Uploaded, digital image width should also be kept to a maximum of 800, when posting it to the forum.
In the image brackets, it would look like this, with the added width size limit: [img width=800]
This way, an entire image fit comfortably on the screen without having to scroll back and forth or up and down in order to see parts of the poster.
And when pic files are too large, they also take longer to load, especially if multiple images are together in one post.