Fuji GFX 50S Review: Image Quality
While medium format is always going to have the upper hand when compared to full-frame in image quality, differences in high ISO performance are going to be marginal, mostly because of the relatively small difference in sensor size. For the below ISO comparisons, I am going to be putting the Fuji GFX 50S against the Nikon D810. Since the GFX 50S has more resolution, I down-sampled images from the GFX 50S to match the D810 to make these tests more meaningful.
However, keep in mind that these tests are still not ideal, since we are only comparing horizontal resolution between cameras – the GFX 50S has a 4:3 aspect ratio vs 3:2 on the D810, so it has more vertical pixels that are unaccounted for. I am also skipping all ISOs below 3200, since there is practically no visual difference in those. Let’s take a look at how the two cameras compare in high ISO performance (Left: Fuji GFX 50S, Right: Nikon D810):
You will notice that the image on the GFX 50S is sharper in this comparison – that’s the result of down-sampling. If you ignore the sharpness differences and concentrate on noise in different parts of the image, you will see that the GFX 50S produces less overall noise. And that’s a given since it is a physically larger sensor. However, the difference is not huge – there is less than a stop of noise performance advantage on behalf of the GFX 50S.
We see a similar situation at ISO 6400, where the difference in ISO performance is less than a stop. And lastly, pushing beyond ISO 6400 obviously results in very grainy images from both cameras, but the GFX 50S again comes out on top thanks to its larger sensor. Again, the differences are not significant – the Nikon D810 holds up pretty well on its own overall.
Image Quality: Dynamic Range and ISO Invariance
What if were to take images three to four stops underexposed and fully recovered them in post-processing? This would not only give us an indication of a camera’s shadow recovery potential, but also allows us to see if the sensor is ISO invariant. Let’s see how both cameras performed in such conditions. We will start at base ISO, because that’s where the two cameras yield the highest amount of dynamic range. This means ISO 100 on the GFX 50S and ISO 64 on the D810 (Left: Fuji GFX 50S, Right: Nikon D810):
The Nikon D810 has one of the best full-frame sensors in the world, with an incredible dynamic range performance at ISO 64 and it really shows here – when looking at the two side by side, we can see that the D810 demonstrates amazing shadow recovery options. However, we can clearly see that the Fuji GFX 50S visibly outperforms the D810 in this comparison, showing less overall noise and better color reproduction. What if we were to increase ISO to 100 on the D810 and compare the two again?
We can clearly see that the D810 loses big time here. There is a drastic difference in noise performance here and the D810 shows much more loss of colors in the image. This shows just how much of a difference ISO 64 can make compared to ISO 100 on the D810 in terms of dynamic range! We see a similar type of behavior at higher ISOs, with the GFX 50S leading every step of the way. So let’s take a look at how the two cameras differ at much higher ISOs above ISO 3200 and this time we are going to compare shadow recovery pushed 3 stops:
Right off the bat, we can see a clear difference in performance between these two cameras and their sensors. The Fuji GFX 50S demonstrates incredible ability to recover shadow details, even at such high ISO as 3200. The Nikon D810 has a lot more luminance and chroma noise and the shadows lose most of their color.
It is fun to look at what happens at ISO 6400, because that’s technically ISO 51200. Here, I can say that there is a solid full stop of difference, with the GFX 50S winning by a huge margin.
And the difference is still great at ISO 12800 pushed 3 stops, which is equivalent to ISO 102,400 – the GFX 50S looks vastly superior, especially when it comes to retaining color.
Image Quality: ISO Invariance
What about ISO invariance? We know that the sensor on the D810 is not ISO invariant, but how does the GFX 50S do when ISO is pushed and compared to its equivalent? Here is ISO 100 again pushed by 4 stops, compared to ISO 1600:
Although there are slight differences in the amount of grain in different regions, the images appear somewhat similar, which is great news – it means that the sensor on the GFX 50S is close to being ISO-invariant at base ISO. This is a bit different than what we have previously seen on the Hasselblad X1D-50c, which showed more grain at base ISO in the same environment. Let’s take a look at what happens when the same test is performed at higher ISOs:
Again, there is very little difference in noise performance at ISO 800 pushed 3 stops and compared to ISO 6400. This shows that the GFX 50S sensor is slightly superior when compared to the Hasselblad X1D-50c in terms of ISO invariance.
Let’s put the two side-by-side at ISO 100, pushed by 4 stops each:
The difference is very obvious – the GFX 50S has far less noise in comparison throughout the frame, particularly in the shadows.
We can now draw a few conclusions from the above tests. First of all, the medium format sensor on the GFX 50S demonstrated incredible dynamic range that not only exceeds the performance of the Nikon D810 (which is currently as good as a full-frame sensor can get), but also exceeds the performance of its prime competitor, the Hasselblad X1D-50c. The ISO invariance test reveals that the GFX 50S can be pushed quite a bit from its base ISO without sacrificing much of its shadow detail, whereas the X1D-50c is only ISO-invariant at higher ISOs. For a landscape photographer, this is another win for the GFX 50S. It looks like Fuji certainly did optimize the GFX 50S output when compared to the Hasselblad X1D-50c…
4:3 Aspect Ratio and the Panorama Shooting Advantage
Having been shooting with APS-C and full-frame cameras for many years now, I am very used to the 3:2 aspect ratio. The Fuji GFX 50S, just like the Pentax 645Z and the Hasselblad X1D-50c, has an aspect ratio of 4:3, which is quite different in comparison. While one can modify aspect ratio in post, I have to say, shooting with a different aspect ratio than you are used to changes the way you frame. Plus, why would you want to lose all that resolution? For me, shooting with a 3:2 aspect ratio yields pleasing, wide images that I am used to working with, whereas 4:3 looks more squarish in comparison. With our computer monitors being mostly wide nowadays, stretching as wide as 16:9, the 4:3 aspect ratio leaves a lot of gaps on the sides. That is certainly a problem for myself and many others when composing tight – if I have to think about 3:2 or other wider options, I have to compose with that in mind. So make sure you take the aspect ratio into account when considering these medium format cameras!
At the same time, there is one distinct advantage that the 4:3 ratio sensor gives you when compared to 3:2 – the ability to shoot less vertical frames when taking panoramas. While it might not seem like a big deal for some, it actually does become a pretty useful when shooting a lot of panoramas, as you end up taking fewer shots and as a result, having to stitch fewer images in post. On one hand, you gain time with fewer images to stitch, but on the other, you lose time stitching higher resolution panoramas. However, you still end up with a noticeably higher resolution image at the end of the day with the GFX 50S. With a 50 MP resolution, I no longer feel the need to stitch multi-row panoramas to yield giant prints, and considering that manufacturers will most likely only increase the resolution of future medium format cameras, I don’t think it is going to be something to worry about for a while.
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