roy4711 Loc: Spring Valley IL.

I have a question about Mega Pixels. On a 16MP. full frame sensor the MP. are larger, would you need a 20MP. crop sensor to be equal, in order to produce the same image quality?

rook2c4 Loc: Philadelphia, PA USA

I think you are confusing resolution with image quality. Not exactly the same thing.

amehta Loc: Boston

First, let's talk about pixels. If you have two cameras with comparable levels of technology, the Nikon D610 (FF 24mp) and the Nikon D7100 (APS-C 24mp). The FF sensor is 2.25x as large as the APS-C sensor, and since they have the same number of pixels, the FF pixels are also 2.25x as large. That means each pixel gathers more light, so the colors will be better and the noise will be lower. If there is plenty of light, this isn't very significant, but when there is less light (higher ISO), the benefits start to show up.

If the APS-C camera has more pixels, then it produces a higher resolution image, but the noise and color issues will be even worse. In the end, a smaller sensor has one main way to win: better technology. If an APS-C camera from today is compared with a FF camera from 10 years ago, it might catch up. For example, the Canon 5D, from 2004, has about the same image quality as the Canon 70D, and slightly lower than the Nikon D7100.

CO

roy4711 is right. Tha larger pixels of a full frame sensor give it a higher signal to noise ratio. This results in lower digital noise and better low light capability. Dxo labs has a camera sensor comparison feature online. You can compare the sensor performance of up to three cameras at the same time on the same charts. Select a cropped sensor and full frame sensor camera to compare. Here is the website:
http://www.dxomark.com/Cameras/Compare