[ZeroID (Brent)]

Bit gutted after what was supposed to be a brilliant night last night. Cool southerly blowing all day so air was clear and the CBD LP dome was minimal. Moon wasn't going to show till a lot later so setup with SONY on the LUNT and decided NGC253 was a starter despite being in the NNE. Added the Astronomik CLS filter just for good measure and took 25 mins at ISO 1600 and 30 mins at ISO 3200. Images looked excellent on the camera screen.
Guiding wouldn't work, couldn't find a star bright enough up there to lock onto but alignment is as perfect as I've ever had so it stayed put for over 100 mins just tracking.
Felt so good I stayed up till midnight and processed 110 x 30 sec frames with darks and flats. DSS looked good
Ok, there is an image but the TIF histogram is plastered up against the left side so tight that there is almost nothing left when I try to expand it.
I suspect the CLS as the culprit but for 55 mins I would have expected a lot more luminance, especially at ISO 3200. I can even get better results processing a single lo-res sample frame jpeg.
Unfortunately I don't think tonight is going to be as good otherwsie I'd be pulling the CLS filter out and just fighting the LP in processing.

Does a CLS (non CCD version) have that much effect on exposure times ?

On the good side I've got the Lunt and the 80 f11 all aligned so I can do visual checks and the seeing was good enough that once I was dark adapted I could just make out NGC253 in the 80mm. And it wasa nice night after all, 3 satellites, 2 meteors and some scan time with the binocs.