[HeavyT]

I'm imaging at f7.6, using an ASI1600mm cooled to -15C.

Taking 900s subs, I routinely clip at least the end of the histogram capturing Sii and Oiii. On Eta Carina I could almost properly expose Ha at 420s.

I like to try to capture faint nebulosity and I know I have the option of increasing gain from 139/15. But I haven't, because I don't want to lose dynamic range.

Perhaps it's desperation, but the thought occurred to me: dynamic range would be the exposure range between highest and lowest exposure. If these values are governed by the speed of your scope, then boosting all signal would increase both highest and lowest values - bringing my "lowest" value into the histogram properly.

So would lowest and highest be increased by the same amount in this situation, or do they get compressed closer together? Given that the scope is slower to begin with, so the photons have a harder time building up on the sensor.

Thinking about say increasing gain to 200 only. I know if I went to extremes with the gain, I'd lose range.

I know the best option would be to collect 3600s subs (I've seen tables with this recommendation for this imaging speed and gain setting), but gathering 75hrs on one target over shorter nights is not something I'm keen to do.

Anyone have thoughts or experiences to share on this?

Thanks and clear skies