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12-09-2012, 02:17 AM   #1
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18-135 refuses to focus

Hi,

I just received my K-30 kit with the 18-135 lens, but the lens simply refuses to focus. Nothing happens when I half-press the shutter button. 1 out of 10 times it will make an effort to focus, but does not even get anywhere close. I know that it is a lens problem, because the 55-300 lens that I also ordered works fine. Anyone have a suggestion how to easily fix the problem (contacts maybe?) that will save me having to send it back?

Thanks,

Charlton

12-09-2012, 04:43 AM   #2
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Are you shooting up too close and beyond the lens' focusing scale? This may cause the lens to stop focusing once it hits the end of the scale and may tinker back and forth a bit in a attempt to reach further in. Try focusing when you are further away from the subject and see what happens.
12-09-2012, 04:56 AM   #3
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My experience of the 18-135 is that, if it cannot focus, it does not even try. "Cannot focus" can be that you are trying to focus too close or there is too little contrast (low light, etc.). My other lenses will hunt, but I am not sure I have ever got the 18-135 to hunt.

Firstly, ensure that ALL the contacts are clean.
12-09-2012, 07:28 AM   #4
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Thanks for the suggestions. The lens refuses to focus, regardless of subject distance or available light. Even when it does respond, it only focuses slightly, without even coming close to achieving accurate focus. The strange thing is that It does not even focus manually! It just seems like I got a dud. Maybe Vietnam isn't the best place to assemble lenses....

,

12-09-2012, 10:43 AM   #5
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QuoteOriginally posted by Charlie70 Quote
Maybe Vietnam isn't the best place to assemble lenses....
Don't be ridiculous.

Last month, Toyota recalled 2.77 million automobiles. Maybe Japan isn't the best place to assemble automobiles....
12-09-2012, 04:06 PM   #6
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QuoteOriginally posted by Charlie70 Quote
The lens refuses to focus, regardless of subject distance or available light.
It is possible that the lens took a knock somewhere between the factory, the retailer, and you, which has thrown out a gear in the lens, or broken a soldered connection somewhere. It happens.

But I am VERY surprised to hear you state that you can't even manually focus. What happens if you set the focus mode switch to 'MF' and try to turn the focus ring on the lens (the little ring, not the big zoom ring)?

Surely the lens it isn't so jammed up that the focus ring won't even turn by hand.
12-10-2012, 01:20 AM   #7
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QuoteOriginally posted by MPrince Quote
Don't be ridiculous.

Last month, Toyota recalled 2.77 million automobiles. Maybe Japan isn't the best place to assemble automobiles....
Point taken. The comment was written out of frustration. For the record, I have nothing against Vietnam or the Vietnamese people.
12-10-2012, 01:25 AM   #8
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Believe me, I was also very surprised. The focusing ring turns smoothly (I'm not a newbie to photography), but has no effect on the focus.

12-10-2012, 02:43 AM   #9
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QuoteOriginally posted by Charlie70 Quote
The focusing ring turns smoothly (I'm not a newbie to photography), but has no effect on the focus.
OK, just had to check.

So, with the lens dismounted from the body, and the lens at maximum zoom, does the focus ring rotate freely, and does the focus ring feel like it is moving across it's full range? (Even though the focus ring spins continuously, you should feel a slight 'bump' at each end of the focus range as you hit the focus limits).

And while you are moving the focus ring across the full focus range, while looking into the inside of the lens from the front, do you see lens movement inside the lens? You should see some up/down movement from the lens elements towards the rear of the lens as you move the focus ring back and forth. It won't be very much movement, but it should be visible. Is that working?
12-11-2012, 02:34 AM   #10
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QuoteOriginally posted by rawr Quote
OK, just had to check.

So, with the lens dismounted from the body, and the lens at maximum zoom, does the focus ring rotate freely, and does the focus ring feel like it is moving across it's full range? (Even though the focus ring spins continuously, you should feel a slight 'bump' at each end of the focus range as you hit the focus limits).

And while you are moving the focus ring across the full focus range, while looking into the inside of the lens from the front, do you see lens movement inside the lens? You should see some up/down movement from the lens elements towards the rear of the lens as you move the focus ring back and forth. It won't be very much movement, but it should be visible. Is that working?
Absolutely nothing. No "bump", no internal lens movement, nada. Anyway, the guys at Emmy photo (purchased through Amazon) have agreed to replace the lens and foot the return shipping charge, no questions asked. They will dispatch a replacement lens as soon as they receive the return tracking number for the "lemon". On a more positive note, I have been playing around with the 55-300 and am pleasantly surprised both by its sharpness and lovely bokeh. The only downside is the focusing noise. As a rule, are lenses with internal motors quicker to focus or is it just the added convenience of near silent focusing?

Last edited by Charlie70; 12-11-2012 at 04:26 AM.
12-11-2012, 03:19 AM   #11
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QuoteOriginally posted by Charlie70 Quote
are lenses with internal motors quicker to focus
Generally, yes. But, speaking just about the lens, the focus speed can also depend on the focus throw of the lens, and the mass of the glass involved too sometimes. Meaning there are some screw drives lenses that are very quick (eg some of the DA pancakes), and some internal DC/SDM/HSM etc lenses that are slow (eg the DA* 50-135 is reputed to be quite slow).

Another factor in the apparent AF speed of a lens may often be related to the amount of light the lens in question lets in, or the contrast of the lens. Sometimes a dark, dirty or simply soft lens (usually one with a crappy UV filter on it...) will make the camera's AF sensor struggle to get a nice contrasty view of the AF target and hence get a lock on it, so the camera's AF may then be forced to hunt for a while until it can see something to focus on.

Anyway, best of luck with your next copy of the 18-135.
12-11-2012, 04:25 AM   #12
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QuoteOriginally posted by rawr Quote
Generally, yes. But, speaking just about the lens, the focus speed can also depend on the focus throw of the lens, and the mass of the glass involved too sometimes. Meaning there are some screw drives lenses that are very quick (eg some of the DA pancakes), and some internal DC/SDM/HSM etc lenses that are slow (eg the DA* 50-135 is reputed to be quite slow).

Another factor in the apparent AF speed of a lens may often be related to the amount of light the lens in question lets in, or the contrast of the lens. Sometimes a dark, dirty or simply soft lens (usually one with a crappy UV filter on it...) will make the camera's AF sensor struggle to get a nice contrasty view of the AF target and hence get a lock on it, so the camera's AF may then be forced to hunt for a while until it can see something to focus on.

Anyway, best of luck with your next copy of the 18-135.
Thanks, I appreciate you taking the time to reply. As a former Nikon/Canon shooter, I am used to the Nikon 70-300 VR and Canon's similar offering, both of which have IF. I wonder how the Pentax 55-300 compares to these two in terms of focusing speed. I should get a chance to shoot BIF this Friday, so I'll report back again after.

In my previous post, I meant "Emmy Photo" not "Sammy Photo" (now corrected).
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