Extension Tubes - Full Disclosure

[Loupey]

Ok, I've been talking about tubes ever since joining PR and have posted some real-world examples in this forum.

So here are some test examples which I hope you find helpful. I thought pencils would be a good universally recognizable (and stationary ) subject.

Since there are so many variables, the following will remain unchanged throughout:

Lens: 70-200 f/2.8L IS
Aperture: f/8
ISO: 200
Focus: manual (rack focusing) at minimum lens setting
Metering: AV
Mirror Lockup: enabled
Shutter Release: remote
File Capture: RAW
Post Processing: None except resize and convert to JPEG (no cropping)

The setup: