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ASI120mc Saturn on 6/21/13

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#1 BKBrown

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Posted 23 June 2013 - 07:24 PM

Friday night was pretty decent so I did a bit of imaging. This shot was acquired through the C11 Edge HD, TV 2x Barlow, and ASI120mc w/ Baader UV/IR cut filter. I stepped up from the Siebert 1.75X Barlow to see how much of a difference in scale I would get , and tried a few other things as well. My settings were as follows: Gain - 100, Gamma - 60, and Exposure (ms) - 19/52 fps nominal. I normally leave the Gain at the default 50, but 60 gave me a brighter image and does not seem to have introduced excessive noise, next time I'll try to push it even higher to get a better frame rate and 50%+ histogram in the red. Anybody else out there tinkering with settings who might like to chime in? Looks like I got a decent NPH and some belt details, I'll be out again tonight giving it a try...

Clear Skies,
Brian

#2 Mitchell Duke

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Posted 23 June 2013 - 07:44 PM

Brian,
The shot looks great, try setting gamma to the default setting of 50, and brightness to 0.

#3 BKBrown

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Posted 23 June 2013 - 08:06 PM

Brian,
The shot looks great, try setting gamma to the default setting of 50, and brightness to 0.


Thanks Mitchell! I have been shooting with the gamma 50 and have been having trouble keeping the frame rates up and the red histogram at just above 50. Pushing the gamma to 60 let me shoot with a frame rate of 53 fps vice the mid 40s I was getting, the red and green histos were at and above 50. Do you think I'm picking up too much additional noise?

Clear Skies,
Brian

#4 Kokatha man

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Posted 23 June 2013 - 08:07 PM

That's a pretty nice image outcome Brian. :)

The gamma setting for the ASI cams is recommended to stay at 50 as you'd know anyway, and an old mantra was that raising the gamma a bit in capture wasn't a bad thing, but tbh I've never done any capture trials to determine the truth of that matter: I usually drop the gamma value in post-processing to "0.9" so if you do something similar maybe you could try lowering it even more.....on my screen your image looks like this might be worthwhile but at any rate you caught a very good image regardless..! :waytogo: :waytogo:

#5 BKBrown

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Posted 23 June 2013 - 08:18 PM

Thanks Darryl. I also tend to adjust the gamma down in post processing and did that with this image. Expect I'll be experimenting with this data for a while since I haven't had a lot to work with this season. Cheers!

Clear Skies,
Brian

#6 zAmbonii

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Posted 23 June 2013 - 08:29 PM

In this thread Smitty had the gamma cranked to 70.

I'm not really sure if noise is really the problem with cranking the gamma, but with my old webcam it would introduce onion skinning in the final image. But it may not really be a problem with the ASI cameras. If you look later on in that thread linked above, he did go back to gamma = 50, and you can see a difference (the planet itself looks more round).

I think with increasing the gamma you are sorta compressing the color values towards the higher range and an uncorrected image will look flat. Like Darryl said above, you can compensate for it by bringing the gamma back down in post processing, but it may not equal the result if the gamma = 50....but who knows, I don't think that anyone has experimented with it before to see how it looks.

I'm thinking of dragging the scope out in a few. There are T-storms that are threatening us from the South so it may be a washout, but I may give it a try with varying gain in captures and then correcting in post processing. We'll see how it goes.

#7 hopskipson

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Posted 23 June 2013 - 10:21 PM

Not an expert, but that image is excellent!

#8 wenjha

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Posted 24 June 2013 - 02:12 AM

Yes,Darryl and zAmbonii is correct about the gamma setting.
wrong use of gamma will cause onion ring.
60 actually won't cause that. but 50 is the recommended setting.
well done Anyway!

#9 lcd1080

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Posted 24 June 2013 - 09:15 AM

Looks like a fine late season Saturn Brian, resolving the NPH and CD across the globe are both heroic acts in the North 55 days past opposition.

Pete

#10 sfugardi

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Posted 24 June 2013 - 11:09 AM

Brian, excellent image especially this late in the season! Color and details look very natural. Congradulations on this beauty and thanks for posting it

Regards,
Steve

#11 BKBrown

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Posted 24 June 2013 - 04:59 PM

Thanks zA, James, Sam, Pete, and Steve :grin: It's been a tough Saturn apparition but the new ZWO cams have definitely been a high point. I am looking forward to trying them out on Jupiter before too long...

Clear Skies,
Brian

#12 leviathan

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Posted 25 June 2013 - 01:09 AM

Looks a bit under corrected in colors. I've slightly changed it, hope you don't mind:

#13 Baron

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Posted 25 June 2013 - 04:27 PM

Nice image!

#14 BKBrown

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Posted 25 June 2013 - 06:07 PM

No, I don't mind ...just don't know what you mean by "under corrected in colors" :grin: I think the overall effect is largely dependent on individual monitors, and most folks do not calibrate theirs regularly.

Clear Skies,
Brian

#15 BKBrown

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Posted 25 June 2013 - 06:08 PM

Thanks Paolo :grin:

Clear Skies,
Brian

#16 RedLionNJ

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Posted 26 June 2013 - 10:53 AM

Brian - that is one of the very, very few ASI120MC images I've seen where the colors don't look "flat". Whatever you're doing with the settings (perhaps in post-processing, too), you're doing it very right!

Most excellent.

Grant

#17 semmyboy

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Posted 26 June 2013 - 11:04 AM

Wow!

#18 BKBrown

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Posted 26 June 2013 - 10:14 PM

Thanks Grant and semmyboy :grin:
Grant - I find the color rendering with the ASI120mc to be a bit flat. The color is being picked up but it is somehow suppressed...at least to my eye. In PS CS4 I have been increasing (slightly) the saturation and then I fidget with the vibrance until it gets to where I like it. Understanding this cool new camera is still a "work in progress" for me...

Clear Skies,
Brian

#19 azure1961p

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Posted 26 June 2013 - 11:10 PM

Very impressive image!!!! I enjoy following your work and through different apertures.

Pete

#20 BKBrown

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Posted 29 June 2013 - 02:32 PM

Thanks Pete!

Clear Skies,
Brian

#21 ohioalfa64

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Posted 30 June 2013 - 12:56 PM

This is wonderful. Thank you for your technical information on your webcam settings and processing tricks.

#22 1227qqww

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Posted 30 June 2013 - 08:38 PM

Nice

#23 BKBrown

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Posted 02 July 2013 - 10:23 AM

Thanks! And you are quite welcome ohioalfa64, I hope that info helps some folks :grin:

Clear Skies,
Brian






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