Screw Mount Lenses

[deaner66]

<p>I have a handful of old SMC Takumar lenses. And to be honest, I read just about everything I could find on getting these older lenses to work properly. I read all about 'stop-down metering' and getting an authentic Pentax adapter for focusing to infinity. Check and check. But still, my shots looked too soft for my eyes. Especially when I read all of the raves people give these lenses on different web sites.</p>

<p>After a LOT of trial and error, I finally figured out what wasn't working right. Behind the aperture ring on the old Takumar lenses, is the AUTO and M slider. I guess I just figured AUTO sounded more up-to-date, so that's where I left it set to.</p>

<p>Wrong.</p>

<p>What I discovered--for my K10D, anyway--was that the slider had to be set to M to work properly. And by properly, I mean the ability to adjust the aperture.</p>

<p>When it is set on AUTO, the aperture stays wide open regardless what you set the aperture to. Apparently, that pin that sticks out from the back of the lens is so you can focus with the aperture wide open. Otherwise, you would have a hard time getting focus when the aperture is stopped down because of the small amount of light coming through. SO, the pin helps keep the aperture open for focusing, then goes to the selected aperture when the shutter is pressed.</p>

<p>I hope I explained that right.</p>

<p>Anyway, as far as my camera goes, that slider needs to be set to M if I want to be able to adjust aperture. And I'm kind of funny that way, I guess, because I like adjusting it. Now, like the old Spotmatics, when you look through the viewfinder and stop down, it gets harder and harder to get in focus, so what I do is either open up the aperture up, or I move the slider to AUTO and when I'm ready to take the shot, I slide it back to M. Now this isn't a quick routine, but no one buys these old lenses to shoot sports or anything else that moves faster than you can focus.</p>

<p>And as far as stop-down metering goes, I think it is very hit or miss. I've read people say it under exposes, but it just seems inconsistent to me. But who cares? I take my shot and work from there. If it's underexposed, I adjust it. Simple stuff.</p>

<p>Not being able to see your aperture is frustrating, yes, but if you get the shot, who cares what value it was?</p>

<p>I know no one asked, but maybe this can help someone who is struggling with their older screw mount lenses.</p>

[personalphotos]

<p>Good explanation. I use the Auto manual switch as you described. I stop the lens to where I want it. Say f8 then switch the lens to Auto. Focus, compose etc and then when I'm ready to take a shot, move the switch back to manual. The camera is set to Av so it makes the exposure decision unless I change the shutter speed. I just find this method faster and you don't have to take your eye off the viewfinder.</p>

[JDMvW]

<p><em>Automatic</em> meant the aperture only in the olden times. I tried to straighten this terminology out for those not accustomed to the older viewpoints from personal experience (<a href="../classic-cameras-forum/00RTpg">link</a> ).</p>

[deaner66]

<p>Thanks, JDM, I wish I would have found your piece when I first bought these lenses. It really is amazing how fine these lenses still are.</p>

[carbon_dragon]

<p>A manual focus camera typically wants to give you a nice bright view while you're focusing and composing. Then when you snap the shutter, the lens quickly stops down and you take the shot. That is probably what A does. When your lenses were on their original camera you could probably set the aperture to say f/22, then when you snapped the shot, presto. I'm guessing the K10D is a digital and doesn't have that capability in its adapter. </p>

[laur1]

<p>I've recently got a screwmount camera so I could see the pin in action - screwmount cameras simply have a lever that pushes forward when you press the shutter and this way it stops down the lens while you're taking the shot - also, this way, pressing the shutter slightly would give you a DOF preview. Nice and simple.<br>

On digital cameras, I prefer the old preset lenses that had two aperture rings - one for setting the aperture and one for moving between wide open and the selected aperture - much easier to use. Using the A/M switch instead works, but that switch is usually harder to access on the base of the lens and I am also concerned about the mechanism getting broken after too many operations.</p>

[jeff_livacich]

<p>Only some cameras will give a preview by pressing the shutter button slightly. Most do not.<br>

On the Pentax Spotmatics, for example, moving the metering lever will stop down the lens and turn the meter, but pressing the shutter button will not. That's much more common.</p>