox at the moment as I suspect my miserable upload speed of 0.2mbps is why the upload keeps failing!  How frustrating is that!!!! 

Annie
Pulsar Observatory; NEQ6/EQ6 wedge; HEQ5 Pro; TS Star 71 Astrograph; Takahashi FSQ 106ed; Skymax 150 Pro; Nikon D600; Canon 550D modified; Canon 5D Mk11; ZWO ASI120 MM-S; Lacerta MGEN stand alone guider.

Offline Carole

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Re: NGC7635 image for C & C
« Reply #10 on: 09:36:46, 08 February, 2018 »
That's a shame Annie, well tell us what your usual processing routine is and we can feedback C&C.

Carole
Mount: NEQ6 (on pier), HEQ5 (for astrocamps),  Telescopes: SW ED120 Pro and SW Evostar ED80 pro, WO ZS71 APO, Cameras: Modified Canon EOS 450D, Atik 460EX, Atik314, DMK21, DBK, Dual rig options. Observatory: SkyPOD & PZT
https://sites.google.com/site/caroleastroimaging/home

Online Annie

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Re: NGC7635 image for C & C
« Reply #11 on: 10:06:54, 08 February, 2018 »
Thanks Carole - have only recently made a 'real' effort with processing so am in the early stages of establishing a 'workflow'.  The bubble was my first attempt to apply an initial stretch using levels and curves and correcting the colour balance  by aligning the histogram through use of the channels in levels ( Steve Richards suggests this in his new book 'Dark Art or Magic Bullet', mentioned in Nimbus' useful books thread).  I then used Straton software to remove the stars , converted the three greyscale images produced by Straton to a colour RGB, did a further stretch of the starless image before layering the original back onto the 'stretched starless'!

However I've been looking at my original light frames and to my eyes the stars look perfectly ok but not when I look at the stacked tif produced by DSS.  Am thinking I should re-stack but without flats and bias?

Have attached JPEG versions of an individual light frame and the stacked version of 21x600sec exps.  What do you think?

Annie
Pulsar Observatory; NEQ6/EQ6 wedge; HEQ5 Pro; TS Star 71 Astrograph; Takahashi FSQ 106ed; Skymax 150 Pro; Nikon D600; Canon 550D modified; Canon 5D Mk11; ZWO ASI120 MM-S; Lacerta MGEN stand alone guider.

Online Annie

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Re: NGC7635 image for C & C
« Reply #12 on: 10:08:13, 08 February, 2018 »
This one is the stacked image.

Annie
Pulsar Observatory; NEQ6/EQ6 wedge; HEQ5 Pro; TS Star 71 Astrograph; Takahashi FSQ 106ed; Skymax 150 Pro; Nikon D600; Canon 550D modified; Canon 5D Mk11; ZWO ASI120 MM-S; Lacerta MGEN stand alone guider.

Offline chris.bailey

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Re: NGC7635 image for C & C
« Reply #13 on: 10:42:48, 08 February, 2018 »
Annie

Stars don't look too bad in either. As mentioned in another thread the Tak106 can be a bit temperature sensitive on focus (the much older ones were less so) so focus can wander as the temperature drops. Not at all unusual for the stars in the stack to bloat a little as a result. Also not unusual to loose apparent star colour in the star. Its there, it just needs a good oomph of saturation.

DSS is getting a little old in the tooth now and things have moved on since it was last updated. AstroPixelProcessor is well worth a try. It works well using the default settings on images such as this and some of its trickery may help keep stars under control a little better. Well worth downloading the trial version and giving it a go. I am using it more and more for my stacks.

Chris
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Online Annie

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Re: NGC7635 image for C & C
« Reply #14 on: 12:48:05, 08 February, 2018 »
Another in the long list of 'keep meaning to' is to consider another stacking process so will have a look at the one you suggest Chris.  Have been working through some tutorials of Adam Block - 'Cosmic Canvas' and he uses something called 'CCD stack' - looks very sophisticated to me. 

Annie
Pulsar Observatory; NEQ6/EQ6 wedge; HEQ5 Pro; TS Star 71 Astrograph; Takahashi FSQ 106ed; Skymax 150 Pro; Nikon D600; Canon 550D modified; Canon 5D Mk11; ZWO ASI120 MM-S; Lacerta MGEN stand alone guider.

 

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