ISO Performance at low ISOs (ISO 100-800)
Let’s take a look at how the Df performs at low ISOs. Here are some crops at ISO 50, 100, 200, 400 and 800:
Keep in mind that ISO 50 is a boosted value, which means that it is simply a software change that darkens the image by a stop. Comparing it to ISO 100, I do not see any differences between the two in noise performance.
As expected, the Nikon Df performs incredibly well at low ISOs.
Boosting ISO to 400 still makes practically no difference, with only a hint of noise appearing at ISO 800.
High ISO Performance (ISO 1600-12800)
High ISO performance is a very important measure of DSLR sensor quality for low-light photography. Here is how the Nikon Df performs at high ISO levels between ISO 1600 and 12800:
ISO 1600 still looks very clean and ISO 3200 adds noticeable grain throughout the image, especially in the shadows. Dynamic range stays very high and colors are not impacted at all.
As we move up to higher ISO values, noise obviously starts becoming an issue. At ISO 6400, we now see more noise and bigger grain in the image. There is a little bit of detail loss. However, the image is still impressively clean at such high ISO. Moving up to 12800 the amount of noise doubles and now we clearly see loss of colors and shadow details. There are some artifacts showing up here and there, but nothing major. Still, pretty impressive performance overall!
High ISO Performance “Boost” (ISO 25600-204800)
Nikon Df also has extra ISO “boost” levels – ISO 25600, 51200, 102400 and a whopping 204800 for extreme situations. Let’s take a look at these:
Higher ISO values than 12800 on the Df are not native to the sensor, which means that it is simply a software boost, similar to ISO 50. As we get to ISO 25600, there is plenty of noise throughout the image and very apparent loss of colors and details. Look in the red lower shadow area of the ship – the reds are now mixing with blacks. Highlight details are still pretty good though. ISO 51200 destroys a lot of details and now most of the shadow details are gone. Lots of artifacts throughout the image. Personally, I would stay away from anything past ISO 25600.
The last super-boost ISOs of 102400 and 204800 result in way too much noise and heavy loss of details, colors and dynamic range. Personally, I would not touch these ISO levels, unless I am shooting in pitch-black darkness and have no other options.
ISO Performance Summary
As expected, the Nikon Df produces very impressive results at the pixel level. ISO performance from 100 to 12800 is definitely in my comfort zone, as it provides plenty of detail and practically no loss of colors and details. ISO 25600 is a little on the noisy side, but also usable in emergency situations, especially if you clean it up with noise reduction software and down-sample to smaller resolution. Anything past ISO 25600 adds a lot of noise and artifacts, while losing a lot of colors and details, especially in the shadows. Personally, I would stay away from anything past ISO 12800-25600 for best results.
Still, it is pretty incredible that you can bump up ISO so high on the Nikon Df. Lower resolution and larger pixels do their job in keeping performance very high at pixel level. As you will see from the next pages of this review, high-resolution cameras can only keep up with the Df when they are down-sampled to the same resolution.
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