Focusing the video lens

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This page describes how to focus FUJINON video camera lens in DFNEXT camera systems (Point grey / FLIR digital cameras) using freeture video capture software.


Stop the freeture SW running as service

systemctl stop freeture.service

Run freeture in to display currently captured video live on screen

Login as user which is not root locally (keyboard + monitor + mouse needed).

Start windows manager


Start terminal. The following commands are to be executed in x-terminal.

Switch user to root may be needed

su - root

Run freeture, zoom in, set window with video full screen or enlarge it to se the focus is sharp:

freeture -m 2 --display -g GAIN -e EXPOSURE_TIME

Use GAIN (0 .. 29.99) and EXPOSURE time (0-33000 in microseconds; max exposure time is driven by frame rate 30Hz) appropriate for the current lighting conditions.

In full screen/enlarged mode, the image update may be slow or freeze. This is related to the CPU load and I/O over USB load - transferring image from video camera over USB and scaling it to screen buffer. Restart the above command if that happens and zoom in only partially or zoom 1:1, but shrink the window.

A tiny hex/allen key (size 0.9 mm) is needed to loosen the DFNEXT's Fujinon fish-eye video lens focus fixing bolts and to tighten them again when focused. There are 3 of these tiny set screws - to access them, the lens needs to be temporarily removed from the camera enclosure (undo the flange bolts from top of the camera system box with M7 spanner). On a new lens, it may be quite hard to get the hex key into the screw head as they are fixed with thread locking glue and some of the glue might be in the hex socket insert.

Note: Set the F-stop (mechanical lever on the lens) to full open, check if the focus is sharp as with f/1.8 or f/2.0. If yes, keep the wide open setting. If not, stop down to f/1.8 or f/2.0.

Stop freeture

By pressing [Esc] in the terminal window where it was started - not in the window with live video stream.

Start the freeture SW running as service again

systemctl start freeture.service