[EE] Operation of DC type Auto Iris CCTV Camerea Lens

[Brooke Clarke]

Hi:

I'm trying to learn how the DC type auto iris CCTV lens works. This appears to
be a standard where the lens has a short cable with a 4 pin plug.
The pin out might be:
1 = Dump- or Control - or Damper Lo
2 = Dump + or Control + or Damper Hi
3 = Drive or Drive + or Drive
4 = Ground or Drive - or Ground

My ususual suspects Google Web, Google patents have not been able to answer how
these work.

The reason it to understand how to setup a CCTV camera for a
Weather/Sky/Astronomy webcam: http://www.prc68.com/I/WebCam2.shtml

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com

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[Xiaofan Chen]

On 9/16/07, Brooke Clarke <bro...@pacific.net> wrote:
> Hi:
>
> I'm trying to learn how the DC type auto iris CCTV lens works. This appears to
> be a standard where the lens has a short cable with a 4 pin plug.
> The pin out might be:
> 1 = Dump- or Control - or Damper Lo
> 2 = Dump + or Control + or Damper Hi
> 3 = Drive or Drive + or Drive
> 4 = Ground or Drive - or Ground
>
> My ususual suspects Google Web, Google patents have not been able to answer how
> these work.
>
> The reason it to understand how to setup a CCTV camera for a
> Weather/Sky/Astronomy webcam: http://www.prc68.com/I/WebCam2.shtml
>

I am not so sure what you want. Do you need the driving circuits?

Anyway Google for "Driving DC type auto iris CCTV lens" and some of
the first page hits are listed here:
http://www.rapitron.it/guidaobaiE.htm
http://www.cctv-lens.com/faq.html
http://www.cctv-lens.com/tips.html
http://www.extremeskills.com/cosurveillance/pdf/lensdata.pdf

Not so sure if this is useful to you or not.

Xiaofan

[Peter P.]

I have posted a message in the past about this, when someone else asked the same
question. Basically the Drive is where you apply control current. Damp is a
speed proportional feedback signal. Speed is the motion speed of the actuator.
Both controls are coils, the actuator is a moving magnet galvanometer with a
return spring. Typically unidirectional current up to about 30-50mA is driven
into Drive and Damp helps to make the movements smooth(er). The control is not
suitable for open circuit operation, it will only work with realtime feedback
(from the video signal).

Peter P.

[Brooke Clarke]

Hi Peter:

When I apply 5 ma to a lens the iris stays closed and by 10 ma it's wide open.
This done with no connection to the damping terminals.

Is the control signal coming from the lens?

Any ideas on where to get the 4 pin plug and socket connectors?

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com

I have posted a message in the past about this, when someone else asked the

[Robert Rolf]

Brooke Clarke wrote:

> Hi Peter:
>
> When I apply 5 ma to a lens the iris stays closed and by 10 ma it's wide open.
> This done with no connection to the damping terminals.
>
> Is the control signal coming from the lens?
>
> Any ideas on where to get the 4 pin plug and socket connectors?

Any good CCTV security company will have them in stock, or can order them for
you. What style does your camera have (there is more than one '4 pin' interface).

Most cameras with the socket will have the needed drive electronics.
You just have to tell it which kind of autoiris is connected (DC vs AC).

As for open vs closed loop control, if your camera has AGC (I believe it does),
you can probably get away with bang-bang control. Wide open a night (when light
level drops. Use a CdS cell and comparator) and partially closed during the day.

Robert

I would suggest tipping your camera up so that is shows more sky and much less tree.
You did call it a 'sky camera' after all.

Other trick. Point camera down at hemispherical security mirror to get an 'all sky' view
from horizon to horizon, 360 degrees. This is commonly used for meteor tracking cameras.
(bolid recovery).