At 12:16 PM 1/24/2006 -0800, you wrote:
>From: "Spehro Pefhany"
> > Should be more current-> more light so that the iris mostly closes
> > with power off.
>
>That is correct
>
> > I think the drive is to drive the iris open, and the cont coil has
> > to do with damping. It's possible it's a velocity output for the
> > control circuitry.
>
>Yes, actually, for other lens models they replace the name "control" by
>"damping", could you elaborate more on this subject?

No, as I know virtually nothing about it with 100% certainty. I don't even
have a lens in front of me, as you do. But I can visualize how the guts
*could* work.

> > Are you (the OP) sure that applying a few volts with the correct polarity
> > (slowly) to the "drive" terminals doesn't open the iris?
>
>Well, it was 11pm and I had 3 shots of bourbon 8^D

Might be worth trying again. Sober or not is up to you.

>I was using a current limiting (30mA) resistor and a pot to give me a
>certain voltage. I thought that opening or closing was done by varying the
>drive voltage.

The voltage across the coil (actually, the current through it) most likely
is what matters.

>Do you think that if I apply a constant 4V to drive + and GND to drive - it
>will keep opening the iris while voltage is applied?

I really don't know. It could work either way, with the lens integrating
the signal from the camera, but I suspect it acts more like a galvo with
the iris 'positioned' according to the current. You'll soon see what it
really does, and hopefully tell us.

You don't happen to have a full schematic of a compatible camera do you?

>According to the lens
>datasheet, the drive winding has an internal resistance of 190 ohms. Does
>that mean that I don't need a current limiting resistor and I can plug the
>5V directly from my psu?

Yes, but I'd measure the resistance first and raise the voltage slowly and
with the correct polarity.

> > This seems to be one of those irritating things where there are quite
> > a few manufacturers of compatible lenses and compatible cameras, but
> > little available on the net in the way of documentation of the interface.
> > 8-(
> >
> > Some of the threads used on cameras are similarly obscure, IIRC.
>
>This is one of those things that don't generate millions of hits on google.
>Some time ago I was trying to get a female jack for that 4 pin plug, I
>simply gave up.

It may be possible to find it online, but only if you already know what
to look for. I'd go to my paper library of obscure and exotic Asian parts.
But only for a large quantity buy-- too much $$ work otherwise.

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff


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