Live Stack changes exposures on the fly

[ChrisR Oz]

Hi Robin,

A strange one for you. Using Live Stack as usual using 60s exposures for a few hours. I notice that the exposure changed at some point. Perhaps it "returned" after the 2s frames while dithering to something new. Checking back in the log, over a couple of hours it changed a few times.

Attached is the log (chopped out a bit to get it under 1 MB). From a time of 20:22:48.969813 it suddenly switches from 60s to 71352.427 ms. Then at 20:25:26.740057 it switches again to 84852.814 ms. Then at 21:44:31.831896 it switches to 100907.57 ms. I only noticed it on one of my last frames as I was preparing to quit with heavy dew. These times are still usable, as with the ZWO 2400 MC Pro I don't use matched Darks anyway.

I enabled logging camera commands around 22:26, so it only got about 12 minutes with this on.

SC v4.1.14247. Setup is as in profile below (ZWO camera, iOptron mount, PHD2 running using ZWO camera, mount and SX AO). It's now on a new W11 laptop, after transferring settings from the old one.

Cheers, Chris.

[admin]

Hi Chris,

the size of the steps exactly match what would happen if you increase the exposure using the 'F2' keyboard shortcut, so it seems likely that the F2 key was pressed a total of 3 times while the stacking was going on. Something similar could happen if you had most recently clicked in the exposure control and then pressed the left/right arrow keys, as in that case the left/right keys are keyboard shortcuts to adjust the control.

For reference, the keyboard shortcuts list is here : https://docs.sharpcap.co.uk/4.1/#Keyboa ... 0Shortcuts

cheers,

Robin

[ChrisR Oz]

Hi Robin,

That explains it. I used "Fn-F2" to reduce screen brightness, which worked OK. It seems you must ignore the "Fn" modifier and used that as "F2" in parallel.

A trap for me to worry about in the future.

Perhaps you can be more specific with your F# keys and interpret all modifiers (Alt, Shift, Ctrl, Fn, Windows, ...), so you only act on the specific SC ones.

Thanks for the quick answer.
Cheers, Chris.

[admin]

Hi Chris,

you are correct that there are no checks on alt/shift/ctrl for the standard hotkeys of F1 through F12 - I will add those checks to stop this sort of thing happening if you press SHIFT+F2, etc. However, I think the 'Fn' key on laptops is different to the usual alt/shift/ctrl - if you use Fn, it doesn't send the normal key code for F2 with a flag saying 'Fn' was pressed, it sends a completely different keycode to the operating system, or for some it bypasses the OS completely and makes adjustments direct to the hardware. There is certainly no way in Windows to detect that the Fn key is in use when receiving a particular keypress.

cheers,

Robin