Sensor size and bokeh samples comparison, response to mirrorlessrumors’ “cheating” accuse video

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

The test setup consists of: Left: Olympus OM-D E-M5 with Panasonic 20mm 1.7, 2x crop factor, I will call it 'half frame' from here onwards. Right: Canon EOS 5D mk II with Pentax 40mm 2.8 XS, full frame
The test setup consists of:
Left: Olympus OM-D E-M5 with Panasonic 20mm 1.7, 2x crop factor, I will call it ‘half frame’ from here onwards.
Right: Canon EOS 5D mk II with Pentax 40mm 2.8 XS, full frame
There is some slight modification required on the 40mm XS lens, to remove the plate to avoid mirror hitting, as well as tape up the aperture to ensure shooting at 2.8.
There is some slight modification required on the 40mm XS lens, to remove the plate to avoid mirror hitting, as well as tape up the aperture to ensure shooting at 2.8.

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)

Left: full frame 2.8 right: half frame 2.8
Left: full frame 2.8
right: half frame 2.8

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.

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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).

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Conclusion

Do not believe everything said on the internet. Understand the principle and enjoy shooting with the merits and cons of each camera πŸ™‚ Sometimes shallower depth of field isn’t always good, smaller sensor has their strength as well.

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7 thoughts on “Sensor size and bokeh samples comparison, response to mirrorlessrumors’ “cheating” accuse video

  1. Dear friend. That is why you should never compare 20mm lens on crop with 40mm on the full frame.
    40 mm on crop will have the same bokeh as 40 mm on full frame with the same size of an object in the frame (the distance should be different). It is a scientific fact that is confirmed by a formula. That is why manufacturers will NEVER mark 20mm optics as 40mm on 2x crop camera.On the contrary, full frame 20mm will have the same bokeh as 20 mm 2x crop (with the same object size in a frame). Try it.

      1. Please, next time do not press Publish button in WordPress. It will surely protect you from any critics. I do not need to do any king of shooting and writing because I know how to use Google Search.
        http://www.have-camera-will-travel.com/field_reports/full_frame_vs_crop_sensor_-.html
        And, yes, I did one mistake, you do not need to frame your shot the same to get similar DOF. It just crops the image, like crop in Photoshop. So, DOF equivalent does not have any sense. Moreover, you do not need focal length equivalent because all manufacturers write view angle info in specs.

        Have a good day!

      2. Dear John, thank you for speaking up! I guess people just have the right to post anything they want.

        Dear Sheva, you were right on the cropping part, and thanks for sharing the link on full frame vs crop sensor though it’s a different thing we are proving here. If you like to criticize directly please go straight to Tony Northups, that is his argument not mine, I am just putting up my test samples πŸ™‚

  2. The only information you posted that is useful at all is dont trust what you read on the internet lol , the only fools who think that simple physics and optical laws does not apply to them are mFT users, specifically Olympus mFT users .Why this the case I do not Know

    1. Were you jealous photographers come up with these erroneous beliefs about m43 truly brightens my day. People like you know nothing about m43 and reading outrageous comments like these shows how ignorant the lot of you are.

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