PENTAX DSLR AF-Fine Adjustment (AF-FA) - Tolerance Problem

Started 3 months ago | Discussions thread
OP Kerusker Senior Member • Posts: 1,405
Example: K-1 and DA 12-24mm

Example: K-1 and DA 12-24mm

Jens is using this lens and he get's great results:

I bought this lens in January at a dealer in Germany for 340EUR for my K-5IIs and then learned that it 's also very usable on FF in the range of 17 to 24 mm. The lens has one year warranty - that's why I want to verify that this lens is ok.
Of course AF-FA is one of the first things to do to get AF/PD as good as it can be.

For my DA 12-24mm F:4 I got the following AF-FA-Tolerance: (see first post)
Target at distance 148cm, K-1 on tripod (etc.) lens wide open, AF/CD for each of the following focal lengths and then several MF/PD to determine the tolerance AF/PD-Tol:

15mm _____ -10, -9, ............,0, .. +2
18mm ______-10, -9, ............,0, .. +2, ... +5
20mm ______-10, -9, ............,0, .. +2, ... +5, +6
24mm _______________-7, ......,0, .. +2, ....... +6, +7, +8, +9

I also got a Tokina AF 20-35mm 3.5-4,5 FF lens which shows a similar pattern (Tokina developed both, this lens and the DA 12-24mm).

Another remarkable effect with the DA 12-24 is that in LV with CD the distance scale turns to larger distances (-> oo) when focal length decreases (target and K-1 positions unchanged). It's well known that you have to refocus the lens after focal length has changed - but what does it mean when the lens shows a different distance? In this case: BF for the LV/CD at the shorter focal lengths ????
Any thoughts resp. explanations are welcome.

I've chosen AF-AF = -2 for a walk and got these shots f.ex.

K-1 + DA 12-24 at 18mm (Hand on top for shade)

K-1 + DA 12-24 at 18mm

K-1 + DA 12-24 at 24mm

K-1 + DA 12-24 at 19mm

K-1 + DA 12-24 at 24mm

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we don't see that we don't see (eye's blind spot)

 Kerusker's gear list:Kerusker's gear list
Sony RX10 IV Pentax K-1 Pentax smc DA 15mm F4 ED AL Limited Pentax K-5 IIs Pentax smc FA 50mm F1.4
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