﻿ Crop factor pixel density and pixel size of Canon 7D II and Canon 5D III: An analysis of the "pixel density advantage" for the Canon EOS 7D Mark II digital camera compared with the Canon EOS 5D Mark III. Pixel pitch of Canon 5D III is about 53% greater th Rob's  Photography  New  Zealand

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Analysis  of  the  "Pixel  Density  Advantage”

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

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

This summary should be read in conjunction with the full explanatory article that you can see  here. Note that the analysis on this page does not include a discussion of the various complex issues that can arise in practice when estimating pixel density and the pixel pitch or area of individual pixels. It is recommended that you study a detailed technical article if you would like to become familiar with these issues. For example, you may find this  DPR forum discussion  about pixel density and pixel size to be helpful. Therefore, the calculations set out below are presented for the purpose of calculating only a very approximate measurement of pixel density, pixel pitch, and the area of one pixel, which can be used for comparing the approximate mathematical relationships between the pixel density and pixel size of different cameras.

This summary provides an example of how to apply the template that is published  here. In this theoretical template, the reconciliations between the percentages shown for pixel density and pixel size, work out exactly, only because the number of megapixels on the sensor is exactly the same as the image width in pixels, multiplied by the image height in pixels.  In addition, the image width divided by the image height, gives the same answer as the sensor width divided by the sensor height. In the theoretical template, the approximate area calculation for the size of one pixel is exactly equal to the pixel pitch squared. In addition, the approximate area calculation for the pixel density is exactly equal to the linear pixel density squared.

However, in the practical example that follows, the arithmetical reconciliations demonstrated in the template do not work out exactly because of roundings in the specifications used, and also because of the way the effective number of pixels of the cameras is calculated (that is, the image width multiplied by the image height, does not exactly equal the effective number of pixels published for the cameras).

Note: The information below is not designed to provide information about the quality of images or the quality of the cameras, because these are separate issues.

The  Canon EOS 7D Mark II  was announced in September 2014. The    was announced in March 2012. This summary shows that, when compared with the Canon 5D Mark III, the Canon 7D Mark II has a linear pixel density that is approximately 53% greater than that of the 5DIII. The approximate “area” relationships for image size, pixel density, and pixel size, are also presented below.

Note: If the (full frame) Canon 5D Mark III had the same pixel density as the (APS-C) Canon 7D Mark II, it would have approximately 52 megapixels, and image dimensions of approximately 8794  pixels x 5863 pixels.

Relevant  Specifications

Canon 7D II: Image dimensions:  5472 pixels x 3648 pixels  (approx. 20.2 million effective pixels); sensor size: 22.4mm x 15.0mm

Canon 5D III: Image dimensions: 5760 pixels x 3840  pixels (approx. 22.3 million effective pixels); sensor size: 36.0mm x 24.0mm

Crop  Factor

Approximately 1.6x  (36.0mm / 22.4mm)

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

7DII =    2443  (5472 / 2.24)

5DIII =   1600  (5760 / 3.60)

Pixel Density Advantage: 7DII is approximately 53% greater than 5DIII

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

7DII =  4.09     (22.4 / 5472 x 1000)

5DIII = 6.25     (36.0 / 5760 x 1000)

Relationship: 5DIII is approximately 53% greater than 7DII

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

Gain in image width (in pixels) as a result of the above 53% pixel density advantage

Uncropped image width of 7DII   = 5472 pixels

Cropped image width of 5DIII

to same  field of view  as 7DII     = 3584 pixels  (5760 x 22.4 / 36.0)

Relationship: 7DII is approximately 53% greater than 5DIII.

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

Gain in comparable widths of print sizes as a result of the above 53% pixel density advantage

If the uncropped image of 7DII (of 5472 pixels width) is printed at 200 pixels per inch (ppi), the width of the print is about 27.4 inches (5472 / 200).

If the cropped image of 5DIII (of 3584 pixels width) is printed at 200 ppi, the width of the print is about 17.9 inches (3584 / 200).

Relationship: The net effect of the 53% pixel density advantage of 7DII, is to produce a print at 200 ppi, that is about 9.5 inches wider (or about 53% wider) than that produced with the same  field of view  from the cropped image of 5DIII.

Crop an image from 5DIII to the same   field of view  as an image from 7DII, and compare the changed field of view of 5DIII with that of 7DII:

Assume that a 300mm lens is on both cameras and that the field of view of an uncropped 5DIII image is 300mm

Field of view of 7DII = focal length of lens  x  crop factor of 7DII = approx. 482mm  (300mm x 36.0mm / 22.4mm)

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

= uncropped image width of 5DIII  /  cropped image width of 5DIII  x  focal length of lens  =  approx. 482mm  (5760 / 3584  x  300mm)

Relationship: The fields of view of 7DII and 5DIII are the same, that is, approx. 482mm.

Note: The image width of a 5DIII image, when it is cropped to the same field of view as 7DII, is approx. 3584 pixels (5760 x 22.4 / 36.0). Click  here  to go to an article titled "Advantages and disadvantages of cropping images instead of using lenses with longer focal lengths". This article gives further details in support of the formulas used above.

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

Field of view of 7DII = focal length of lens  x  crop factor of 7DII = approx. 482mm  (300mm x 36.0mm / 22.4mm)

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

= uncropped image width of 5DIII  /  cropped image width of 5DIII  x  focal length of lens =  316mm  (5760 / 5472 x 300mm)

Relationship: 7DII is approximately 53% greater than 5DIII.

Note:  Click  here  to go to an article titled "Advantages and disadvantages of cropping images instead of using lenses with longer focal lengths". This article gives further details in support of the formulas used above. Click  here  to see a forum discussion titled: "How do you calculate the reach advantage? Sony A900 vs Nikon D3S" Digital Photography Review, Sony SLR Talk Forum, April 2010.

Approximate  Area  Relationships

Pixel density (in megapixels per square centimetre)

Pixel density in megapixels per square centimetre = number of megapixels on the sensor  divided by  sensor area in square centimetres

7DII =      6.0119    (20.2 / 3.36)

5DIII =     2.5810    (22.3 / 8.64)

Relationship: 7DII is approximately 133% greater than 5DIII

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

7DII =      16.6337   (336,000,000 / 20,200,000)

5DIII =     38.7444   (864,000,000 / 22,300,000)

Relationship: 5DIII is approximately 133% greater than 7DII

Crop an image from 5DIII to the same  field of view  as an image from 7DII:  Gain in image area  (based on image sizes in megapixels)

Uncropped image area of 7DII = 20.2 megapixels  (5472 pixels x 3648 pixels)

Cropped image area of 5DIII

to same  field of view  as 7DII  =  8.56 megapixels  (3584 pixels x 2389 pixels)

Relationship: 7DII is approximately 136% greater than 5DIII

Click  here  to go to an index of further camera comparisons showing the mathematical relationships between image size, pixel size, pixel density, and reach etc.

Click  here  to go to the index of all the technical articles and blogs on this site.