I'm having difficulties with a RASA 11 V2: even smaller stars seem to be clipping.
I'm new to the RASA, and I'm still trying to get a feel for her. I started by using the fantastic Celestron RASA LPR filter and an ASI294MC-Pro. The filter was not very necessary at my dark-sky site (Bortle 4), and it physically interferes with the flatness of my image train when using the Baader UFC system, so I removed it. I also switched to the ASI183MC-Pro. I feel like both these changes were a step in the wrong direction: I'm letting in more light (30s exposures vs 3m), and the full-well depth of the ASI183MC-Pro is only 15k.
After astronomical darkness settles, I run through the SharpCap Smart Histogram feature to estimate the subframe exposure length and gain for a 5-hour set. I typically get around Gain 120 and 31 seconds, which I round to my standard settings of Gain 139 and 30 seconds (I know, that's not linear for both settings but G139_30s is what's in my dark library).
That has been yielding frames where many stars are clipping (as seen in PixInsight after stacking). See attached.
Ordinarily I would reduce exposure length and/or gain... but something strange, I seem to loose more of the nebulosity than I save in terms of star clipping. I need to play more with this.
I'm wondering what the best course of action is.
- I could switch back to the ASI294MC-Pro, but it's under sampled with this OTA.
- I could find a new camera, but Santa isn't likely to bring me an ASI6200MC-Pro, and I like my kidneys.
- I could figure out how to get the Celestron RASA 11 LPR to work with the Baader UFC (or get an image train custom-engineered for OSC use).
- I could buy a filter for the Baader UFC filter drawer, but didn't want the expense of a 50mm square LPR filter when I already have a great one with the RASA.
- And as I said above, I could figure out what's up with shorter exposure times even with more subs.
To make matters worse, I'm planning on heading to two Bortle 1 zones over the next two months. I need to have this worked out by then.
Anyone have any "handling" insight for the RASA?