Human reaction time and shutter lag?

[John_Reed]

I got to thinking about shutter lag. It seems so quick on my FZ15, from when I'm pre-focused and AE locked, there seems to be no delay at all. But then I got to thinking about human reaction time, particularly the time it takes, for example as a driver, to see a hazard, sense it, and apply the brakes. According to this (http://www.visualexpert.com/Resources/reactiontime.html) reference, that amounts to about 0.5 seconds for sensing, and about 0.2 seconds for moving the foot and applying the brakes. Yet, I have photos like this one:
http://john-reed.smugmug.com/photos/15606522-M.jpg
Now, that Raven (I used to think it was a Crow) just dropped off that post and started flying away. I was watching through my EVF, already AE and AF locked, and when I saw it drop, I snapped the shutter. From the above reference, that should have taken me ~0.7 seconds (plus the FZ15 shutter lag, supposedly 0.06 seconds) to do, yet, I think in that much time, the Raven would've been long gone. What am I missing here? Is it maybe because the 0.7 comes from communication all the way down to my foot, whereas communication to my fingertip is much shorter? Anyone have any feel for the numbers there?

[Rhys]

I suspect you anticipated the movement somewhat. This is what all good photographers begin to do and then don't notice they're doing it.

[PeteD]

You possibly didn't start the 0.7 second process when it actually dropped, you were so keyed up you started to react as it stepped forward, or it squatted to jump off the pole, or it leaned forward a bit.

Also, foreshortening means the bird might actually be 5 or 10 yards beyond the pole, and ravens arent speed kings either. That shot may be after 1 or 2 wing beats, at whatever speed ravens flap, I dunno.

But I like the shot, it would have made a great sequence, especially if the bird had veered to one side.

[hornpipe]

I got to thinking about shutter lag. It seems so quick on my FZ15, from when I'm pre-focused and AE locked, there seems to be no delay at all. But then I got to thinking about human reaction time, particularly the time it takes, for example as a driver, to see a hazard, sense it, and apply the brakes. According to this (http://www.visualexpert.com/Resources/reactiontime.html) reference, that amounts to about 0.5 seconds for sensing, and about 0.2 seconds for moving the foot and applying the brakes. Yet, I have photos like this one:
http://john-reed.smugmug.com/photos/15606522-M.jpg
Now, that Raven (I used to think it was a Crow) just dropped off that post and started flying away. I was watching through my EVF, already AE and AF locked, and when I saw it drop, I snapped the shutter. From the above reference, that should have taken me ~0.7 seconds (plus the FZ15 shutter lag, supposedly 0.06 seconds) to do, yet, I think in that much time, the Raven would've been long gone. What am I missing here? Is it maybe because the 0.7 comes from communication all the way down to my foot, whereas communication to my fingertip is much shorter? Anyone have any feel for the numbers there?

We all differ in our reaction times. Check your own by double clicking to start and stop a standard stopwatch. It will vary a bit but typically it will be about 0.15 seconds with a best of about 0.10 seconds. Double this to establish your reaction time to an anticipated event such as the shutter operation.

hornpipe

[John_Reed]

You possibly didnt start the 0.7 second process when it actually dropped, you were so keyed up you started to react as it steeped forward, or it squatted to jump off the pole, or it leaned forward a bit.

Also, foreshortening means the bird might actually be 5 or 10 yards beyond the pole, and ravens arent speed kings either. That shot may be after 1 or 2 wing beats, at whatever speed ravens flap, I dunno.

But I like the shot, it would have made a great sequence, especially if the bird had veered to one side.Then the DOF is adequate to keep the launching post still in sharp focus? 5-10 yards would be a pretty deep DOF at that focal length (~100mm actual, ~600mm equivalent). Here's a hummer shot, again, where the little guy just started to flit when I saw it and snapped the shutter:
http://john-reed.smugmug.com/photos/15235054-M.jpg
In 0.7 seconds, a hummer can move quite a way!

[PeteD]

I didn't mean to sound as if I was challenging your reaction time, John, I was just putting forward ideas.

Other comments that might irk you are:

How far away is the post, if a long long way away, there may well have been quite afew yards DOF.

In 0.7 seconds the hummer was actually fairly still, or there would have been a lot more motion blur DURING the shot, perhaps?



But I will reiterate my most important comment, doubly so now I have seen the lovely shot of the hummer.

You take damn good photographs of bird life.

Maybe you are in a position to rejoice that you have a talent that is probably vital in a wildlife photographer - the ability to anticipate the perfect moment to release the shutter.

To my sorrow, I don't even seem to have that ability when doing architectural photography...

[Ray Schnoor]

In 0.7 seconds, a hummer can move quite a way!

Or, it doesn't even move at all, but just hover.

[John_Reed]

I didn't mean to sound as if I was challenging your reaction time, John, I was just putting forward ideas.

Other comments that might irk you are:

How far away is the post, if a long long way away, there may well have been quite afew yards DOF.

In 0.7 seconds the hummer was actually fairly still, or there would have been a lot more motion blur DURING the shot, perhaps?



But I will reiterate my most important comment, doubly so now I have seen the lovely shot of the hummer.

You take damn good photographs of bird life.

Maybe you are in a position to rejoice that you have a talent that is probably vital in a wildlife photographer - the ability to anticipate the perfect moment to release the shutter.

To my sorrow, I don't even seem to have that ability when doing architectural photography...I'm not trying to brag about my "great" capability, I'm just puzzled (maybe amazed?) as to how the "system" works. In both cases I've shown, I'll admit that I was pre-focused on the subject, AE-locked, shutter button half-depressed. Then, through the EVF, I saw the action (i.e., the raven dropping, the hummer's wings flapping), and instinctively snapped the shutter as the result of my seeing the action. When I speak of the "system," I'm referring to the combination of me and the camera. By all rights, if that "0.7 seconds" is an average "sensing + reaction" time for a typical human being, my times should be longer, given that I am a 65-year old man. So the results still puzzle me. When people speak of getting cameras with "instant shutter lag," are they really kidding themselves, as long as the shutter lag is less than the human "reaction time?" Or is there a sort of "hyper-channel" for quick reactions that people like us develop which bypasses the "typical" times? Comparing the test, maybe so. (Thinking "out loud" here...) When you're driving along with your mind on what a nice day it is, can't wait to see what that lake is looking like today... and suddenly you see a deer jumping into the road in front of you, your brain has to first sense the event, then compute the proper reaction, and then execute that action (i.e., jamming on the brake pedal) quickly, and all that processing and slewing of your internal systems rightly takes the full time. But with the camera trained on a subject, finger poised on the shutter button, attention totally absorbed, subject moves, SNAP! may take a lot less time, (since all the channels are already "slewed," and ready to go) which is what I think is happening. Thanks for indulging my curiousity!

[erichlund]

First, the .5 for sensing is from an unanticipated need. Your reaction time to something you are actually waiting for is going to be significantly less. Second, the .2 to hit the brake means the foot must change positions (from the gas pedal). Your finger is already on the shutter, and it doesn't need as much throw or muscular effort to activate the switch. Finally, I don't know what the numbers are based upon, but I would hope they are not talking best possible conditions, because then the numbers would be relatively useless.

Frankly, I'd be surprised if your reaction time were much greater than .1 second.

Cheers,
Eric

[PeteD]

Think of the Olympic 100 metre sprint, it is only if they are below about .1 that they are considered to have "jumped the gun", isn't it?

[John_Reed]

First, the .5 for sensing is from an unanticipated need. Your reaction time to something you are actually waiting for is going to be significantly less. Second, the .2 to hit the brake means the foot must change positions (from the gas pedal). Your finger is already on the shutter, and it doesn't need as much throw or muscular effort to activate the switch. Finally, I don't know what the numbers are based upon, but I would hope they are not talking best possible conditions, because then the numbers would be relatively useless.

Frankly, I'd be surprised if your reaction time were much greater than .1 second.

Cheers,
EricI was not actually waiting for the raven or the hummingbird to fly, I was just focusing on each of them, had snapped a few poses, etc., but wasn't actually thinking that each was about to flit away. So in a sense, their actual "taking to flight" was not anticipated. But I think the act of snapping the shutter was actually a kind of "reflex" reaction, which may explain the short delay. Anyway, thanks for your opinion.

[gary_hendricks]

Then the DOF is adequate to keep the launching post still in sharp focus? 5-10 yards would be a pretty deep DOF at that focal length (~100mm actual, ~600mm equivalent). Here's a hummer shot, again, where the little guy just started to flit when I saw it and snapped the shutter:
http://john-reed.smugmug.com/photos/15235054-M.jpg
In 0.7 seconds, a hummer can move quite a way!

Very nice shot of that humer...