On Sun, 23 Mar 2003, Roland Mabo wrote: > >There's more to a camera's AF system than speed and sensitivity, >though. > > But speed and sensitivity are very important factors if we talk about > AF *performance*. Low light sensitivity is a major drawback of the > Canon system, because it must light the AF assist beam earlier and > this drains batteries. Pentax can still focus when the Canon needs > assist.
It's one factor, yes, but not necessarily the most important. If I'm trying to follow a running kid, I want multiple AF points, especially if I don't want them framed dead-center every time. If I'm shooting indoors, I want quiet AF. If I'm shooting fast-moving sports, I'd love something like lock-on focus tracking. Obviously low-light ability is imporant, but for some people who take pictures during the day, there are more important factors. > >Pentax has the noisiest AF of the Big 4, and when the lens has trouble > >locking on a subject the noise becomes very noticeable in quiet > >situations. > > The noise depends on the lenses. Only to a degree, as the focusing motor is in the body. > My Sigma AF 24 f/2.8 is more noisy than the smooth sound of my FA 50 f/1.7. > My 135 f/2.8 seems to be least noisy. I've used both of the Pentax lenses you mention and they seem quite noisy to me when they hunt. I'm not saying that they're not good lenses, just that they're noisier than N/C lenses. > If you are in a quiet situation and don't like the noise, then you can > always focus manually. Exactly. Or I could use a N/C and use AF. > The shutter noise of my MZ-5n is low and smooth. Again, I find it a bit loud. Fire it side-by-side with an F80 and you'll see the difference. > >Also, until the MZ-6, entry-level Pentax bodies > > "bodies"? Only the MZ-7 had 3-point, all others had a single point. Good point. That reinforces what I was saying. Even the crappy Rebel G has three points, all of which are user-selectable. Nikon's F65 has 5 points, while Canon's Rebel 2000 has 7. Single point AF works well for some subjets, but not for all. > Pro-photographers prefers center AF, because the AF gets more speedy this > way. Sweeping generalization. There's a reason multiple-AF-point cameras exist, and pros who take photos of moving subjets are one of them. > Multiple focusing points slows down AF operation. I finds a center > sensor easier to operate. For you and your subjects, that fine. That doesn't mean that other every other pro shoots the same subjects as you, or even the same way as you. > You forget that the MZ-5 entered the market at the same time as Dynax > 606 Classic. This one had also only a 3-point AF system, just as Dynax > 808. It was very well received in it's days. The MZ-5/5n is the oldest > body in it's category, but it's also the most unique one. It's the > only one left with a retro approach, and this alone makes it an > excellent buy. The MZ-3 was awarded "top class" by the swedish > magazine FOTO. Now "top class" means that the camera is one of the > best on the market, regardless of the selling price. They liked the AF > performance a lot. Don't get me wrong... I like the styling and handling of the MZ-5n/3. I love the retro idea, and I'm glad that Pentax came out with a camera like that. That being said, I used a 5n for several years, and the AF system was nowhere near what C/N have. > When Practical Photography tested the MZ-3 against F80, Dynax 808 and EOS > 30/33 (february 2002), they didn't found the AF to be inferior to the > competition. The MZ-3 offers fewer overall focusing points (no verticals at all!), fewer user-selectable focusing points (one, instead of 5 or 7), and it's noisier to boot. I don't really care what any particular magazine thinks is important about an AF system, as those qualities I mentioned are also important. > >Canon's focusing may be slightly slower than Pentax (though their USM > >lenses are quite fast) > > The USM lenses isn't fast on Canon's entry level bodies. And the difference > is more than "slightly". You've obviously never used a Rebel Ti. Put one of those up against an MZ-6 and you'll be blown away by how much faster the Ti is. USM lenses are still fast on entry-level bodies because the USM is in the lens (body has a relatively small role to play in focusing speed). And I have no idea how you can claim that Pentax's AF is more than slightly faster than Canon's. I used Pentax's AF on an MZ-5n for years, and played with Canons on a daily basis, and there's very little discernable difference. Now that the Rebel Ti is out, it blows away anything else in its category. > Personally, I can't see how the option of having several AF sensors is about > AF performance. Performance is how the AF system *performs*, not how easy it > is to select different AF sensors. "Performance" is how the AF system locks onto your subject. If your subject isn't dead-center in the frame, then having more than a center AF point becomes a useful tool. I'm not talking only about your ability to manually select different points, but also about the camera's ability to change focusing points automatically to follow moving subjects. > Anyway, I guess that you're thrilled by the fact that Pentax has > developed an even faster AF system with 11 sensors, all of them can be > user selectable. And Pentax uses more cross sensors than the > competition. Now, isn't this *nice*? If it's true, it'll be very nice. It's a very good start. Now, if only they could do something about that noise. > Instead of complaining about what Pentax hadn't done in the past, can > we focus on what they're doing? Obviously, Pentax has listened to you > and tailor made an AF system - just for you. Isn't this fantastic? > Shouldn't they be praised for this? Of course, but that wasn't what this discussion was about. We're talking about the AF performance of current Pentax AF bodies when compared to current Nikon/Canon AF bodies. You had trouble understanding why someone said that Pentax's autofocus wasn't as good as the competition's, and I'm trying to point out that, while it may be good in some ways, it's horrible in others. chris
