It occurs to me that some customers and potential customers might be wondering how Lens•Lab figures its calculations. In the spirit of openness, honesty, and transparency, I present to you the methods I use.
First of all, the primary sources I used for the formulas are:
- Wikipedia’s article on Depth of Field
- Wikipedia’s article on Aperture
- Wikipedia’s article on F-Stops
Additionally, I used the following websites to either double check my calculations or to understand how crop factor influences depth of field:
- Cambridge in Colour article
- Bob Atkins article
- DOF Master online calculator
- Max Lyons online calculator
- DPAnswers article on crop factor (and DOF)
- Earthbound Light article on crop factor
Here is how I do the calculations:
hyperfocalDistance = ((focalLength * focalLength) / (apertureInFStops * circleOfConfusion)) + focalLength
depthOfFieldNear = ((hyperfocalDistance – focalLength) * (focalDistance)) / ((hyperfocalDistance + focalDistance) – (2.f * focalLength))
depthOfFieldFar = ((hyperfocalDistance – focalLength) * focalDistance) / (hyperfocalDistance – focalDistance)
depthOfFieldTotal = depthOfFieldFar – depthOfFieldNear
All distances are in mm and circleOfConfusion is set based on the sensor format:
- Full Frame = 0.029mm
- APS-H = 0.023mm
- APS-C = 0.019mm
- Four Thirds = 0.015mm
I’ve double-checked the calculations that Lens•Lab produces with other depth of field calculators and they match up.
There you have it! Questions or comments? That’s what the box below is for!