Today’s Question: Is it true that a sensor with a greater resolution will result in photos with more noise? If so, is this a reason to avoid higher resolution sensors?
Tim’s Quick Answer: Yes, it is fair to say that all other things being equal a sensor with a higher resolution will result in more noise. However, there is tremendous variability involved, and this issue should not cause you to intentionally seek out a camera with a lower resolution sensor.
More Detail: By definition if a sensor of a given size has a greater number of pixels, the individual photodiodes that capture the pixel data will be smaller. Smaller photodiodes aren’t able to capture as wide a range of tonal values, meaning they have lower dynamic range. That, in turn, contributes to a greater amount of noise.
However, that is not to say that just because a sensor has more pixels than another that it will produce images with more noise. There are a great many factors that contribute to the noise levels for a given sensor, such as the use of microlenses, in-camera noise processing, photodiode quality, and much more.
If a manufacturer were to produce two sensors that were of the same size and identical in every way except for the number of photodiodes, and that as a result the lower-resolution sensor had larger photodiodes, you could expect lower noise levels for that sensor. But the reality is that two different sensors generally differ much more than simply the number of photodiodes.
So, the most important thing is to test the actual noise behavior of the camera you’re considering. In general, cameras today perform very well when it comes to minimizing noise. We are able to use much higher ISO settings now compared to years ago, for example, when it was often important to restrict yourself to relatively low ISO settings to avoid excessive noise.
Keep in mind that the advantages of higher sensor resolution will generally outweigh the risk of significant noise with today’s cameras. Furthermore, even if an image exhibits noise, software has advanced to the point of being able to minimize the appearance of noise without significant degradation in image quality.

