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06-02-2009, 08:50 PM   #1
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AF with Pentax?

Hey all,

So I've been doing some research on the K20d/K10d in anticipation of having the money to actually buy it, and I've come across more than a few threads on some forums that mention Pentax cameras in general have problems acquiring focus. Is this true?

Specifically, the AF system is loud (compared to Nikon or Canon's respective systems), has to hunt for a while, and even when it locks doesn't always lock well.

Now, I used a K20D for about 30 seconds in a Wolf Camera store (didn't have the money to buy and didn't want to waste the clerk's time as I wouldn't be buying from them anyway), and didn't notice those problems. But camera store vs. in the field are two very different things indeed.

What are your experiences? Although I will MF most of my fine art work (coming from MF film cameras, I still don't fully trust AF for portfolio quality fine art work), I want a very reliable AF system to use when I shoot sports and such, much of which will be done on slower zooms until I can build up my system with faster glass.

Thanks!

06-02-2009, 11:23 PM   #2
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Pentax AF is not the fastest around, but it shure locks well. It also depends on which lens you use. Lenses with SDM are quiet.

But if you really need fast AF you should go for canon or nikon. But then again, I have no experience on how much faster they are...
06-03-2009, 12:25 AM   #3
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Pentax AF is slower than others but does tend to be more accurate.
With sports, it's more important to be familiar with the sport you are shooting so that you can anticipate, Without that skill, it doesn't really matter how good the AF in your camera is.
06-03-2009, 01:14 AM   #4
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I have just spent two days shooting a down hill mounting bike race. I found the AF to be very good.

The AF system is just a helper to make life easier. Just remember to pre-focus.

06-03-2009, 01:59 AM   #5
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The problems you're describing about Pentax AF is mostly experienced in low-light situations. In those conditions, Nikon and Canon shine a lot more than Pentax. The K-7 will probably revolutionise Pentax in the AF arena with its advances on the K10D/K20D.

Having said this, the K20D and K10D I have have done the job remarkably well, even in low light, especially with my DA* lens. Mostly, I shoot with the AF540 flash in low light conditions and so use the spot beam as AF assist. Even then, it's not very fast (hunts a little), but when it locks, it's right.
06-03-2009, 07:20 AM   #6
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Pentax AF

I think that some of the reports of lousy AF in Pentax cameras have been overblown. I have a K10D and have never noticed a real problem, but then I don't shoot sports and I seldom shoot in very low light.

A couple of years ago, before I had my K10D, I attended the wedding of my brother's daughter. As father of the bride, my brother had been told, in no uncertain terms (by the mother of the bride) that he could not take pictures during the wedding. So, he asked me to use his Nikon D200, with a Nikon 18-200mm VR zoom lens.

The wedding was held outdoors on a September afternoon, in St. Petersburg, FL, so light levels were not a problem. Several times while I was shooting, the D200 hunted very badly, going from close focus to infinity and back again, before locking on target.

Ever since then, when someone on this or another forum complains about Pentax AF and waxes euphoric about how fantastic Nikon's AF is, I take it with a huge grain of salt. The only thing about Nikon AF that is better, as far as I can tell, is the focus-assist light on the D200. Pentax has corrected this deficiency with the K-7.

I suspect that Nikon is not much better in low light than Pentax. Its just that, with the focus assist light, they don't encounter low light (for focusing purposes). It really is shameful that Pentax neglected to add this on their high-end cameras. How much could a white LED cost?

The screw drive AF is, indeed, loud. The HSM lenses are virtually silent, so that, too, has been addressed.

And, the early reports are that the K-7 shutter/mirror is extremely quiet.
06-03-2009, 07:49 AM   #7
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QuoteOriginally posted by brofkand Quote
Hey all,

So I've been doing some research on the K20d/K10d in anticipation of having the money to actually buy it, and I've come across more than a few threads on some forums that mention Pentax cameras in general have problems acquiring focus. Is this true?

Specifically, the AF system is loud (compared to Nikon or Canon's respective systems), has to hunt for a while, and even when it locks doesn't always lock well.

Now, I used a K20D for about 30 seconds in a Wolf Camera store (didn't have the money to buy and didn't want to waste the clerk's time as I wouldn't be buying from them anyway), and didn't notice those problems. But camera store vs. in the field are two very different things indeed.

What are your experiences? Although I will MF most of my fine art work (coming from MF film cameras, I still don't fully trust AF for portfolio quality fine art work), I want a very reliable AF system to use when I shoot sports and such, much of which will be done on slower zooms until I can build up my system with faster glass.

Thanks!
I'm member of a photo club and the only Pentax owner (K10D).
Our side by side comparison made the following clear:
- My K10D focusses slower (up to 1 - 2 secs in low light).
- It focusses BETTER (more in focus!)
- It hunts more in low light and with slow long lenses, but only in REAL low light you can see the differences.

Most of the other guys have Canon. Its faster but not as accurate.

It has never been a problem with my photography so far.
But he, I've got 2 dials, Sv, Tav, multiple exposure, +/- 5 bracketing, and dust / weather sealing!
Don't forget the raw and green buttons, Pentax ergonomics is so much better...

- Bert
06-03-2009, 09:26 AM   #8
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Thanks everyone for the real-world examples. As I said I plan on using MF most of the time.

When I shoot sports, it's as a bystander in the stands, mostly shooting college basketball or other college sports. The court/field is very well lit. I don't think I've ever had to focus in low light (at least when I relied on autofocus).

Do Pentax cameras quickly flash the on-board flash like some Canons without the AF-assist lamp, or do they just hunt around in low light?

06-03-2009, 01:30 PM   #9
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They use the flash as a focus-assist if you have it popped up, but that commits you to actually using flash, unless you focus first then close the flash, whcih I think you'll find more a bother than it's worth.
06-03-2009, 02:33 PM   #10
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QuoteOriginally posted by Marc Sabatella Quote
They use the flash as a focus-assist if you have it popped up, but that commits you to actually using flash, unless you focus first then close the flash, whcih I think you'll find more a bother than it's worth.
I think that is exactly how Canon cameras without AF assist lamps work. Are there any hotshoe flashes that include AF assist lamps and work with the K20D?
06-03-2009, 07:26 PM   #11
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QuoteOriginally posted by brofkand Quote
I think that is exactly how Canon cameras without AF assist lamps work. Are there any hotshoe flashes that include AF assist lamps and work with the K20D?
Pentax AF 540 FGZ for one.
06-03-2009, 07:44 PM   #12
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QuoteOriginally posted by brofkand Quote
I think that is exactly how Canon cameras without AF assist lamps work. Are there any hotshoe flashes that include AF assist lamps and work with the K20D?
Pentax P-TTL Flash Comparison: Auto-Focus Assist / Spot Beam
06-03-2009, 07:58 PM   #13
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Rumour has it that Pentax takes longer to focus because it uses a check-back system. It approximates the focus, then fine tunes it. According to the same rumour mill, Canon and Nikon don't do the second step, so they are not quite as close to perfect focus sometimes, but are somewhat faster than Pentax, particularly in low light.
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