[tduell]

There is a dearth of information on the use of the AE-L button in my K-1 and K-3 II manuals, and I would like some clarification on the use of this button.
Lets assume that I am using spot exposure.
I would expect that I can choose a point in the scene, press AE-L to lock the exposure at that point, recompose, press AF (back button focussing) to fix the focus where I want it, and shoot. Is this a correct understanding of how it all is meant to work.
What if I use matrix metering?
What happens if I have exposure locked to the focus point?

Cheers,
Terry

[pschlute]

Yes that is exactly how it works. If i remember correctly the AE-L will hold the exposure setting for a certain time after it is pressed. It will also i think continue to hold the same exposure while the shutter button or Back-button AF is pressed while AE-L is locked (not 100% sure on this).

The little green star symbol will light in the viewfinder during AE-L. The metering mode does not affect the operation, it operates the same way.

Locking exposure to the focus point is completely different. It will lock the exposure when the focus is locked, so will not be useful in your scenario to meter then recompose/focus

[shardulm]

Yes. That is how it is in fact meant to be used and works like a charm when you know what part of the picture is to be exposed correctly meter that using the AE-L and let the camera do the rest. Often used in situations when the background is much brighter than the subject.. (For ex. someone is standing in between the sun and the camera and you need a correct exposure of the face then meter that) the background overexposes but the face is correctly exposed). This button can be decoupled from the AF lock which is important. If you keep the AF/AE-L coupled together then even if you meter the light it is re-metered at the time of focus lock.
Matrix, Center weighted, Spot are the areas int he frame used by the meter for measuring the light in the frame. So metering in Matrix mode is useful when you want a consistent exposure between the shots of lets say a group of same people wearing lighter clothes in one shot and darker clothes in the other or vice-versa. The meter can hang on to the measured light (locked) until the set time.

[pentaxfall]

There is a dearth of information on the use of the AE-L button in my K-1 and K-3 II manuals, and I would like some clarification on the use of this button.
Lets assume that I am using spot exposure.
I would expect that I can choose a point in the scene, press AE-L to lock the exposure at that point, recompose, press AF (back button focussing) to fix the focus where I want it, and shoot. Is this a correct understanding of how it all is meant to work.

This is how I also use it.

What if I use matrix metering?

I think the concept of AE-L goes with Spot metering. I combine AE-L lock with spot metering.

What happens if I have exposure locked to the focus point?

I have not tested this combination.

I very much depend on AE-L when doing Panorama + HDR and this is what i found.
AE-L spans bracketed frames. AE-L locks exposure for 20sec, this can be extend for another 20sec by pressing the CLICK button once more. I tend to keep CLICK button pressed until I complete all the frames.

I would like a custom setting for choosing the duration of AE-L.

[photoptimist]

AE-L works in matrix, center-weight, spot, and and even in spot-linked-to-AF.

At least in my experience, it is not unlocked by any subsequent AF activity and stays locked from frame to frame. But as pentaxfall notes, it does time-out after a while.

[tduell]

Thanks to all who have replied, your comments and help much appreciated.

Cheers,
Terry

[kiwi_jono]

Great answers but just one more point to add if you use MANUAL mode:
* AE-L will lock the current exposure amount (i.e. assumes the current settings will result in the exposure you want)
* Now if you change say the aperture the camera will automatically change the shutter speed to achieve the same exposure. Likewise with shutter speed (will automatically change aperture).

This is very handy when working in manual mode as you can make changes while keeping the exposure you are already happy with.

[mikesbike]

Great answers but just one more point to add if you use MANUAL mode:
* AE-L will lock the current exposure amount (i.e. assumes the current settings will result in the exposure you want)
* Now if you change say the aperture the camera will automatically change the shutter speed to achieve the same exposure. Likewise with shutter speed (will automatically change aperture).

This is very handy when working in manual mode as you can make changes while keeping the exposure you are already happy with.

As described here is a feature of the exclusive Pentax Hyper System. In the Manual mode, using the green button to instantly achieve a meter-centered exposure reading, instead of twirling the thumb and finger dials to get the meter's center reading. This is an amazingly fast, efficient way to take spot meter-readings around a scene. Then you can proceed to use the AE-L button as above, if you want to change the aperture or shutter speed to a different value, while preserving your meter-centered exposure! This is the Pentax Hyper-Manual operational design.

Of course the AE-L feature also works in other exposure modes, including Program. it can be quite handy, even in Program mode, even using matrix metering, when using a zoom lens. You can zoom in on a particular subject in a scene, especially in tricky lighting situations, and hit the AE-L button to bias the exposure for than particular area of the scene, then zoom back to recompose, and take your shot.

Getting back to the Pentax Hyper System itself, and getting away from the topic of the AE-L button, perhaps you've not been aware of this, the fastest, most efficient operational design among all brands of DSLR. In Program mode, for instance, if you wish a different aperture or shutter speed than the camera has chosen, you can just use your thumb or finger dial to simply change it to what you wish- simple as that! The first click freezes the value as is, subsequent clicks change the value. You have instantly switched to Av or Tv operation without having to go to the mode dial first and then make your choice. You can even go back and forth- Av-Tv! The camera will remain in this operational mode, lighting permitting, until you either shut the camera off, or to return to full Program with a touch of the green button. This is the Pentax Hyper-Program operational design. Simple, efficient, and ingenious. If you want to operate in Av or Tv mode when periodically turning the camera off and on, then of course, use the mode dial.