I Thought it would be interesting to demonstrate how much difference there is between an 8mm wide angle lens and one of 10mm (that’s 12 mm and 15mm to full frame cameras).
Here are four pictures that illustrate the difference. The room is 350 cm / 11’6″ wide and the desk 160 cm /5’3″ long.
It only sounds like a small difference but in practice it is a lot! The 8mm lens is difficult to use, the level of distortion can be contained in use by carefully placing the horizon near the frame centre and avoiding having straight lines in the corner of the frame because they will distort. In practice however those rules cannot always be followed while achieving the desired composition. Sometimes I can correct the distortion in Lightroom using a preset there for an 8mm Sigma lens and just a little tweaking, on other occasions I have to resort to the “Free Transform” tool in Photoshop.