SharpCap Forums

Hi all. Sorry in advance if this is a foolish question. I’m about to take my first attempt next week at Deep Sky Imaging. To say I’m a Newbie at this would be an understatement. With that in mind the Smart Histogram seems like a golden tool for me to determine optimum exposure time on my new rig. Next week I am taking delivery of a new Redcat 71 WIFD, an AM5 mount and L-Ultimate filter (I live in a Bortle 8/9).

I currently own a Celestron Evolution 8 and ZWO ASI533MC. I plan on using that camera with the Redcat and an ASIair Plus. So my question is as follows:

Can I use the Smart Histogram using the camera while it’s connected to the Celestron C8 to determine my exposure times if I input the the same settings I would use in the redcat. My thought process was the smart histogram is using data from the sensor analysis done with the camera and the tools built into SharpCap so the scope it’s connected to (all settings being equal) shouldn’t matter? But I’m brand new so my opinion thoughts on this is worthless hence why I am here!

Does anyone know if I can make this determination while it’s on my c8 or it’s an absolute must that I connect to the redcat in order to figure out the best exposure time? Thanks in advance!

Hi,

the sensor analysis process and the data it produces is only influenced by the camera, not the telescope that you have it attached to (you can also do the analsis with a simple lens attached, or even with an open sensor). So, you only need to do the analysis once (or not at all if your camera is a popular one and SharpCap has pre-measured sensor data for it).

The smart histogram uses the sensor data, but also it uses a measurement of the brightness of the image background, and that *is* dependent on your telescope, so that part needs to be re-done if

* You change telescope
* You add/remove filters or barlow lenses or focal reducers
* You change camera (may have different sensitivities or pixel sizes)
* You move to a significantly different area of the sky that might have more or less light pollution
* different observing sessions that might have better (or worse) transparency or the moon contributing to light pollution levels

As an example, your Redcat is about f/5 while your SCT is f/10. With everything else unchanged, the sky brightness will be 4 times lower in the SCT than the Redcat due to the larger f-ratio, meaning SharpCap will recommend longer exposures when using the SCT.

cheers,

Robin