Jupiter + GRS - 18th April UT

[iceman]

Hi all

This image was taken yesterday morning, 02:52 local time in variable seeing. The GRS is just about at CM, and shows the dark grey material on the West side of the GRS. The white spot leading the NTB outbreak is just past the CM.

The seeing started off horrible at 0130 (3/10 at best) but slowly improved over the next 1.5 hours until it was about 6.5/10 when I packed up at 3am.

I left the scope and laptop setup (while ppmcentre crunched away) and went back to bed, and came back out at 0530 to try and capture Mars before dawn, but a thick fog had rolled in and I couldn't see any stars - let alone a dim Mars in the East. Oh well, maybe next time.

12" newt on EQ6, DMK21AF04 + 5x powermate. 100% gain, 18 gamma, 40 seconds on each channel @ 30fps (1/30s exposure). 500 frames stacked in each channel.

Thanks for looking.

[andyschlei]

Awesome as usual Mike.

I really need to take the time and learn your R/G/B separate method (with PPMCentre) since you really get excellent results.

[iceman]

Hi Andy.

Thanks for your feedback.

Is it possible to upload one of your better avi's (of whichever planet)? I can have a go at processing it using my methods, and you can see whether it's better or worse..

Or send me a CD/DVD etc?

[andyschlei]

Hi Andy.

Thanks for your feedback.

Is it possible to upload one of your better avi's (of whichever planet)? I can have a go at processing it using my methods, and you can see whether it's better or worse..

Or send me a CD/DVD etc?

Mike,

That would be great! I'll put an AVI up tonight (Los Angeles time) that you can get through anonymous FTP.

--Andy

[iceman]

Thanks Andy. Depending on its size, I can give you details of the IIS FTP site to upload it to - if you don't have enough ftp space.

[andyschlei]

Mike,

I uploaded the AVI of the shot I posted back on April 2.

After a 45 minute upload of the ~165mb file it is available at (following to guarantee serious processors)
ftp obsballona.net
get the file:
Saturn f30 070331 02.zip

And private e-mail at andy.schlei at obsballona.net

Thanks Mike!

--Andy

[iceman]

Thanks Andy, I've grabbed it.

Can you tell me the scope + camera you used, plus the capture settings?

[andyschlei]

Thanks Andy, I've grabbed it.

Can you tell me the scope + camera you used, plus the capture settings?

Mike,

Sorry for the late reply, I've been out of town at a conference for work.

I used a C-11 at f30 (Televue 3x Barlow) for an effective focal length of 8400mm. The camera is a Phillips ToUCam Pro.

Unfortunately, I don't have the exact settings on the exposure. I had set it to 640x480 format, and then adjusted the exposure so it looked decent. Probably 15 frames per second (that is default, but I think the Phillips controller does not report it accurately) and the exposure setting at 1/25 of a second with gain at about 75-80%.

I'm looking forward to see what you can do with the data!

Clear skies,

--Andy

[iceman]

Hi Andy

I'm more interested in the other capture settings - it looks to me like you had the in-camera sharpening on?

You have a nasty dead pixel on your camera, and there's a black ring around it which usually means there's some sharpening occurring already, even in the raw frames. The cassini division also looks sharper than I would expect in the raw frames, again leading me to believe the sharpening is already set in the capture settings.

Here's my result - you can see the dead pixel has even made its way onto the final stack, as the blurred line in the top of the image. You should try to keep the planet moving so it doesn't show up in the final stack, or get a new ToUcam or a DMK.

The blue channel was also terribly messy and noisy, much worse than it should've been given the altitude and seeing conditions.

The potential is there for a very good image. Keep at it!

[andyschlei]

Hi Andy

I'm more interested in the other capture settings - it looks to me like you had the in-camera sharpening on?

I could not find that setting. I have attached screen captures of all the settings I could access for the camera. As far as I know, it is not sharpening, but I defer to your greater knowledge.

You have a nasty dead pixel on your camera, and there's a black ring around it which usually means there's some sharpening occurring already, even in the raw frames. The cassini division also looks sharper than I would expect in the raw frames, again leading me to believe the sharpening is already set in the capture settings.

Yes, it turned up on this specific imaging session. I think I killed it with my air blaster by letting the propellant freeze the ccd.

Here's my result - you can see the dead pixel has even made its way onto the final stack, as the blurred line in the top of the image. You should try to keep the planet moving so it doesn't show up in the final stack, or get a new ToUcam or a DMK.

The blue channel was also terribly messy and noisy, much worse than it should've been given the altitude and seeing conditions.

The potential is there for a very good image. Keep at it!

Thanks for taking the time -- it is a very nice result.

I do think it is time for a new camera. The DMK looks interesting, a bit more expensive, and requires FireWire. Time for a little review reading...

Thanks again Mike!

--Andy

[iceman]

hmm it must be the Toucam 900nc I'm thinking of, that has a "sharpening" control.

Looking at your other settings, I'd never use more than 10fps with the ToUcam, otherwise you're getting nasty compression. I'd also set the gamma to around 50% and saturation near maximum.

The DMK does require firewire, but my laptop didn't have it either. You have to get a PCMCIA firewire card, and a 240v powered firewire hub. Not to mention the filterwheel + filters.

So it's definitely more expense, but it's a much better camera and your results will significantly improve.

There's a lot of threads on IIS about what you need to get a DMK up and going. Good luck!

[andyschlei]

Looking at your other settings, I'd never use more than 10fps with the ToUcam, otherwise you're getting nasty compression. I'd also set the gamma to around 50% and saturation near maximum.

The 15fps is the default. I actually found the control for fps on Friday night (after 2+ years with the camera ) and tried some Moon shots at both 30 and 10 fps. I was thinking that a higher frame rate would be better because each image would have less distortion from seeing changes over time. Is that not the case?

If it is clear tonight (I'm not hopeful) I will try the gamma and saturation changes.

The DMK does require firewire, but my laptop didn't have it either. You have to get a PCMCIA firewire card, and a 240v powered firewire hub. Not to mention the filterwheel + filters.

At the ImagingSource website I saw they have color cameras as well. Are the results better with black and white? How do you deal with things like Jupiter's rotation (which IIRC can cause problems at the range of 90 seconds or so)?

There's a lot of threads on IIS about what you need to get a DMK up and going. Good luck!

I'll take a look. BTW, the beanie arrived and it's top notch!

Clear skies,

--Andy

[iceman]

The 15fps is the default. I actually found the control for fps on Friday night (after 2+ years with the camera ) and tried some Moon shots at both 30 and 10 fps. I was thinking that a higher frame rate would be better because each image would have less distortion from seeing changes over time. Is that not the case?

In theory, yes, the higher frame rate is better because you have more chance of capturing good frames and more frames to choose good ones to stack.
However the ToUcam is only USB1.1 and so it has to compress the data to shove it down the pipe. The higher the frame rate you use, the more it has to compress. So you get compression artifacts as a result.

If you have a USB2 or firewire camera, then these can do 30fps uncompressed, so with these cameras (like the DMK21AF04) you DO want to use as high a framerate as possible.

Unfortunately it's just not the case for the ToUcam. I'd never go above 10fps.

At the ImagingSource website I saw they have color cameras as well. Are the results better with black and white?

The colour range of cameras are good in that:
a) You still get uncompressed data so you can use high framerates
b) It's cheaper and more simple because you don't need to worry about capturing individual colour channels and recombining them.

However the monochrome camera will give better images, and here's why:
1) The colour camera uses a bayer matrix to give you the colour. So the chip is broken up into capturing 25% red, 50% green and 25% blue data. So effectively you're only using 1/3 of the resolution in each colour channel.
A monochrome camera, in combination with R,G,B colour filters, means you're using the whole 640x480 resolution in each colour channel. So you'll get a more detailed, smoother, higher resolution image as a result.

2) The colour camera captures all 3 channels in 1 go. You can't refocus each colour channel, and you can't change the capture settings for each colour channel.

In practise, each colour channel can sometimes require an ever-so-slightly different focus position. So with monochrome+filters, you can refocus between capturing, ensuring you get sharp focus with each channel.

Also, the monochrome+filters allows you to change the capture settings for each colour channel. The blue channel is usually dimmest, so you can raise the gain to ensure that each channel has the same exposure and fills the histogram.

While capturing a "colour" image is quicker, easier and cheaper, in practise I also ended up processing the "colour" avi as 3 separate R,G,B images, using the techniques described in my Planetary Imaging and Image Processing article.

So the processing side is no different with a monochrome camera. You capture 3 runs (R,G,B) and process them independantly, recombining them into a colour image after they've each gone through registax.

How do you deal with things like Jupiter's rotation (which IIRC can cause problems at the range of 90 seconds or so)?

It can be a problem, with Jupiter you have to be quick. However it's not limited to 90 seconds. I regular go for 2 minutes, or 2.5 minutes, at over 10m focal length.

The length of capture time allowed on jupiter depends on your focal length. Higher resolution (longer focal length) images will need to capture for a shorter time than someone imaging at only 5m resolution (for example).

With RGB imaging, each capture run lasts only 30-40 seconds, with approx 10 seconds in-between for filter change/re-focus/change settings. So each colour channel in itself doesn't have any rotation, but when you recombine/re-align the channels into a colour image, the blue channel has "rotated" when compared to the red. In practise, this means you simply have to shift the green channel 1 or 2 pixels to the right, and the blue channel 2 or 3 pixels to the right to ensure the features are lined up in each colour channel.

With a colour camera (ToUcam, DFK), limiting to 90 seconds is probably wise if you're using a long focal length, because you could be stacking frames together from the start and end of the run, which may have rotated and will cause some blurring if registax doesn't shift them to the right when aligning. I guess it may depend what feature you're aligning on in registax.

I wrote a comprehensive post on LRGB imaging here on IceInSpace in response to someone's question. It contains similar info to what i've posted here plus a bit more.

I hope I've been helpful.

BTW, the beanie arrived and it's top notch!

Glad to hear it

Thanks

[andyschlei]

Unfortunately it's just not the case for the ToUcam. I'd never go above 10fps.

I'll look at the two different versions of Plato I took the other night, one set at 30 fps the other at 10. That could show a difference.

<snip> It can be a problem, with Jupiter you have to be quick. However it's not limited to 90 seconds. I regular go for 2 minutes, or 2.5 minutes, at over 10m focal length.

I've been shooting at 8.4m and 11.2m focal length. So it sounds like I could work with a black & white camera and filters...

I hope I've been helpful.

Very helpful Mike, as always. Thanks!

Clear Skies,

--Andy