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Old Sep 24, 2006, 8:47 PM   #1
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I have and old 50mm 1:1.4 Pentax-A manual focus prime. Am I to understand that if MF is NOT selected on the camera that the shutter will not fire unless focus is achieved? Additionally, if MF IS selected the shutter WILL fire regardless of focus setting, and either mode will offer the "in focus" indicator in the viewfinder along with Beep if activated? So it is not necessary to switch to MF on the camera as long as the camera focus point can be satisfied?

I also find no mention of whether the lens will function properly in Auto Pict and P modes, just Tv, Av and M modes. I have used the lens in Auto Pict and P modes with apparently correct exposure in various lighting conditions.

In short, it seems that the lens works exactly like the kit 18-55 exposure wise with the obvious exception of Auto Focus.

While I understand this is explained in detail in the Manual, my old thick skull can't seem to decipher it to my satisfaction. I might also mention the lens is always locked to the "A" setting on the aperture ring.

Any light that can be shed will be greatly appreciated!

Dan
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Old Sep 24, 2006, 9:21 PM   #2
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Sounds like you've got it all figured out, though I've never tried to use Auto with my only A lens. Focus works like how you describe, though I find that the K100D's shutter isn't quite as "locked up" as the DS when using a manual lens (don't know if that quite says what I want it to, but its close). The reason I'll usually use manual focus with my manual lenses is that sometimes I'll focus on something off-center and the camera won't think it's in focus. Saves me from having to center what I want in focus, half press to convince the camera its in focusand then reframe to shoot. Also, it'll save me from wondering why the camera isn't working when I forget about it.

If you take the camera off of the A setting, it will still work in any of the modes but it will be shooting wide open (camera won't stop down the lens when you take the picture). You have to have the camera set to M if you want to set the aperture on the ring.

Looks like you've figured out the manual pretty well (and yes, I found that it doesn't exactly explain things all that well - it does a good job with the what, but not the why).
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Old Sep 24, 2006, 9:26 PM   #3
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Hmmm, I have never tried taking a picture with my A lens except in MF mode. In manual focus mode using AV it does work as you describe. I can say that I have found the focus indicator lights to be less than 100% and I am trying to get away from relying on them so much.

Tim


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Old Sep 25, 2006, 12:22 AM   #4
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According to my manual the 11 focus points and the P-TTL flash doesn't work with A-lenses. I have a DS and don't miss any of these two, since I prefer single focus point and TTL flash. The latter don't work on the DL, K100D, K110D or K10D though and that is maybe a problem. Please fill in, flash-users!

Kjell
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Old Sep 25, 2006, 1:16 PM   #5
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There's a technique called "trap focus" where you set the focus at a certain point, but use a manual lens. Once the bird/car/bike/whatever reaches the desired spot, the shutter fires.

This can be done with a manal-focus lens with the camera sert to autofocus.
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