Lab – Canon EOS R10: how does the buffer work?

The Canon EOS R10 and EOS R7 are the two latest additions to the manufacturer’s mirrorless camera range. The R7, more upscale, was able to convince us without difficulty, in particular thanks to an excellent reactivity and a powerful autofocus. Precisely, while we test the EOS R10 and its responsiveness for the test, we found that its buffer was smaller than the more upscale model.

What is the buffer ?

This is therefore an opportunity for us to dig into this question a little more than usual. But before delivering our data, it is worth answering the following question: what is the buffer memory or the buffer of a camera?

When capturing a photo and more particularly a series of photos thanks to the burst mode, the device saves the images on an internal memory in the box before transferring the files to the storage card. This temporary memory which makes the buffer between the box and the SD card varies between boxes by its size or its speed. A more or less long recording time is to be expected depending on the camera models.

Simultaneous write

In addition, more and more devices can simultaneously capture images, save them to the buffer and write to the SD card or CFexpress card inserted in the device. Under these conditions, the filling and the concomitant emptying of the memory increase the maximum number of views that the device is capable of collecting.

And that’s precisely how the EOS R10 works. The device does not hang when saving files. The menus or settings remain accessible while it is possible to resume a series of shots as soon as the buffer memory begins to free up.

To better understand how the buffer, we have carried out a series of additional tests in addition to those that we take into account in our rating. We used three SD cards:

• An SD card with a maximum theoretical speed of 45 MB/s in reading,
• A mid-speed card equipped with the UHS-I bus, the SanDisk Extreme Pro 128 GB SDXC UHS-I 170 MB/s,
• A very high speed card, the SanDisk Extreme Pro 128GB SDXC UHS-II 300MB/s.

Variable performance

To carry out our tests, we set the camera to continuous autofocus, i.e. Canon’s AF-Servo mode. To push the device to its limits, we chose the burst called “high speed burst +” in the “acquisition mode” menu. This is the fastest available with the EOS R10, except for the special “raw burst” mode. Finally, we carried out our tests in both mechanical and electronic shutters.

First observation, in the fastest mode obtained by using the electronic shutter, no change in the number of views actually available by changing the memory card. This burst mode announced by Canon at around 23 fps is too fast for the buffer has time to write to the memory card and thus “artificially” increase the maximum number of possible views. In all cases, we get 15 views in raw+jpeg, 23 views in craw+jpeg and 37 views in jpeg.

An advantage over slower speeds

On the other hand, the differences occur as soon as we use the mechanical shutter designed to reach 15 fps. We can thus verify what we mentioned previously. With our slowest SD card, we managed to save 16 images in jpeg+raw or 50 jpegs. The measurements are not so far from what it is possible to achieve with an electronic shutter.

Fortunately, performance improves with the two faster SD cards. The fastest, the SD Extreme Pro 128 GB SDXC UHS-II 300 MB/s, allows the EOS R10 to unload the internal buffer the fastest. In this case, we were able to capture 19 views in jpeg+raw, 33 in jpeg+craw and 93 in jpeg alone.

A quick card for more convenience

With a performance difference of 20-80% between the chosen settings, it’s clear that investing in a fast SD card is a good idea if you use burst mode a lot. Despite everything, the general performance on this particular point is really not exceptional from the EOS R10.

Finally, we carried out a final complementary measurement. If the H+ burst mode is planned for around 23 fps, the one just below and a little slower, the H mode, is promised for a rate of around 15 fps, in electronic shutter. In this case, we were able to record up to 47 jpeg+raw views and over 500 jpeg-only images before the camera filled the buffer and interrupted the burst.