Originally posted by RioRico
So my question is: How do we factor AOV rather than FL into the SR and 1/FL equations?
I don't think any changes to the 1/fl rule are needed because the angles involved are very small; it isn't really the focal length of the lens that's important, it is the distance from lens to sensor. Besides the 1/fl rule is just an approximation.
Here's how it works; when the camera turns at a particular rate (like it was sitting on a turntable turning at some RPM). As the camera rotates, an image point moves across the sensor:
image.point.motion = 2Pi*RPM/60*Exposure.time*focal.length
To avoid motion smear the image point must move less than about 1/1000 of the sensor width (equivalent to one display pixel), or about 0.025mm..Rearranging the equation to solve for exposure.time,
Exposure.time.sec = (0.025mm*60)/(2Pi*RPM)/Focal.length.mm
It turns out (for most people) that
Exposure.time.sec ~ 1/focal.length.mm
This implies that the average camera rotation rate (like it was sitting on a turntable) is about 1/4 RPM
Clearly this is not a precise rule and there will be a large dependence on the individual and situation. The result also depends on the sensor size but not so much as one might think because for the same scene one chooses focal lengths that are proportional to sensor size so there's no predicted crop factor effect. (I didn't realize that clearly until writing this post.)
I hope this is not too confusing...
Dave