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5 Days Ago   #1
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DA 50-135 and autofocus

Dear All,

I wuold like to have some suggestions.

I used K70 and 50-135 for model shots, It missed some photos. They are clearly out of focus.

My questions are:

Does the 50-135 perform in a better way in another camera? (k3, kp ,...)

Is there a particular setting that can help the k70 to focus the subject?

Are there alternative over the 50-135?

Many thanks

Davide

5 Days Ago   #2
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Did you try using live view? Have you carefully calibrated the focus? What f stop? Can you post some examples? Is the lens converted to screw drive?
5 Days Ago   #3
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Did you try using live view? No

Have you carefully calibrated the focus? No, Because other photos are in focus

What f stop? 2.8

Can you post some examples?, yes asap

Is the lens converted to screw drive? No

Many thanks

Davide

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5 Days Ago   #4
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First I would calibrate focus at the distance and focal length that you will need the most critical focus from.

If workflow permits, live view is the best chance for accurate focus. Pdaf has problems with zoom lenses for to minor shifts in the focus at various focal lengths.

Screw drive conversion can sometimes help. However your lens' symptoms as described don't seem to fit that pattern. I've converted at least a handful of 50-135s that seemed to have focus issues (failure to lock focus) and after conversion the tentative hesitant focus was decisive and more accurate.

5 Days Ago - 1 Like   #5
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QuoteOriginally posted by Davidex Quote
Have you carefully calibrated the focus? No, Because other photos are in focus
I think the question to ask is if you use AFA, AFC or AFS?
Second question to ask is, when you see the subject in the viewfinder, do the focus point cover the subject area of focus during the whole time when the camera is focusing the lens on the subject?
Usually, Pentax AF.S lock is very repeatable, but it is when the subject moves between the time of focusing and the time of exposure than leads the subject to be out of focus. When I understood this, I never had a picture out of focus again.
5 Days Ago   #6
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I have a K-3ii and a recently purchased used Da 50-135 that is in mint condition and i knew the person that bought it from new so i know it was in perfect condition and i run into the same problem. I have calibrated the focus but at times it just flat out misses focus, i fully understand the shallow depth of field this lens can produce and i am very careful about moving the camera or the subject moving. I tend to use AF. S. and the center focus point with the viewfinder, sometimes it misses to the point it can clearly be seen in the viewfinder and yet i get focus confirmation from the camera? Live view works well but there are times when that is a little too slow. I kinda wish the SDM would quit so i could convert it to screw drive..
5 Days Ago   #7
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Hi Davidex,

Can you post samples with the EXIF intact? Otherwise it's not possible for someone to see if you're doing something wrong, or if the lens needs you to calibrate it with your camera.
5 Days Ago   #8
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Are you using the centre focus point and re-composing, or shifting the focal point to suit your framing?

4 Days Ago   #9
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QuoteOriginally posted by Davidex Quote
Dear All,

I wuold like to have some suggestions.

I used K70 and 50-135 for model shots, It missed some photos. They are clearly out of focus.

My questions are:

Does the 50-135 perform in a better way in another camera? (k3, kp ,...)

Is there a particular setting that can help the k70 to focus the subject?

Are there alternative over the 50-135?

Many thanks

Davide

What Auto focus setting were you using?
As in Center, Selected point or camera chosen AF point?
4 Days Ago   #10
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QuoteOriginally posted by shardulm Quote
What Auto focus setting were you using?
As in Center, Selected point or camera chosen AF point?

I used center focus point and AF.C.

---------- Post added 08-14-2019 at 07:46 AM ----------

QuoteOriginally posted by Sandy Hancock Quote
Are you using the centre focus point and re-composing, or shifting the focal point to suit your framing?

I used centre focus point without re-composing. The models were to quick
4 Days Ago   #11
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The 50-135 is a great lens, but is slow to focus.

What were the models doing when you shot? You said 'The models were to quick' which suggests possibly fast movement?
4 Days Ago   #12
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QuoteOriginally posted by Davidex Quote
I used center focus point and AF.C
Oh, so where are the pics, David? We need to diagnose.

Did you just point at a person and not a line on the person?



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