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

Started 4 months ago | Discussions thread
OP Kerusker Senior Member • Posts: 1,409
Re: PENTAX DSLR AF-Fine Adjustment (AF-FA) - Tolerance Problem

JeremieB wrote:

Kerusker wrote:


thanks for your comments

JeremieB wrote:

Kerusker wrote:

PENTAX DSLR AF-Fine Adjustment (AF-FA)
(2) Making minute focus adjustment in AF mode for the optimum performance of camera and lens

True - somewhere in the tolerance range the best value should reside.

With Pentax method though, I visually inspect the result (eventually in live view x16) to see which direction should be taken (FF/BF).

But you don't know where your start value inside the tolerance - you assume it's always the best value (see assumption above) - I think that's wrong.

Not exactly, I assume that the end value is the "best", because if I repeat above method multiple times,

Yes - that's the best method because the AF/PD has a tolerance and a statistic will (may) result in the best value. But my hope is that 'my' simple procedure of determining the tolerance might shorten the process to generate the statistics. (Because meanwhile i'm tired to do AF-FA ober and over again for several bodies and lenses.)

whatever start value, normally I should get closer and closer to the best AF_FA (by moving it in the right direction, based on my visual inspection in live view). The "start" value could even be completely outside of the Tol range in fact.

I will add 'K-1 and DA 12-24mm' as an example in a post in this thread (soon).

One of the latest AF discussions was:
Focus Oscillation in K3 iii?

The K3 III has the latest PD-System (13) - what's about AF/PD-Tol on this body?

asahi-man stated in that thread:

This is not a K-3 lll problem, it's made by the Pentax Tamron lens.

You will find the same issue with other brands and the comparable Tamron lens.

I was asking for explanation - but of no avail.

I would have been interested too, I have no idea about what could cause this.

same here

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