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Old 21-03-2010, 07:21 PM
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ballaratdragons (Ken)
The 'DRAGON MAN'

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Never trust what you first see in an image.

Yep, just as the title says. Never trust what you first see in an image.

At camp I started out using Berts 8" f10 Klevtsov.
After doing some test images I was really dissappointed with the results from a scope that is 95% the optical quality of an RC.

At 15 minute exposure times I was only getting faint smudges of bright objects!!!!
(Yes, focus was spot-on)
I always do a test shot of an object first to make sure it is centre of frame, right orientation etc.

The first object was M83. All I saw in the test image was a blurry dot just a tad larger than a star.

Then I tried a brighter object: Omega Centauri. Usually a bright object even at around 2 minutes.
At 15 minutes it was barely visible.

I packed it in for the night and went around watching what everyone else was doing.

Danielsun helped me the next day to replace the Klevtsov with my ED80 so I could get some imaging done.
The remaining nights at camp were spent imaging with the ED80

Today I was going through all the files from camp and I spotted those dismal dark failures.
I decided to run them through Photoshop anyway to see if the focus was as good as I thought.

That's when I got a suprise!!!!!!!

If you look at the images attached, you will see why I will never again trust what I first see in an image. What I thought was totally usuless data turned out to be almost usable!
If I had've gone a bit longer on these exposures they would be chock-a-block full of good data.

What did I learn: There is data hidden in almost any shot

These are single 15 minute frames with no guiding. In the original images you'll see why I didn't continue with imaging them.

Omega Centauri original as I saw it on the laptop screen on the night:
http://i493.photobucket.com/albums/r...s/Lesson-1.jpg

The same image after running it through Photoshop Curves and Levels!
http://i493.photobucket.com/albums/r...s/Lesson-2.jpg

M83 original as I saw it on the laptop screen on the night:
http://i493.photobucket.com/albums/r...s/Lesson-3.jpg

The same image after running it through Photoshop Curves and Levels!
http://i493.photobucket.com/albums/r...s/Lesson-4.jpg

I will be giving the Klevstov another go soon, and I will take longer images than 15 minutes, and I will stack and process them no matter what I see on the laptop.
I now know that at f10 I need to go a lot longer in exposure times
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  #2  
Old 21-03-2010, 07:49 PM
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leon
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Well there you go Ken, well done mate, not half bad for what you described.

Leon
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Old 21-03-2010, 08:33 PM
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erick (Eric)
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Talk about somethin' out of nothin'! That's amazing. What is going on, Ken?
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Old 22-03-2010, 07:07 AM
Hagar (Doug)
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There you go Ken, At the time I said the scope couldn't be that bad just because it was F10. This is a nice sub and a few of these and you will have a lovely detailed image.
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Old 30-03-2010, 11:05 PM
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Jen
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wow Ken i better go back and have a look at my pics again thats what mine look like on the laptop If only i knew what to do once i got into photoshop Looks like thats my next mission at the next camp
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Old 31-03-2010, 04:32 AM
gbeal
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Hi Ken,
I agree, your comparisons are ideed as your title says. Why? That is what I have been asking myself since looking at them. While I agree, the on the screen sub and the Photoshop result are always going to be different, usually any subs show something, certainly more than what your before shots indicate.
Is the initial result able to be changed with an on screen setting, "stretched" I think the term is, like Maxim (and others) does? If you can change this it would have saved the anguish you had.
Gary
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Old 31-03-2010, 11:04 AM
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MelD (Melvyn)
Mel Davis

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A very valuable lesson! Many thanks for giving me the enthusiasm to persist in trying to get good images with my ED80 and modified Canon 300D.
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Old 31-03-2010, 12:08 PM
cfranks (Charles)
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I feel you bumped into what every astro photographer learns early on. An image straight off the camera is (16 bit image) from 0 - black, to 65575 - white. A computer screen (or printer) is 8 bit 0 - black, to 255 - white. All the data is in your camera image, it just has to gently stretched to make it visible.

oops, Gary beat me to it.
Charles

Last edited by cfranks; 31-03-2010 at 12:10 PM. Reason: addition
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