a bit ambarrassing is I don’t keep the camera chip very clean, and my mount tracks quite well, so you see there is dirt on my final image.

here reply Nico’s questions,

1. I used DMK21AU04.AS, with Atik electric filter wheel and Baader LRGB filter set, but only later on I found L channel is not neccesary. I use a IBM Thinkpad X60s notebook computer to capture the image, and write the video onto a mobile hardisk in real time, that’s a Buffalo 500G hardisk with Turbo USB connection, very good speed that everything captured by the camera, even at 60fps, is able to write onto the hardisk in real time.

2. I used a 12mm TMB Supermonocentric eyepiece, the image is taken through eyepiece projection >5x, so the overall effective focal ratio is ~f40. Of course TMB Supermonocentric eyepiece is famous or it high definition and contrast, but I have no preference on eyepiece projection over barlow, the only reason I use this approach is I can zoom the Jupiter until the image scale reach certain optimum parameter, i.e., 1/30 exposure, 30fps, full histogram range on L channel when I set the gain at 800, and ~180 for R, G, and >128 on B when I push the gain to 1023. So that I need not change anything else when taking hundred RGB video without any mistake.

3. Only 400 frames out of 600 frame per RGB channel is stacked, because I want to control everything within 1/30sec exposure and maintain 30fps, so the gain is quite high. As I though L channel will be very clean so my plan was to rely on that. But later on I found L channel actually do harm to the final image quality, especially Jupiter is below 50 degree so we can’t solve the atmospheric aberration from a mono image. If I do it over the next time, I will shrink down the image scale a bit, set the gain lower, stack may be 400 frames out of 800, and I will get a much smoother image.

4. I don’t have a quantifiable rating, but I would say it’s 8 to 9 out of 10. Usually in Spring or Summer, and if the location is right (e.g., sea side), we will enjoy may be 2 or 3 nights a month on such seeing. One month prior to this imaging night we got a more stable night, we barely detect the surface features on Ganymede under this 203mm APO refractor at 500x, an good quality 450mm Dobsonian aside deliver not better resolution, but a bit higher contrast, at the same time image is a bit less stable than the view from APO refractor. The seeing on this imaging night is actually a slightly bit worse, transparency about the same, but strangely, I can easily see the surface feature on Ganymede under 500x, it’s like a dark belt running across the disk. So if I rate my own image, I just capture what’s seen from my telescope, that’s all….

cheers,
Savio Fong
http://hk.myblog.yahoo.com/galaxyscientific

My congretulations with these excellent images of Jupiter. In particular the numerous details in the cloud belts and zones. Most striking are the surface details on Ganymede. I have four questions:
1. Which camera did you use?
2. Which type of Barlow lens did you use?
3. What has been the number of frames used for the AVI’s?
4. Can you quantify the seeing during the recordings?
Thanks in advance for the answers!
My best regards,
Nico

D Simpson.