I have been following mirrorlessrumors.com on their rumors of latest cameras and I appreciate their articles’ truthfulness and accuracy. In response to video by Tony Northups’s cheating accuse video which contain inaccurate and misleading information about photography, I feel the same way as the editors from mirrorlessrumors.com; the video is wrong about the myth on aperture. You can find the article here.
Therefore, I want to make a simple test, just to debunk the ‘myth’ about aperture, brightness and bokeh once and for all.
The questions to ask are:
1) Does smaller sensor size has less bokeh comparing equivalent focal length? -> yes
2) Is aperture number an universal unit used by companies to calculate brightness? -> yes
Here’s the test setup by comparing a full frame sensor with the micro-four-third (x2 crop factor) sensor
Following parameters are constant:
1) Environment lighting
2) custom white balance fixed at 5000
3) shutter speed fixed at 1/8
4) ISO fixed at 500
5) Camera set with tripod, though there maybe slight movement and the inconsistency of the actual sensor position relative to the tripod mount.
Comparison of 40mm (35mm equivalent) with different apertures (click for full resolution):
Comparing side-by-side of 2.8 (somehow the company default white balance is offset although I set custom 5000)
Both cameras at 2.8 with same parameters throughout should produce images with similar brightness. With a closer look, you can also see the off-focused area of the right image is clearly sharper.
Next, here’s the 100% crop of the ‘windows logo’ of my laptop, which is the off-focused object:
As far as I had experimented (not shown in the above, I used to compare Pentax 25mm c mount on Olympus OMD with Pentax 50mm K mount on Canon 5D mkII, but the lens quality is not a fair comparison), there is no direct formula towards equivalent bokeh of smaller sensor to full frame. In another words, 2.8 on a half frame x2 crop factor sensor may not produce the same bokeh as a 5.6 full frame. Other parameters such as focusing distance and the equivalent focal length may affect the result (correct me if I am wrong, as I am not an optic engineer).
Do not believe everything said on the internet. Understand the principle and enjoy shooting with the merits and cons of each camera 🙂 Sometimes shallower depth of field isn’t always good, smaller sensor has their strength as well.