Canon 100-400II: actual mm's

[Mario]

Today I tried to determine the actual mm's of Canon 100-400 II and hence the level of focus breathing.

I determined the horizontal field of view at 1, 2, 3, 4, 5, 10 and 20 meters (distance subject to sensor). It was a quick and dirty method so the error of measure is rather cm's than mm's .

This is what I got:

Distance (meters) - Horizontal field of view (meters)

1 - 0.118
2 - 0.207
3 - 0.301
4 - 0.394
5 - 0.487
10 - 0.945
20 - 1.87

From this I calculated the angle of view and further the actual mm's. This is what I got:

Distance (meters) - actual mm's

1 - 305
2 - 348
3 - 358
4 - 365
5 - 370
10 - 380
20 - 384

When I extrapolate the data to 100 m distance, I get 388 mm, so we're probably getting close to 400 mm at infinity.

First time I've done this type of calculation (I am a chemist, I am used to do math on concentrations, molecules and atoms, not optics ), so please feel free to check the math and correct me if I am wrong.

Cheers,

Mario

 

[Mt Spokane Photography]

The numbers look pretty typical, so they are likely correct or close enough.

 

[masitauncen]

It was something that I had never come across.

คาสิโนออนไลน์

 

[AlanF]

Mario
I am also a chemist, and came up with a figure of 380mm at about 20m by comparing with the 300mm/2.8 plus 1.4 or 2xTCs, assuming they are correct. Remember also that there is a slight pincushion at 400mm.