Analysis  of  the  "Pixel  Density  Advantage” 

Canon  EOS 7D  compared  with  the  Canon  EOS 5D Mark II

Summary of approximate mathematical relationships between image size, pixel density, and pixel size

This summary shows that, when compared with the Canon 5D Mark II, the Canon 7D has a linear pixel density that is approximately 49% greater than that of the 5DII. The approximate “area” relationships for image size, pixel density, and pixel size, are also presented below.

Note: If the (full frame) Canon 5D Mark II had the same pixel density as the (APS-C) Canon 7D, it would have approximately 47 megapixels, and image dimensions of approximately 8370 pixels x 5580 pixels.

Relevant  Specifications

Canon 7D: Image dimensions: 5184 pixels x 3456 pixels  (approx. 18.0 million effective pixels); sensor size: 22.3mm x 14.9mm

Canon 5DII: Image dimensions: 5616 pixels x 3744  pixels (approx. 21.0 million effective pixels); sensor size: 36.0mm x 24.0mm

Note:  The  Canon 5D Mark III  was announced in March 2012. Click  here  to see a summary of the approximate mathematical relationships between image size, pixel density, and pixel size for the Canon 5D Mark III compared with the Canon 7D.

Crop  Factor

Approximately 1.6x  (36.0mm / 22.3mm)

Approximate  Linear  Relationships

Pixel density  (in pixels per linear centimetre)

Pixel density in pixels per linear centimetre = image width in pixels  divided by  width of sensor in centimetres

7D =     2325  (5184 / 2.23)

5DII =  1560  (5616 / 3.60)

Pixel Density Advantage: 7D is approximately 49% greater than 5DII

Pixel pitch  (in microns)

Refer to the reservations  here  about calculating the "true" width and area of an individual pixel.

Pixel pitch in microns  = width of sensor in millimetres  divided  by  image width in pixels  multiplied by  1000

7D =    4.3  (22.3 / 5184 x 1000)

5DII = 6.4  (36.0 / 5616 x 1000)

Relationship: 5DII is approximately 49% greater than 7D

Crop an image from 5DII to the same  field of view  as an image from 7D

Gain in image width (in pixels) as a result of the above 49% pixel density advantage

Uncropped image width of 7D = 5184 pixels

Cropped image width of 5DII

to same field of view as 7D      = approx. 3479 pixels  (5616 x 22.3 / 36.0)

Relationship: 7D is approximately 49% greater than 5DII.

Crop an image from 5DII to the same  field of view  as an image from 7D

Gain in comparable widths of print sizes as a result of the above 49% pixel density advantage

Crop an image from 5DII to the same   field of view  as an image from 7D, and compare the changed field of view of 5DII with that of 7D: Assume that a 300mm lens is on both cameras and that the field of view of an uncropped 5DII image is 300mm

Field of view of 7D = focal length of lens  x  crop factor of 7D = approx. 484mm  (300mm x 36.0mm / 22.3mm)

Changed field of view of a 5DII image when it is cropped to the same field of view as a 7D image

= uncropped image width of 5DII  /  cropped image width of 5DII  x  focal length of lens  =  approx. 484mm  (5616 / 3479  x  300mm)

Relationship: The fields of view of 7D and 5DII are the same, that is, approx. 484mm.

Note: The image width of a 5DII image, when it is cropped to the same field of view as 7D, is approx. 3479 pixels (5616 x 22.3 / 36.0). Click  here  to go to an article titled "Advantages and disadvantages of cropping images to gain extra reach". This article gives further details in support of the formulas used above.

Pixel area (approximate area of one pixel in square microns)

Refer to the reservations  here  about calculating the "true" width and area of an individual pixel.

Area of one pixel = area of sensor in square microns  divided by  the number of pixels on the sensor

7D =    18.4594   (332,270,000 / 18,000,000)

5DII = 41.1429   (864,000,000 / 21,000,000)

Relationship: 5DII is approximately 123% greater than 7D

Examples of the practical application of the "pixel density advantage" template: