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05-25-2010, 05:55 PM   #1
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Question about using old lens on K-x (difference between A and M series lenses)

Thinking about getting a M or A prime lens on Ebay, what exactly is difference between M series and A series? I believe they only manual focus, how about aperture? Is it also manual when it's used on K-x? Would like to have some comment from anyone who has experience on this.

05-25-2010, 06:42 PM   #2
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A series lenses have automatic aperture, you set the aperture on the camera. K and M series lenses do not have automatic aperture. K and M series lenses only work in M mode, you set the aperture with the ring then press the AV +- button to set exposure. You can set up the green button for another function, like RAW or Optical Preview.
05-25-2010, 08:56 PM   #3
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Yes they will only do manually focus on any camera but you still get the focus conformation via the green light in the viewfinder and boriscleto already covered the apature part of your question.
05-26-2010, 11:22 AM   #4
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I'm noving this to the beginner's forum, since it seems most appropriate there. The other place it could have been posted is the Lens forum.

Note there is an excellent guide on this site that explains the various types of lenses. And see the sticky thread at the top of the beginner's forum on how to use manual lenses (meaning, "M" and older lenses as opposed to "A").

05-26-2010, 11:31 AM   #5
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See here for the difference between A and M lenses: Pentax K-Mount Lenses Explained

Essentially, they're the same except that A lenses allow for use of auto aperture mode. Both lens series are manual focus. Some A lenses started incorporating plastic constructions, while most M lenses are all-metal.

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