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10-24-2006, 05:56 AM   #1
Ed in GA
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Auto Focus. How fast does it really need to be?

If auto-focus on a given camera took 5/10 of a second instead of 3/10 of a second, would it really make a difference?

Or, in a world of instant gratification, do we just expect things to be that fast even if they don't need to be?

10-24-2006, 08:56 AM   #2
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I think it does make a huge difference to some.
If you are photographing the face of an athlete as they bike by, you'd miss the shot if autofocus was too slow. Any sort of action requires fast focus.
This is one of the problems with the P+S cameras. By the time some of them
get a handle on the situation, the situation is history and you don't get a pic.
10-24-2006, 09:15 AM   #3
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It probably IS unnecessary when unnecessary - shooting stationary things, working slowly to frame etc. But you sure feel it necessary when you do need it - as leaton says. The fact of af forces you to depend on it - for the mf side usually suffers in design of both lens and camera. So yes, the game's different than in the mf days.

If af speed correlates directly to price (ie. other factors are price-independent) then there'd be a choice based on photographic style. Unfortunately I don't think af speed is the only variable...
10-24-2006, 10:34 AM   #4
Ed in GA
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I could be wrong, but.....

It would seem to me that the average photographer would have a really difficult time telling the difference between 3/10 and 5/10. I can tell you for certain that I couldn't.

As far as action shots are concerned, I would think a good photographer would know his camera and lens well enough to prepare for most scenarios using shutter speed and f-stop. Again, I could be wrong.

Also, with the availability of continous focus in most DSLRs, the need to "freeze focus" an action shot shouldn't be neccessary. Again, I could be wrong.

25 years ago, when the only automatic part my camera had was the exposure (which I used very little), you could set the depth of field utilizing markings on the lens and while portions of the photo "may" have appeared to be out of focus in the view finder through a wide open lens, the finished product was very much in focus. I have noticed these markings don't seem to appear on the new auto focus series of lens. Of course lens such as the DA don't even have aperature rings. Still, I would think a good photographer would know the capabilities and limitations of his/her equipment. As before, I could be wrong here as well.

I wonder how many of todays "really good" photographers even use autofocus?

10-24-2006, 11:13 AM   #5
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Surely it depends a great deal on the sort of photography you're doing. Seems to me the "nobody needs feature X, really" arguments ultimately come down to that. It's true that once I got my hands on some manual focus primes I have used autofocus very little on my DL, but there are times I really need it to get a certain shot. Those times aren't determined by how lazy I am feeling, but the situation.

Ever read or hear somebody ranting about how stupid is to shoot in raw? Similar kind of argument about how "really good" photographers work. MIght make sense for the situations that person usually shoots in; doesn't apply to everybody though.
10-24-2006, 11:48 AM   #6
Ed in GA
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Well me dispel something here very quickly.

I'm not trying to minimize any use of auto focus, or any other feature on today DSLRs.

My entire point is that a camera spec calls for autofocus speed of .xxxms, and I see comments that call it slow and I simply don't think that the average photographer (read that me) can actually tell the difference between 3/10s and 5/10 in auto focus speed.

Anyway, enough of my rant on this subject.
10-24-2006, 01:53 PM   #7
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I almost always use manual focus. I get to focus exactly what I want, and I can't get angry with my camera. For me rather than faster AF easyer MF is advantage over P&S cameras.

I still don't know where fractions 5/10 and 3/10 came from?
10-24-2006, 02:03 PM   #8
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speedy autofocus can make a huge difference. The other day I was all set to do a panning shot of my pal as he drove by. By the time I got focus lock the shot was ruined. I was ready to cut my wrist because I decided to satiate my immediate desire to have a new camera (k100d) instead of being smart and waiting for the k10d.

If your not used to dealing with 10ths of a second it can be hard to comprehend the difference between 3/10s and 5/10s.

I enjoy racing my car, and 2 10ths of a second can be an eternity.

When traveling 120mph you are going 176 feet per second. So the difference between 3/10s and 5/10s is 35 feet when traveling 120mph.

I also used to be involved in competitive lock picking where I would pick a 4 pin lock in under 2 seconds.

2/10ths can mean life or death, winning or losing or getting a shot of a lifetime or throwing your camera into the river.

10-24-2006, 02:40 PM   #9
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The dark side of the autofocus speed spec, something that just occurred to me: these numbers are usually referenced using a 50mm f1.8 lens and good lighting and focus target, ie pretty near ideal conditions.

Use a slow zoom in lower light while not shooting dead zebras, and that difference between 3/10ths and 5/10ths MAY be the difference between actually locking focus and hunting -zip, zip, zip, zip- for an eternity.
10-27-2006, 05:19 AM   #10
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Cool Nesster - dead zebras! I love it. Is that the way the speed is tested,
to get the lowest number for marketing?
Kinda like when they come up with EPA 20mpg rating for a Sherman Tank?
The test is downhill with a tailwind and the hill was greased!
10-27-2006, 06:50 AM   #11
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QuoteOriginally posted by leaton Quote
Cool Nesster - dead zebras! I love it. Is that the way the speed is tested,
to get the lowest number for marketing?
Kinda like when they come up with EPA 20mpg rating for a Sherman Tank?
The test is downhill with a tailwind and the hill was greased!
Totally off topic, if I ever started a gang of misfit photogs they would be called the Dead Zebras.

LOL!
10-27-2006, 10:26 AM   #12
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Sounds like we might have a club starting up here!!!
10-27-2006, 11:07 AM   #13
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I think we have ourselves a mascot.

http://home.comcast.net/~acrbill/dzc1.jpg

alright.... back on track.

When the k10d comes out I am definitely going to give it a try at the local store.
I'm far from a not being a total amatuer but I might be able to justify a new body if it steps up where the k100 falls short. Namely the hunting and speed of the AF.

I might even wait till the k10d is replaced by the next generation.
11-01-2006, 09:56 AM   #14
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I don't know if this relates to speed of autofocus, but I find that occasionally during fast action I can't lock on quick enough to a moving subject. This seems slightly different than me whipping the camera around to take a fast shot of a stationary object. In that case, the camera focuses plenty fast for me.
11-01-2006, 10:12 AM   #15
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QuoteOriginally posted by acrbill Quote
speedy autofocus can make a huge difference. The other day I was all set to do a panning shot of my pal as he drove by. By the time I got focus lock the shot was ruined. I was ready to cut my wrist because I decided to satiate my immediate desire to have a new camera (k100d) instead of being smart and waiting for the k10d.

If your not used to dealing with 10ths of a second it can be hard to comprehend the difference between 3/10s and 5/10s.

I enjoy racing my car, and 2 10ths of a second can be an eternity.

When traveling 120mph you are going 176 feet per second. So the difference between 3/10s and 5/10s is 35 feet when traveling 120mph.

I also used to be involved in competitive lock picking where I would pick a 4 pin lock in under 2 seconds.

2/10ths can mean life or death, winning or losing or getting a shot of a lifetime or throwing your camera into the river.
I think once they come out with the line of lenses that have the autofocus motor on the lens, there could be an increase in focus speed.

That way your K100D purchase will make more sense.

cheers
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