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09-20-2016, 09:59 AM   #1
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K100D Autofocus Issue? Hanging / Freezing

Hi,

I have a K100D which I brought a little while ago second hand (from a reputable shop) and I have noticed that when in Autofocus mode (which is what I mainly use) quite a bit of hunting and (more than occasionally) refusing to fire.

I assume the 2 are connected and the refusal to take a pic is linked to the autofocus issue.

It seems to happen more regularly if I am using either of my Tamron 18-200mm or Sigma 70-300mm. The Tamron is the worst offender (and the reviews mention this). The Kit lenses are better, but can still have the same problem occasionally. All of my lenses are pre-owned, but again, from reputable shops.

I am finding other limitations with the K100D which are prompting me to look at investing in a K5 or K3. The question is - will this problem go away with either camera?

The K5 will, of course, be cheaper, but there is no point in buying one if I am going to have the same problem, or even investing in the K3 if that will not fix it.

Thanks,

Robin

09-20-2016, 11:11 AM - 1 Like   #2
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Focus accuracy and speed is tremendously better on the k-3 than the k100. I own both and I can say this with clarity.
09-20-2016, 11:40 AM - 1 Like   #3
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A newer camera will AF faster and more accurately. But those older, slower zooms might still hunt a bit, especially in low light or low contrast situations.
09-20-2016, 12:29 PM - 1 Like   #4
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I'd place the blame on the slower aperture from the zooms. Do you get similar results from a faster lens like a 50mm prime?

But yes, the K100D's AF is archaic by modern standards. Even a cheap used K-30 or K-50 would blow it out of the water.


Adam
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09-20-2016, 01:16 PM   #5
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QuoteOriginally posted by Robin CB Quote
It seems to happen more regularly if I am using either of my Tamron 18-200mm or Sigma 70-300mm.
On my K100D I had problems with a Sigma 70-300mm focusing in AF. Same lens on my K-50 does hunt but not nearly as much as the K100D did. Hope this helps.
09-20-2016, 02:01 PM   #6
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QuoteOriginally posted by Adam Quote
I'd place the blame on the slower aperture from the zooms. Do you get similar results from a faster lens like a 50mm prime?

But yes, the K100D's AF is archaic by modern standards. Even a cheap used K-30 or K-50 would blow it out of the water.
I haven't been able to try it with a good modern AF lens, but will see if I can find one locally to do so.

Sounds as if trying a modern body would be a good idea too (if I can find one locally).
09-20-2016, 02:30 PM - 1 Like   #7
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QuoteOriginally posted by Robin CB Quote
I haven't been able to try it with a good modern AF lens, but will see if I can find one locally to do so.

Sounds as if trying a modern body would be a good idea too (if I can find one locally).
K100D súper is excellent , Its 6 MP CCD sensor has some mágic. Af is not fast , but for landscapes, portraits is a fantástic camera ,
09-20-2016, 02:34 PM - 1 Like   #8
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I occasionally have trouble with that. I've been using my K100D with a Sigma 35-80mm macro zoom lens to photograph items to sell online and it'll hang if I'm too close to the subject. Often it will focus but not fire. Usually the problem corrects itself if I back up a foot or so.

09-20-2016, 05:03 PM - 1 Like   #9
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QuoteOriginally posted by pasorro Quote
K100D súper is excellent , Its 6 MP CCD sensor has some mágic. Af is not fast , but for landscapes, portraits is a fantástic camera ,
My k100d super was excellent, I'm not saying that it was terrible, just that the k-3 is faster and more accurate and misses less often.

The issue could be related to dirty autofocus sensors couldn't it?
09-20-2016, 11:41 PM - 1 Like   #10
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I own both a 100D and a K5. I use the K5 almost all the time, but when i occasionally return to the 100D I notice exactly the same thing you mention. I have a Tamron 28-300 which I use with the 100D and it often refuses to auto focus at 28mm. I was very happy with the 100D, but love my K5. Next stop k1.
09-22-2016, 03:35 PM   #11
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Thanks guys. It sounds as if I am not alone.

It also sounds as if both the K5 and the K3 would reduce (but not necessarily fix) the problem. The question then is one of scale.

I can probably get a pre-owned K5 (or that generation) for a reasonable sum, but would the K3 be significantly better for this (ie better enough to pay more than double)?

I might have the chance to try both at a local camera club - hopefully......

---------- Post added 09-22-16 at 03:38 PM ----------

QuoteOriginally posted by UncleVanya Quote
......

The issue could be related to dirty autofocus sensors couldn't it?
How would I test / resolve that?

---------- Post added 09-22-16 at 03:42 PM ----------

QuoteOriginally posted by pasorro Quote
K100D súper is excellent , Its 6 MP CCD sensor has some mágic. Af is not fast , but for landscapes, portraits is a fantástic camera ,
I agree that the K100D can produce good photos in good conditions - even in my clumsy mits, but I need something capable of more action / challenging light..
09-22-2016, 05:10 PM - 1 Like   #12
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Re: testing af sensors
I read this Cleaning Auto Focus Sensor: Pentax SLR Talk Forum: Digital Photography Review
09-23-2016, 12:33 PM   #13
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QuoteOriginally posted by UncleVanya Quote
Thank you UncleVanya. I will give that a go

I did have the main sensor cleaned a short while ago. I am guessing that the AF sensor wasn't done then as there was no difference in the focus issue. That is a bit of a shame.
09-23-2016, 02:04 PM - 1 Like   #14
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Under the "Rec. Mode" menu, there is an "AF Mode" option. If this is set to AF.S, the camera will refuse to take a picture if it can't lock focus. If it's set to AF.C, it will try to focus on the half press, try to maintain focus as long as you're half-pressing, and will take a photo no matter how off it is on the full press.

I can throw in my comparison for the k100d to a k5iis - it's a night and day difference. AF went from something I mostly gave up on, to something I use regularly. It's not the fastest thing out there, but it works in pretty low light and when it locks focus it generally does a great job of it.

I think the k5ii and k5iis had some AF improvements over the k5 and the k3 is even better, how much $$ this is worth is a tough question. Hopefully you'll get a chance to do some hands on comparisons for yourself, that's really the best way to decide.
09-24-2016, 08:57 AM   #15
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QuoteOriginally posted by BrianR Quote
Under the "Rec. Mode" menu, there is an "AF Mode" option. If this is set to AF.S, the camera will refuse to take a picture if it can't lock focus. If it's set to AF.C, it will try to focus on the half press, try to maintain focus as long as you're half-pressing, and will take a photo no matter how off it is on the full press.

I can throw in my comparison for the k100d to a k5iis - it's a night and day difference. AF went from something I mostly gave up on, to something I use regularly. It's not the fastest thing out there, but it works in pretty low light and when it locks focus it generally does a great job of it.

I think the k5ii and k5iis had some AF improvements over the k5 and the k3 is even better, how much $$ this is worth is a tough question. Hopefully you'll get a chance to do some hands on comparisons for yourself, that's really the best way to decide.

Thanks Brian. I will have a play with the menu as well.

EDIT:

I have just checked my menu - AF Mode is greyed out and AF.S is alongside, but I don't seem to be able to change it.

My firmware is up to date (or as up to date as a K100D can be), so it looks like I luck out there.

Last edited by Robin CB; 09-24-2016 at 10:11 AM. Reason: Update
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