I'm using a Microsoft Surface Studio... a little pricey, but great color, pen input for selections and masking in PS, and 28" touchscreen that tilts down to use as tablet.

I'm 70 years old and shooting with Canon 5D4, 600mm f4, 2.0 TC (all latest versions), and switching more and more from tripod to hand-held (often using a tree or fence to steady myself) for most of my pictures... tripods are great, but they add weight and slow you down for fast moving birds. It seems like there's never enough mm so I recently bought a short extension tube so I could stack the 2.0 and 1.4 TC resulting in 1680mm. This setup does require manual focus and a tripod... the results are sharp. If you have a high-end lineup, then it works out great... very expensive, but I was frustrated with being underpowered and I'm not patient enough to always wait for the birds to come to me. For the 600 + 2.0 TC (my usual setup) hand-holding works when there is enough light for a relatively fast shutter speed (1/800 to 1/1000, depending on the bird's movements). I also have done some upper body workouts to make it easier holding the beast. Also, the 5D4 handles low light with high ISO much better than the 7D2 that I started with. From my experience, there is negligible loss in image quality with TC's and high-end equipment... with bodies like the 7D2 you give up some ability to add TC's. In addition, because of the low-light capabilities and more pixels of the 5D4, results are better with a full-frame body and cropping than a crop-frame body and not cropping (5D4 cropped vs. 7D2 straight).