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01-23-2016, 11:38 AM   #1
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2xKAX Teleplus MC4 issue

If my KAX lens is infront of my autofocus lens, the camera wont autofocus. Is this supposed to happen?

At the moment I am just using the autofocus lens on its own and it autofocuses correctly.

01-23-2016, 12:06 PM   #2
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If it's the same as the one reviewed here, it is not autofocus

Kenko 2X KAX Teleplus MC4 Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database

Slower zoom lenses might have issues autofocusing on a 2x converter anyway.
01-23-2016, 12:31 PM   #3
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QuoteOriginally posted by Thekillerqueen Quote
If my KAX lens is infront of my autofocus lens, the camera wont autofocus. Is this supposed to happen?

At the moment I am just using the autofocus lens on its own and it autofocuses correctly.
"in front" made me confused. Do you mean between the mount on the camera and the lens? Or do you mean between the subject and the front element (which is what in front of means to me)?
01-23-2016, 12:31 PM   #4
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QuoteOriginally posted by boriscleto Quote
If it's the same as the one reviewed here, it is not autofocus

Kenko 2X KAX Teleplus MC4 Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database

Slower zoom lenses might have issues autofocusing on a 2x converter anyway.
Ah i see thank you! Would there be any advantages to having that infront of another lens and using manual focus?

01-23-2016, 12:41 PM - 1 Like   #5
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QuoteOriginally posted by Thekillerqueen Quote
Ah i see thank you! Would there be any advantages to having that infront of another lens and using manual focus?
Unless I am missing your point, the reason for the Tele-extender is to increase the focal length of your existing lens. That comes at the penalty of reduced image quality and two stops of light. With this particular TC you also lose auto-focus.

So to answer your question if you have a 50mm f/1.8 lens auto focus lens and you add the TC you get a 100mm f/3.5 manual focus lens. That is really the only point to putting it "in front". I should add that in general usage "in front" means in front of the front of the lens. In this case I think you mean "in back" in other words between the auto focus lens and the camera.
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