Posts Made By: Alan Friedman

Hi Mike -

As long as you capture luminance data in short bursts (within two minutes or so) you have the option of preparing the data both for beauty and for analysis of saturn weather. I usually capture streams 1200 frames in length for saturn - and in a stretch of good seeing, collect a dozen or more of these. A spot such as the one in Jim's image will show up fine in an image made of 300 frames from one of these streams and a comparison of several over the course of a half hour will show some movement and confirm that the spot really exists.

Most of Saturn's features as observed from earth will be radial in nature and not harmed by averaging data over a longer period of good seeing. Averaging together a dozen 300 frame stacks captured over a half hour will still present a high resolution picture of the ring brightness variations, divisions and cloud belts.

Unlike with Jupiter, color data for saturn can be collected independently of luminance. To help the exposure, binning or imaging at a shorter FL can be used. You can even apply color data from a different imaging session within a week or so of the luminance without any noticeable effect on the final image.

best -
Alan

Hi Jim -

That's looking a lot better!

best-
Alan

Hi and hanks for your comments.

Normally the color streams of saturn in my 10" are too dim and grainy for me to use for luminance, but they were so nicely detailed on this night that I didn't have to process them much. Not sure if the luminance data I took will add any more information to the picture - but it will probably make it smoother, Will post an update when I get it finished.

By the way, my identification of the moons on this image is worng - it should read "counter-clockwise!"

best -
Alan

Hi Mike -


1) I found a significant problem, about 1/2 my frames have a lot of electrical noise in them.

It's been a few years since I've used a ToUcam - but noise at low light levels and high gain settings is a problem with all streaming cameras. Even in the DMK, dim frames will show a "rhythmic" noise that can confound the frame selection and stacking process - sometimes producing stacks that have a corduroy texture to them. Generally, you have to find settings that will feed your camera enough light to do the job.

2) I am wishing the Toucam ran faster (I am usually at 40 ms frames) so that it would get around the seeing better. I have tried shorter frame times, and the frames look sharper on screen. Unfortunately the image gets really noisy due to the loss of brightness.

I believe the ToUcam is constrained to 5 fps download speed for non-compressed data, regardless of the shutter setting. A firewire camera would help you here.

3) Looking through R,G and B channels, B looks awful, noisy, and quite a bit dim comparatively. Is this a Toucam sensitivity issue? Also, would the lesser color correction of the TEC160 ED versus (for example the fluorite version) be noticable in the quality of this blue frame?

No need for flourite - the blue channel will (almost) always looks awful - the effects of atmospheric turbulence on the image stability increase as you move from IR-R-G-B. Of course the deck is stacked against you as the potential resolution of the wavelength runs in the opposite direction with IR being the lowest and B being the highest. The better the seeing, the tighter the quality across the visual wavelengths - but with most subjects (Mars being the exception) I exclude the blue channel when working on the resolution of the image. One of the advantages of a monochrome camera is the ability to record these channels separately so you can isolate the sharper wavelengths for the detail component of your image.

Is this a "Buy an $80 webcam and get $80 webcam problems." story? How much would a Lumenera or DMK type camera go towards alleviating points #2 and #3 above?

The Lumenera or DMK (there are a couple of other choices as well) monochrome cameras offer a lot of advantage - higher resolution and sensitivity, better noise handling, faster throughput, better software - if you are thinking of doing this type of imaging more than on a casual basis you should consider the upgrade.

hope that helps -

Alan

What a great image! The transformation in the GRS since last apparition is startling - I look forward to seeing more of you images from this night.

thanks -
Alan

Hi Oliver -

A beautiful panorama - I think your DMK camera is happy on the moon!

best -
Alan

Hi Johannes -

An excellent result. The red filtered stream looks very good. At the current ring tilt it is not an easy matter to capture a sharp Cassini division in front of the planet.

thanks for sharing this nice image here.

best -
Alan

Hi Eric -

Very good resolution from your C9.25. I hope you have an opportunity to collect new data this spring. Nice to see a post from you.

best regards -
Alan

Hi Andreas,

Bravo - a great montage!

I wonder if Hyperion is in reach with a longer shutter? A little less than 1.5 magnitudes fainter than Mimas, I think.

Thanks for posting this nice picture -

Alan

Wonderful!!

Alan