File this under “just for fun.” I have both a Nikon D4 and Fujifilm X-T1. Both cameras are roughly 16MP resolution, but the Fuji uses an APS-C sensor while the Nikon D4 is a 35mm sensor. I performed this quick ISO comparison simply to see how well Fuji’s sensor stacked up against that of my D4, which is a low-light champ. Before I go on, please understand that these are two very different cameras, for very different uses. I like them both for different reasons!
I shot both cameras in RAW, on a tripod. I focused the D4 using Live View. I focused the X-T1 manually using live view focus peaking. I did not go beyond ISO 6400, as the Fuji does not capture raw images above this value. I compared ISO 800, 1600, 3200, and 6400.
I used my 24-70mm f/2.8 Nikkor on the D4, and the Fujinon 23mm f/1.4 prime on the X-T1. I set the 24-70mm lens to 35mm, which roughly matched the focal length on the crop-sensor Fuji. I set each lens to f/4. I processed both images in Lightroom 5 using identical sharpening settings.
Here’s the two shots at ISO 6400, scaled for web size (click to enlarge):
At web size, both images look perfectly good. The main differences are with White Balance (the D4 image looks warmer) and exposure. Interestingly enough, while the D4 exposure was 1/60s, the X-T1 required 1/30s. I’m not sure if that’s due to slight changes in ambient lighting, or a difference in the way each camera meters the scene. In theory, I should have gotten nearly identical exposures using the same ISO value.
Here are side by-side comparisons at 1:1 of each tested ISO. In each case, the X-T1 image is on the left (click to enlarge).
Both the Fujifilm X-T1 and Nikon D4 exhibited luminance noise at ISO 1600 and up. The grain pattern was not what I would call problematic in either camera; subjectively both produced good results. The colors from the Nikon D4 were slightly better (more saturated) at the higher ISO values. I also discovered that in Lightroom, using the default setting (25) for Chrominance NR was too strong for the X-T1 images and created artifacts. Setting Chrominance NR to 8 solved this problem. The D4 images had the appearance of slightly better detail; this could also be due to slight differences in focus. Overall, I was impressed by the quality of the X-T1 images at ISO 6400.
The reason I performed this test was not to see which camera was better, but instead to get a benchmark for the X-T1, which I don’t usually choose as a low-light camera. The Nikon D4 has some significant advantages over the X-T1 with respect to low-light shooting. Not only are the images slightly sharper and have better color, but the D4 can shoot raw files above ISO 6400; something the X-T1 cannot do. Plus, the D4 has better ergonomics, 10fps shooting, and a killer flash system. Nevertheless, the X-T1 image quality was pretty darned good for a crop-sensor (APS-C) camera. When I want to go light, I choose the X-T1. When I need maximum performance, I go with the D4. Considering the price difference between these two cameras, it’s nice to see this kind of ISO performance in a $1500 camera.