Compared to Nikon D90
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 Nikon D3100.
To make sure that I do not get major differences in depth of field, I changed the aperture to f/8.0 on both cameras. I turned off Active D-Lighting and Noise Reduction on both cameras and used exactly the same shutter speed and ISO. To get to a similar field of view, I slightly zoomed in with the Nikon 70-200mm VR II lens when shooting with the Nikon D90. Focusing was performed via Live View contrast detect. Nothing else was changed during the test.
Nikon D3100 vs D90 ISO Comparison at low ISOs
At low ISOs between ISO 100 and 800, both Nikon D3100 and Nikon D90 have about the same noise levels with slightly cleaner shadows from the D90. Details also look very similar, but the colors from the D3100 certainly look different. Take a look at the below crops at ISO 100 (L 1.0 on Nikon D90), 200, 400 and 800:
Nikon D3100 vs D90 High ISO Comparison
What about high ISO levels above ISO 800? Let’s take a look:
ISO 1600 and 3200 look about the same to me – there is hardly any difference in highlights and shadows, besides some differences in colors. ISO 6400 looks a tad worse on the D90 to me, because I see more larger artifacts across the frame. The grain on the D3100 at ISO 6400 looks a little finer and the colors are retained better. Either way, I personally would not shoot above ISO 1600 on either camera.
Nikon D3100 vs D90 Summary
As you can see, both cameras perform very similarly at low and high ISOs, which gives an advantage to the Nikon D3100, because it has 2 more megapixels than the D90. Does this mean that you should purchase the Nikon D3100 over D90? No, because these are two different class DSLRs. Remember, the above are only ISO sample image comparisons. Nikon D3100 is the most basic, entry-level DSLR, while Nikon D90 is a semi-professional camera with plenty of features not present on the Nikon D3100 (too many to list). Nevertheless, the Nikon D3100 clearly demonstrates that the newer sensor technology is getting better and better, even as more pixels are squeezed into the same size sensors.
Compared to Nikon D7000
For the Nikon D3100 vs D7000 test, I used the same focal length at the same distance. 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.
Nikon D3100 vs D7000 High ISO Comparison
Low ISO performance between ISO 100 and ISO 800 looks almost identical on both Nikon D3100 and Nikon D7000, 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 D3100 vs D7000 Summary
Although the Nikon D3100 does not have many of the Nikon D7000 features, it performed quite well against the D7000. I believe Nikon uses the same noise-reduction algorithm on both cameras, because noise pattern and levels look very similar on both. The Nikon D7000 still wins though, because it has 2 MP more resolution and seems to retain details better at high ISOs.
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