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Old Jun 24, 2006, 7:25 AM   #21
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Hi sage,
I have a KM5D, very similar to the A100.
I am very happy with it, but I can tell you that it focuses significantly slower than my friends' old Canon 300D. I am not a tele or action person so it doesn´t matter to me.

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Old Jun 24, 2006, 9:35 AM   #22
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jnrob wrote:
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Hi sage,
I have a KM5D, very similar to the A100.
I am very happy with it, but I can tell you that it focuses significantly slower than my friends' old Canon 300D. I am not a tele or action person so it doesn´t matter to me.
And did you test them in theidentical conditions with the same subjects, using comparable lenses?

If you use a lens that's geared for finer accuracy, it's going to focus slower. If you use a lens that's not very bright, it's going to struggle in less than optimuim lighting. Sure, USM is quiet, and sometimes seems faster. But, just because you remember it seeming faster,doesn't make it the true if you actually time them. ;-)

I doubt the new Rebel XT is slower than the old Rebel.

Acording to tests performed by PopPhoto, the Konica Minolta 5D's AF system was able to focus faster and in lower light (focuses in -1 EV light), compared to the other entry level DSLR models they tested (comparing the Konica Minolta 5D, Canon Rebel XT, Olympus Evolt E-500 and Nikon D50).

They said this about it:
Quote:
The 9-zone AF system is the fastest of this group and works down to EV -1, very dim light indeed.
http://www.popphoto.com/cameras/1924/hotshot-shoot-out-page3.html

They clocked it as follows in various light levels. It's my understanding that a 50mm f/1.4 is the lens most commonly used by them to test DSLR AF performance.

Konica Minolta Maxxum 5D AF Speed: EV 12: 0.32 sec; EV 10: 0.33 sec; EV 8: 0.41 sec; EV 6: 0.57 sec; EV 4: 0.59 sec; EV 2: 0.86 sec; EV 1: 0.87 sec; EV 0: 0.93 sec; EV -1: 1.85 sec.

The closest competitor in the Autofocus Area was the Nikon D50. The other models were left a bit behind, especially in very low light (even the Rebel XT couldn't lock focus in light lower than 0 EV, and it took over 2 seconds to lock focus there). In EV 0 lighting, the KM 5D was more than twice as fast.

Of course, don't expect AF to work in light that low without a decent lens (kit lenses aren't going to be bright enough to cut it, and a dim lens impacts how much light is seen by the camera's AF sensors). For example, the 18-70mm f/3.5-5.6 kit lens for the 5D is down to f/5.6 by the time you zoom into 35mm with it. That's not very bright. A 50mm f/1.4 would be exactly 16 times as bright compared to a lens that was at f/5.6. ;-)

Ditto for a lens that's not as sharp at wider apertures (impacts the image seen by the AF sensors, since a camera always focuses with the aperture wide open).

I've been pretty surprised at how low of light I've been able to lock focus in using a KM 5D with a decent lens on it.

In one of the local restaurants here with live music, light is so low I need to underexpose 1/3 stop just to get shutter speeds up to 1/10 second shooting with a Minolta 100mm f/2 wide open at f/2 and ISO 3200, and I can still lock focus using an *outside* focus point (albeit with some difficulty). I keep forgetting to ask them if they'd mind moving a candle or two closer to the performer.
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