Jupiter/Ganymede, poor seeing, March 1, Brisbane.

[matt]

Not much to write home about with this one...but I'm happy because it's my first RGB of Jupiter this apparition using the DMK 21AF04 and Astronomik filters.

The seeing pretty much obliterated any fine detail.

Not to worry. It was more about the process than the final result.

Quite happy with the colour and overall appearance. This one shows pretty bad onions rings on the Mrs' monitor...but looks OK on mine

I think the rings were introduced at capture, but wasn't aware the DMK was capable of producing rings? Perhaps I need to boost gain and gamma, or increase the exp length to get a more full histo? It was barely past the halfway mark on the graph. I'm sure I didn't correctly expose.

Looking forward to better conditions.

[Alchemy (Clive)]

looks ok to me, just wish i could do it.... i took a rgb set of saturn from last night and have no idea how to mix them together.

Any chance you could pm how to do or provide a link ?

Cheers Alchemy

[iceman (Mike)]

Nothing wrong with that matt, some useful detail there for sure.

Alchemy, I wrote a post about a year ago with some indepth detail on recombining RGB images in photoshop - i'll dig it out when I get more time. In about a week or so, a longer article will be ready which will explain everything.

[Alchemy (Clive)]

excellent i will wait til it pops up and then see if i can give it a try.(article)

[Dennis]

Good stuff Matt – nice to see such a good result from your 1st RGB of Jupiter; it certainly bodes well for when the seeing improves and Jupiter climbs higher.

It may just be wishful thinking on my part, but I "feel" that this RGB image has a different quality about it compared to previous ToUcam ones?

Cheers

Dennis

PS - you guys are fast with your filter change overs!

[matt]

Thanks guys.

Alchemy - definitely try and find that old article of Mike's. It's a handy reference piece. Mike was also kind enough to offer a few handy bits of advice when I was having a bit of a struggle with Photoshop a bit earlier on.

Like most things RGB capture/combining is quite straight-forward once you get the hang of it. It's the processing which is the real artform and the area where I'm still very much just the enthusiastic beginner. I just keep practicing and experimenting and hopefully make little improvements over time. There are also plenty of good imagers on IIS who are good enough to offer constructive criticism and advice.

Mike - looking forward to that upcoming article. Should make for interesting reading

Dennis - not sure what the different quality might be? I've certainly taken sharper, more detailed images with the ToUcam than this...but those were in much better seeing.

It will be interesting to see how things go when I get better data. It goes without saying the DMK is a better camera. It just comes down to how well I capture and process. I hope I can do it justice.

[IanL]

Matt looks good to me mate. You have done a fine job. Nice to see some clear sky's in Brisbane. I was out myself tonight with the same camera as yourself taking shots of Saturn. But i could not get any good detail on Saturn as i think the seeing was poor. But you jupiter is VG considering the seeing conditions.

Cheers
Ian

[bird (Anthony Wesley)]

Hey Matt, not a bad image considering the conditions!

"onion rings" are a symptom that will show up in any camera under the right conditions - that happen when the camera doesn't have enough dynamic range to represent the data and a lot of pixels all end up on the same value.

It's most prevalent on 8 bit data, cause you only have 256 values available from black to white, and when some of your image is very dim (ie the limb of Jupiter) then a lot of the pixels will end up getting the same brightness value, and after you stack them you get areas where the pixels are exactly the same value instead of slightly different.

Monitors can show the same problem, take a look at any dim image on an lcd monitor, you'll find a viewing angle where the image looks awful.

Best ways to avoid it is to increase the brightness of the subject (eg longer shutter) or switch to a camera that can capture in 12 bit, pretty much any of the more expensive cameras like the dragongly2 or SkyNyx.

Hope that makes sense :-)

cheers, Bird

[matt]

Thanks for the info, Anthony.

Yeah...I figured it could be an exposure issue.

I captured the red and green at 30fps and 1/30sec...but that might be too short and not enough light for the 9.25 working at f30 this far out from opposition.

I may need to drop down to 15fps and 1/15 sec ...and even slower for the blue channel But that's not many frames in 30 seconds.

And then, of course, there are those other cameras

[davidpretorius]

i like it matt.

tell me, what are the astronomiks like for focus at this image scale.....are they reasonably parfocal.

also thanks Bird, that is the best explanation of onion rings i have read (gee you are a wealth of knowledge)

[matt]

Hey dave.

WRT - to astronomik filters and focus. Yes, they are pretty much parfocal. They're very close.

Funny enough, I found last night that the best way to go was to get the best focus on the blue channel and work from there.

The blue channel was the clearest of the three, which is not usually the case. The transparency wasn't too flash, which impacted the normally sharper red channel quite significantly.

Other times I get my focus on the red...the green looks good, and I need to 'tweak' the blue.

[edwardsdj (Doug)]

Very impressive given the Brisbane conditions Matt.

Lets hope the conditions improve soon.