K3 AF fine adjustment

Started Sep 1, 2014 | Discussions
Andreas Stuebs Contributing Member • Posts: 924
K3 AF fine adjustment

I have for the first time played a bit with AF fine adjustment on my K3. I find a setting +5 seems to nail it. Question - has anybody else got expirence in that, is that a big value, or does that match roughly the expirience of others.

Lens used: 18 - 135

I will also try out my 85mm 1.4 (AF)   and my 100mm f4.0 macro (M) manual focus lens. I would guess that the 85 1.4 will be a lot more critical at aperture 1.4

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sleepwalker400 Senior Member • Posts: 1,849
Depends

on the LENZ

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DAVID MANZE Veteran Member • Posts: 4,629
Re: Depends

You would be wise to calibrate all your lenses at full aperture as nearly all but two of my lenses need some sort of adjustment. Strangely my Sigma 50-150 needs more than -10 on the K3, where it needed very little on the K5.

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PhotoHawk Contributing Member • Posts: 816
Re: K3 AF fine adjustment

Andreas Stuebs wrote:

I have for the first time played a bit with AF fine adjustment on my K3. I find a setting +5 seems to nail it. Question - has anybody else got expirence in that, is that a big value, or does that match roughly the expirience of others.

Lens used: 18 - 135

I will also try out my 85mm 1.4 (AF) and my 100mm f4.0 macro (M) manual focus lens. I would guess that the 85 1.4 will be a lot more critical at aperture 1.4

The 18-135 did not need any MFA on my K5 or K3.  My Tamron 17-50 needed adjustment (+8) on my K5 and none on my K3.  The 55-300 I'm still tuning on both.  I'm not really happy with it and its gone back for checking and adjustment itself.  Other lenses like my Sigma 10-20 don't need adjustment on either.  It takes a fair amount of work to accurately dial a lens in.  On the longer lens you may find that the MFA adjustment at the wide end doesn't match what it needed in the middle or the long end.  In that case pick your poison - where you use the lens most or an average setting.

Petroglyph
Petroglyph Veteran Member • Posts: 5,878
Re: K3 AF fine adjustment

Andreas Stuebs wrote:

I have for the first time played a bit with AF fine adjustment on my K3. I find a setting +5 seems to nail it. Question - has anybody else got expirence in that, is that a big value, or does that match roughly the expirience of others.

It takes what it takes. As long as you're on the scale you're good to go. Try to shoot test shots or MFA charts at 50X focal length distance.

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CatchAlive Regular Member • Posts: 130
Re: K3 AF fine adjustment

I need more than +10 for my 16-50 f2.8 with my K3 but "only +7 with my father's K5 II. Should I get another 16-50?

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DS21 Senior Member • Posts: 2,084
Re: K3 AF fine adjustment

Andreas Stuebs wrote:

I have for the first time played a bit with AF fine adjustment on my K3. I find a setting +5 seems to nail it. Question - has anybody else got expirence in that, is that a big value, or does that match roughly the expirience of others.

Lens used: 18 - 135

I will also try out my 85mm 1.4 (AF) and my 100mm f4.0 macro (M) manual focus lens. I would guess that the 85 1.4 will be a lot more critical at aperture 1.4

There would be no need for AF fine adjustment if the AF sensor was precisely and repeatedly accurately positioned inside the cameras during the manufacturing process. Since this is probably too time consuming and difficult for the manufacturers, AF fine tune comes into play. The more the AF sensor is miscalibrated, the more weirdly the numbers will vary with different lenses, because when the AF sensor is miscalibrated, the different optical properties and different aberrations of lenses will influence the result in a different way. For example, I have two K-x bodies, one is dead accurate with any lens I try on it, the other front-focuses slightly, and there are slight differences with lenses, and a K-7 which also needs slightly different numbers on the lenses that are all perfect on the properly in factory adjusted K-x. The small differences between various lenses AF correction needs sometimes don't show all that much when the AF sensor is only slightly out of position, (except on very fast and short DOF lenses), so most users can live with this.

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Gesture Veteran Member • Posts: 5,055
Re: K3 AF fine adjustment

At least Pentax offers in-camera adjustment across a broader range than any other OEM, I believe.

Petroglyph
Petroglyph Veteran Member • Posts: 5,878
Re: K3 AF fine adjustment

CatchAlive wrote:

I need more than +10 for my 16-50 f2.8 with my K3 but "only +7 with my father's K5 II. Should I get another 16-50?

I never used a Pentax 16-50 so I can't help with any experience.  But if it is off the scale maybe you can send it in for a lens calibration.  Still under warranty?

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Petroglyph
Petroglyph Veteran Member • Posts: 5,878
Re: K3 AF fine adjustment

Gesture wrote:

At least Pentax offers in-camera adjustment across a broader range than any other OEM, I believe.

If you mean on more different camera models I believe that is true since entry level Canon & Nikon usually don't have the ability to adjust.  CDAF, now that it is getting faster, doesn't need adjustment in theory, on mirror less models is becoming a more attractive option.  In fact, it is interesting to check a camera's PDAF against its own CDAF when adjusting.

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arnelie
arnelie Regular Member • Posts: 382
Re: K3 AF fine adjustment

My K-3 is spot on with my Sigma 17-50/2.8, DA21f3.2, and my other lenses seems fine without any AF adjustment. My K-7 was however much more difficult, some Pentax lenses were fine, but the SIgma 17-50 was impossible to fine tune correctly.

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