Question on using monochrome cameras

For those of you using high-speed monochrome cameras: When you image using separate LRGB filters, how long do you capture a sequence for? On Mars, for example, I currently capture up to two minutes and don't capture any more because of planet rotation. If you are capturing four separate streams. Do you cut your capture time in four? Must you also quickly switch filters between runs?

Just curious.

thanks!

Steve

Hi Steve. The rotation blurring will depend on your image scale - the larger your scale then the less time you have.

Each planet is different - for Mars, most of the visible detail is in the red channel, so as long as your red channel is ok then you'll get a decent image. So I calculate the length of time I can use, and then apply that to each channel - e.g. if 2 minutes was the limit then I would capture for 2 minutes on each channel for a total of 6 minutes. The green and blue channels will show a little bit of rotation but they are so low in detail anyway that it's not going to cause a problem.

I use a computer-controlled filter wheel, and it takes less than a second to switch filters. This helps a *lot* on planets like Jupiter where you only have about 90 second to complete a full run (30 seconds in each colour).

On Saturn, which rotates in about 10 hours, same as Jupiter, you have a choice - if you want to try and capture any cloud detail then you have to limit your imaging runs to about 90 seconds or so, on the other hand if you just want to capture a low-noise image showing smooth cloud bands then you can go as long as you like.

regards, Anthony