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05-22-2010, 04:48 PM   #1
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K100D on Drugs

The auto-focus stopped working with all my lenses recently. I was dealing with it, shooting manual focus again. But I accidentally happened to bump the "OK" button on the back when I was shooting recently and noticed that doing so caused the lens to auto-focus. The piezo beeped, the little green LCD hexagon popped on at the bottom of the viewfinder and the red focus spot indicator lit up in the viewfinder....just like it used to when I'd push the shutter button half-way down.

I called Pentax tech support and they told me they'd never heard of such a thing.

The only way I can imagine this happening is some weird firmware scramble, but generally when firmware scrambles, it doesn't result in a functional camera.

I have the latest firmware rev in place. Anybody ever seen this before?

The only other weird thing about this camera is that it will only function on Lithium Ultimate batteries. New alkalines will deliver a couple of shots before the low battery indicator comes on. I don't know if those two items could be related in some strange way.

05-22-2010, 05:00 PM   #2
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There's a custom option that causes exactly what you are are seeing - no AF with shutter half-press, but instead with OK button. Sounds like you must have accidentally set that option. Just set it back the way it was.

As for batteries, your camera isn't *supposed* to work with alkalines - only rechargeables (preferable, as they are MUCH cheaper long term) or lithium.
05-22-2010, 05:57 PM   #3
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K100D AutoFocus

You're exactly right on the auto-focus. If anyone else experiences this problem, look under "Custom Settings" and the submenu "OK Button when shooting".

Funny, though, Pentax Tech Support did not recognize the condition! Even when I asked if there were some setting I could have changed that would have caused that behavior.

As to the batteries, I originally used NiMH exclusively when the camera was new, but within a year, a good set of freshly recharged batteries would not operate the camera but for a few shots. (My guess was that alkalines would have been able to provide more available energy than NiMH batteries since they are rated 1.5V new versus the 1.2V rating of the NiMH batteries, so I'm not sure why the camera won't run on the alkalines if it will run on the NiMH batteries).

Regardless, I seem to get a thousand or so shots out of the Lithium Ultimates, so the ten bucks for a set is not unreasonable.

Thanks Marc
05-22-2010, 07:45 PM   #4
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QuoteOriginally posted by hriddle Quote
The only other weird thing about this camera is that it will only function on Lithium Ultimate batteries. New alkalines will deliver a couple of shots before the low battery indicator comes on. I don't know if those two items could be related in some strange way.
The low battery indicator is a voltage measurement. You could have plenty of power in the batteries, but if the voltage drops a bit, it will register low battery. It happens even with NiMH batteries, and I usually ignore it, and keep a set of spares in my bag.

05-22-2010, 07:54 PM   #5
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That is disappointing to know that Pentax support could not recognize this. The least they could have done was to suggest that you reset all of the custom settings back to the default.

As for the batteries, the K100D is supposed to be able to run off of alkalines, that is what came with the camera. You can only expect 60-80 shots but they will work. But like all things results are not typical and your mileage may vary.
05-23-2010, 04:39 PM   #6
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Have you tried Sanyo Eneloops?
They usually work a treat in terms of holding the charge and operating the camera longer than standard NiMHs would do. You may want to check out more K100D tips & tricks.

Regarding the "OK button": Really disappointing that the Pentax rep. couldn't help. BTW, it is my preferred focus setting. Try it for a while, it decouples focusing from shooting. Many more advanced cameras have a dedicated AF button on the back. I'm glad the K100D gives me the option even though it means I have to give up the "reset AF point to centre position" functionality.
05-23-2010, 04:43 PM   #7
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QuoteOriginally posted by Class A Quote
Have you tried Sanyo Eneloops?
You will never use anything else again.
05-23-2010, 04:51 PM   #8
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QuoteOriginally posted by rparmar Quote
You will never use anything else again.
+1. Eneloops, properly charged, will give Lithiums a run for their money.

Cheers, Mike.


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