Compared to Nikon D90
Any time a comparison between two different sensors is made (especially with different megapixel counts), one has to make sure that the tests are performed carefully, since any error could result in incorrect/invalid results. Resizing images in software to compensate for the field of view/resolution differences is never a good idea. Therefore, I used the Nikon 70-200mm f/2.8G VR II for this test (which is very sharp across the zoom range) at different focal lengths to get equivalent sizes of objects at different resolutions. The only other method was to move my setup back and forth or show crops at different fields of view, but I did not want to do that, because it would be hard to compare the images. The Nikon D5100 was shot at approximately 86mm and the Nikon D90 was shot at approximately 102mm. To make sure that I do not get major differences in depth of field, I changed the aperture to f/8.0. I turned off Active D-Lighting and Noise Reduction on both cameras and used exactly the same shutter speed and ISO.
Whenever manufacturers increase the number of pixels on the same size sensor, pixel density increases and individual pixel size decreases. This ultimately results in less dynamic range and higher amounts of noise, unless new sensor technologies and noise-reduction algorithms are employed. So far Nikon has been doing a pretty good job in keeping ISO noise levels to the minimum whenever a new sensor with higher resolution is released. Let’s see if the same holds true for the new D5100.
Nikon D5100 vs D90 ISO Comparison at low ISOs
At low ISOs between ISO 100 and 800, both Nikon D5100 and Nikon D90 have about the same noise levels with slightly cleaner shadows from the D90. In terms of details though, the Nikon D5100 images appear a little more “punchy” and slightly more detailed than D90 images. At first, I thought that it was a focus issue, but then I retested both cameras after carefully acquiring focus through Live View and got the same results. Take a look at the below crops at ISO 100 (L 1.0 on Nikon D90), 200, 400 and 800:
Please note that ISO 100 on the Nikon D90 is not the base ISO. That’s probably why the D90 image at ISO 100 came out slightly brighter.
As you can see, the amount of noise is very comparable at ISO 100 and 200, but the D5100 fur details look better.
At ISO 400 and 800, the noise levels on the D90 look slightly better, but the D5100 still leads with the amount of details.
Nikon D5100 vs D90 High ISO Comparison
What about high ISO levels above ISO 800? Let’s take a look:
At ISO 1600, the amount of detail and the level of luminance noise on both D90 and D5100 are about the same, although D5100 seems to retain detail a tad better.
As we increase ISO to 3200, both again look very similar, with D90 starting to add some larger artifacts to shadows. Nikon D90 also starts to lose some colors when compared to D5100.
ISO 6400 is not a native ISO mode on the Nikon D90 (H1.0), so we start seeing some amount of chroma noise and more artifacts on the D90. The Nikon D5100 image has about the same amount of luminance noise, but retains the colors slightly better. Shadow details on both look about the same, while the highlight details on the D5100 are still better. Either way, I personally would not shoot at ISO 6400 on either camera.
Nikon D5100 vs D90 Summary
As you can see, the Nikon D5100 is very similar to Nikon D90 in terms of handling noise, which is great, given the 4 MP difference between the sensors. I was surprised to see images from the D5100 with more details in both highlights and shadows though. With the higher number of megapixels, it should technically be the other way around. In addition, the Nikon D5100 seems to be retaining the colors at high ISOs better than D90, with less artifacts and chroma noise. I personally try not to shoot above ISO 800-1600 when using cropped-sensor/DX cameras, so performance differences above ISO 3200 are not as vital for me.
Compared to Nikon D3100
For the Nikon D5100 vs D3100 test, I used the same focal length at the same distance due to a relatively small difference in megapixels and field of view (Nikon D3100 has a 14.2 MP sensor, while the Nikon D5100 has a 16.2 MP sensor). Again, both cameras had the same aperture, shutter speed and ISO values and Noise Reduction + Active D-Lighting were turned off as well. Focusing was performed via Live View contrast detect. Please note that the below comparisons are solely based on sensor performance. If you would like to see differences in camera features, please see my Nikon D5100 vs D3100 article.
Nikon D5100 vs D3100 High ISO Comparison
Low ISO performance between ISO 100 and ISO 800 looks almost identical on both Nikon D3100 and Nikon D5100, with a very equivalent amount of noise and detail. The same seems to hold true for high ISO performance – take a look at these crops at ISO 1600, 3200, 6400 and 12800:
At ISO 3200 the Nikon D3100 seems to add some artifacts here and there and the shadow detail seems to be lost more. However, the amount of noise is about the same on both cameras, which is good news for the Nikon D3100.
ISO 6400 looks poor on both, with lots of noise and loss of detail/sharpness.
And ISO 12800 is even worse, pretty much unusable on both.
Nikon D5100 vs D3100 Summary
Surprisingly, the Nikon D3100 performed quite well against the D5100. I believe Nikon uses the same noise-reduction algorithm on both cameras, because noise pattern and levels look very similar on both. The Nikon D5100 still wins though, because it has 2 MP more resolution and seems to retain details better at high ISOs.
Let’s move on to the next comparison between Nikon D5100 and Nikon D700 – click the next page below.
Compared to Nikon D700
There is no such thing as a fair comparison when you put a DX sensor against an FX sensor. A larger sensor means larger pixels, which translates to cleaner images. I know FX vs DX is always a heated debate, with plenty of people defending each side, but for me – the low ISO performance of a full-frame sensor was something that made me permanently switch to FX. I was simply never happy with noise showing up even at base ISO on DX sensors. Everybody talks about high ISO performance difference between FX and DX, but people rarely show examples of low noise of the FX sensor at low ISOs. Take a look at this crop from D5100 at ISO 200 and compare it to a crop from D700 at the same ISO:
See what I mean? Images from full-frame sensors will always be cleaner at low ISOs when compared to DX and the above example is a clear demonstration of this. The same is true for all ISO levels between ISO 200 and ISO 800 – FX looks better in all cases.
Now let’s take a look at what happens at high ISOs between ISO 1600 and ISO 25600.
Nikon D5100 vs D700 High ISO Comparison
I typically set my Auto ISO max value to ISO 1600 on my Nikon D700, due to low amount of noise and plenty of detail in both highlights and shadows. Let’s see how the Nikon D5100 compares against the D700 at ISO 1600:
As you can see, the difference is pretty clear – the Nikon D700 is much cleaner at ISO 1600. What about ISO 3200?
The situation at ISO 3200 is very similar to that of ISO 1600 – Nikon D5100 is showing plenty of noise in comparison.
ISO 6400 is my threshold on the D700 for worst case scenarios where I need to use a high ISO. D700 is still much cleaner than D5100 and it certainly retains a lot more details in shadows and highlights.
ISO 12,800 and 25,600 is a little better on the D700, but still unusable on both cameras for my taste.
Nikon D5100 vs D700 Summary
Once again, comparing a cropped-sensor camera to a full-frame camera is never an apples-to-apples comparison. I decided to provide the above crops simply as a reference, for people to see how the new D5100 compares against the older D700 full-frame DSLR. Yes, the Nikon D5100 is a superb high ISO performer when compared to other cropped sensors, but it still is not on the FX league in terms of noise handling, especially at low ISO levels. Obviously the Nikon D5100 has a 4 MP advantage we should not forget about, but even downsizing images to 12 MP does not ultimately result in the same clean look FX gives to images. Even ISO 3200 on the D700 looks better than ISO 1600 on the D5100, so there is still more than a stop of difference between the two.
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