Image Quality: High ISO Performance
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 Hasselblad X1D-50c against the Nikon D810. Since the X1D-50c has more resolution, I down-sampled images from the X1D-50c 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 X1D-50c 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: Hasselblad X1D-50c, Right: Nikon D810):
You will notice that the image on the X1D-50c 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 X1D-50c 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 X1D-50c.
We see a similar situation at ISO 6400, where the difference in ISO performance is less than a stop.
And although I normally would not shoot past ISO 6400 on any camera, it is still interesting to see how cameras perform when pushing ISO 12800 and higher. Here, we can clearly see that both images produce very noisy images, but the X1D-50c still clearly takes the upper hand. There is visibly more chroma noise on the D810 and there is also more loss of color.
Again, the differences are not significant though – 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 64 on D810 and ISO 100 on the X1D-50c (Left: Hasselblad X1D-50c, 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. Although the amount of noise is comparable, it shows slightly more loss of colors, so it is definitely worse in comparison. However, the difference is very marginal and the D810 holds up very well here. But what if we increase ISO to 100 on the D810 and compare the two again?
Now we can clearly see that the D810 loses big time here. Although noise is comparable, there is a lot 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 X1D-50c 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 huge difference in performance between these two cameras and their sensors. The Hasselblad X1D-50c 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 X1D-50c 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 X1D-50c looks vastly superior, especially when it comes to retaining color.
What about ISO invariance? We know that the sensor on the D810 is not ISO invariant, but how does the X1D-50c do when ISO is pushed and compared to its equivalent? Here is ISO 100 again pushed by 4 stops, compared to ISO 1600:
Unfortunately, it appears that at lower ISO levels, the sensor is not ISO invariant. There is a visible amount of grain added to images when underexposing and then pushing ISO through post-processing, as can be seen from the two crops presented above. However, take a look at what happens when the same test is performed at higher ISOs:
Here, when looking at ISO 3200 pushed to 3 stops compared to ISO 25600, we see practically no difference between the two images. The sensor is ISO invariant, but only at higher ISO levels.
So we can draw a few conclusions from the above tests. First of all, the medium format sensor on the X1D-50c demonstrated incredible dynamic range that overall exceeds the performance of the Nikon D810 (which is as good as a full-frame sensor can get). While the differences at base ISO on both cameras is very minimal, with the Nikon D810 being only slightly worse in color loss, everything starting from ISO 100 and higher shows the superiority of the X1D-50c sensor, especially at higher ISOs. This difference in dynamic range can be very important when dealing with high dynamic range situations, giving a distinct advantage to the X1D-50c. Second, the X1D-50c demonstrated partial ISO invariance, with definite differences from ISO 100 to 400, but practically no difference at higher ISOs above ISO 800.
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 Hasselblad X1D-50c, just like the Pentax 645Z and the Fuji GFX 50S, 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 pretty clear 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 X1D-50c. 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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