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06-01-2019, 08:14 AM - 1 Like   #1
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Auto-ISO conundrum solved

I recently picked up a K-5 IIs from a member in the Marketplace. As I fooled around with its settings and experimented, I noticed that sometimes I could not set the ISO lower than 200 on the top LCD. Looking at the Auto-ISO range in the menu (Rec menu page 3), I also could not set it below 200. Hmmm. I went to Custom menu page 1, item 3 (expanded ISO sensitivity) and turned this on. Back to the Auto-ISO range setting, and now I could set the low value to 160. An improvement, but why couldn't I set it lower?

This morning I happened to be reading a K-5 II/IIs review on D P Review, and ran across this tidbit:

'The K-5 II features a Highlight expansion function which applies to both JPEG and Raw; Shadow Expansion can also be applied to the camera's JPEG output. With Highlight correction activated, ISO 160 becomes the minimum sensitivity setting...'

Well, that explained it. Sometimes I had highlight correction turned on and sometimes not. With HC off, I can now set the ISO on the top LCD and in the Auto-ISO range in the menu all the way down to 80. Thanks D P Review. If this little caveat is mentioned in the Pentax manual or in Yvon Borque's e-book, I don't remember seeing it.

06-01-2019, 08:39 AM   #2
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I'm not sure if it's in the eBook, but it's definitely something that's been brought up and answered on the forum several times, and in our reviews. The nice thing is that on newer models, they added a default auto setting to the highlight correction so that it only kicks in when you're not at base ISO, and so you're never prevented from choosing the ISO you want

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06-01-2019, 08:45 AM   #3
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My apologies for beating a dead horse. I should have searched the forum first before posting. I have done this on other topics.
06-01-2019, 11:26 AM   #4

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It's about the same with older models like the K200D, and even some more sophisticated old Optio models (I think the Optios A30 and A40).
With the K200D, Iso200 replaces Iso100 if correction is switched on.

06-01-2019, 12:04 PM   #5
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My K10D does not have highlight correction, so I was unfamiliar with this behind-the-scene gotcha on a new-to-me camera.

Let's keep Adam happy and stop this thread from going any farther.

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