Dynamic Range

Sunset image with shadows lifted and selectively warmed.

Canon RF 24-70mm F2.8 L IS USM | ISO 200 (Highlight tone priority) | F5.6 | 1/400 sec
Photo: Richard Butler

The EOS R6's dynamic range is generally very good but there are some details worth being aware of.

Key takeaways:

  • Raw dynamic range looks good but this declines if used in electronic shutter mode
  • Some noise reduction is always applied to low ISO Raws

ISO Invariance

Our ISO Invariance looks at images shot with the same exposure settings but different ISO settings. This lets us see how much electronic (read) noise there is to be overcome using amplification.

In mechanical and the default electronic first curtain shutter modes, the R6's performance is very good. The sensor adds a noticeable amount of read noise, meaning the deep shadows of an ISO 100 image are noisier than an image shot at ISO 6400. But the difference is much less significant for an ISO 200 shot and negligible by the time you've reached ISO 400.

This is a good performance when compared to anything but the best of its peers. This low read noise can be exploited in low light situations by using the shutter speed and aperture settings of a high ISO but setting the camera to ISO 200 or 400. There's little-to-no noise cost to doing so, but you retain an extra stop of highlight information for every one-stop reduction in ISO you make, which can be helpful for retaining neon signs or other bright areas in otherwise poorly lit scenes.

It's worth noting that shifting to electronic shutter mode drops the sensor down to 12-bit readout. This reduces the amount of dynamic range that can be preserved in the Raw file, which is seen as an increase in noise in the deepest shadow regions. So there's only a slight difference if you compare the ISO 400 files but if you push further down into the shadows by looking at the ISO 100 and 200 images, the difference becomes very apparent.

Exposure Latitude

Our Exposure Latitude test does what you might be temped to do in bright light: reduce the exposure to capture additional highlights, then brighten the shadows. This is analogous to what Highlight Tone Priority mode does in bright light conditions.

Highlight Tone Priority

HTP is one of the camera's modes for exploiting the dynamic range of its sensor. It essentially uses 1 stop lower amplification than usual, for every ISO setting. In bright light, this means using base ISO but with ISO 200 exposure, which means capturing an extra stop of highlights, compared to standard mode.

Canon recommends using HTP mode if you're shooting HDR PQ images or video, to make sure you capture the brighter highlights that HDRTVs can display.

Again the Canon performs well in this test: reducing the exposure by five stops and pulling the shadows up still produces a very usable image. It's a little noisier than the best of its peers, but not to a degree that matters.

However, the read noise difference we saw in the ISO Invariance test rears its head when you go to the extreme of trying to use the very deepest shadows of the Raw file. Again, a switch to electronic shutter mode introduces more noise. Not much at first, but having a significant impact if you try to use the deeper shadow tones of your images.

Noise reduction

The other factor worth being aware of is that the detail appears to smear a little if you push all the way down into the deep shadows. It appears Canon is applying some noise reduction to the darkest regions of its Raw files, resulting in a loss of detail. Whether this is preferable to losing those tones to noise is a matter of taste, but we're always disappointed to see noise reduction applied to Raw data without an option to turn it off.

Here are our ISO 6400 and ISO 100 + 6EV images from the ISO Invariance test, reprocessed with noise reduction minimized:

As you can see, there's a loss of low contrast detail in the brightened ISO 100 shot, meaning your practical dynamic range will be impacted by the sensor performance and noise reduction.

HEIF HDR images

The phrase High Dynamic Range (HDR) can refer to two distinct things: tone-mapped attempts to convey a wide range of tones into a standard DR (SDR) image or workflows for conveying a wide range of tones on devices that can display a wider-than-standard dynamic range. It's this second, more naturalistic type of image that the R6 can create using its HDR PQ modes.

As well as being used to create HDRTV-ready video, the R6 can also shoot stills in HDR PQ, which are then stored in the 10-bit HEIF format, rather than conventional 8-bit JPEGs.

Canon recommends you engage Highlight Tone Priority when shooting HDR PQ stills or video footage, which makes sense: it's a mode that changes the relationship between exposure and amplification within the camera, increasing the amount of highlight information that you can capture. Our only real disappointment is that there doesn't appear to be any way to quickly access this option, short of saving a custom mode that engages both features (which also embeds many other camera settings).