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One Saturday ago I shot some frames on Iris nebula. There should be 21x300s frames at ISO1600 taken with an unmodded Canon 550D, Tair 300s at F5.6 on an AZ-EQ5 guided with dithering. Enough darks and bias, no flats yet. I could take the flats later for vigneting removal, but I could spare some margins.

The result of what I processed until now is here, I could probably lower a little the noise, but I'm not good at processing. Yet :D

I wonder if anyone would mind to show me what they can pull out of my data. The stack is made with DSS, unbalanced and converted with GIMP to 16 bit integer tiff from the original autosave file.

jpg: https://drive.google.com/open?id=0ByhJ_xuQxcnjMlhTT0sxMk5VY3M

tiff processed: https://drive.google.com/open?id=0ByhJ_xuQxcnjM1RJTENwU2l2QVE

tiff unprocessed: https://drive.google.com/open?id=0ByhJ_xuQxcnjcjZ0bzNON1ZDcFE

Thank you,



Edited by moise212
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Looks to me like you're getting it right. The dusty clouds which fill this frame simply do require an awful lot of capture time. You'd have an easier time processing it with ten hours' data...


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I did have a quick go earlier but didn't really improve it much. As has been said, the best way to improve it is to get more data, especially with Iris as she has a lot of dusty stuff around her that needs depth to bring out.

I did think the black point was slightly clipped, try and leave a bit of space to the left of the histogram.

It is a really nice image though and you have good colour from the 550D. Lovely round stars as well

Really good!

Edited by StargeezerTim
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The Iris nebula for me too was a very tricky object. I was only able to get anything satisfying with 9.8 hours exposure time and thats using LRGB method, pure RGB it would have taken ages.

The 'issue' is that that dark area of the dust in this target is one of the focus points, and getting dark areas with low noise is like getting the background to a low noise level, takes either lots of integration time, or you have to process the heck out of it.
If i were you i would try to add more data if you are able to do it and go for longer exposure times if you sky allows it.

All in all though a very nice image, you retained way more star color than i could (i blew most of it away with 600s exposure :/ )

Kind regards, Graem

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Thank you all!

Supposedly I could get to a dark side the next cloudless-moonless weekend, what exposure time - ISO would you choose?

For this session I used 300s@ISO1600. Would you keep the same exposure and ISO in order to stack all the subs together, or would you go for a lower ISO, maybe ISO800 and 600s or even 900s and blend the 2 stacked results afterwards?

I stacked the subs with DSS and processed the resulting image with Star Tools and GIMP, mostly GIMP.

@toxic, thanks! Let it be noise then. I shot with a 300mm FL so that I could get the dust clouds. However, the stars in your image look much better.

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Thought I would have a go as well!

I always find Iris difficult to process and the dust can be brought out, but only at the expense of lots of noise. I think you have to aim at an acceptable compromise, which depends on taste! :smile: (the Camera Raw filter in PS is OK for for adding detail, and other stuff, but you have to go easy on it).




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Alex, I wouldn't be hard on your efforts you have a good rendition of the nebula and have done all that can be with the available data. You are trying to do the most difficult thing that is teasing dust out of a dark background and it will need lots and lots of more photons to show detail there. 

I have processed it in StarTools and first noticed a lot of gradient at the bottom. I subsequently reprocessed after cropping to leave the central portion of the image which ST found easier to process in the COLOR module-


Best regards,

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Thank you all! The problem is that I wanted to shoot Iris more for the dust clouds. Unfortunately, our clouds are much easier to be seen than theirs.. but.. I won't rest in peace until I don't acquire more data.


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