Reconciling the Thick Lens Model with P2P Optical Bench

Started 3 months ago | Discussions thread
OP Garry2306 Regular Member • Posts: 108
Re: DoF estimates

@Bill

I’ve come to a generalised conclusion that I would welcome your views on.

Using your Optical Bench Hub I’ve explored various lenses that allow focus exploration.

My general conclusion is that, the position of the front principal, relative, to the sensor, will always be closer to the sensor as you focus away from the MFD, towards infinity.

Assuming I’m right, this supports my focus bracketing logic to use a fix hiatus (i) throughout the focus range, calculated at the MFD, where we at least have manufacturers data as well as a measurement we can make.

Adopting this approach we ensure a positive focus overlap, as knowing the sensor to object distance, we can position H at (1+m)f+i, because the distance we then use in the DoF calculations will always be less than the actual distance from H to the object.

BTW I can’t find a general rule for pupil mag, ie knowing the pupil mag at the MFD can we say something general about the way the pupil mag changes, higher or lower, as we focus towards infinity, ie for a retro and tele lens.

Cheers

Garry

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