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Please help with processing

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#1 Takashi

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Posted 09 March 2013 - 05:43 AM

A couple of days ago I was out with my friend, this night we captured the andromeda galaxy and the horsehead. We were using a Equinox 80mm APO, unmodified Canon 600D and with a CLS clip-on filter. Everything was guided with a Meade LX200GPS 12" with f3.3 reducer/GPUSB/Meade dsi Pro.

For M31, the total image time was 51 min (30X60s + 43X30s)
For Horsehead, the total image time was 39 min (39X60s).
All ISO1600.

Darks were taken and everything was combined using DSS.

The result:
Posted Image

Posted Image

The problem now is: why are the images so lousy? First of all, the stars in the corner are not sharp at all. Im using a field flattener for the megrez 88, which apparently is not working well with this equinox. Guess I'll have to try another field flattener for that. Second... 51 minutes for Andromeda... I had higher expectations of what it would look like than the above.

Following all sorts of tutorials on the net, I can't manage to get any good images from my processing.

I've uploaded the original stacks (each and one about 100mb in size) in my skydrive:
https://skydrive.liv...8C259486!287...

Anyone here that can give me any good tips?

About a month earlier I took an image of M31 which was only 12 minute total which is looking way better than the one above (51 minutes)!!! What am I doing wrong?

http://nineplanets.s...iewer.asp?ID=62

Maybe someone here might try to process the raw stacks above (from the skydrive folder)?

#2 jambroseus

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Posted 09 March 2013 - 08:43 AM

I think the elongated stars at lower left are the result of the camera not being square to the optic axis. Check to see if it is loose in the focuser or the camera weight may be bending the focuser a bit.

As for image density, I think you just need longer subs to really catch the fainter edges. I did some processing on your image (neutralized background and digital development in ImagesPlus) and got this... You need longer exposures...

John

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#3 stelios_STI

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Posted 09 March 2013 - 03:11 PM

well i think you need more exposures and more time. now with the CLS is necessary. don't go over iso800 is very noisy
also try to stack without the dark frames. maybe the darks are failed

#4 Aboy

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Posted 10 March 2013 - 04:14 AM

can you update the Tiff Files in another site? I can try to help you.. but I can Download the files

#5 Takashi

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Posted 10 March 2013 - 12:18 PM

Hi!

Is there any reason you can't access the TIFF-files from my skydrive? It should be no problems? I dont know any other place that allows uploads of >100mb size images.

#6 fco_star

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Posted 10 March 2013 - 02:44 PM

I have seen those before and I remember I blame it on my darks
Try to process it with out darks and see what you get..
what DSS version are you using to process?

#7 RedLionNJ

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Posted 10 March 2013 - 06:09 PM

60 seconds with a CLS on an 80mm isn't going to get you deep enough for these targets. I'd be trying 240 seconds or even longer - try to get the sub-exposure histogram up to around 2/3 at least.

The vertical streaks are likely due to mismatched darks. Make sure you have at least ten darks, taken at around the same sensor temperature as the lights.

Flats (and flat darks) as part of the calibration process will also let you stretch the resulting data more with less side-effects.

And as John says, above, it looks like the sensor (or some optical component) is tilted with respect to the image plane. Stars near the top left look fine, while those on the bottom right are far from it.

#8 Takashi

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Posted 11 March 2013 - 01:22 PM

Thank you all very much for the answers.
What do you mean when you say "historgram up to around 2/3 at least"?

This mismatched darks may be correct, as I took all the darks just before finishing the night (but then I took about 30 minutes worth of darks). Maybe I should take darks more often than that. I didnt note how the temperature varied during the night, but will try to do so next time.

#9 fco_star

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Posted 11 March 2013 - 04:39 PM

What I do is take some darks at the beginning, some in the middle and some at the end, this works for me.
Some others create a darks temperature library to use the same darks in the future just matching the temperature.
About the histogram, 2/3 or 25% to the left is like a rule of tomb, I have learn that sometimes this will change for a little bit depending of what is your target , a faint object or a bright galaxy, I'm not an expert but this is what works for me.

#10 scopemankit

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Posted 16 March 2013 - 05:04 AM

I use the Gimp. The Andromeda image seems noisier than the HH. Here is the HH with only a "Curves" adjustment - nothing else. The image has promise.

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