# What is mFT FoV?

Started Jan 27, 2013 | Questions thread
 Like?
 Re: practical measurement with 20mm In reply to Vlad S, Jan 28, 2013

Anders W wrote:

Vlad S wrote:horizontal field of view: 19 7/32 in - 3 7/32 in = 16 7/32 in = 16.21875 in.

19 7/32 - 3 7/32 = 16 as far as I know

A typo. It's rather 19 7/16 instead. The pic shows it. I hate the fractions that the imperial tapes use. Only unnecessary complications for math.

diagonal field of view: 16.21875 / 4 * 5 = 20.2734375 in.

Diagonal angle of view: 2 * arctan (20.2734375 / 2 / 20) = 53.7550599 degrees

I suppose 20 in this formula corresponds to the distance from the sensor plane to the horizontal measuring tape. But that's not what you want for the formula to work. You want the distance from the principal plane of the lens to the measuring tape.

Sure. But a I am already satisfied with 6.7% accuracy, and I would rather spend the time on figuring out the lighting for my next project, instead of figuring out how many inches I can fit in the frame to the first decimal.

Why did you do the exercise in the first place then? The error you made is sufficiently large to explain the entire discrepancy between the official specs and the value you found. And had the discrepancy been real, it would have been large enough to suggest that the official specs refer to the FoV before rather than after correction (which is not the case). So what was the point of your test as a response to gollywop?

Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +21 more
Complain
Post ()
Guy:New
Keyboard shortcuts: