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Old Jan 29, 2007, 5:21 PM   #1
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I've just bought a K100D with 18-55mm kit lens and the 55-200mm zoom.

I don't have a shoe mount flash (yet) and find both lenses a bit slow in-doors in low light. Don't have much left to spend on a good prime or the flash so I'm looking at the used market. On the K100D what issues should I be aware of in using older lenses with the A or M designation. I see that the A lenses have anA on the aperature ring, and the M doesn't. I realizeneither willautofocus, but will the camera be able to meter off of either the A or the M, or will it all be manual? Which camera modes can I use, P, Av, Tv, M?

I'm looking at the 50mm f/2.0 (A), 50mm f/1.7 (A) or (M), advice please?
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Old Jan 29, 2007, 5:28 PM   #2
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The A lens will work in any of the automatic metering modes-when the in the A position.

The M lens will only work in the manual mode.

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Old Jan 29, 2007, 7:07 PM   #3
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Just yesterday I got lucky and managed to pick up a 50mm f/1.7 A rather cheap. I wasn't expecting to get one so soon, so I had already picked up a few other 50mm lenses, two screw mount lenses, a 50mm 1.4 and a 55mm 1.8, and one K mount 50mm 1.7 M which is on the way.

The A lens, when the aperture is set to A, will work exactly like any standard lens you can get for your camera except that you have to focus it. If you manually set the aperture, it will work like an M lens.

The M lens will work two ways. One is to have your camera in M mode. In M mode, you have to meter by pressing the AE-L button which will quickly stop down the lens and set your shutter speed. You can't use exposure compensation, so you have to tweak the speed after metering if you want it darker or lighter.

The other to way to use it is to put the camera in aperture priority mode. In this mode, the camera will automatically meter and set the shutter speed, and exposure compensation is available, but you can only use the widest aperture.

You might want to take a look at screw mount lenses. With a screw mount lens attached using an adapter, you can use M mode but it will not do anything automatically. However, if you use aperture priority mode, you can set the aperture on the lens and the camera will automatically set the shutter speed. Exposure compensation is also available. In some ways that makes the screw mount lens faster and more functional than a K mount M lens. However, the big drawback is that you have to look through the lens with the aperture stopped down, so at smaller apertures it can be hard to see.

A few things to look for. The A lens is probably the best of these to go with, not only because it's easier, but I've read at a few places that they are the sharpest lenses of all of them. If you don't go with an A lens, look for lenses that say SMC on them, which means Super Multi Coated. These will be sharper than ones that are not, and less prone to glare.

My brightest lens is a Super Takumar 50mm f/1.4. It's not SMC, so it does get pretty ugly glares and weird flares sometimes. However, when there is not harsh lighting it does take pretty sharp pictures; http://www.stevesforums.com/forums/v...mp;forum_id=80

If you want to try out some screw mount lenses, be sure to get an adapter that will let you focus to infinity. The Pentax brand adapter will certainly work, but it's a bit pricey and hard to find. It is available at pentax.com though. I use a Roxsen adapter that I got off Ebay and that works very well. I just wish it were a bit easier to take in and out. If I were just using screw mount lenses it wouldn't be a big deal, but it does take some time and effort to switch from screw mount to K mount lenses and vice versa.
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