Mechanism with radio control

With all digital cameras equipped with wide angle zoom, it is tempting to command the zoom.. The Ricoh GX100 has horizontal angles up to 71°, and with the additional wide converter lens DW6 up to 85°. (See at the bottom of this page the focal lens and the equivalent angular fields)

Set some electric connexions on the camera body just appeared to me impossible, and I just resigned myself to use a servo-motorI
The first trials begun in June 2007, and I have very soon been convinced of the advantage obtained. Unfortunately this first mechanism was not reliable. 
 The principle of the positioning and of the pushing of the cross was wrong.. I was setting two arms to each end of the zoom button that I tried to push with one of them. It was difficult to adjust.


First arrangement
 Moreover, I found out that when the zoom button is kept pushed it is impossible to fire the camera. If by lack of chance the neutral of the zoom command was offset it was necessary to bring back the cradle to adjust it again.
Finally, after more thoughts and analysis of the movements and rotation angles I ended to the (obvious) solution as shown hereunder which eliminates all the fore problems.
 Correct arrangement


 The servo-motor is 22,4x22x11,2 mm and the cross is 20 mm width.
An arm of the cross is shortened and is located at the center of the zoom button. The two perpendicular arms are bent at their ends.
When the joystick is pushed to one direction the cross turns about 30° and one arm comes and push one side of the zoom button.
The reverse is done for the other side.


The servo-motor is mounted on a small bracket which has some flexibility when an arm is pushing the zoom button.


Step Zoom

The Ricoh GX100 can be set as continuous zoom or as step zoom.
When using continuous zoom; the zoom button must be maintained pushed until the desired focal length.
In step zoom, at each action on the zoom button, the focal is changed to the next "standard" focal length either upper or lower depending on zooming up or down.
The step zoom is the function that I use. To set it,  open the "setup" menu, choose the "step zoom", function as"off" for continuous zoom and "on" for step zoom.
Moreover I saved the MY1 programme with the zoom set on the second focal length (focal 4,7 mm or 6,0 mm with the converter ).
By experience there are sometimes pictures blurred when zoom set on 10,5mm and very often when set on 15,3mm.


Equivalent focal length

These are the measured angular fields and the declared focal length on the Ricoh GX100. The equivalent 35mm film focal length are indicated.

focale    ............... angles .................  équivalent  mm       diagonal   horizontal    vertical   en 24x36 Avec le complément optique DW6:             
  4,0        97°             85°             69°       19mm
  4,7        88°             77°             60°       22mm      5,8        76°             65°             50°       28mm   8,3        57°             48°             36°       40mm  12,1       41°             35°             25°      57mm
Sans le complément optique:
  5,1         84°             71°            56°       24mm   6,0         75°             63°            49°       28mm   7,3         63°             53°            40°       35mm  10,5        47°             38°            29°       50mm  15,3        34°             27°            20°       72mm
More is explained on focal length of digital cameras on this page "Angular field"  

Photographs shot with the rig at the same place

Horizontal angular field: 71°



Horizontal angular field: 38°