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10-02-2006, 07:44 PM   #1
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Can someone walk me through the steps?

I've just picked up a Pentax-F SMC 100-300mm autofocus lens 4.5-5.6.

I mounted it on my K100D with Tamron 1.4 TC, but the lens apparently will only focus manually and in a limited range (up to about 150mm).

Is there a problem with the lens or am I missing something?

If I'm missing something, can someone please walk me through the steps?

All help appreciated.

10-02-2006, 07:59 PM   #2
Ole
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Tom, Could you elaborate?

1) Is the Tamron 1.4 TC supposed to allow for autofocus?

2) Does the lens work correctly when mounted directly on the camera )without the converter)?
10-03-2006, 03:10 PM   #3
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QuoteOriginally posted by Tom Lusk Quote
I've just picked up a Pentax-F SMC 100-300mm autofocus lens 4.5-5.6.

I mounted it on my K100D with Tamron 1.4 TC, but the lens apparently will only focus manually and in a limited range (up to about 150mm).

Is there a problem with the lens or am I missing something?

If I'm missing something, can someone please walk me through the steps?

All help appreciated.
Tom,

I am looking at picking up this TC but does the manual not say that Autofocus for any lens only works if it is F4 or faster? I don't have it yet but if that is the case then it looks like manual focus only for us slower lens users.

Last edited by equinox; 10-03-2006 at 03:10 PM. Reason: Typo's
10-03-2006, 06:02 PM   #4
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Welll...

Hi Ole:

Yes- the TC works fine with my DA50-200, all functions work 100%.

I didn't get a chance to try the lens alone as I worked until after dark tonight, but will give it a try in the morning, if there's enough light before I head out for the day.

equinox - I'll have to check out the manual. Dpesn't seem right that the camera won't/can't autofocus a slower lens than f4?

10-04-2006, 02:26 PM   #5
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I have the Tamron AF 1.4x tc also and the instructions do say it may not work as AF at F4 or smaller but it has always worked with my DA 50-200 regardless of aperture setting
10-04-2006, 03:04 PM   #6
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Hmmmm...

I've just tried the lens on my K100 without the TC.

Setting the focal length at infinity, the lens will only focus up to approx. 140 mm. Anything beyond that is a total blur???

So- it's not the TC.

What could be wrong with the lens?
10-04-2006, 05:05 PM   #7
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Better send it back. Something is out of alaignment.
10-05-2006, 09:47 AM   #8
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How far away is the object that you are trying to bring into focus and does it have sufficient contrast?

10-06-2006, 07:29 AM   #9
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Does this lense have a macro switch? If so, make sure it's off.
10-06-2006, 01:38 PM   #10
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Hmmmm...

Here is a shot @100mm, focussed to infinity:



Same shot/scene @300mm, focussed to infinity:



Manual focus on both. No macro switch.

Lens is a dud?
10-06-2006, 06:00 PM   #11
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It sure looks like a dud. It must have been dropped or something.
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