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01-20-2010, 08:43 PM   #1
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K2000 firmware update?/ K7 M lens compatibility

I'm enjoying the k2000 I have very much so far, but have one question. My manual (and what I've read on here) says that my M 50mm f2.0 I should have to go to manual and press the exposure compensation to set the shutter speed (due to lack of aperture info), and that was how it worked until connected to the computer to read an sdhc card (only had an sd reader at the time). Now, whenever I hook up the manual lens, the metering works fine on any aperture setting in aperture priority mode after inputting the focal length. Suppose this isn't a problem per se, but wanted to know if this was the case for all new pentax dslr's (particularly the k7) or is unique to the K2000 as I have a friend with a collection of old M lenses that he would like to be able to use this simply.

01-21-2010, 12:27 AM   #2
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QuoteOriginally posted by xeric92687x Quote
I'm enjoying the k2000 I have very much so far, but have one question. My manual (and what I've read on here) says that my M 50mm f2.0 I should have to go to manual and press the exposure compensation to set the shutter speed (due to lack of aperture info), and that was how it worked until connected to the computer to read an sdhc card (only had an sd reader at the time). Now, whenever I hook up the manual lens, the metering works fine on any aperture setting in aperture priority mode after inputting the focal length. Suppose this isn't a problem per se, but wanted to know if this was the case for all new pentax dslr's (particularly the k7) or is unique to the K2000 as I have a friend with a collection of old M lenses that he would like to be able to use this simply.
Hi,

In Av mode, the camera always shoots at max. aperture, no matter what aperture you set on the M or K lenses. In order to control the aperture, you have to shoot in M mode and use the green button (on K10D, K20D, K-7) or the AE-L button (on K100D/K110D, K200D, Km, Kx) to set the shutter speed.

Couple things to remember when shooting M and K lenses:
1. Attach the lens before you switch the camera on in order to set the focal length for SR to work.
2. Go into Menu and set Using Aperture Ring to "Permitted"
3. Use M mode rather than AF-S or AF-C, unless you want to use Catch-in-Focus. This way you keep the screw driver retracted. This is not critical though.
4. If you want to use Catch-in-Focus, then use AF-S (not AF-C). You may need to switch that option on in the Menu, depend on the camera (K-7 yes, K100D no).

Hope that answer your question. By the way, you should check out the Q & A for Beginners section. It has all the answers with photos showing you step by step. What I wrote here are what I learned there.

Peter
01-21-2010, 01:30 AM   #3
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QuoteOriginally posted by xeric92687x Quote
I'm enjoying the k2000 I have very much so far, but have one question. My manual (and what I've read on here) says that my M 50mm f2.0 I should have to go to manual and press the exposure compensation to set the shutter speed (due to lack of aperture info), and that was how it worked until connected to the computer to read an sdhc card (only had an sd reader at the time). Now, whenever I hook up the manual lens, the metering works fine on any aperture setting in aperture priority mode after inputting the focal length. Suppose this isn't a problem per se, but wanted to know if this was the case for all new pentax dslr's (particularly the k7) or is unique to the K2000 as I have a friend with a collection of old M lenses that he would like to be able to use this simply.
You may want to double check what's actually happening.

Av mode will appear to be working for M and K lenses, and it indeed does work when set to the widest aperture of the lens. However, stop it down and you'll see it doesn't actually function correctly. The shutter speed will be adjusting, but only for a wide open aperture.
01-21-2010, 01:37 AM   #4
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An easy mod to the lens for it to work as a stop-down lens (like m42 lenses) is to drill a second locking hole into it, so it sits turned only halfway into the mount... This way, the aperture lever is not depressed by the camera, and the aperture physically moves as you turn the aperture ring...

01-23-2010, 12:04 AM   #5
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Original Poster
After checking this out, it appears it is not working as I had thought. In Av, I can stop down physically on the lens, but there appears to be no effect as on the same scene I end up with the same exposure time, whereas on manual exp. time goes up when stopped down. Does the camera being in Av mode actually physically block the aperture lever on the lens? This is the only explanation I can think of.
01-23-2010, 12:22 PM   #6
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I don't know that it "blocks" the aperture lever; it simply ignores it. M lenses are designed to stay open when you turn the aperture ring, and only stop down when the camera moves the lever. In any mode but M, the camera simply never moves the lever.
01-24-2010, 12:56 AM   #7
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QuoteOriginally posted by xeric92687x Quote
After checking this out, it appears it is not working as I had thought. In Av, I can stop down physically on the lens, but there appears to be no effect as on the same scene I end up with the same exposure time, whereas on manual exp. time goes up when stopped down. Does the camera being in Av mode actually physically block the aperture lever on the lens? This is the only explanation I can think of.
When you have the lens off camera you can move the aperture ring and watch the blades move with it. Place the lens on the body and as you mount it the aperture lever of the lens is moved so the lens is wide open. Stop the lens down to it's smallest aperture, mount it on the body, and watch it happen. This is true no matter the mode. In M mode that lever is moved and the aperture is adjusted to what you manually pressed when you press the Av button so the light meter functions and sets the shutter speed. In Av mode the lens is just constantly wide open. It will always read for wide open. This means Av mode actually works, but only for wide open. If you adjust it to any other aperture you'll have the wrong exposure since the light meter is only metering off wide open.
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