But I've noticed contrast differences from devices for decades. To me that explained it well enough.
As to Sling improvements, be sure to contact Sling and ask where their forums are.
Hi. I just recently cut the cord from my cable set- top box to using Slingtv (Blue with extras) and my AppleTv 4k. In general I’m happy with the change but notice that when I am viewing programs within Slingtv’s own app, through the guide or Channels or other grid offering the picture contrast is not very sharp. In fact I am not seeing 4k or at least high even though settings are set to “best.” When I go out of the Slingtv app, to the plain channel app downloaded from the Apple App Store, the picture is much more crisp. Why does this happen and how can I improve my Slingtv’s visual performance?
I am using a Mac High Sierra 10.13.5, a Vizio E43-E2