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Forum: Pentax K-3 & K-3 II
12-24-2014, 05:30 AM
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Thanks a lot for your answers!
I was inded unsure it was a usable technique, but it seemed (on the lcd screen at least) that the focus was more precise this way.
Now when the images finally arrived on a big screen, they would indeed sometimes be slightly out-focused.
So to sum it up: I should choose my appropriate zoom level, and then focus and shoot without changing it, right?
Last (but not least, i'm taking the plane tonight) question: Have you seen a benchmark in terms of image quality between those two lenses? (18-250 tamron vs 18-135 pentax)?
I tried to do some comparison today and it seems to me the tamron has
- bigger zoom (obvious)
- better sharpness at 250 and 135mm when subjects afar (comparison on the lcd screen of the camera, zooming to the max)
while the pentax has
- weather resistant body (also obvious, and this is the reason i bought it in the first place)
- better sharpness when subject is mid to close range (even zoomed to 135mm)
But somehow it doesn't seem logical that a 8yo lens from tamron would produce better images than a brand new pentax lens with about the same price
So, maybe I'm doing it wrong
Which one of the two would you advise taking if you had to take one.
Note: I also have the 35mm and 50mm plastic pentax lenses that i never tried yet
Note 2: i'm going australia / new zealand :)
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Forum: Pentax K-3 & K-3 II
12-23-2014, 04:00 PM
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Hey all,
just to let you know, changing the body of the K3 solved everything indeed
now autofocus works as a charm with all my lenses, fast and seems precise, both with motorized and screw-driven lenses.
So it was indeed a body problem, specially linked to the focus screw
:) :) :)
Now I just have a newbie question:
when using my tamron 18-250 to shoot wide to normal angle, I would first zoom to 250, make my focus on the subject I wanted, then zoom out while maintaining my finger on the button, frame, and then shoot. The focus distance/point would stay the same.
It still works with this lens and the K3 instead of my K10, but curiously it doesnt work with the 18-135 from pentax: if I zoom out or in, the camera changes its focus distance, and I have to re-focus with my final framing.
Anything that could explain this? Another thing linked to motorized vs screw-driven (I could imagine this having a link to that)? some parameter I should configure?
Thanks for your answers
Ido
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Forum: Pentax K-3 & K-3 II
12-20-2014, 07:13 AM
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Hey all,
I think I better understand the issue here.
To recap:
- I have my old faithful K10D with a 18-250 Tamron lens (autofocus is screw driven)
- I bought the K3 (recondittionned) with both the 50mm (screw) and the 18-135 from Pentax (motorized)
I tried all the combinations and ho and lo, here is what comes out of them:
- any lens on the K10D works fine
- the 50m and the 18-250 on the K3 cannot focus (really cant), but the 18-135 works like a charm
My hypothesis: my K3 has a problem using screw-driven lenses
Maybe that is also what happened to you?
I sent it back to Amazon and am waiting for a new one. Crossing fingers :)
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Forum: Pentax K-3 & K-3 II
12-19-2014, 08:34 AM
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Hi thepavuk
Good news bad news: you are not alone!
I have exactly the same problem, no way to make the 50mm focus (single spot, AF mode s) on anything in quickly. I thought my model had a problem (it was a reconditioned on amz) so I changed it for another (also reconditioned) but the issue remains.
It looks to me as if this lens is not usable in any other mode than manual with the k3.
To note: I do not have the same problem with my other lenses in the same conditions (tamron 18-250 and Pentax 18-135) so to me the problem lies in the lens, not the camera.
I'm thinking about giving up on this lens despite all the "plastic magic" I read everywhere :'(
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