ExpoDev version 1.1 has been submitted for App Store approval and is waiting for release. Version 1.1 is a minor update that includes a few fixes and enhancements, most notably being that the Bellows Extension Factor calculator has been completely revamped. As you can see below, this new version now supports bellows extension factor compensation by using either the subject distance, the actual bellows extension, or a magnification factor.


When working with subject distances you can use either meters or feet and inches, as measured from the subject to the lens board. For Extension, the actual bellows extension is measured in millimeters. Magnification is a decimal magnification factor with 1.0 being a 1:1 reproduction factor.

ExpoDev will now directly tell you the calculated bellows factor and as such, ExpoDev no longer tries to determine whether a subject is a close-up or not. This leaves the photographer in charge of determining whether or not to apply a bellows factor as they see fit. ExpoDev does place some reasonable limits on factors though: if the calculated bellows factor results in less than 1/6th of a stop then no factor will be applied. 1/6th of a stop is well within the margin of error, all things considered. ExpoDev will also place a limit on the maximum factor of 65,536 (about 16 stops). In both of these cases, ExpoDev will let you know what is going on so that you, the photographer can make informed choices.

A few other minor improvements are included in this release. It is now possible to use lenses up to 2000mm and the minimum aperture has been increased to f/2048 (for pinhole photographers).

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Flux and Mutability

The mutable notebook of David Jade