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10-03-2012, 09:44 PM   #1
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K100d autofocus vs K-x K-r


Quick question from a newbie.

Does anybody know how much faster the K-x or K-r is with respect to autofocus? I am looking for a new camera and was wondering if I would see a difference with either of the k-x or k-r models as opposed to the older K-100d I currently use. I actually miss a lot of pictures due to the slow autofocus.

thanks in advance

10-03-2012, 11:18 PM   #2
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Owning both of these cameras, I can decidedly say that the K-x is both more accurate and quicker to lock on than the k100d is. The speed in which the autofocus motor drives the lens, however, is about the same. Note that I power both my K-x and k100d with second generation eneloop rechargeable AA's.

Low light performance with the k100d (relative to the K-x) is simply abysmal. I was shooting a wedding this past summer with the k100d as a back up body with a Fa 50mm f/1.4 mounted on it. Later in the evening, when the light was fading, I ended up giving up on AF of the k100d and defaulted to manual focusing. While AF would lock on occasionally, it needed two or three full focusing cycles from nearest to farthest, and when it did lock on it was rarely in sharp focus. Meanwhile, my K-x, with a lens that is two stops slower (a tamron 70-200mm f/2.8) kept on locking on with the middle autofocus point, under similar light conditions.

Other food for thought:
The K-x lacks illuminated af points in the viewfinder, where the K-r and k100d both have illuminated points. The K-r's autofocus is, apparently, less accurate than the K-x in low tungsten coloured light. I can't confirm this, though, as I don't have a K-r.

Any way you slice it though, the K-x or K-r will give you measurably better autofocus performance than the k100d. If I was to buy one of these three cameras, I'd personally choose the K-r.

(The best camera for the job would be the K-5 ii, which promises to be the best on all autofocus fronts, but at a much greater cost.)
10-03-2012, 11:26 PM   #3
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Thanks Gerbermeister for the response.

What you are describing is exactly what I am trying to figure out. It isn't that it is slow, it is slow to lock on. And at times it doesn't lock and I have to have it refocus on a different object. Meanwhile, the camera can't do anything as it is not if focus.

The illuminated AF points are something I was considering and may end up with a K-r.. does the k-7 have it?

Since you own both cameras (K100d and K-x) is the K-x noticeably smaller? Do you find the lack of top side lcd display inconvenient?

thanks again.
10-04-2012, 04:31 AM   #4
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QuoteOriginally posted by Gerbermiester Quote
Owning both of these cameras, I can decidedly say that the K-x is both more accurate and quicker to lock on than the k100d is. The speed in which the autofocus motor drives the lens, however, is about the same.
I've had 'em both, too & what you say is correct. The K-x also locks on in lower light than the K100D is capable of.

For what it's worth, EscoF350, I thought I would miss the top LCD, but I don't. Looking at the rear screen rather than the top was very quick to get used to. I have 2 K-x bodies & the lack of AF indicators are no big deal for me, either. I always use the center point AF anyway, so it's kinda moot.

10-04-2012, 06:49 AM   #5
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I have the K100D, K-x, and K-r (it just kind of worked out that way). The K-x/K-r run circles around the K100D in low light. I'll second Gibby's comments on the top LCD - I thought I would miss it, but don't. The K-x/K-r are a little smaller in the hand (except for the flash housing, the bodies are the same). I use a lot of manual-focus glass, so the AF points aren't a big deal to me. The K-x and the previous K-m/K2000 are the only models without AF points in the finder.

It seemed like my K-r's focusing was a little off in low light, but only with my Tamron 17-50/2.8. I thought it was the lens, but neither of the others had the problem. I tried switching from AF.A (automatic) to AF.S (single), and the problem pretty much went away. It seemed like it was always automatically choosing AF.C (continuous), and continuous would just guess wrong on that lens. Your mileage may vary, but don't let it scare you away from the K-r. Besides the AF points, the LiveView focusing is MUCH faster (something you really notice when holding the camera over your head), and the ~6 frames per second are handy for those "spray and pray" moments.
10-04-2012, 07:32 AM   #6
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I have a K-x and used a K100D Super for a couple of years. I don't see any difference in auto focus between these two in good light. There is a significant difference in poor light, the K-x will lock focus in situations where the K100D (and my K20D) will hunt.

I don't trust the auto-focus system on the K-r, or the K-5 for that matter, due to many reported complaints of unreliable AF in tungsten light (I owned a K-5 with severe front focus in tungsten). I suggest you upgrade from the K100D to the K-30, which beats the K-x and K-r in AF and noise performance, has vastly superior controls including front and rear dial, superior Live View AF with peaking, AF adjust for each lens and is weather-resistant.

Last edited by audiobomber; 10-11-2012 at 05:14 AM.
10-04-2012, 11:54 AM   #7
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I found that the size difference between the K-x and the K100d isn't all that significant. The weight difference is fairly obvious though. The K-x is much lighter as it has a poly-carbonate plastic frame rather than the k100d's steel frame.

Does the K-7 have illuminated auto focus points? Yes

Do I prefer having a top LCD panel? Yes.
Do I miss not having it on the K-x? A little bit. One of the interface differences between the K100d and the K-x/K-r is that when you turn on the K100d, the rear screen stays off. When you turn on the K-x/K-r, however, the rear screen lights up with all of your Aperture, Shutter Speed, and ISO information displayed. So, it's not much hassle to find out what your settings are at.
Admittedly, the K100d viewfinder could use some work, having to press the 'ok' button every time you want to see what your ISO is set to is a bit of an annoyance.

How long the rear screen stays on with the K-x/K-r is programmable too, and it can be turned off at any time by pressing the 'info' button twice. Oddly enough, my K-x can take more shots on a single set of batteries than my K100d can, despite the fact that it has an energy sucking screen that is lit up most of the time.

Hope that helps
10-10-2012, 10:59 PM   #8
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Thanks everybody for the information. It is nice to hear from people with experience using the exact same platform I am and their opinions. Seeing that I don't have access to any other pentax cameras, I appreciate the direct comparison from a common point (K100d)


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