Hello folks!
I have a question for those who are not only mathematically inclined but more so understand digital photography, sundry nuances of sensor efficacy etc as it relates to pixels and final picture quality out of a digital camera.
Background to question: Assume:
• You have a Canon 5D Mk II (full frame 21mp) and a Pentax K3 (APS-C 24mp).
• The sensor quality of both cameras is not the same. It remains what it is in real life.
• The 5D sensor size is 24x36 = 864 sq mm and the K3 sensor size is 16x24 = 432 sq mm.
• On both bodies you use a Sigma 50mm lens in respective mounts. The two lenses are electro-optically identical in terms of picture quality.
• No special in-camera processing or correction is applied.
Now, you shoot the a subject with both cameras with identical settings/lighting. What you get is:
- Canon – a 50mm perspective photo using 21mp on 864 sq mm surface area = 24,305 pixels per sq mm.
- Pentax
– The 1.5x crop factor gives you a 75mm perspective photo using 24mp on 432 sq mm surface area = 55,555 pixels per sq mm.
Next, you crop the Canon photo to equate the Pentax coverage of 75mm. In doing so, you delete portions of the Canon file from all sides to retain a portion such that the Canon photo matches the Pentax photo in angular coverage.
As I see it, you have now cropped the Canon photo from 864 mm size to 432mm size to achieve Pentax’s 75mm angle.
What you now end up with is effectively a Canon 432 sq mm size file of 10,500 pixels and a Pentax 432mm size file having 55,555 pixels.
You now make prints of both photos enlarging them to size 16x12 inches (400x300mm) using identical inputs for the printer.
The question – Keeping in mind difference in sensor quality of the two cameras in real life – pixel pitch/size favouring Canon and the file size favouring Pentax -
- Which file will give a better quality image?
- Is the Canon sensor so good as to make up the difference of 5x additional pixels in the Pentax file?
If anyone here has both cameras and can arrange to do a test and put up results, it would be revelatory!
Thanks in advance to all of you who can offer some informed inputs.