Superman's Reaction Time

Post-crisis Superman have shown nanosecond reaction time at least twice, but anyone has any theory/calculation or even opinion on Superman's perception speed? I also knew that Superman have to "calibrate" his perception speed, which mean he must take some time to bring his reaction time to another magnitude.

But I heard that in Superman: Grounded, it's stated that Superman can detect events happened at attosecond (or even zeptosecond, but I don't remember). I need a scan to verify this claim, anyone have it? Please post it here, thank you.

@angryhulks: Reading Superman 709 (after looking up which Supermans Barry appeared in, so I didn't have to read them all, lol) - those are 2 different scenes. Superman just says that everything froze around them in the diner, while Flash said that he (himself) percieves things that "last for less than an attosecond".

And just in general, I don't think anyone who doesn't use the Speed Force would actually be able to will their perceptions up. (The way a Flash can stand still & see things going slow). You would naturally be able to perceive faster things as you-yourself are moving faster (ie: you don't have to do anything for other cars on the highway to look normal speeds, just be going around as fast as they are).

Idk about superman but Flash (new 52) has a reaction time of a Femtosecond, which is one quadrillionth of a second 10^-15 of a second

@hellion_96: atto is 10 ^-18. (But really it doesn't matter because all these writers do is look up random scientific words or number-notations & throw them around willy-nilly to make feats impressive to readers. We shouldn't hold them to consistency or use them comparatively between different writers writing different characters).

Gallery

@segamarvel said:

Gallery

Catches a train that has already fallen in Metropolis, before it hits the ground.....when he started off sitting in Rome as Clark. He goes to another country, gets a bottle of wine, gets back into the house, changes into Clark in the time it takes for Lois to say goodbye.

Gallery

He Sees kryptonite radiation blast coming and evades it with superspeed. And Superman Gets in front of Booster Gold’s light attack at superspeed. (the encyclopedia confirms it's a laser, so superman outraced the light before it hit batman at pointblank range)