2600mm pro - bias frames or darkflats, gain 101?

The purpose of taking darks is not to reduce random thermal noise, which is impossible to eliminate, but repeatable non uniformity in the baseline value of pixels ( mean dark current pattern or signature). All sensors, whether they have amp glow or not, benefit from this. You don’t need to take bias frames for CMOS cameras unless you plan to scale your darks. You can simply calibrate your lights and flats with darks taken at the same time and temperature, as it appears you did for the 1600.

With respect to the dynamic range - remember that the dynamic range at gain 100 is achieved by reducing noise but also by substantially reducing full well capacity. Gain 0 allows you to use the complete full well capacity of the sensor. The noise difference - 3,5 versus 1.5 - is not a major concern. Read noise is very rarely the major source of noise at these levels unless you are using short exposures. 

Also- it is fine to calibrate your flats with just a bias, as long as your flats are short in duration (won’t work for the 294MM but probably fine for the 2600). When people say dark flats are unnecessary- they are basically making an assumption that the mean dark current is small for short exposures. When you take dark flats, you don’t have to make that assumption.

Arun H:
With respect to the dynamic range - remember that the dynamic range at gain 100 is achieved by reducing noise but also by substantially reducing full well capacity. Gain 0 allows you to use the complete full well capacity of the sensor. The noise difference - 3,5 versus 1.5 - is not a major concern. Read noise is very rarely the major source of noise at these levels unless you are using short exposures. 

Also- it is fine to calibrate your flats with just a bias, as long as your flats are short in duration (won’t work for the 294MM but probably fine for the 2600). When people say dark flats are unnecessary- they are basically making an assumption that the mean dark current is small for short exposures. When you take dark flats, you don’t have to make that assumption.

It's not true Arun, I have the 294MM and work perfectly also with 30/40s of flat (SkyFlat).
Darkflat was necessary with old CMOS cameras having really bad changing of pattern related to the time used for flat .. this is something true for the 1600 sensor or old DSLR .. not for the latest CMOS sensor and especially for the 16bit.

At a minimum, flats.  I do darks, dark flats, and flats for calibration.  I don't see a need for bias since with cooled cameras you can take darks for the specific temperature.  For the target temperature, depends on ambient temperature.  I try to keep the cooler at 80% power or less.  Might push to 90% in the summer with the assumption that it will cool down overnight.  You want the cooler to be active, else you'll get more variation in the sensor temperature.  For gain, I run either 0 or 100.  I try both on any setup to see what exposure times are like.  It's possible I might go gain 0 if the subs are very short for gain 100, typical for L filter, sometimes also for RGB filters.  For 100 vs 101 gain.. run the camera through SharpCap sensor analysis and see what it tells you.  I had an ASI533MC I ran at gain=101 not "just in case" but because the analysis for my specific sensor recommended 101.  HCG kicks in at 100.

In my limited experience and from previous discussions a few years ago about this,  I've found that Bias frames don't work well with CMOS sensors.   They're more well suited for the older CCD cameras which are becoming few and far between now.   In addition to taking darks and flats,  I exclusively use Dark flats for calibration of the flats and I'm very happy with the results.  I don't bother with Bias at all.

CS,

Patrick

I only take Flats, and calibrate with Bias frames. Seems to be doing fine. 

As to the temperature question, it depends on your skies. For most locations with light pollution, anything less than 0 has no significant benefit. This presentation sheds a lot of light on some of your questions and is highly recommended. 

https://www.youtube.com/watch?v=3RH93UvP358

The essence from that discussion is, broadband go for gain 0, narrowband with a fast scope go with 0, narrowband with a slow scope = 100.

There is rationale for that recommendation, which is a sensible one. For narrowband, with a slow scope, there is the possibility that you simply are not getting enough sky background shot noise to overwhelm the read noise, even as low as it is. It is much less of a concern for broadband/faster scopes.

The key purpose of my post was to highlight the great benefit of the IMX 571 sensor - which is that, in many cases, you can use the complete full well capacity of the sensor by operating at Gain 0, and do so with very little or even no penalty. This is not something you could do with older sensors - where you had to worry about things like banding at low gains, the only way to get rid of which was to operate at higher gains to reduce the amount of sky background noise you needed to overwhelm the banding.

I stick with the old protocols of darks, flats, and bias and haven’t seen a reason to change. 

Also, the camera gain goes to 300. I have good results at that level, too. Some dim targets benefit nicely. I try to use 100 gain most of the time, but will go to 300 for filters like the Triad Ultra, which lets so little of the spectrum through. 

With enough subs (and dithering), there is little difference in  the quality of final images at any gain level on the 2600. 

we have CMOS sensors to thank for such versatility. 

the point is: if you aren’t a scientist and just want to make beautiful Astro-art, use all available settings any way you want to get the results you want. You will be rewarded.

Poll created… Still much confusion, I get different answers..

Jonny Bravo:
You get different answers because this is one of those topics that's eternally debated. You've got staunch supporters on both sides of the argument. Coke or Pepsi? Tastes great or less filling? Dark flats or biases? These things may never be answered

agreed

@Daniel Renner try both and choose your best

Jonny Bravo:
You get different answers because this is one of those topics that's eternally debated. You've got staunch supporters on both sides of the argument. Coke or Pepsi? Tastes great or less filling? Dark flats or biases? These things may never be answered

What Johnny said 

Also, I don't understand the point of polls. Everyone will have a different opinion. Should you weight their opinions equally? Better by far to do a search on those using the 2600 MC or MM (easily done on AB), find someone whose images you like and you feel like they know what they are doing, and ask through a PM. This is what I did when I wanted to learn how to collimate my Newt. There are a dozen different ways, a poll will give you a dozen different opinions, each equally convinced they are right.