85 1.8 vs 85 1.2

[neuroanatomist]

Focused on one given spot with my 85 1.2 @ 1.2 = 1/125. Then bumped up to 1.8 = 1/60.


I'll let the brains figure out the decimals. I know it something over 1 stop. Obviously the 85 1.8 may expose differently.

Realizing the 1/125 and 1/60 may skew the numbers, I tried a scenario where 1.2 was 1/320 and then 1.8 turned out to be 1/160.

Thanks, Keith. So at least for that lens, it's a 'complete' stop. 1/320→ 1/160 and 1/125→ 1/60 areboth one-stop changes in shutter speed. Each stop represents a rough (but not necessarily exact!) doubling/halving of the amount of light. The full-stop scale is 1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, etc. Underlined jumps are not exact divisions by 2. Your first example just happened to fall on one of those.