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08-23-2010, 09:27 PM   #1
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Manual Focus and Link AF Point

I was wondering if there a way to utilize 'Link AF Point and AE' feature when shooting with manual focus lenses. Its use with AF lenses is obvious but when using MF lens, I just shoot when I find the desired object in focus. So if this feature is turned ON, what would be the exposure based on. Would it be incorrect to use this at all? Also, how it impacts when AF/MF switch in either position (say when using trap focus)

Yusuf

08-23-2010, 10:18 PM   #2
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I don't think it would work. The Kx uses the center point only on manual lenses. Others may correct me if I am wrong.
08-24-2010, 05:46 AM   #3
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This is an excellent question that I was curious about as well. I just recently turned that option off since I imagine it's linking AE to that center point, which if I wanted that I'd use spot metering.
08-24-2010, 06:40 AM   #4
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Well, with manual A lenses, it will work exactly as with AF lenses: select a focus point, then half-press and shoot... It will behave somewhat like a focus-point-center-weighted metering mode, nearly a spot mode...

With old PK, PK-M or m42 lenses, the camera will revert anyway to center-weighted (matrix mode will be unavailable).
There is still a trick to get it to work : you have to short the A pin on the mount. the camera will be tricked into thinking it has an actual A lens currently mounted. But you'll then have metering problems in Av mode if you're not careful, and some other problems...

08-24-2010, 07:00 AM   #5
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QuoteOriginally posted by dlacouture Quote
Well, with manual A lenses, it will work exactly as with AF lenses: select a focus point, then half-press and shoot... It will behave somewhat like a focus-point-center-weighted metering mode, nearly a spot mode...

With old PK, PK-M or m42 lenses, the camera will revert anyway to center-weighted (matrix mode will be unavailable).
There is still a trick to get it to work : you have to short the A pin on the mount. the camera will be tricked into thinking it has an actual A lens currently mounted. But you'll then have metering problems in Av mode if you're not careful, and some other problems...
Do you have more info on what other consequences of shorting the A pin in the mount?

Thanks,
08-24-2010, 11:56 AM   #6
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Well, In M mode, it won't close the lens anymore to take a reading with the Green button, as it will just base its metering on the open aperture and then use whatever aperture you selected on the body...

Av mode will also be badly underexposed, as it will meter again wide open and use whatever aperture you selected on the body (so far you can nearly believe you just transformed your PK lens into a PK-A!), but then the camera would not move the lever far enough for the lens to be fully closed down...

Regarding PK-M lenses, a good DIY mod is to drill a second locking pin so the lens only turn halfway into the mount and then behaves just like a preset aperture lens (as m42s).
If you don't use small apertures, it's a breeze to use!

Now, extra bonus with those m42 and modded pk-M: if you short the A and Data pins, you can use P-TTL with your old lenses! The full regalia : wireless, HSS and so on!
Only thing to do : select the biggest aperture available on the camera (for whatever actual aperture you're using on the lens).
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