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second attempt at M42 - with guiding

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Second go at imaging M42 last week. Used guiding to take a run of 28 x 180 second subs at ISO 800 on one of the cold, clear nights we've had recently. No wind and no cloud meant that I could use all 28 subs, a first for me. Stacked and processed them all in Pixinsight with darks and bias (no flats). Tried not to stretch the stacked image too much to prevent bringing out noise in the images and keep a dark, even background. 

post-47153-0-73383300-1453066195_thumb.p

Clear Skies

Richard

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nice image you need to take some shorter exposures now then add them to your image to bring out the core in your first image, there are plenty of video's on utube showing you how to do it

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That is a fantastic image.  Loads of detail, pin point stars. colour in the stars.   I do hope you have a very smug look on your face.  I've been trying on an off for years and still haven't come anywhere close to that.

hopefully this year :D

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nice image you need to take some shorter exposures now then add them to your image to bring out the core in your first image, there are plenty of video's on utube showing you how to do it

I agree the core is overexposed. Next time I get a clear view without a bright moon in the way that'll be my next project and then learn how to layer/merge them.

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Very nice, I actually prefer your colours, compared to modded camera colours on M42

Now your guiding I suggest you drop your iso to 400 (or even lower) and increase your exposure time. 

The longer the individual subs the better. and iso is really only software amplification, it doesnt actually make the sensor

any more sensitive. 

just a note, your background looks a little clipped, and thats where the faint nebulosity lives. you may well be able to pull alot more data of 

of it! even more than your STF may initially suggest. 

Edited by JR1987

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Very nice, I actually prefer the colours you get with an unmodded cam on m42.

Now your guiding I suggest you drop your iso to 400 (or even lower) and increase your exposure time.

The longer the individual subs the better. and iso is really only software amplification, it doesnt actually make the sensor

any more sensitive.

just a note, your background looks a little clipped, and thats where the faint nebulosity lives. you may well be able to pull alot more data of

of it! even more than your STF may initially suggest.

Agree, dropping the ISO is the direction is like to go. Versus earlier images I took without guiding at ISO 1600, the noise is greatly reduced, aided I guess by the dithering I introduced too. Quick question, what is STF? I'll look at the processing again as I tried not to clip too much with the histogram transformation but maybe I overdid things with the curves.

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That is a fantastic image. Loads of detail, pin point stars. colour in the stars. I do hope you have a very smug look on your face. I've been trying on an off for years and still haven't come anywhere close to that.

hopefully this year :D

Thanks for the kind comments. I'm very pleased with this image. Auto guiding is the way forwards for me!

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Thanks to all for the kind comments. Looking forward to sharing more in the coming months.

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Agree, dropping the ISO is the direction is like to go. Versus earlier images I took without guiding at ISO 1600, the noise is greatly reduced, aided I guess by the dithering I introduced too. Quick question, what is STF? I'll look at the processing again as I tried not to clip too much with the histogram transformation but maybe I overdid things with the curves.

You mentioned in your original post you processed in pixinsight.

Screen Transfer Function (or STF) is like a false stretch so you can work on an image in its linear state (doing all your background extraction, colour corrections etc) without having to actually stretch it yet. It shows a really big stretch and once youve done your background extraction you can see what kind of data youve picked up. if you havent used it already, its in the Processes, or cmd + A is the shortcut. 

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Hi. Yes thanks. I do use that, just didn't recognise the acronym

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Very nice, I actually prefer your colours, compared to modded camera colours on M42

Now your guiding I suggest you drop your iso to 400 (or even lower) and increase your exposure time. 

The longer the individual subs the better. and iso is really only software amplification, it doesnt actually make the sensor

any more sensitive. 

just a note, your background looks a little clipped, and thats where the faint nebulosity lives. you may well be able to pull alot more data of 

of it! even more than your STF may initially suggest. 

I think this depends on the mount. I run several mounts here and they each thrive on different sub lengths, varying from under a second to 4 or 5 seconds. Experiment is the answer, I think.

Very good M42. Maybe just a tad green in the background? SCNR Green should nail it. As for the short core subs, this is an excellent blending method. http://www.astropix.com/HTML/J_DIGIT/LAYMASK.HTM

Olly

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Had another play around with this following the comments. I've reduced the amount of clipping so that there is more of the nebulosity present (although you can now see stacking artefacts in the corner which I know are from the dithering - next time I'll dither a little less!) and also ran the SCNR process to remove the green as suggested. I guess it's a case of beauty in the eye of the beholder, this one has more of the nebulosity showing, but looks a little more "hazy" than my first attempt.

post-47153-0-40436300-1453241144_thumb.p

Extracted the luminance to give a moody B&W version too. Quite like these vs. the full colour - gives a bit of an old school feel to things.

post-47153-0-55616200-1453241565_thumb.p

Next step will be to take some shorter exposures (once the moon and clouds get out of the way) and then I'll look at blending to get a bit more core detail. Thanks again for the hint and tips.

Clear Skies

Richard

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I prefer the first one, to be honest! I don't know anything about PI, as I only use PS, so I don't know how you would combine shorter shots to get the Trapezium. I might need to ask you when you do it for when I get PI!

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