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11-14-2011, 08:52 PM   #1
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K5 not focusing to infinity?

Hi All,

My story is that I think that my K5 doesn't reach infinity focus.

I didn't notice untill I got lenses that have a hard stop at infinity. Now I'm pretty sure that I should be able to focus on distant objects even if my lense is at f2 or 2.8.

I felt that the focus point is at about 15 meters. I have attached some samples, the sharper one is an F28/2.8, the softer is an M28/2.
Both lenses were at infinity. The light bottom left is on top of a building 100 meters away.

I'm hoping someone can tell me if this is so. Obviously I'm not shooting landscapes wide open, but even at f8 distant objects seem out of focus.

My 50-135 can focus on the moon etc, but this is because it can go past infinity. At 50mm it doesn't seem to get all the way there.

Any help would be great.

Thanks

T

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11-14-2011, 09:16 PM   #2
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The moon can be a challenging object. An alternate focus test of a daytime scene with several far and medium-range objects might make it easier to figure out what's going on with your camera and lenses.
11-14-2011, 09:46 PM   #3
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- DeadJohn: Thanks, I've shot a very long street and a few scenes with a range of objects and it seemed that the focus was at about 10-15 meters or so.

Last edited by Turtle; 11-15-2011 at 01:28 AM. Reason: Syntax
11-14-2011, 10:12 PM   #4
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Both lenses at infinity: M28/2 first, F28/2 second.

The lamp post is 10 meters away.



11-14-2011, 10:58 PM   #5
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Sometimes true infinity can be before/after the mark, depending on your lens and the temperature.

Adam
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11-14-2011, 11:26 PM   #6
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Thanks Adam, I assume that's because of camera expansion.

I'm brainstorming via images here, here is f2 vs f8. Focal plane appears to be near the car headlight (15m).

The core of my question is: Should the focal plane (at F2) be at infinity (or a few Kilometres), or nearer the camera (15m)?
--------------------
11-14-2011, 11:30 PM   #7
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Nothing caused by the body I believe. It looks like a lens problem. The focusing ring must have been shifted so the barrel cannot move enough to reach infinity focus. The ring needs to be adjusted.
11-15-2011, 01:11 AM   #8
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fg-one: Thanks for that. I can understand that it may be the case as the lense was recently serviced.

Here are three more comparisons from: F28/2.8, 50-135 @ 50mm, 50-135 @ 123mm, at both f2.8 and f8.

The F28 was at hard stop and the focal plane appears to be at similar distance to the M28 (15m).
The 50-135 could focus way past infinity at 135mm, where as at 50mm it could just go past (focus ring markings relate). So I manual focused this lense.

Having gone through the process of systematically posting images here, I now see that one can indeed have the focal plane at infinity (or a few Kilometres) away.

Thought it does appear that both 28mm lenses cannot reach infinity.

So my current question is:
-Is likely that the two lenses are out of calibration, or the body?

Thanks for all the help, and participating in public brainstorming.

T
-------------------------------

The F28 @ infinity:




The 50-135 manual focus, at 50mm:




The 50-135 manual focus, at 123mm:


11-15-2011, 09:21 PM   #9
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Bump. Any ideas people?

Is it:
-2 lenses out of calibration (possibly the 50-135 too)
or
-the body out of calibration?

Any help would be grand.

Regards,
T
11-15-2011, 09:44 PM   #10
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I dropped my old K20 once from three feet. It was never the same after that and all lenses will now not focus to infinity. I believe the shock changed the position of the focal plane inside the camera. Still works great from inside of three feet

Jack
11-16-2011, 03:03 AM   #11
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Oh, so a dedicated macro camera Jack...
11-16-2011, 08:50 AM   #12
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One of my KA mount lenses would not focus to infinity either all the time. It would if you bumped it in the front, but when you ran the focus from in to out and back, it would not focus at infinity again. It had a loose element inside. I removed the back plate, tightened the element, and all is well. If you check this, be careful that you do not lose the small ball and spring under the plate. Without those the camera will not know they type of lens is mounted.
11-16-2011, 12:25 PM   #13
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QuoteOriginally posted by toooldtocare Quote
One of my KA mount lenses would not focus to infinity either all the time. It would if you bumped it in the front, but when you ran the focus from in to out and back, it would not focus at infinity again. It had a loose element inside. I removed the back plate, tightened the element, and all is well. If you check this, be careful that you do not lose the small ball and spring under the plate. Without those the camera will not know they type of lens is mounted.
I just bought a K5 with the kit lense 18-50mm and that has a problem focussing but only on the right side, it's quiet blurry and the left size lkooks OK. If you look at this photo and zoom in on the right side you can see it. This onlt happens at the 18mm zoom range.
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11-16-2011, 02:53 PM   #14
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Ross: That sounds like a decentering, where the optical elements within the lense are out of alignment. I would assume the problem is there all the time, but is most noticeable at 18mm.
11-17-2011, 01:31 PM   #15
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QuoteOriginally posted by Turtle Quote
Ross: That sounds like a decentering, where the optical elements within the lense are out of alignment. I would assume the problem is there all the time, but is most noticeable at 18mm.
I have been intouch with T Dimension and they wanted photos which I sent, they have agreed to replace it but they haven't any more instock so they have offered me the 18-135mm but I'm sceptical about Pentax lenses after my experience and reading your problems, so I have ask could they get me a Tamaron 17-50 f2.8 and I pay the difference.
Your problem sounds like what I experienced with a Nikon D7000 I had, I have read lot about the focus problems with that camera on DP Review. I ended up getting rid of it as all my photos looked very soft and not focussed properly and it wasn't user error as a lot of people on forums blame. After having DSLR's for 10 years I new how to use and set a camera up properly, my previous camera to this was a Nikon D90 and that was a great little camera nicely focussed sharp photos.
I would send the camera and lens in and ask it to be checked for proper calibration as it seems out.

Last edited by ross; 11-17-2011 at 01:47 PM.
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