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07-05-2012, 07:43 AM   #1
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Select Mode AF Area Size Adjustment? Accuracy

Dear K-01 users:

I was struggling in deciding to purchase either K-01 or K-30 given that I could preorder and receive K-30 in 7 days here but the going price for body only for K-30 is twice of body only price of K-01, which makes me look into K-01.
I plan to get K-01 with my existing 15mm and 77mm as a travel kit together with my Ricoh GXR 28mm and 50mm for my upcoming trip.

I will probably use manual focus most of the time but I am curious about the AF area size adjustment under Select Mode. As I was reading somewhere on the internet(Xitek from China) that you can adjust the size of AF area. Is it true? If so, will the focus accuracy improve so when shooting portrait, it will focus on the eyes instead the noses? How about speed ( does it take less time to contrast focus as the the area it takes to judge is smaller)

This is my first post and would like to thank you for all your help.

07-05-2012, 08:02 AM   #2
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Yes, you can adjust the size up to 25 points at a time, but in selective mode it will not perform face detection.

If you care about AF performance, though, definitely get the k-30. See our in-depth k-01 review for more info on the k-01's AF.

https://www.pentaxforums.com/reviews/pentax-k-01-review/autofocus-performance.html
07-05-2012, 08:35 AM   #3
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There are 4 diffent settings for AF.

The AF area is built of 10x10 blocks. Looking at the backscreen of my K-01 the picture size is 6x4 cm and the total area for the 100 AF blocks is 4,5x3 cm, covering 56 % of the total area to choose from and lock AF on. The AF-blocks are more wide then height.
  1. Face recognition: Wich is the biggest centerpart of 6x6 blocks.
  2. Tracing, wich is a square centrepoint with the function off staying on a point while moving the camera (very slowly).
  3. Selecting points: Wich is a block to move around (2x2 or 4x4 or 6x6 blocks) the AF area.
  4. Spot AF, wich is a square centre AF block (just one block).

For selecting you can change the number of blocks and thus the aeria to look for contrast to put your AF-point on. I think it will be faster with less blocks, but mainly it is about enough contrast I guess. So more contrast things get faster AF. Also faster lenses (more light for the sensor) are faster when the amount of light/contrast is decreasing. With the big area (10x10 blocks) you don't always get what you want, since you give the camera the choice to look into that field and AF-lock on something.

I took this picture yesterday with FA31mm and small block pointed at the eye on the left. With f1.8.

Last edited by RonHendriks1966; 07-05-2012 at 08:50 AM.
07-12-2012, 08:25 AM   #4
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Small object accuracy

Adam and Ron. Thank you both for the detailed and prompt reply. I have one additional question before I make the purchase as travelling with my K10D and GXR are pretty heavy. Hoping K-01 can save some weight.

One experienced user here in Taiwan reported that if the object is really small that is smaller than the smallest focus block (1x1) then K-01 will mis-focus completely

Does this symptom appears on your K-01s too? (A bit worried since there hasn't been any firmware update since K-01 release and my trip is upcoming next week)

Thank you

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