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First go at M42 (my 3rd attempt at DSO)


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Hi SGL

After a magic night out at Sandvretens Observatory (the club's own dark site). I came up with this little image:

First attempt at M42.

I kinda feel I failed at proessing this one, so it's bound for a revisit. Still I like the image, and I'm happy with it being my 3rd stack alltogether. I could really learn to go slowly with processing however.

There is some fainter nebulosity I've failed to bring up since with it comes a gradient I havent been able to combat. I think my flats are probably wrongly exposed and I made the mistake of moving the camera before taking them so I had to precisely try to line it up again. Atleast it's a lesson learned for next time.

The whole evening was really nice, I took some other pictures of the comet in Auriga and some one sub tries at DSO, plus a whole lot of visual observing. Will add some more threads on this later.

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You've done extremely well for a first attempt :) This is a notorously difficult image to process. In fact to keep the inner core trapazium stars and still get the outer dust clouds you need two sets of data at different exposures and blend them together.

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A good start i think on this (i am also attempting this for the first time so) i see what you mean about the colour but actually i find it quite pleasant.

i dont know much about the AP road yet but i think what Gina means is that you need to take much shorter subs - rather than just different ISO - to not burn out the core (30 seconds for instance ) and then blend the 2 resulting images together so you get the full glory of M$2 but with the inner core less exposed.

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A good start i think on this (i am also attempting this for the first time so) i see what you mean about the colour but actually i find it quite pleasant.

i dont know much about the AP road yet but i think what Gina means is that you need to take much shorter subs - rather than just different ISO - to not burn out the core (30 seconds for instance ) and then blend the 2 resulting images together so you get the full glory of M$2 but with the inner core less exposed.

Thank you, even if the colors are a bit off, and I lost the star color in this try at processing, I'm still pretty satisifed.

Actually a lower ISO works just fine as you can see. THere is still detail in the core, you should have seen it before I added the lower ISO core through layer masking.

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I like this image very much, especially the diffraction pattern on the brighter stars. I find the image very crisp, and in fact the colour looks pretty similar to what i see visually. Actually, most astrophotos seem to have a false colour, in that the various regions of the spectra are enhanced so that we can see them. it can look very nice, and of course shows stuff we can't normally see, so they are interesting also. But sometimes I find that natural colouring is more satisfactory, and this image seems to me to look natural. I presume that the camera is un-modified?

Chris

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A good start i think on this (i am also attempting this for the first time so) i see what you mean about the colour but actually i find it quite pleasant.

i dont know much about the AP road yet but i think what Gina means is that you need to take much shorter subs - rather than just different ISO - to not burn out the core (30 seconds for instance ) and then blend the 2 resulting images together so you get the full glory of M$2 but with the inner core less exposed.

Well yes, that is the better method :) And yes, the core is a bit overexposed. I've found ISO 1600 about the best but 3200 is OK - 6400 is much more noisy. You need very short exposures for the core, the idea being not to saturate the stars of the trapezium as that causes them to spread into blobs.
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Yeah the camera is unmodified.

Next time I'll try to go down to 1600 like you've said Gina, maybe try increasing exposure time a bit when I get a cheap remote timer, I tried a 2 minute unguided sub on horse and flame area, and it turned out fine enough.

I'm still tearing my hair out a bit over the processing. I'll revisit this pretty soon, but my issues are:

1) Getting a gradient over top side of the picture when I try to eke out more nebulosity, especially the hints of it you see below the main nebula.

2) I cannot seem to tease out different color in the stars, even though my different subs have more information, that informatin isn't translated well via DSS and Photoshop for some reason.

3) Maybe my flats are too dark? I couldnt get my camera to fire on auto when I tried taking the flats (white t-shirt, torch). So I took 1/30 sec flats. They looked grey enough, histogram being about midways, but then when I see other people's flats they look brighter.

Any ideas?

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