70D
vs 5DIII
(small sensor vs large - image quality)
(small sensor vs large - image quality)
As a wildlife photographer I seldom have enough focal length to make the subject as large in the frame as I would like. Many images require cropping 50% or more. Full frame cameras never had much appeal to me because of the "apparent" loss of focal length, though the usable high ISOs do to the bigger pixels generating less noise has merit. I decided to compare the Canon 70D I currently use against a Canon 5DIII which is currently the highest pixel count full frame Canon camera available. Both cameras have a similar pixel count (1) but the 70D with the smaller sensor though noiser requires less cropping and should produce more detail compared to a 5DIII image when cropped to the same size. To test this I shot frames at ISOs 100, 400 and 1600 of books on a shelf. Tripod, studio flash and a 100mm Canon Macro lens were used, f8 was chosen for all images as the lens is sharp and Depth of field sufficient to cover slight focusing differences. The frame size was duplicated with the 70D by moving the camera farther (2) from the target until the frame matched the image from the 5DIII. Images were shot RAW and converted to 8 bit TIF. No sharpening or noise reduction was applied. Two small croped areas representing bright and dark areas of the images are compared side by side from both cameras at 100, 400 and 1600 ISO. Tifs were converted to JPEGs and displayed below. The last two images shown are from the target shot at the same camera to subject distance and displayed same size.
Target Image
The
images compared
below are the two red bordered crops of the above image
Camera distance to
target was set to make the target the same size in the frame
with both cameras
Camera distance
to
target was set to make the target the same size in the frame
with both cameras
Camera distance
to
target was set to make the target the same size in the frame
with both cameras
Camera distance
to
target was set to make the target the same size in the frame
with both cameras
Camera distance
to
target was set to make the target the same size in the frame
with both cameras
Camera
distance to
target was set to make the target the same size in the frame
with both cameras
Camera
at the same target
distance
Camera at the same target distance
Conclusion:
Clearly the 5DIII images taken when the frame size is the same as the 70D are noticably cleaner at 1600 ISO and somewhat cleaner at 100 and 400 ISO though not by much. Dark areas show more noise than light areas. However when one looks at the crops taken at the same camera to target distance then resized to be the same size on the screen it is clear that the small sensor camera produces more detail when significant croping is needed. This is as expected as the pixel density per unit area is much higher.
Notes:
1. Sensor pixels\mm: 70D 20.2 Megapixels, 22.5x15.0mm 5DIII 22.3 Megapixels, 36.0x24.0mm
2. Distance camera to target 70D 67", 5DIII 44"
3. The Auto focus micro adjust had been performed on both cameras prior to the test
copyright Ken Newcombe 2014