Friday, 9 August 2013

[photography] Comparison of sensors: Fuji X-E1 versus Ricoh GR-D III

There’s no good reason I decided to do this, just that I was pixel-peeping files from my Fuji X-E1 in Capture One, when a silly thought occurred to me: how do these files compare to my Ricoh GR-D III?

The comparison is also completely unfair: the GR-D is a pocket-sized camera with a fixed 28mm-e lens, whereas the X-E1 is much larger and heavier (and I used the 18–55mm lens for it, which by itself is bigger than the Ricoh, although Fuji’s 18mm f/2 lens is much smaller and would be a slightly fairer comparison).

Fuji X-E1 and Ricoh GR-D III
Fuji X-E1 and Ricoh GR-D III.

Sensor Dimensions

The X-E1 has an APS-C–sized sensor, meaning it’s 23.6 × 15.7 mm, or around 370mm2. The GR-D’s sensor is 7.6 × 5.7 mm, or around 43 mm2. Here’s a visual illustration of the sizes:

1/1.7” sensor compared to APS-C sensor and Lego minifig

So clearly the Fuji’s sensor is huge in comparison, which means it has much more surface area for gathering light, and despite being 16 megapixels versus the Ricoh’s 10, those pixels are still much larger. All else equal, larger pixels gather more light for the same exposure, so they need to be amplified less than smaller ones, resulting in less noise.

Noise Differences

This image, taken in low light, shows the same scene as shot by the GR-D (left) and X-E1 (right):

Full image comparing Ricoh GR-D III and Fuji X-E1 in low light

Both were processed in Capture One Express 7. At this size they both look okay. Now here’s a comparison of the images at 100% zoom:

Comparison of Ricoh GR-D III and Fuji X-E1 in low light, showing crops at 100% zoom
Ricoh: ISO 1234; Fuji: ISO 3200

Now the difference is much clearer. Obviously the Fuji has more detail in it simply because it has more pixels, but the advantage goes much further than that: the amount of noise in the Ricoh’s image has destroyed a lot of the detail, despite it being shot at less than half the ISO of the Fuji. In addition, the camera is not very sensitive to blue light, so the middle book has lost all of its real colour, whereas the Fuji represents it accurately. You can click the image for a much larger 100% crop.

Highlight Recovery

Another advantage of larger sensors is that they tend to offer smoother-looking transitions to blown highlights, and often allow recovery of more image data in raw processing:

Example of highlight recovery in a Fuji X-E1 image

By comparison, the small sensor in the GR-D III doesn’t allow as much:

Example of highlight recovery in a Fuji X-E1 image

Notice how although the globe is darker, there’s not actually any more detail to be seen in it – Capture One has done a pretty good job of guessing what colour the globe should be, but it can’t recover detail that wasn’t there to start with.

Depth of Field

One last major difference between sensor sizes is their depth of field:

Example of difference in depth of field between Ricoh GR-D III and Fuji X-E1

Note how even though the GR-D III is using a ‘larger’ aperture, the image still has much more in focus than the X-E1. I put ‘larger’ in quotes because the the aperture number takes focal length into account (that’s what the ‘f’ part is), so the Ricoh’s aperture diameter is actually 6mm/1.9, or 3.16 mm, whereas the Fuji’s aperture is 18mm/2.8, or 6.43 mm.

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