6 replies to this topic

[msamazing]

I am wondering if anybody knows baseline recommendations when using the ASI2600 mono Duo camera for broadband and narrowband.

 

Thank you in advance. 

[bobzeq25]

Depends on the optical speed. But a good start is gain 100, where the low read noise kicks in.

https://www.zwoastro.../asi2600mc-duo/

Offset can be set by test bias exposures. Set offset to zero, shoot a bias, look at the histogram.

See how the lefthand edge of the curve is truncated by the lefthand axis? THAT'S what you want to avoid.

Increase offset until you can just barely see a gap between the curve and the lefthand axis. That's your minimum offset.

Increase it just a bit to be safe, a little excess offset is of no consequence. Truncating the curve is a big deal, you need every last bit of the bias data.

Edited by bobzeq25, 08 December 2024 - 06:50 PM.

[idclimber]

You can use gain `100 for both. The only other gain I sometimes use is 0. The former is the standard setting I recommend for most. The main reason to use gain 0 is if you want longer exposures and you plan lots of exposures. This gain allows for about double the exposure and as such will have less files. You need really good tracking and enough subs for rejection. 

 

The classic place for longer exposures is with a RASA at f/2 were 30" can often be too long. Moving to gain 0 helps and gives you less files to deal with. 

 

Offset is simply a value added to the raw data. If you follow Bobs test you will find that at an offset of 0 many pixels will be at zero, especially on the dark and bias. That is not good and will negatively affect your calibration. 

 

On the ASI2600 cameras an offset of 50 will add 500 ADU counts to each sub frame. This is on a 16 bit file that has possible values up to 65k. An offset of 50 is also the default. There is little reason to change this to something else. 

 

That said, I personally use an offset of 30. I do however know how to monitor for zero values and do so when processing. I do not recommend this unless you wish to learn the same. I am also fluent in manually pre processing images and do so often when I help others with calibration problems here at CN. 

[msamazing]

If I understand correctly, you are using the same setting for narrowband vs. broadband?  I ask because QHY recommends different gain and offset settings as a guide for their camera.

[idclimber]

If I understand correctly, you are using the same setting for narrowband vs. broadband?  I ask because QHY recommends different gain and offset settings as a guide for their camera.

QHY more modes you can implement with this sensor. Gain 100 on the ZWO isn't the same as on QHY. 

[Stewww]

https://youtu.be/mCY...A8dISqNWhqiyf_s

 

Watch this guys channel! 

 

I took info from this video and applied it to my ASI2600MC Duo and found at the recommended offset of 50 my min pixel value was till way above zero.

[PIEJr]

You shouldn't compare a QHY to an ASI. That's like comparing Banana's to Apples.

That said, I'm presently using 100, and 35 as my Gain and Offset and they seem to be working great for my ASI2600MC Pro.

No duo here.