Karl in NY

All set now. Thanks.

Actually, the PT680-24SL, the one with 360° pan, I would like to liquidate, but only to a good home I can't forsee any use for that feature with the projects I'm working on. I only have $115 invested in it (about a third of that in shipping costs because it's so heavy). So, if anyone needs that model, cheaply, let me know. -Karl (near Albany)

My goof. I looked at these units again in better light, and there is indeed a third wire in the tilt wire bundle. Don't how I overlooked it the first time, except for the poor lighting. I also discovered that one of the units has no pan switch or wiring, so it must be one of the 360-degree models. Never saw one before, and not too useful to me.

I bought several surplused Pelco PT680-24P pan/tilt units, and don't understand what I have. I have deployed many similar units, but these confuse me. 24VAC, that's a given. I have the both the Pelco Install manual and Service manual for this model number. The pan motors are what I expected: three wires, Red, Blue, Gray. The tilt motors only have two wires, Yellow and White. The manuals show that both the pan and the tilt motors for these models should be the same, but, they are not, in my case. One motor wire missing, and the other two the wrong colors. My first guess was that the tilt motors with only two leads might have the motor "common" grounded to the frame, eliminating one of the three leads, but the ohmmeter shows no connection between the pan/tilt common (brown wire) and anything metal. I'm hesitant to fry anything without some guidance... Any knowledge out there about these? Regards- Karl

I'm coming to the conclusion that C-mount zoom lenses, when mounted on a CS-mount camera (with the necessary 5 mm ring) behave as varifocals and not true zooms. Of the three I have tried, all have done the same thing, but at least they will focus over their entire zoom range. The lenses are very usable that way, but just not as convenient having to refocus after each zoom.

The Arecont camera has no hardware or software backfocus provision...the OEM lens (a CS-Mount Computar 4.5-12.5 f1.2) had a shim ring behind it, less than a mm in thickness.

The camera does not have any lens-mount adjustment...my only recourse is to use shims, like 0.5 mm, which permits focus from both least to greatest focal length, but still without focus-tracking as the lens is zoomed...

I just got my first network camera capable of using interchangeable CS- or C-Mount lenses. (Arecont 2100). However, when I mount any of my older C-mount zoom lenses (using the necessary 5mm spacer, of course, to convert to the CS mount), the zooms behave as varifocals...whenever I zoom, I have to refocus. I'm not talking about a slight correction, but a major refocus. All of my 2/3" and 1/2" format C-Mount zoom lenses (mostly older models like the Canon 17-102mm V6x17) are acting as varifocals. I can focus at any focal length, but without focus-tracking while zooming... Is this typical of using C-Mount zooms on a CS-mount camera with a 5mm spacer? Any wisdom would be appreciated.