It is my understanding firecapture uses the video stream to measure how the planet is drifting and send corrections to the mount directly. This is due to the short exposures during video capture so you can use two consecutive frames, measure drift and react accordingly. That process would likely not work for long exposures as you require. You will need two different cameras. Your mc90 would likely make a nice guidescope, provided you find a way to mate it to your main, imaging scope. The benefit with this approach is you can use the mc90 with a planetary camera and firecapture to guide and image the planet at the same time you use your main scope and long exposure camera to capture the intended target. Sort of a comparison if you will, or maybe an overlay or double exposure of sorts.
can’t wait to see what you get out of it. Planetary spectroscopy and narrow band imaging sound quite interesting to me.
Thank you very much for this explanation. I couldn't figure out how they could autoguide and image using a single camera. I figured if that was possible, no one would buy autoguiders or guidescopes. It only works for short exposures then, since it uses alternating frames for imaging versus guiding. Very clever to be able to do that, but since I want autoguiding for long-exposure planetary and Solar imaging, it won't work and I still need a guidescope.
I already own a 1000/90 MCT, but I need a portable tracking mount for eclipses, so was thinking to get the 90SLT plus AVX 700. However, with both a 1000/90 MCT and a 2700/180 MCT, I am concerned that the 1250/90 MCT might end up being redundant and perhaps useless if I can get the 127SLT instead of the 90SLT (1500/127 would be more useful as an intermediate MCT between 1000/90 and 2700/180). But if I can use the 1250/90 MCT as a guidescope for the 2700/180 MCT, then that would make purchasing a 90SLT plus AVX 700 more cost-effective, since I don't want to remove the dovetail bar from the 1000/90 MCT if I don't have to (this is my preferred 'scope for full-disc Solar and Lunar imaging with APS-C).
My primary concerns are mechanical, i.e. a) weight and b) length. I am thinking that the 2700/180 MCT plus the 1250/90 MCT on guide rings might end up being about 25 pounds (out of 30 pounds for the AVX), but not sure how well that will work for long exposures at 2700 mm of focal length. The other concern is that the guide rings would have to be clamped onto the MC180 dovetail bar, and I'm not sure if there is enough length on the dovetail bar for that. Otherwise a piggyback or side by side would be needed instead, which could increase the weight and/or flexure.
The alternatives I figure would be using a more traditional guidescope on the finder shoe, or a small refractor on guide rings, but I don't know if that would need to be Barlowed for planetary autoguiding at 2700 mm of focal length. For a native focal length longer than a small refractor but a smaller weight than an MC90, there is also a 700/60 MCT available from Omegon (only 1.3 pounds). Traditional guidescopes want a wide field of view and a fast focal ratio to find guide stars, but that shouldn't be necessary for on-axis planetary autoguiding (only one bright object in the center of the field of view).
I am assuming that the MC90 has to be on-axis with the MC180 for planetary autoguiding? I think the 90SLT dovetail bar is 1/4-20 threaded, so it could be piggybacked but without guide rings or a guidescope mounting, it won't be on-axis with the MC180.
My question about FireCapture though still stands: does planetary autoguiding with FireCapture work for the phases of Venus and Mercury? A shorter focal length would make them appear more pointlike, but might not be as accurate for guiding.
Edited by Nicole Sharp, 23 September 2021 - 09:41 AM.