After you click Zoon in, can you check the value of eoszoom in the INDI control panel? it should be set to 1... try to set it to 1 yourself and see if that has any effect.

Regarding the 4K.. unless someone steps in and fixes it, you'd have to wait until I get a 4K monitor sometime hopefully this summer and I'll resolve the hidpi issues by then.

When I start Ekos, eoszoom is set to 0 . When I change it to 1 manually, nothing happens. When I press the zoom in button, the value is changed to 5 but the display remains unchanged. Once I press the zoom out button, the value reverts to 0. After pressing one of these 4 buttons it takes 2-3s before the value in the Indi control panel is changed.

Right it needs to be set to 5. Maybe for your camera model it needs to be a different value? I'm not sure.

Jasem,

7 days ago I reported the zoom in button works but the zoom out button does not. I provided a video and logfile. The logfile did look like this:

"[2019-01-22T17:45:51.744 CET DEBG ][ org.kde.kstars.indi] - GPhoto CCD : "[DEBUG] Setting text widget eoszoom: 0 "
[2019-01-22T17:45:51.785 CET DEBG ][ org.kde.kstars.indi] - GPhoto CCD : "[DEBUG] Setting new configuration OK. "
[2019-01-22T17:45:53.249 CET DEBG ][ org.kde.kstars.indi] - GPhoto CCD : "[DEBUG] Setting text widget eoszoom: 0 "
[2019-01-22T17:45:53.251 CET DEBG ][ org.kde.kstars.indi] - GPhoto CCD : "[DEBUG] Setting new configuration OK. "
[2019-01-22T17:45:55.130 CET DEBG ][ org.kde.kstars.indi] - GPhoto CCD : "[DEBUG] Setting text widget eoszoom: 5 "
[2019-01-22T17:45:55.143 CET DEBG ][ org.kde.kstars.indi] - GPhoto CCD : "[DEBUG] Setting new configuration OK. "
[2019-01-22T17:45:57.377 CET DEBG ][ org.kde.kstars.indi] - GPhoto CCD : "[DEBUG] Setting text widget eoszoom: 5 "
[2019-01-22T17:45:57.377 CET DEBG ][ org.kde.kstars.indi] - GPhoto CCD : "[DEBUG] Setting new configuration OK. "
[2019-01-22T17:45:58.640 CET DEBG ][ org.kde.kstars.indi] - GPhoto CCD : "[DEBUG] Setting text widget eoszoomposition: 0,2 "
[2019-01-22T17:45:58.653 CET DEBG ][ org.kde.kstars.indi] - GPhoto CCD : "[DEBUG] Setting new configuration OK. "
[2019-01-22T17:45:58.802 CET DEBG ][ org.kde.kstars.indi] - GPhoto CCD : "[DEBUG] Setting text widget eoszoomposition: 0,4 "

Obviously 5 is the correct value with the 5D. One week later the logfile looks much differently and the message

"[2019-01-28T17:28:14.035 CET DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 5D Mark II : "[DEBUG] Setting text widget eoszoom: 5 "
[2019-01-28T17:28:14.082 CET DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 5D Mark II : "[DEBUG] Failed to set new configuration value (camera busy), retrying... "
[2019-01-28T17:28:14.256 CET WARN ][ default] - Corrupt JPEG data: premature end of data segment
[2019-01-28T17:28:14.949 CET WARN ][ default] - Corrupt JPEG data: premature end of data segment
[2019-01-28T17:28:14.951 CET DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 5D Mark II : "[DEBUG] Failed to set new configuration value (camera busy), retrying... "
[2019-01-28T17:28:15.067 CET DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 5D Mark II : "[DEBUG] Failed to set new configuration value (camera busy), retrying... "
[2019-01-28T17:28:15.968 CET DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 5D Mark II : "[DEBUG] Failed to set new configuration value (camera busy), retrying... "
[2019-01-28T17:28:16.093 CET WARN ][ default] - Corrupt JPEG data: premature end of data segment
[2019-01-28T17:28:16.096 CET DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 5D Mark II : "[DEBUG] Failed to set new configuration value (camera busy), retrying... "
[2019-01-28T17:28:16.592 CET WARN ][ default] - Corrupt JPEG data: premature end of data segment
[2019-01-28T17:28:17.138 CET WARN ][ default] - Corrupt JPEG data: premature end of data segment
[2019-01-28T17:28:20.330 CET WARN ][ default] - Corrupt JPEG data: premature end of data segment
[2019-01-28T17:28:20.855 CET WARN ][ default] - Corrupt JPEG data: premature end of data segment
[2019-01-28T17:28:21.468 CET WARN ][ default] - Corrupt JPEG data: premature end of data segment
[2019-01-28T17:28:21.538 CET DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 5D Mark II : "[DEBUG] Setting text widget eoszoom: 0 "
[2019-01-28T17:28:21.585 CET DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 5D Mark II : "[DEBUG] Failed to set new configuration value (camera busy), retrying... "
[2019-01-28T17:28:22.516 CET DEBG ][ org.kde.kstars.indi] - Canon DSLR EOS 5D Mark II : "[DEBUG] Failed to set new configuration value (camera busy), retrying... "

does not look like the 5D needed a different value, does it?

In INDI Control Panel.. Canon ---> Streaming, is the format set to JPG or RAW? Try to set it to RAW. Subframed should be enabled also there. Try to set the esozoom yourself to 5, then start the stream, does it start zoomed?

With the Ekos CCD-Tab LiveView window open, I can _manually_ change magnification by pressing the appropriate button on the camera. The 5D's live view has 3 magnification levels: 1x, 5x, 10x and the button makes the display switch between these levels. With Ekos' CCD live view window open though, pressing the button once leads to a 5x magnification, a second press doesn't change anything and a third press brings magnification back to 1x.

Maybe replace the zoom in / zoom out buttom with a dropdown that says 1x , 5x , and 10x?

RAW.

It was disabled. That value had never been changed by me.

Unfortunately, no.

With subframe enabled, FPS is at 25 now.

I tested more and now while it still does not start in the 5x mode although eoszoom is manually set to 5 in Indi, it actually does activate magnification when I press the zoom in button at a later time!

Now this is weird. When I manually set eoszoom back to 1 in Indi, nothing happens. When I press the Set button AGAIN, magnification is set to 1! So you have to press the Set button TWICE to have an effect.

The software does not always perform as intended. What seems to be clear is eoszoom should be set to 1 instead of 0 to achieve 1x magnification.

_Sometimes_ I have to either press the Set button twice or click at the liveview window in order to make the change have an effect. I've attached a video so you can see what happens. Sometimes it works, sometimes it doesn't and needs additional action.

Ok I just updated KStars to set the values twice... can you git pull KStars and try it out?