Help with aperture...please?

paolojackson · 08-30-2008, 12:53 PM

So I got my first manual lens (k mount) today without the A setting. I went to the menu and set it so that I could use the aperture ring and I also set it on manual focus. Taking pictures is no problem.

My question is, why, when I change the aperture from say 4 to 11, nothing seems to change, most notably the shutter speed? I would assume that when you go from f/4 to f/11, the shutter would be open for longer?

alohadave · 08-30-2008, 01:00 PM

You'll need to tell the camera to check the exposure when you change the aperture (either the green button or the AE-L button, depending on the body you have).

The camera can't tell with an M series lens because there is no communication between the lens and body. By using the green/AE-L button, you tell the camera to close the aperture and it can calculate exposure.

paolojackson · 08-30-2008, 01:08 PM

Ahh I finally figured it out. I didn't know that you had to also have your camera in Manual mode versus any other mode. In any other mode, the green button simply set it to AUTO iso.

Thanks so much for your quick answer

JCSullivan · 08-31-2008, 07:08 AM

Good question - although short, nice discussion.

gowerray · 08-31-2008, 07:35 AM

There is a good illustrated guide for M lens use here: Manual Lens
It's for the K100D Super but the settings are pretty much the same for your camera. Helped me understand where I was going wrong (again ) Hope it helps, Ray

paolojackson · 08-31-2008, 05:05 PM

Before anything, please excuse incorrect use of terminology =P

Yet another question....in shooting with my new manual k-mount lens, I noticed that when I press the green button to stop down the aperture and set the shutter for correct metering, it only works up to about f/5.6. Starting from the widest open, I press the green to get the correct shutter speed. I move a stop down, and press again, to get the new shutter speed a stop lower. When I do this a few more times, it gets to the point where the shutter speed stays the same but the aperture gets smaller and smaller. I know this is incorrect as evidenced by severely underexposed shot in smaller apertures. To compensate, I correct the shutter speed myself.

Is there a limitation when using a manual K lens? Or maybe it has something to do with the metering mode: spot, center, and matrix?

nixcamic · 08-31-2008, 08:35 PM

How long are the exposure times in question? I've noticed I sometimes get underexposure on manual lenses using the green button when exposures go over a second or two.

*Canada_Rockies* · 08-31-2008, 09:18 PM

Originally Posted by paolojackson

Before anything, please excuse incorrect use of terminology =P

Yet another question....in shooting with my new manual k-mount lens, I noticed that when I press the green button to stop down the aperture and set the shutter for correct metering, it only works up to about f/5.6. Starting from the widest open, I press the green to get the correct shutter speed. I move a stop down, and press again, to get the new shutter speed a stop lower. When I do this a few more times, it gets to the point where the shutter speed stays the same but the aperture gets smaller and smaller. I know this is incorrect as evidenced by severely underexposed shot in smaller apertures. To compensate, I correct the shutter speed myself.

Is there a limitation when using a manual K lens? Or maybe it has something to do with the metering mode: spot, center, and matrix?

The metering mode does not affect this problem - matrix will automatically switch to center weighted with any lens pre-A series. Spot metering is usable. I have found with my M lenses that they have a certain range of apertures at which the exposure is acceptable. Outside that range, they over or under expose. I have taken, for example, with my M 400 to meter at f/8 and interpolate from there. On occasion I just use the sunny 16 rule. If I meter at f/5.6 or f/16 or more, the meter is not accurate. This apparently has something to do with the camera not knowing exactly what lens you have mounted. It doesn't matter though, the old "f/8 and be there" seems to work with both my M lenses. Av only works wide open, so it is basically useless.

Marc Sabatella · 08-31-2008, 09:36 PM

Originally Posted by paolojackson

Starting from the widest open, I press the green to get the correct shutter speed. I move a stop down, and press again, to get the new shutter speed a stop lower. When I do this a few more times, it gets to the point where the shutter speed stays the same but the aperture gets smaller and smaller. I know this is incorrect as evidenced by severely underexposed shot in smaller apertures. To compensate, I correct the shutter speed myself.
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Well, the meter needs a certain amount of light to work. In bright sun. I'd think there would be enough even when stopped way down. But in dimmer situations, by the time you get to f/8 and beyond, perhaps you are getting below the threshold.

Reports of the K10D metering inconsistently with manual exposure lenses as you stop down are pretty common, and supposedly installing a different focus screen helps. Apparently the DS, K100D, and K200D are better in this respect. I know I've tested my K200D (in bright light) and found it slows the shutter after hitting the green button on each click exactly as expected, and the resulting pictures are exposed almost identically.

Or maybe it has something to do with the metering mode: spot, center, and matrix?

Also, note matrix metering isn't actually supported with manual exposure lenses. If you normally have matrix selected, it will change to center weighted.

slowpez · 09-01-2008, 08:10 AM

Originally Posted by gowerray

There is a good illustrated guide for M lens use here: Manual Lens
It's for the K100D Super but the settings are pretty much the same for your camera. Helped me understand where I was going wrong (again ) Hope it helps, Ray

You know, the best part about this website are the links everyone takes the time time to post for all of us newbies. I can't tell you how much they are helping me and how much I appreciate it.
Thanks Ray and to all of you other guys who have done the same thing, Susan

paolojackson · 09-02-2008, 10:35 AM

Originally Posted by Marc Sabatella

Well, the meter needs a certain amount of light to work. In bright sun. I'd think there would be enough even when stopped way down. But in dimmer situations, by the time you get to f/8 and beyond, perhaps you are getting below the threshold.

I think what you have said is spot on. Most of my first shots were inside so I could properly meter at around f/5.8. When I got the chance to go outside, I was able to get correct exposure all the way up to f/22.