Thought I'd share this as I was not aware of it before. So...
1) It should be possible to drive the focus system quite fast. Not
sure why the current driver does not seem to utilize this capability...
2) This explains why the camera makes almost no noise during focus change
and why it returns to infinite focus after losing power.
Best,
Alex
----- Forwarded message from "Russell L. Harris" <[EMAIL PROTECTED]> -----
From: "Russell L. Harris" <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Subject: [Linux-uvc-devel] logitech quickcam pro 9000 autofocus mechanism
X-Spambayes-Classification: spam; 0.27
X-Spambayes-Trained: ham
Hi.
I have not yet subscribed to [Linux-uvc-devel], so you may wish to
pass on this information to the list.
Please refer to the web page at:
http://www.logitech.com/index.cfm/69/3231&cl=us,en
According to the web page, the autofocus mechanism for the Logitech
Quickcam Pro 9000 is of the voice coil variety. This is nothing other
than the combination of a magnet and a coil of wire, mounted
co-axially, such as is used in a typical audio speaker. In the
de-energized condition, a mechanical spring holds the lens in the
position against a mechanical stop for focus at infinity. A dc
voltage is applied to the coil to pull the lens into position for
focusing upon objects which are near. The greater the voltage
applied, the greater the displacement of the lens. Operation of the
system is completely silent. The displacement range of the lens
likely is very small, and may be almost imperceptible.
This is a nice focusing system, because it consumes no power when the
lens is in the infinite-focus position, and because the infinite focus
position (which typically is suitable for objects more than a few feet
from the lens) is the normal or default position.
RLH
----- End forwarded message -----
_______________________________________________
Linux-uvc-devel mailing list
[email protected]
https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
