I thought Nikon D3100 must be more advanced than D3000 (because of the higher number and the increased price).

But, the D3000's sensor size is 23.6mm x 15.8mm and the D3100's sensor size is actually smaller at 23.1mm x 15.4mm.

Well, D3100 has an extra feature, live view. Fine, but is there any special reason that they decided to reduce the sensor size in a more advanced camera?

Is there anything in D3100 which "makes up" for the reduced sensor size, or am I simply missing some point?


The basic answer to "why" is: because it doesn't matter in any practical way.

To put it into perspective, this is a 4.8% difference in sensor area. Or, linearly, it's 2.3% difference in crop factor.

This is not very much, and generally other measurement tolerances will be less precise. For example, if you measure the actual focal length of, say, a bunch of different models of 50mm lenses, they probably have a greater variation in field of view.

In general, newer sensor technology moves forward, and in this case there's no exception: the D3100's sensor is significantly better, particularly for controlling noise at high ISOs. From dpreview:

The D3100 offers little to complain about in terms of image quality, and its new 14Mp sensor delivers very good results. High ISO performance is substantially improved over the D3000 [...].

Basically, the small difference in sensor size is insignificant compared to the improvements in terms of image quality, and the small difference in framing is likewise a non-issue.

  • Yes, the differences will almost surely not matter in your field of view. – dpollitt Feb 9 '12 at 15:29
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    It is also entirely possible the new fewer black-level pixels which are usually masked out and the area used can still be identical. – Itai Feb 10 '12 at 2:50
  • Wikipedia lists the different sizes Nikon employed in its aps-c sensors: en.wikipedia.org/wiki/Nikon_DX_format#Real_sensor_size – Berzemus Mar 6 '13 at 16:37

The "Why" the size differs is hardly related to camera technology (image quality) as already stated above, but more likely an issue of production and/or the engineering of the sensor. I believe this will be hard to confirm, but smaller sensor consumes less energy, is cheaper to produce, easier to fit in a slightly smaller camera body. These are all issues that tend to sell well, and loved by the marketing department of the camera brand. Longer battery life, lower price of the camera, slightly smaller body. All this without negative effect on the image quality! Remember this is an industry, where market share and profit rule.

Okay, this is not a confirmed fact, and i should not post opinions as an answer to a question. But i know about industry in general, about profits of big numbers, about cutting costs, as i do work in a mass production industry. (though not even near to cameras)

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