ZWO 2600MC Duo:Sensor Analyses and SharpCap Gain

[Brian1973]

I recently purchased a ZWO 2600MC Duo. I conducted a sensor analyses and it revealed that a Gain of 100 is optimal.

Issue- When I set the Gain to 100 in SharpCap all of my images appear black as if the cover is on the OTA. After experimentation, I found that I have to set the Gain at a minimum of 500 for any image to appear. If I goto 700, the image is completely White. Per ZWO Spec sheet (see attached), a gain of 500 severely diminishes dynamic range and other specs are compermised.

I had this same issue with my AA26C after updating SharpCap. I am not sure when this update occurred, it was several updates ago, but all the Gain levels appeared to drastically change. For example, with my AA26C I used to set the Gain at 100 for broadband and 200 for Narrowband, now, I have to set the Gain nearly 400 to 500 for broadband and well into the 800's for Narrowband.

I tried locating documentation on why the Gain levels were drastrically altered but could not locate any information.

Two questions- Does a Gain of 100 now equate to 500- in otherwords, is there a table that crosswalks old Gaion settings to ShaprCaps new Gain system?

Second question- where do I locate information on ShaprCaps new Gain system?

Kind regards

Brian

[admin]

Hi,

Nothing has changed in the way SharpCap works gains, however, it's important to note is that the way the gain values work is different for ZWO and Altair cameras.

Altair Cameras:

Minimum gain is 100, a gain value of 1000 means that the image is 10x brighter than it would be at minimum gain, 2000 is 20x brighter and so on

ZWO Cameras:

Minimum gain is zero. a gain value of 200 means 10x brighter than minimum gain, 400 means 100x brighter, 600 means 1000x brighter.

Because of this difference, you can't transfer gain values from one brand to the other. If you hover the mouse over the gain slider in SharpCap, it will show a number like '4.56x', indicating that the currently selected gain is brightening the image by 4.56 times over minimum gain - those values are comparable, but the gain numbers are not.

So, looking at your figures for the 2600MC Duo, if you are setting gain 500 to take visible images then that (compared to gain 100) is brightening the image by about a factor of 100. If you went back to gain 100 and set your exposure 100x longer then you should get a similar image.

It's not really possible to comment on whether what you are seeing is an issue because we don't know the exposure you are using, or the f-Ratio of your equipment, or what you are imaging - all of those also feed into the brightness of the image on screen.

cheers,

Robin

[Brian1973]

Thank you Robin-

Your explanation regarding the difference in how Gain is handled between the two cameras is very helpful as it help me to better understand how to interpret the numbers. I have taken a screenshot of your explanation and added it to my field notes as a reference.

Thank you again,

Brian