This can be a rather complex topic, but in short: yes you will want to adjust settings compared to your other setups.
Shooting at f/2 will saturate your camera's pixels 10 times faster than at f/6.3 and 25 times faster than at f/10. As such (and assuming filters, etc. all remain equal) you can simply reduce your exposure time by a factor of 10 and receive an equivalently exposed sub. Alternatively you can drop the gain to increase your pixels full well depth which will increase how long you can expose for before saturating pixels. The 585 has most dynamic range at 0 gain (~12.5 stops), and that drops to ~11 stops at the high gain conversion (unity gain is actually 198, but that's a different story and probably not what you're after).
Ideally you want to expose for as long as you can without clipping any data. An easy way to check for this is to look at your images without stretching. If you can make out obvious stars then you're probably clipping and losing data on and around your stars.
Based on your gear & location your minimum exposure length at 252 gain is around 1 second (anything above that will swamp read noise just fine). For 0 gain your minimum exposure time is 24 seconds to swamp read noise.
Assuming your current images are exposed well, there's 2 things you can try.
- Drop exposure time by 10 / current exposure time and keep gain at 252.
- Drop gain to 0 but keep exposure time at the same 1-5 minutes.
Both of these will continue to swamp the read noise and sky glow. You can of course increase exposure time as you see fit from the above mentioned, just check for clipping in stars.
