Jupiter 07/07/2006 - First DMK RGB

[iceman (Mike)]

Hi guys.

Here's the results of my very first RGB image with the DMK21AF04, taken on Friday night in fluctuating 4-6/10 seeing. I took 11 avi's in total, but only managed to salvage 5 images due to the fluctuating seeing. The best 2 i've attached here, all 5 are in an animation below.

What I've learnt so far:

- The image scale is slightly larger than what I used with the ToUcam when it was pulled out as far as it would go. The filter wheel and adapters probably add about 40mm to the image train, which turns the 5x powermate into a 6x, giving approx 7500mm, or 7.5m FL.

- Using a manual filter wheel isn't difficult at all. I keep the avi recording, when it gets to 35 seconds I hold on to the wheel housing with the left hand, turn the wheel with the right and keep holding for a second to help stop the dampening. The image is steady again within 4-6 seconds. I do the same at the 1:15 mark, and so I get approx 35 seconds for each colour channel, at 30fps, giving approx 1000 frames for each colour channel.

- I open the avi in virtualdub, note down the start and end frame for each colour channel, and delete all the in-between frames where I changed filters. I then save the avi as BMP files. I copy each "set" of BMP's into their own red/green/blue directory, and then run PPMCentre through them. I then process the same way as normal through registax and astraimage.

- The seeing was not bad, but the transparency was shocking as the moon was very close. I had to use 100% gain to get a bright enough image, which caused lots of grain in the image. Processing was fairly difficult because of the grain and I think registax had a hard time distinguishing features from noise.

- My red channel was the dimmest, while green and blue were about the same. Not sure why yet. When transparency is better i'll play around with adjusting gain for each channel.

- I usually focused on the red channel. There does appear to be slight focus change between the red and the blue channels. I need to experiment some more, but need to think about factoring in a focus adjust into my 2 minute window.

- Colour balance and intensity needed some work, the colours were much redder/pinker than what I got out of the ToUcam. It's still not exactly how i'd like it, but will experiment some more in better transparency.

That's about all so far, it's challenging but the results will be worth the effort. At 100% gain, the ToUcam images would be very grainy but the DMK has far less noise than the ToUcam. I didn't do ANY levels adjustment (apart from the usual curves adjustment) and I still have a black background.


Ganymede is in the shot, transiting the planet (shown as the blot) at the bottom of the image. Some markings can be seen even during transit.

Anyway here's the animation:
Jupiter Animation (330k gif)

And here's the 2 best frames. Comments welcome.

[acropolite (Phil)]

IMO a better result than the ToUcam despite the conditions Mike

[Robert_T]

Mike,

This looks great to me, you just about got me sold on R,G,B and mono

I got my first imaging in last night for a nearly two weeks (been on holidays), but nothing near the finess of detail here. Great stuff

cheers,

[RB (Andrew)]

I agree, it certainly is a great result and well worth the extra effort in technique.

[gbeal]

Very nice Mike, and what a novel way to beat the manual filter change. I envisaged you changing the filter once the first colour had finished, not on the fly. Nothing wrong with these two, at all.

[Lester]

Hi Mike,

Very nice detail. You have taken to the DMK like a pig in mud.

[[1ponders] (Paul)]

Very nice Mike. Definately a step up from the ToUcam given the conditions.