ASI2600 ASCOM Gain scale

buckeyestargazer

I have a question about the ASCOM driver for an ASI2600. The gain scale goes from 0-100. Is this an absolute number, meaning does gain 100 in the ASCOM driver = true camera gain 100?

Or is the ASCOM gain scale a sliding scale where gain 100 = true camera gain 450?

jwaters125

Very good question buckeyestargazer. I have the same issue / question. IMHO the ASCOM device driver needs to upgraded so the Gain scale (0-100) maps to the Read Noise, Dynamic Range, Full Well ...etc vs. Gain plots (0-450) on the ZWO website.

I posted a question about this and ZWO has not replied....

jwaters125

FYI - An email exchange I got from somebody. It looks like a gain of 22 using the ZWO ASI Driver equals 100 on the ZWO Dynamic Range, Full Well, Read Noise vs. Gain Plots. I am setting my gain to 22. Now I only need the clouds to go away.

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Thanks for the fast reply. I want to make sure I understand. The ZWO ASCOM ASICamera Setup V 6.0.x driver has a Gain scale that goes from 0 to 100. The Read Noise / Dynamic Range / Full Well …etc vs. Gain plots for all cooled camera’s on the ZWO website go from 0 to 450.

Are you saying that when I set the Gain on the ASICamera Setup driver to 100 (Max) it corresponds to a Gain of 450 on the ZWO website?

That is correct, depending on the software, if the range is 0-100, 100 is equal to 450.

If you are using SharpCap for example, the range it shows is 0-450. The term unity gain can also be set from this point.

The ASCOM driver has no direct access to the hardware and relies on ASCOM itself to report the setting hence why you only see 0-100

buckeyestargazer

jwaters125 wrote:

FYI - An email exchange I got from somebody. It looks like a gain of 22 using the ZWO ASI Driver equals 100 on the ZWO Dynamic Range, Full Well, Read Noise vs. Gain Plots. I am setting my gain to 22. Now I only need the clouds to go away.

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Thanks for the fast reply. I want to make sure I understand. The ZWO ASCOM ASICamera Setup V 6.0.x driver has a Gain scale that goes from 0 to 100. The Read Noise / Dynamic Range / Full Well …etc vs. Gain plots for all cooled camera’s on the ZWO website go from 0 to 450.

Are you saying that when I set the Gain on the ASICamera Setup driver to 100 (Max) it corresponds to a Gain of 450 on the ZWO website?

Reply

That is correct, depending on the software, if the range is 0-100, 100 is equal to 450.

If you are using SharpCap for example, the range it shows is 0-450. The term unity gain can also be set from this point.

The ASCOM driver has no direct access to the hardware and relies on ASCOM itself to report the setting hence why you only see 0-100

Thanks for posting this Jim. But how do you know that the ASCOM 22 = camera gain 100?

Great, now I need to retake my darks!

jwaters125

I ran Nebulosity 4.4.1. I connected to my 2600 and played around with the Gain settings. Nebulosity Gain scale goes from 0 to 450. I set the Gain to 450 and the Nebulosity % indicator indicated 100%. I then set the Gain to 100 and the % indicator indicated about 21 / 22%. I may use 23% just to make sure.

I am still waiting on a reply from ZWO...

http://www.stark-labs.com/downloads.html

The e-mail text above was from Woodland Hills Camera & Telescope.

buckeyestargazer

OK, please let me know what ZWO says or post it here so I see it.

buckeyestargazer

jwaters125 wrote:

Are you saying that when I set the Gain on the ASICamera Setup driver to 100 (Max) it corresponds to a Gain of 450 on the ZWO website?

Reply

That is correct, depending on the software, if the range is 0-100, 100 is equal to 450.

If you are using SharpCap for example, the range it shows is 0-450. The term unity gain can also be set from this point.

The ASCOM driver has no direct access to the hardware and relies on ASCOM itself to report the setting hence why you only see 0-100

I have done some testing and measuring using PixInsight's BasicCCDParameters script and the above information is NOT correct.

My tests show that Gain 100 in the ASCOM driver = Gain 100 on the camera, but some of the numbers don't make sense when compared with the published plots by ZWO.

Test 1 - ASCOM Driver Gain=0

Read Noise = 3.469 e-

Full Well = 50,109

Dynamic Range = 14,443

Test 2 - Ascom Driver Gain = 23

Read Noise = 3.375 e-

Full Well = 38,235

Dynamic Range = 11,329

Test 3 - ASCOM Driver Gain=24

Read Noise = 3.347 e-

Full Well = 37,514

Dynamic Range = 11,209

Test 4 - ASCOM Driver Gain=25

Read Noise = 3.36 e-

Full Well = 37,301

Dynamic Range = 11,101

Test 5 - ASCOM Driver Gain=30

Read Noise = 3.344 e-

Full Well = 35,349

Dynamic Range = 10,572

Test 6 - ASCOM Driver Gain=100

Read Noise = 1.483 e-

Full Well = 16,274

Dynamic Range = 10,973

If ASCOM driver gain 100 = camera gain 100, then the read noise and full well looks right, but the dynamic range is really low compared to what ZWO says it should be.

I really don't know what to make of this. I think it is silly that the system driver would have a gain range from 0-450, but the ASCOM driver is 0-100. This makes it very confusing and means we have to "guess" where the magical Gain 100 really is.

buckeyestargazer

OK, so I've learned that the Dynamic range numbers above need to be converted to Db or stops. If I do that with ASCOM gain =100, then the dynamic range is 13.46 stops, which is consistent with ZWO's numbers as well.

This means that ASCOM gain 100 = camera gain 100 (NOT 450 like the ZWO reply above said).

This kind of confusion would easily be avoided if both the ASCOM and system drivers used the same gain scale 0-450.

chad

Wow, why do you think so? it is strange～

For 2600 in ASCOM, setting 100 is set the gain to 100, it is not a percent. So it is not 450.

In another word, in ASCOM, you can set the gain range is (0-100), but in SharpCap or ASICap, the gain range is (0-450).

Why we do not support 450? Because when you set gain to 100, the readout noise has reached a lower level. Increasing the gain does not significantly improve the read noise. You can find it in the camera's description, but the DR will reduce.

Thanks

Chad