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Old Nov 7, 2006, 9:43 AM   #1
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all this K mount lenses I havbe figured out, but I'm still confused about M42. If I use them with adapter, what happens when I stop down the lens? does the viewfinder goes dark and lens is stopped immediatelly or does it work like manual lens (lesn stops down when i press the shutter)?

One more: do I really need an M42 Takumar 300mm f4? (I'm thinking of buying one from ebay), I've seen photos from that lens and they're pretty good.

about wideangle: I was looking for wide prime lens for my landscape photos but couldn't find any Pentax 21 or 24mm on ebay. would they be much better than kit lens in terms of sharpness, contrast and color? I want something between 21 and 24mm., 18 is too wide for me. what about M42 Zeiss lenses? anyone has experience with them?
and one more thing is M42 the same as screwmount Zeiss lenses?

thanks

greg
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Old Nov 7, 2006, 10:26 AM   #2
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Greg - I used an M42, 28mm most of this year with the Pentax adapter. Regardless of what you read, the M42 is a full manual lens on the K-mount. The M42's have a pin that goes in and out to work the aperture when in the auto position and the K-mount has a lever, so they don't function together.

Here is how I did it. Make sure to set your custom menu to allow aperture ring and set the dial to theM postition. I also set the focus to MF. Set the lens switch to manual and say you want to shoot at F8. Set the lens to F8, click the Av button to activate the light meter (or push shutter halfway), then push the AE-L button to take a light meter reading,this alsosets the shutter speed to match the reading. You can then take the picture. I liked to focus wide open, so would manually set the aperture wide open, focus and then stop down again before taking the picture. You don't need to reset the light meter everytime if light conditions are not changing.

This all sounds rather involved, but after you do it a few times it becomes like using the old manual cameras, just one continuous motion. The main differance between M42 lenses and M, K-mount lenses is the M lens has the lever and so stays at wide open until you take the picture, so you don't need to change aperture to focus. When you press AE-L it stops down and sets the speed and also you can use the preview lever to see the depth of field. Of course you don't need to do this with the M42, because you are manually stopped down and can see the depth of field. I hope all this makes sense.

Having said all this, I have sold all my M42's (4) on Ebay and purchasedthree M, K-mounts to replace them. To me it was important to be able to focus without having to change the aperture each time and also the quick change of the bayonet mount compared to the screw mount. Both types of prime lenses give the same results optically though, so you can go either way. Good luck to you- Bruce

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Old Nov 7, 2006, 10:30 AM   #3
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If I use them with adapter, what happens when I stop down the lens? does the viewfinder goes dark and lens is stopped immediately or does it work like manual lens (lens stops down when i press the shutter)?


Yes the viewfinder will go dark and stay dark until you manually open the aperture again. No mechanical connection between Camera and Aperture mechanism.

what about M42 Zeiss lenses? anyone has experience with them?
and one more thing is M42 the same as screw-mount Zeiss lenses?


Be careful with some of the older Zeiss lenses. Some of them had an M39 screw mount. There is an M39 to M42 adapter available.

I want something between 21 and 24mm

I have a Sigma 24mmEX f1.8 prime. It is huge and heavy, but the image quality is excellent. I can recommend it, but it is 3 times as big as a comparable Pentax lens. They also make a 20mm version.





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Old Nov 7, 2006, 5:09 PM   #4
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You can use your M42 lens in Apeture priority mode with teh lens stopped down.

This gives you the advatage of automatic exposure if this mode suits a particular situation. Of course you can still make the exposure in full manual mode.


I use a number of m42 lenses for sports. I compose and focus for a particular area and wait for the action to arrive. So I only really focus once for a series of shots.

This one was taken with a Vivitar 200mm F3 m42 mount prime


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