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Old Apr 29, 2018, 1:11 PM   #1
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Default AE/AF lock

Hi,
I'm a little confused about the AE/AF lock. I only have one camera that has this function (the FZ150); and I'm not really sure how to use it, or even what it does. I'm thinking that it allows me to choose the exposure I want then re-aim and re-focus. Is that the plan? If so, where does AF come into it?
I would also like to know if I can do something similar on my point and shoot (ZS1), which I don't believe has this capability. It seems like spot metering might allow this?
Thanks,
..... john
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Old Apr 29, 2018, 2:48 PM   #2
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Generally, when you half-press the shutter button, the camera locks exposure and focus, which allows you to re-compose until you complete the shutter operation. AE/AF lock does the same thing, but you can release the shutter button. If you are using only AE lock, you can set the exposure and then re-compose, and also re-focus. The focus lock would be used when you wanted to just keep focus on one subject, but change the composition and/or exposure, such as having a person in a panorama. Usually used with spot focus.
Spot metering would be for setting the exposure for just one part, such as a person's face, and let the rest of the photo be washed out or too dark.
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Old Apr 29, 2018, 3:21 PM   #3
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Thanks VTphotog,
I find that I can pretty much nail the exposure using spot metering, even get subtle changes; but once I move to a different subject the focus changes, unless it's the same distance away. I guess that's were AE lock would come in handy. Is that your understanding?
.... john
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Old Apr 29, 2018, 4:53 PM   #4
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OK, let's be sure we are talking about the same thing when we use the terms. Spot metering sets the camera exposure at the area you aim at with the spot. Spot focus sets the lens focus at that spot. You can, if you want set the exposure for somewhere other than where the camera is focused.
If your spot focus and spot metering point are set at the same place and AE lock also locks focus, you can then move the camera and it will retain the settings when you pressed the AE lock. If AE lock and AF lock are set separately, then you would be able to set exposure based on one point and focus based on another point.
Am I confusing you completely yet?
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Old Apr 29, 2018, 5:26 PM   #5
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G'day John

The AE/AF button is a specialised button - and one I use regularly

Within the camera's main menu you can decide whether a push of the button will a) lock exposure for a while, b) lock focus for a while, or c) lock both exposure and focus for a while. It self-cancels when you power 'off' or press the button a 2nd time

My cameras are menu set for a) mode

I use it for all my panorama stuff ... aim the camera [mostly] at the centre of the scene, press the button, move to the extreme LHS and start taking pics. I might have 8 to 15 images crossing 60 deg to 150 deg of coverage, [later stitched using PIXTRA software].

I can see occasions [maybe in a nightclub or live theatre] where I might need to lock focus to speed up the camera's response to a subject where the exposure might be altering frequently, thus setting the camera to AF mode rather than AE mode

Hope this helps,
Phil
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Old Apr 29, 2018, 5:38 PM   #6
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Hi guys,
OK. I get it. So, I can get what I want with my FZ150 which has AF/AE lock. But if I don't have this lock, as my ZS1 does NOT. There isn't any way I can meter on one spot, move the camera and assume it will still be in focus, unless the distances between the camera and the two spots is the same ...... right?
..... john
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Old Apr 29, 2018, 8:15 PM   #7
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Right. If your camera has manual exposure, you could do it that way, but it seems from what you're saying that it doesn't.
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Old Apr 29, 2018, 9:26 PM   #8
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OK. Good. At least I have that cleared up.
Thanks,
..... john
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