Body

Which is the RX10 III and which is the RX10 IV?

The body of the RX10 IV is nearly identical to that of the RX10 III. If you sat both cameras down on a table, you'd be hard pressed to notice any difference between the two. But there are a few subtle changes. The most significant is the inclusion of a touchscreen.

The camera also gains a focus limiter switch to keep it from hunting all the way to its minimum focus distance.

Touchscreen and touchpad AF

The touchscreen on the RX10 IV cannot be used to navigate the menus, to swipe between images in playback, or to select options from the Function Menu. So, uh, what can it be used for? Its primary function is moving/placing AF areas, and it's very responsive when used to do this. Even if you drag the point around the screen there is very little lag. The touchscreen is also useful for videographers – it's an effective way to rack focus between two subjects: simply tap the screen.

The other function of the touchscreen is to zoom images to 100% in playback. To do this, scroll to the image you'd like to zoom in on (again, you can't use the screen to swipe between photos) and double tap: this will cause the image to zoom into 100% – you can now drag your finger to pan around. Double tap again to zoom back out.

When it comes to placing an AF point with one's eye to the finder, AF joysticks are the crème de la crème, but the next best thing is a touchscreen that functions as a touchpad, and the RX10 IV's touchscreen can also be used in exactly this manner.

This is half the list of Touchpad AF area options. The same positions are offered on the left side of the screen for left-eyed shooters.

We found it to be a responsive and effective way to place an AF point. Even if you're a left eye shooter, the camera can be set to have only certain areas of the screen able to initiate touchpad AF. And you can toggle between absolute and relative positioning. This reviewer, a right-eye shooter, preferred absolute positioning using the right half of the screen as the operation area.

User interface

Sony addressed many of our user interface complaints about the RX10 III in the RX10 IV. The menus have been updated and are now organized more similarly to the Sony a9 with color-coded tabs: the RX10 III used the old, cluttered Sony menu layout. It's still long and complex but at least there are text and color clues to help you understand where you are in the menu structure. Like most recent Sony cameras, there is a 'My Menu' area for storing settings you often need.

Users can also now customize any button to activate autofocus. For our use while testing, we assigned AF-on to the 'AEL' button. Furthermore, the RX10 IV gains the a9's Memory Recall modes – a nifty way to temporarily switch multiple camera settings at the push of a single button. It also gains AF Area Regist., allowing users to customize a button to change the focus area to one of their choosing for easy access.

In addition, the Function Menu can store up to 12 different options – but can not be separately customized for video shooting. In addition, 10 physical buttons can be customized, with different functions in shooting mode and playback.

Connectivity

The Sony RX10 IV can be controlled via smart device over Wi-Fi connection using the Sony Play Memories Mobile app. Connecting the camera to one's device over Wi-Fi is fairly straight forward – once paired the app offers control over zoom, shutter speed, ISO, exposure comp., drive mode, white balance and the self timer. However the shooting mode and aperture have to be set on the camera itself.

Browsing images for transfer is done from the camera – simply scroll to the one of your choice and hit the 'Fn' button to initiate the transfer via Wi-Fi. If you are on an iOS device you will need to manually connect either to the camera by scanning a QR code displayed on the LCD, or from within your devices' Wi-Fi settings. Android users with NFC are luckier because the RX10 IV offers 'one-touch sharing' functionality: once paired one need only tap the camera to their device to make the connection and transfer.

The RX10 IV also gains Bluetooth, in addition to Wi-Fi and NFC, however its purpose is singular: to maintain a connection for sharing location data including GPS coordinates, date and time. Bluetooth can not be used to maintain a low power connection, as is the case with some other Bluetooth enabled cameras.

Battery life

Battery life is CIPA rated to 400 shots per charge, compared to 420 on the RX10 III. Despite the modest drop, expect to easily get through a whole day or two of stills shooting on a single charge. If you intend to shoot a ton of video, plan on carrying two batteries – it eats up the battery far faster than still shooting.

Auto ISO

The RX10 IV offers the same excellent Auto ISO behavior as the RX10 III. Users can specify a lowest shutter speed threshold beyond which the camera should increase the ISO sensitivity. The options include five settings (Slower, Slow, Standard, Fast and Faster) that auto select a shutter speed based on the focal length being used. Standard tends to be 1/ focal length, with 'Faster' being 1/ double the focal length and so on.

You can also use Auto ISO when shooting in Manual mode, while also using Exposure Compensation to define the desired image brightness in both stills and video.