I increased PHD2 hysteresis. Wow!

[Stuart1971]

1 hour ago, vlaiv said:

For many cameras, native driver is optimized for high FPS and SNR in single exposure is not as good as with ASCOM.

Guiding is similar to imaging - you want the best data you can have and ASCOM is preferred method for long exposure imaging.

Another thing is that 8bit seems to be sufficient for guiding, but I've found that 16bit gives better results and it is much easier to get 16bit data from ASCOM (I can't choose 8/16 bit with native drivers in PHD2 on my camera).

Because level of bias / dark signal depends on gain setting. If one new exact e/ADU values for different gain settings - one could scale one dark to match the gain of another - but it is far simpler to do another set of darks and don't bother with all that gain stuff.

 

So if you have an ASI camera for guiding, with native driver selected, before you connect it in PHD click the settings button next to the connect button, and you will get a box that asks if you want 8 bit or 16 bit….works on all ASI cameras….

Also why would PHD select a star for guiding that was well saturated, with a flat top on the peak chart, yet the SAT label stays green…..?? 🤔 I had to lower my gain to 15% in PHD which is 60 gain setting in ASCOM driver, which seemed really low….is this normal….?

[vlaiv]

25 minutes ago, Stuart1971 said:

o if you have an ASI camera for guiding, with native driver selected, before you connect it in PHD click the settings button next to the connect button, and you will get a box that asks if you want 8 bit or 16 bit….works on all ASI cameras….

I was not aware of that.

If you look at screen shots of peoples PHD2 screens - you'll notice something - SNR is usually around 30-40 maybe 50 range:

That is indicative of 8bit camera. With ASCOM drivers - I'm getting much higher SNR - like hundreds (I don't have an image to show)

Another indicator is max star value found in star profile - it is usually around 100 or so for most people.

I get nice "16 bit" numbers with ASCOM driver:

I have no idea where that setting is - maybe latest version of phd2? In version 2.6.5 - it is not there:

[scotty38]

FWIW I just checked my figures at this moment in time and approx 51000 for peak and 127 for SNR.....

[Stuart1971]

1 hour ago, vlaiv said:

I was not aware of that.

If you look at screen shots of peoples PHD2 screens - you'll notice something - SNR is usually around 30-40 maybe 50 range:

That is indicative of 8bit camera. With ASCOM drivers - I'm getting much higher SNR - like hundreds (I don't have an image to show)

Another indicator is max star value found in star profile - it is usually around 100 or so for most people.

I get nice "16 bit" numbers with ASCOM driver:

I have no idea where that setting is - maybe latest version of phd2? In version 2.6.5 - it is not there:

Hmmmm, strange as I use the native ASI driver in PHD2, and I get signal to noise in the hundreds too, and I also get 16 bit star peak numbers also, so it’s nothing to do with which driver is used…..oh, and I use the “Saturation by max ADU in native driver also in latest PHD..🤔

Edited February 25, 2022 by Stuart1971

[vlaiv]

19 minutes ago, scotty38 said:

FWIW I just checked my figures at this moment in time and approx 51000 for peak and 127 for SNR.....

Are you using ASCOM driver or native one, and is there option to set 16bit vs 8bit in version of PHD2 that you are using?

[vlaiv]

Just now, Stuart1971 said:

Hmmmm, strange as I use the native ASI driver in PHD2, and I get signal to noise in the hundreds too, and I also get 16 bit star peak numbers also, so it’s nothing to do with which driver is used…..🤔🤔

Maybe it is the latest version of phd2?

[Stuart1971]

2 minutes ago, vlaiv said:

Maybe it is the latest version of phd2?

I use the very latest PHD2

[vlaiv]

I can't find anything related to this in phd2 change log ...

[vlaiv]

Just now, Stuart1971 said:

I use the very latest PHD2

I haven't updated mine, so will need to do it. Above screen shots are taken with earlier versions.

In any case - ASCOM was recommended due to default 8bit on native and ability to set to 16 bit in ASCOM - it seems to default to 16bit now for native as well, so there might not be benefit in choosing ASCOM with this version.

[Stuart1971]

3 minutes ago, vlaiv said:

Maybe it is the latest version of phd2?

I think you are confused, there is the option to use saturation by ADU in the native driver…this causes the figures to change to higher numbers….

[scotty38]

4 minutes ago, vlaiv said:

Are you using ASCOM driver or native one, and is there option to set 16bit vs 8bit in version of PHD2 that you are using?

ASCOM and set to 16bit in there I think. As mentioned above you can get to it from the driver set up area in PHD2

[Stuart1971]

I think we have moved away from my original issue, why does PHD2 choose a star that’s well over saturated and has no peak and is flat, yet the saturation label stays green, does not make sense to me, I had to reduce the gain down to 40 from over 200 on my ASI174m to get a peak on the star…