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ST3 Pro on a 4K monitor - PMSchu - 2019-04-18

Hi Greg,

I upgraded my computer monitor to a 4K model and ST3 Pro no longer displays the telescope window correctly (Visual Sky Simulation). A sample of the problem is attached. The constellation outlines, etc. are shifted up and to the left at ~45°.  The Target Object crosshairs are offset in the same direction. The same thing happens on the Atlas, Overhead Sky & Naked Eye displays too. I tried using some of the compatibility mode settings in Win 10 (v1803), but that put 5 green stars in the Object Rating column for all of the objects in the Observing list Blush . I didn't check the Sky Simulations though. I can live with the green rating stars if the Sky Simulations work correctly.

Any suggestion on how to get the correct display back again? Do I need to reduce the display resolution to 1920 x 1080? I didn't try that yet.

ST4i is working great on the new monitor at 3840 x 2160 resolution by the way.


Phil S.

RE: ST3 Pro on a 4K monitor - theskyhound - 2019-04-18

Hi Phil,

This is a bug in the graphics driver, which started when Windows 8 came along, and it keeps coming back despite being fixed again and again. The problem found it's way into a range of drivers, apparently via shared low level code, because it affects more than one manufacturer. The problem is only indirectly related to the high resolution. It has to do with the Windows scaling of text and icons so they aren't too small to read.

For starters, you should check to see if there is newer driver available that resolves the problem.

Otherwise, try different windows screen item scaling factors. Normal (100%) scaling will always work, but it is often too small on higher resolution screens. Other scale factors will sometimes work correctly too, so try them all. Note that in order for the change to take effect, you must log out and then back in again after changing the scale. Tedious, I know, but it is the best way to find a scale factor that works, yet is still large enough to read.

If all else fails, people have reported that lowering the video resolution resolves the problem because you can use the normal (100%) scale factor, yet still be able to read it.

We have a support page that may also help:

SkyTools 4 uses a different graphics subsystem and I am glad to hear that it is unaffected.

RE: ST3 Pro on a 4K monitor - obrazell - 2019-04-18

Yes and now you understand why we poor visual observers are waiting for ST4 as well. The only workaround I have found is to edit the properties of the icon and set under compatibility mode -> change high DPI settings and check override high DPI scaling behaviour and set scaling performed by application. If this does not work for you then join the queue waiting for ST4V.

RE: ST3 Pro on a 4K monitor - PMSchu - 2019-04-19

Hi obrazell,

I tried to set the Compatibility Mode setting to override the scale factor for high DPI monitors (or whatever Win 10 calls it). When I did that ST3 Pro opened with 5 green stars in the Object Rating column for all objects in the observing list. When I tried to open the atlas or a telescope Sky Simulation, ST3 Pro crashed with no error given.

When I first installed the 4K monitor, all of my desktop icons were in the top left quadrant of the screen  Sad . I increased the display resolution to 225% to get a nice looking desktop again. Some programs worked fine after that and some like, Photoshop, produced microscopic icons and text (unreadable/unusable). I've been applying the override DPI settings under the compatibility mode tab for programs that produce small icons or text & that usually works.

I've also installed a new video card to go with the new monitor. The drivers are less than a week old so they should be OK. The new video card & drivers worked fine with the old, lower res monitor.

Next I'll lower the display resolution to 1920 x 1080 & see what happens. I won' need to exit & reenter Windows to do that, but it will probably scramble all the desktop icons  Sad Sad .

Thanks for your help,

Phil S.

RE: ST3 Pro on a 4K monitor - PMSchu - 2019-05-04

I finally got around to testing ST3 Pro on the new 4K monitor at 200%, 150% and 100% screen scaling. The 200% and 150% scale factors do not correct the problem of the offset overlays on the sky simulations. The 100% scale factor provides the correct display of the information overlays and the star fields, but the letters are too small to read (see the attached file). ST3 Pro is the only program that I've found that seems to scale the 2 parts of the display (overlays & starfield) differently. Setting a 100% scale factor yields unreadable text & icons on the desktop and in all the programs (including ST3 Pro) at 4K screen resolution.

I looks like I'll have to await ST4 Visual too.

Phil S.

RE: ST3 Pro on a 4K monitor - theskyhound - 2019-05-05

To be perfectly clear: SkyTools does not scale anything separately. This is done in Windows via something called GDI, but most of the code is actually in your video driver. This is a problem in your video driver! The only thing I can do to fix it is to completely change the graphics system, which was a huge job that took over a year. That is what is coming in SkyTools 4.

RE: ST3 Pro on a 4K monitor - theskyhound - 2019-05-05

(2019-05-04, 10:29 PM)PMSchu Wrote: The 100% scale factor provides the correct display of the information overlays and the star fields, but the letters are too small to read (see the attached file).


If the text in the dialogs is too smal we can't do anything about that, but on the charts, you can customize your text to any font, color or size. See the chart Preferences to change the font size for any chart element.

RE: ST3 Pro on a 4K monitor - PMSchu - 2019-05-05

Hi Greg,

As you can see in the attachment to my 5/4/19 post, the actual sky simulation for the 100% scale factor is just fine, as you predicted. It's the additional info at the top & bottom of the chart that's too small to read. I'm using Nvidia driver v. 430.39 on an EVGA RTX 2070 graphics card at 3840 x 2160 resolution, the monitor's native resolution.

Here's a screenshot that shows the 2 different scalings for the star field and for the overlay info. The stars & their designations look fine. The overlay info like the eyepiece & finder circles, the constellation lines & the horizon line on the naked eye section of the chart are shifted ~45° to the upper left, occupying the top left quadrant of each of their respective sections of the chart. The icons & hypertext at the top & bottom of the chart also look fine. The telescope simulation is pretty unusable when the stars don't line up with the other symbols like the galaxies, eyepiece circle, etc.

Phil S.

RE: ST3 Pro on a 4K monitor - theskyhound - 2019-05-06

Hi Phil,

Have you tried contacting the makers of your video card? I know you want me to solve this problem, but all I have a workarounds because I cannot address the actual problem in the driver.

RE: ST3 Pro on a 4K monitor - PMSchu - 2019-05-06

Hi Greg,

That's an excellent idea. What is the designation of this bug? EVGA makes the video card, but the GPU & video drivers come from Nvidia.

Is anyone else in SkyTools land using a 4K monitor with an Nvidia chipset video card? Do you experience this issue? I'd be happy to revert the drivers to an older version, if I knew which one would work correctly.

Since this is a recurring problem, do you recall what part of the SkyTools 3 display code is calling the buggy part of the video driver? I'd like to point the EVGA/Nvidia  folks to the appropriate problem area.


Phil S.