laser triangulation, ir or ultrasonic distance measurement combined with a servo or microstepper attached to a follow focus (example http://www.philipbloom.net/wp-content/uploads/2009/06/microff_v2_15mm_lg1.jpg ) to adjust the lens focus according to distance. different lenses might need different adjustments.

This is possible, can this be merged with the OSArduino FF? It was a part of expanded design in the project.

i have used a Sony EX3 with Fujinon zoom optics which has autofocus and electric zoom. to that was 2 controllers attached, left and right on the handles of a sachtler tripod.

this for focus: Fujinon EPD-1CA
http://camelot-berlin.de/wp-content/uploads/2014/03/1000144.00.jpg

and this for zoom: Fujinon ERD-T22 Zoom
http://www.hyperactivebroadcast.com/public/upload_product_image/Fujinon_Zoom_Control_Hire.jpg

for a broadcast studio setup this is really great!

there are a lot of focus systems for manual zoom optics. there is one part with a servo attached to the lens and one controller, attached with a cable or wireless. i think a cable is better for less delay.
most of them are quit expensive, but there are DIY projects out there.

some examples:
http://www.arri.com/camera/pro_camera_accessories_electronic_control_system/products/wireless_compact_unit_wcu_4/
http://www.chrosziel.com/news.asp?wdid=17&wpid=237&sid=0
http://www.marcotec-shop.de/de/products/cat_327/detail_2286.htm
http://www.hocusproducts.com/store/index.php/axis-1/axis-1-remote-follow-focus-kit.html
http://heden-engineering.com/start/
http://store.redrockmicro.com/Catalog/microRemote-Bundles/Remote-wireless-focus-bundle.html
http://www.cinegearpro.com/pdmovie-remote-air-follow-focus.html
http://www.cinegearpro.com/tilta-wlc-t02-wireless-lens-control-follow-focus-system.html
http://www.varizoom.com/focus-zoom-camera-lens-controls-s/1814.htm
http://www.protech-nipros.com/Products/Remote/index.html

http://www.youtube.com/watch?v=dImw2MZ0Sv8
http://adisoffer.tumblr.com/post/25422476290/you-read-the-post-now-watch-the-movie-arduino-follow
http://www.indilib.org/support/tutorials/143-diy-remote-focuser-with-indi.html
https://www.kickstarter.com/projects/24shots/silencer-follow-focus-system
https://www.kickstarter.com/projects/1608311032/lenzhound-wireless-lens-motor-control-system

if we have such a system, the axiom firmware can control it for automatic focussing or manual focus with a smartphone.

we could just attach a servo with a housing to our rig since we have a board to control it. maybe 2 for focus and zoom.

This can be grouped in with the Open Source Arduino Follow Focus, motor controlled auto focus using various methods, one of which included a manual calibration method of calibrating a manual focus lens or unknown lens.