Manual lenses and F stops

jjhenders · 11-29-2011, 02:46 PM

Hi. I,ve had my Kx for probably a year now but still feel like a beginner, so that's why I post here. I have three auto lenses and four manual lenses (the best of which I suppose is supposed to be the M50 1.7). I'm finally getting a better hit rate for focus. My main problem now is that the background blur looks the same (very blurry) no matter which f stop I have it set to (1.7--22, no difference at all). When I look into the lenses under bright light, it looks like the iris is stopping down (happens kind of fast, but that's the way it looks), but when its on my camera taking pictures, stopping down seems to have no effect. I have my camera set to MF on the side of the camera, but is there some crucial thing I'm not doing? PS. I'm talking here about pics taken at close range. I just did a shootout with my auto lenses to try to determine whether it was worth throwing any more money into manuals, and the background blur clears right up on the auto lenses. Thanks, Jim

JinDesu · 11-29-2011, 02:48 PM

Are you using AV mode or manual mode for your settings? Under AV mode, the camera forces the lens wide open no matter what setting you put the lens at.

RioRico · 11-29-2011, 03:03 PM

Originally posted by JinDesu

Are you using AV mode or manual mode for your settings? Under AV mode, the camera forces the lens wide open no matter what setting you put the lens at.

Quite right. First, you've probably already set USING APERTURE RING to PERMITTED. This lets you use any AF or MF lens with an aperture set to something other than A. If you're shooting A-type or adapted lenses (like M42 screwmounts), you can preset the aperture and shoot in Av mode. But with an M- or K-type lens, which have only a mechanical aperture linkage, you need to put the camera in M mode and use the Green button for stop-down metering and exposure. In any auto mode, a K or M lens remains wide open, just as you describe.

jjhenders · 11-29-2011, 06:21 PM

OK and thanks to both of you. That's exactly what I've been doing--using my manual lenses in Av. I figured that it seemed to work and cut out the step of pushing an extra button for metering. Well, I guess I'll start adding that extra step and see if the background changes. Thanks again! Jim

**TomB_tx** · 11-29-2011, 07:13 PM

When you say the background blur doesn't change, are you talking about on the resulting picture, or in the viewfinder? Auto-diaphragm lenses always focus wide open, so you won't see the difference in the viewfinder unless you manually stop the lens down. I believe the green-button just momentarily closes the lens. I don't have a K-x, but the K-5 has a stop-down lever on the power switch, which will let you see the focus-effect of stopping down with M lenses.

11-29-2011, 02:46 PM	#1
jjhenders Inactive Account Join Date: Jan 2011 Location: Broadway, VA Photos: Albums Posts: 99	Manual lenses and F stops Hi. I,ve had my Kx for probably a year now but still feel like a beginner, so that's why I post here. I have three auto lenses and four manual lenses (the best of which I suppose is supposed to be the M50 1.7). I'm finally getting a better hit rate for focus. My main problem now is that the background blur looks the same (very blurry) no matter which f stop I have it set to (1.7--22, no difference at all). When I look into the lenses under bright light, it looks like the iris is stopping down (happens kind of fast, but that's the way it looks), but when its on my camera taking pictures, stopping down seems to have no effect. I have my camera set to MF on the side of the camera, but is there some crucial thing I'm not doing? PS. I'm talking here about pics taken at close range. I just did a shootout with my auto lenses to try to determine whether it was worth throwing any more money into manuals, and the background blur clears right up on the auto lenses. Thanks, Jim

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11-29-2011, 02:48 PM	#2
JinDesu Veteran Member Join Date: Jun 2011 Location: New York City Photos: Gallery Posts: 5,638	Are you using AV mode or manual mode for your settings? Under AV mode, the camera forces the lens wide open no matter what setting you put the lens at.

11-29-2011, 03:03 PM	#3
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	Originally posted by JinDesu Are you using AV mode or manual mode for your settings? Under AV mode, the camera forces the lens wide open no matter what setting you put the lens at. Quite right. First, you've probably already set USING APERTURE RING to PERMITTED. This lets you use any AF or MF lens with an aperture set to something other than A. If you're shooting A-type or adapted lenses (like M42 screwmounts), you can preset the aperture and shoot in Av mode. But with an M- or K-type lens, which have only a mechanical aperture linkage, you need to put the camera in M mode and use the Green button for stop-down metering and exposure. In any auto mode, a K or M lens remains wide open, just as you describe.

11-29-2011, 06:21 PM	#4
jjhenders Inactive Account Join Date: Jan 2011 Location: Broadway, VA Photos: Albums Posts: 99 Original Poster	OK and thanks to both of you. That's exactly what I've been doing--using my manual lenses in Av. I figured that it seemed to work and cut out the step of pushing an extra button for metering. Well, I guess I'll start adding that extra step and see if the background changes. Thanks again! Jim

11-29-2011, 07:13 PM	#5
TomB_tx Loyal Site Supporter Join Date: Jun 2011 Location: Texas Photos: Gallery Posts: 1,446	When you say the background blur doesn't change, are you talking about on the resulting picture, or in the viewfinder? Auto-diaphragm lenses always focus wide open, so you won't see the difference in the viewfinder unless you manually stop the lens down. I believe the green-button just momentarily closes the lens. I don't have a K-x, but the K-5 has a stop-down lever on the power switch, which will let you see the focus-effect of stopping down with M lenses.