So, I took my narrowband setup for a test drive, mainly to check what kind of exposure times I'm up against. Gear:
Sharpstar 61EDPHII 274mm F/4.5
Astronomik 6nm SHO filters
ZWO UV/IR cut filter
I followed my usual routine: slew to the target, auto focus, plate solve, all using the Luminance filter. So far so good. Then I switched to SII and fired up SharpCap in order to measure optimal exposure time using the Smart Histogram feature. I noticed that the test exposures were taking longer than what I'm used to see with my OSC, so I let it do its thing and went to grab something to drink. Half an hour went by and SharpCap has finished measuring. Optimal exposure time: 1700 seconds!!!! (115 gain)
SharpCap suggested 30 minutes as optimal exposure time at unity gain. Bare in mind that this is a Bortle 6 zone we are talking about. My regular AP site is Bortle 4, which translates to even longer exposures!
I guess my question is....is this normal? I cannot imagine being able to calibrate the amp glow properly with 30 minutes exposures. Hell, that's not even the biggest problem! Even with decent guiding and spot on polar alignment, 30 minutes will definitely be a stretch for my CEM25P.
Should I "trash" my Sharpstar and go for a f/2 lens in order to reduce the exposure time on my subs? That would also mean getting other filters, since the 6nm ones won't be suitable for f/2....
Any suggestions are highly appreciated!
Edited by nyx, 19 September 2020 - 06:49 PM.