On this page, I describe how you can lock focus and/or exposure on the Sony RX10 M3/4 camera. This topic is neither served well on the page on focusing, nor on the page on exposure, because both are intertwined.I start with a general part that is more or less the same for each camera, and then the camera-specific information follows.
Locking exposure and/or focus are two methods for, on the one hand, relying on the camera automatics for exposure and focus, and on the other hand, manually manipulations the results or even overriding them according to one's needs. You may want to override the camera's autofocus system, because it focuses on the wrong target, such as objects in the foreground. You may want to override the camera's automatic exposure, because it exposes the image not to your liking when you frame the image to your liking.
So what does locking exposure and focus mean? Here are my brief definitions:
Both can be combined or used alone, which leads to a numer of different cases:
There are different approaches to locking exposure and or focus:
The methods can typically be combined to lock both focus and exposure independently. But there seem to be hige differences between cameras how this can be achieved. This is described for the Sony RX10 M3/4 in the following.
The introduction shows that the locking of focus and exposure is somewhat "intertwined" and therefore cannot be easily discussed separately. So I try to discuss these matters together as well - here for the Sony RX10 M3/4.
The Sony RX10 M3/4 provides the following options for locking exposure and/or focus:
As shown below, the shutter button and the AEL button as well as other functions can be used in combination to lock focus and exposure independently. There is, however, some complexity involved when using the newer RX10 models...
While the technique of pressing the shutter-release button down halfway is (more or less...) easy to use and remember, the coupling of exposure and focus lock can lead to problems. For example, when I take a picture of a landscape, and the image looks too dark, I point the camera lower to brighten the image up - but now the focus may be too close. The other way round, when I point the camera to the sky to darken the image, focus may no longer find a target. So, this approach does not always lead to the desired result, and I have to look for alternatives...
As an alternative, you may want to lock focus or exposure first, then either set the other parameter (that is, exposure or focus), and finally take the picture without having to reframe - or lock the other parameter (that is, exposure or focus), and then reframe again before you take the picture. On the RX10 M3/4 this can be achieved by combining the AEL button with the shutter button. The shutter button locks the focus so that you can reframe the picture again for the actual shot. Please note that this does not work the other way round, like on the RX100 M1! You can, however, lock focus first, then reframe, and just take the shot without further reframing, that is, exposure has to be correct for the "final frame."
"AEL Button": As I found out, this is documented nowhere, the shutter button locks just focus after you locked exposure with the "AEL button" (this behavior will only be shown when the "AEL button" as long as a star symbol (see Figure below) indicates that AEL is active). Note that the AEL button can be configured either as a "hold" or a "toggle" button, which I prefer, and also to use "Spot" measurement. The AEL functionality can also be assigned to other custom keys, but this does not make much sense to me...
Thus, on the RX10 M3/4, you can lock exposure and focus separately and thereafter even reframe again for the final shot while still pressing the shutter button down halfway. However, you do not have the free choice of whether you want to lock exposure or focus first, like you have on the RX100 M1 - exposure has to be locked first. The second caveat that I see is that you have to press the shutter button down halfway all the time for locking focus. A second "toggle" function would be welcome (for me).
Figure: The AEL button (left); AE lock is indicated at the bottom right of the screen by an asterisk (right) (Sony RX10 M3 shown, the same for the M4...)
When I configure the AEL button to lock exposure it does just this (depending on how I configured its behavior, either as a "hold" or as a "toggle" button). But how can I lock focus as well? I found out, this is nowhere documented, that half-pressing the shutter button now locks focus only. Please note that for locking focus you have to half-press the shutter button all the time.
On the RX10 M3/4, there is an alternative to half-pressing the shutter button for locking focus. Pressing the Focus Hold button with its default assignment, the Focus Hold function, also locks focus. Please note that for locking focus you have to press the Focus Hold button all the time (you can assing the Focus Hold function to custom buttons as well).
A more "relaxing" method would be to assign the AF/MF Ctrl Toggle function to the Focus Hold button for locking focus. This function switches the focus mode from AF to MF using the previous distance value that AF set as a starting point for MF. You can either leave the focus as is (which is like a focus lock) or even make manual corrections to the focus using the focus ring. Note that the shutter button does no longer lock focus when the camera is in MF mode (or focus can be considered as always locked...). I assigned the AF/MF Ctrl Toggle function to the Focus Hold button at the lens.
Figure: I use the Focus Hold button at the lens as "AF/MF Ctrl Toggle button"; below it, there is the Focus Mode switch
When you want to lock exposure and focus independently on the Sony RX10 M3/4, you have to lock exposure first. Focus can be locked most conveniently thereafter, when you assign the AF/MF Ctrl Toggle function to the Focus Hold button.
For locking exposure and/or focus, there are several approaches available on the Sony RX10 M3/4, which mostly combine the Focus Hold button with the AEL button, because this camera has a lot more external buttons than the compact RX100 models; the shutter button can, of course, also be used like on the RX100 M4. The RX10 M3/4 approach is not as simple as the one on the RX100 M1 (and not documented), but simpler as on the RX100 M4 because of the external buttons. For locking exposure and focus independently, you have to lock exposure first.