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12-31-2009, 05:49 PM   #1
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stop down metering?

Hi all,
I've been shooting Pentax SLR's for about 30 years and quite often I've heard the terms; "stopping down" or "stop down metering".
About the time I think I have it figured out, someone makes a comment about it that makes me wonder- Just what is stop down metering? Tomorrow's my birthday (yeah, 1/1/10) and I'd like to start the new year knowing something !
Any and all help is welcome and sincerely appreciated; aannd-
HAPPY NEW YEAR!


....oh, by the way, I shoot a Spotmatic, a K1000, and a ZX-50.


Last edited by jonhock; 12-31-2009 at 06:12 PM.
12-31-2009, 05:53 PM   #2
Ash
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Stopping down means to reduce the size of the lens's aperture, i.e. increase the f/ number.

Stop down metering is usually referred to in M mode for M lenses, when the only way one can meter a scene with such a lens is to hit the green button after composing, which tells the camera to stop the lens down (engage the diaphragm to achieve the desired aperture) and allows the camera to meter at that aperture, and gain the exposure values for that scene.

Hope that helps.
12-31-2009, 06:43 PM   #3
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Yes, that does help. I was always pretty sure that stopping down meant going to a smaller aperture, but the "metering" part that goofed me up. On my K1000 with an SMC 50MM 1.2, wouldn't it always be stop-down metering to get the right exposure? Or stop-up to let in more light? (I've never heard; "stop-up metering")
I recently purchased a Takumar 50mm 1.4 with the A/M switch (really nice!) which is what got me wondering about this subject again. I thought I might be doing something wrong by metering with it in manual then shooting with auto so I've been metering and shooting with it in auto. . I haven't had the film developed yet, a couple rolls, and now I'm wondering just what I am going to end up with.
And when I say recently, I'm meaning about 2 weeks ago.
12-31-2009, 06:50 PM   #4
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Thanks for asking the question, jonhock--it's a term I never got (but survived anyway.) Turns out I've been doing it without knowing I was :~) Have a happy birthday!

Oh and thank for the answer, Ash!

12-31-2009, 07:31 PM   #5
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QuoteOriginally posted by jonhock Quote
On my K1000 with an SMC 50MM 1.2, wouldn't it always be stop-down metering to get the right exposure? Or stop-up to let in more light? (I've never heard; "stop-up metering")
Yes, you'd be manually adjusting all settings, so you're stopping the lens down to meter on the camera in any case.

I believe enlarging the aperture is considered 'opening up' or any similar variation to this.
12-31-2009, 08:37 PM   #6
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Thank you Ash and Dadipentak. Opening up does sound a lot better!
01-01-2010, 01:44 AM   #7
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QuoteOriginally posted by jonhock Quote
Yes, that does help. I was always pretty sure that stopping down meant going to a smaller aperture, but the "metering" part that goofed me up. On my K1000 with an SMC 50MM 1.2, wouldn't it always be stop-down metering to get the right exposure? Or stop-up to let in more light? (I've never heard; "stop-up metering")
I recently purchased a Takumar 50mm 1.4 with the A/M switch (really nice!) which is what got me wondering about this subject again. I thought I might be doing something wrong by metering with it in manual then shooting with auto so I've been metering and shooting with it in auto. . I haven't had the film developed yet, a couple rolls, and now I'm wondering just what I am going to end up with.
And when I say recently, I'm meaning about 2 weeks ago.
If I understand you correctly you're using a k1000, a K to m42 adapter, and a screw-mount 50mm f1.4, then you cannot use the auto setting. Auto sets the lens to be stopped down by the camera. The k1000 lacks the part to actuate the pin to trigger the diaphragm so the lens will be constantly wide open. Instead, you should be using the manual mode. However, you could use the switch to pop between wide open and stopped down for focusing purposes.

Of course, if you use the Spotty, then you can use either mode since it has the part to actuate the diaphragm. In auto the lens will be stuck wide open, but when you push the meter switch up it triggers the diaphragm pin and stops the lens down to the aperture you set.

BTW - the switch settings on the lens is auto when the word "auto" is visible and manual when the word "man" is visible.

Last edited by wasser; 01-01-2010 at 11:08 AM. Reason: grammar
01-01-2010, 08:37 AM   #8
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Stop down metering is metering with the lens at the shooting aperture. The green button kludge with non A series lenses is stop down metering.
The downside of it is that it is possible to run out of metering range if metering is done at small apertures.
Open aperture metering is what we are more used to with fully integrated camera/lens combinations.

01-01-2010, 04:00 PM   #9
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Thank you ALL! Now I think I've got a good grip on the situation.
I'd been away from photography for a while but have recently re-kindled my interest with a vengeance. No offense meant to anyone, but them darn digital cameras almost finished me off That would be the "pocket" digitals, not the DSLRs.
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