Why "crop factor" is so pervasive

[John Chardine]

Good comments all.

Michael- The viewfinder shows more or less (97-100%) of what the sensor is "seeing" so I think we are talking the same thing regarding magnification in the viewfinder and my comment that crop sensors cut the edges off the a full frame image.

Allan- Pixels on the subject is essentially what is graphed on the y-axis in the figure above, with more pixels on the subject as the pixel area decreases. Smaller sensor cameras tend to have more pixels on the subject. Correct on your last statement. Only the D800 and marginally the D3x puts as many pixels on the subject as the mid-crop cameras.

Roger- The modern trend for sure is to bring those FF points down on the graph but I was surprised to see at least two modern cameras (D4 and 1Dx) fit the trend quite well. Overall I guess we will see the slope of the line decrease as more and more pixels are stuffed onto sensors but I know you have said in the past that there is a point of diminishing returns beyond a certain pixel size.

Arash- Agree it's not marketing. I suppose large sensors with lots of pixels are hard to make perfect and this is why they have been relatively slow to come to the consumer market?

I don't know whether folks are familiar with gapminder.org. Hans Rosling has developed this amazing (and quite simple) data visualisation concept that animates 2-D graphs with the time-dimension creating the movement. I have often thought that visualising how camera sensors have evolved over the years using this software would be really instructive.

[arash_hazeghi]

Agree it's not marketing. I suppose large sensors with lots of pixels are hard to make perfect and this is why they have been relatively slow to come to the consumer market?
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yes they are basically two issues, 1) yield and 2) the electronics needed to process the massive files. Also beyond certain point it becomes diffraction-limited so diminishing returns.