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09-12-2017, 01:41 PM   #1
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Issue on autofocus of K1

Recently, using my k1, in the evening at 3200 Iso, in a vertical position, I realized that the focus system is not working well. To do a deeper test, I set the camera so it can not shoot if the subject is not in focus. Well in this condition I could not take a picture and I had to return the camera horizontally.
This issue also comes on my K20, but I was honestly thinking that in K1 what had been resolved.

09-12-2017, 01:48 PM   #2
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Which lens (and is it the same lens that you used on the K20)?

What happens if you try it with the camera vertical the other direction (shutter down versus up)?
09-12-2017, 01:50 PM   #3
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QuoteOriginally posted by nunzio Quote
Recently, using my k1, in the evening at 3200 Iso, in a vertical position, I realized that the focus system is not working well. To do a deeper test, I set the camera so it can not shoot if the subject is not in focus. Well in this condition I could not take a picture and I had to return the camera horizontally.
This issue also comes on my K20, but I was honestly thinking that in K1 what had been resolved.
The K-1 is a LOT more sensitive in low light than the K20D, but you still need to have a contrasty subject. Could you post a photo of the scene and let us know what lens you were using?

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09-12-2017, 01:59 PM   #4
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QuoteOriginally posted by Adam Quote
The K-1 is a LOT more sensitive in low light than the K20D, but you still need to have a contrasty subject. Could you post a photo of the scene and let us know what lens you were using?
You also need a lens that is sufficiently contrasty wide open. A number of older (and, in some cases, quite good) lenses result in relatively poor AF performance in less-than-ideal situations because of their low contrast. So, yes - would be good to know which lens we're talking about

09-12-2017, 02:06 PM   #5
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QuoteOriginally posted by nunzio Quote
Recently, using my k1, in the evening at 3200 Iso, in a vertical position, I realized that the focus system is not working well. To do a deeper test, I set the camera so it can not shoot if the subject is not in focus. Well in this condition I could not take a picture and I had to return the camera horizontally.
This issue also comes on my K20, but I was honestly thinking that in K1 what had been resolved.
Am I reading correctly that you have had problems with focus in vertical orientation with the K20D? Is there any chance that the problem is related to a specific lens? It would help to have an example photo including aperture/shutter speed/ISO (e.g. light value, LV) and the AF settings (including where you set the focus point).


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09-12-2017, 02:13 PM   #6
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The lenses are different. With the K20 I used a 16/50 2.8, with the K1 I used a 24/70 2.8.
I tried to make several shots to the subject I was sending, but only one was possible
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09-12-2017, 02:15 PM   #7
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Were you hitting the minimum shooting distance perhaps? Looks like that may have been the case.

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09-12-2017, 02:36 PM   #8
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No, Adam, it's not a problem away from the subject, it was possible to shoot after positioning the camera horizontally.

Focal length 45 mm
1/40 sec f 2,8
average weighted reading at the center

09-12-2017, 02:53 PM   #9
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The middle 25 points are much, much more accurate, especially in lowish light, than the other 8. I've even had issues with the outermost two columns (when held horizontally). And if you're using the 3 on each side of the outside of the middle 25...those are pretty dicey at f/2.8, even in good light.

I'm guessing that when you held it vertically, you were using one of the non-cross sensors; those are shaky. When you switched it to horizontal, you got to use one of the good sensors.
09-12-2017, 04:37 PM   #10
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Use vuew finder and spot or center-weigh metering. Sometime Live View problem AF like my K-70.
09-12-2017, 09:07 PM   #11
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Nunzio, please post some pictures of a printed out test chart, at ISO 3200, in the vertical position.
09-12-2017, 11:25 PM   #12
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QuoteOriginally posted by nunzio Quote
No, Adam, it's not a problem away from the subject, it was possible to shoot after positioning the camera horizontally.
Unless you post a corresponding pair of shots (from tripod obviously so the center of the chosen focus point is really 100% pointing at the same part of the subject) of a contrasty test subject with FULL metadata (incl. makernotes) and in full res it's not really worth anybody's time to speculate here.

I see no evidence here which says this is not some simple user error.

Invest 5 minutes to make the test shots and upload the ooC JPGs somewhere to share them.
09-14-2017, 08:31 AM   #13
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I sincerely tried to shoot and recreate the same environmental conditions as when the problem occurred, but the camera has always shot and focused perfectly. I will continue to make other checks and keep you informed.
Thank you all.
09-14-2017, 11:04 PM   #14
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QuoteOriginally posted by nunzio Quote
I sincerely tried to shoot and recreate the same environmental conditions as when the problem occurred, but the camera has always shot and focused perfectly.
I can't remember a similar "issue" being reported in the ten years I have been active on this site. At this point, without an example photo with intact EXIF, we have no way to help troubleshoot this "issue". If you get another pair of horizontal vs. vertical where the vertical is consistently mis-focused, please upload the original out-of-camera files (both horizontal and vertical) to a location where they are available for download so we can do a little look-see. You may want to contact Pentax to see if they can find the problem and fix whatever problem is happening with your K-1.


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09-15-2017, 10:23 AM   #15
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I will do it no doubt, Steve.
Thank you
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