Planetary Captures

[tyavfm]

Hi. Can anyone give me the basic camera and BYES settings for capturing Saturn and its rings in Planetary mode? I've been trying for three months to capture Saturn's rings but all I've been able to capture is a white blob. The rings are not showing up unless I use very long exposures like one minute or very high ISO, which blows out Saturn itself. And even with very long exposures and high ISO, the rings barely look like like rings. They are mostly blown out. I use an 8" SCT and either a 2x or 3x barlow or even 25mm eyepiece projection. But none of them are showing distinct rings of Saturn. Thanks.

[astroman133]

First, how are you focusing the telescope? Since the sky is all effectively at infinite distance you should critically focus on a star first, then slew to Saturn (or other target).

Second, Planetary images are very short exposures. If you are getting 15 LiveView frames per second, then the true exposure duration is somewhat less than 1/15 of a second, or 67 milliseconds. You adjust the brightness of the captured image by adjusting the ISO and exposure duration. Changes to the exposure duration do not affect the frame rate or the true exposure, but exposures less than 2 seconds do affect the brightness. Even so, captured images should appear very dark, until you stretch the stacked image. Do not overbrighten the raw images.

I hope this helps.

[s3igell]

As Rick says, your immediate issue is Focus.  And his suggestion of Focusing on a Star - select a moderate-brightness Star so you don't have to deal with Star Bloat - is the best trick.

Since you are using an SCT, make sure to select your Focus Star in the same quadrant as Saturn (to avoid any Mirror-Flop).

The Exposure parameters that you used for the image in your OP is just about right - the Rings will just BARELY show before Stacking.   This is as much because the Rings are Dimmer than the Planet's Atmosphere AND because for this year and the next few those Rings are almost exactly Edge-On to Earth.  The somewhat longer Exposure Times are required because you are Imaging at f20 or even f30 with your setup.