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10-11-2020, 05:39 PM   #1
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Really basic "green button" question

I've been trying to improve my understanding and use of stop-down metering.

I've read (and re-read) the very useful "Pentax Green Button Guide." I've also read (and re-read) the linked post, "How to use/meter Manual & M42 lenses .... " and watched the video on the same topic. (And I have one of the E-books for my K-5.)

I can't seem to get an answer to what seems to me to be a very basic question.

I have no problem setting the aperture with any of the relevant lenses (K, M, M42).

I understand that when I push the green button, the camera will measure the light coming through at my selected aperture, and set the shutter speed for me.

I'd like to confirm that the camera will remember the shutter speed it has set while I'm dinking around, say, making sure that the subject is in focus. Or some other distraction ...

In effect, I just want to confirm what I assume that it doesn't "time out" for some reason.

I assume that it doesn't because if it did, I also assume that someone would've alerted me to it in the very helpful guides and posts.

Still, I'd love to have someone confirm it for me. One can only get so far with assumptions.

I know that while I'm dinking around, the ambient light might change enough so that the initial shutter speed is no longer the appropriate measure. So I'd push the button again. And were I to change the aperture after first pushing the button, I'd need to push it again. And I imagine that if I moved the camera enough to change my distance to subject , it could well affect the amount of light that comes through. So, another push ...

But if none of the above 3 situations have occurred, can I be confident that the shutter speed will remain as initially set?

Thanks in advance.

10-11-2020, 05:54 PM   #2
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In M mode, The only "time out" that might matter is "Auto Power Off" setting found in "Wrench" Set-up #3 menu. If the camera shuts off, it may forget/reset the exposure settings depending on the "Memory" settings found in Camera Rec. Mode menu #5 (see page 312).
10-11-2020, 06:15 PM   #3
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QuoteOriginally posted by Roam Redway Quote
But if none of the above 3 situations have occurred, can I be confident that the shutter speed will remain as initially set?
yes correct
10-11-2020, 06:33 PM   #4
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QuoteOriginally posted by pschlute Quote
yes correct
Thanks to both of you!
Greg

10-12-2020, 01:29 AM   #5
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BTW, on M42 you do not need to use green button stop down metering.
As the camera is not involved in stopping down M42 lenses before exposure, you can just as well use aperture priority with them.

On M42 lenses you will have to switch between wide open aperture and stopped down aperture manually before exposure, so the meter will adjust to that.
10-12-2020, 03:16 AM   #6
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Elaborating slightly on what Fogel70 said, with M42, any aperture smaller than f6.3 is going to get progressively darker in the viewfinder so you need to slide the switch to open the aperture, allowing you to focus. If you are in aperture priority, when you close the aperture again it will expose automatically. You have the option to take your exposure from a different spot then lock it in before recomposing. In Manual, once you have closed the aperture, hitting the green button sets the shutter speed, I think, anyway it locks these settings until you point it somewhere else and hit the green button again. You do have the option of changing any aspect once it has been set, it just gives you a good starting point.
10-12-2020, 08:55 PM - 1 Like   #7
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One suggestion: when you think the ambient light has changed and you need to re-meter, take a guess at the new shutter speed before pressing the green button. Then see if you're right. That builds a skill of not relying on the meter. If you can get good at that, using manual lenses can be way faster.
10-13-2020, 12:34 AM   #8
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QuoteOriginally posted by Fogel70 Quote
BTW, on M42 you do not need to use green button stop down metering.
As the camera is not involved in stopping down M42 lenses before exposure, you can just as well use aperture priority with them.

On M42 lenses you will have to switch between wide open aperture and stopped down aperture manually before exposure, so the meter will adjust to that.


I've made this mistake … as recently as a week or so ago, believing that "Green Button metering" in "M" mode was the same as Av with an M42 lens fitted … it's not, certainly not in every circumstance, in my experience.
I'll agree that, in theory, it should all work, and often does, but, just occasionally the Av metering "gets it wrong", sometimes by a stop or more, whereas the Green Button never lets me down.
Maybe it's my technique, maybe it's my camera(s), but I'd not recommend relying on Av when using a stopped-down M42 lens.


Last edited by kypfer; 10-13-2020 at 12:36 AM. Reason: punctuation
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