Lens Problems

[mikeald]

Hi all,

i have a baxall camera on site (dont know model sorry), it used to have a fixed fujinon EI lens on it, which worked fine. Transmitting the video over fibre to the control room.

The other day I removed this lens, and fitted a DD varifocal computar lens, I plugged my spot mon in to the rear of the camera, focussed it up, and picture was fine.

Then I plugged the coax back in, since I have done this all I get back at the control room is 'video loss', and an intermittent flickering image. Yet the picture is fine before the fiber transmitter!

This has completely confused me, any ideas? As I have had to refit the old lens temporarily. Which works 100%.

Could it be that the DD circuitry in the camera simply just wont drive this computar lens properly?

mike

[camerabloke]

it is DD colin and i do agree it may be the problem colin

[mikeald]

yes perfect 1 volt peek to peek.

[Rich]

Strange one, but if the lens works when you have your test meter on the back of the camera, but not when you connect the coax to the fiber transmitter, you say its fine before the transmitter because you have probably connected the coax end that goes into the transmitter into your test monitor.

So it seems that when you connect the screen of the camera to the transmitter the problem starts, I would start looking at your 0v levels, it might be that you haven't quite got the lens connections to the camera right.

[mikeald]

correct, I put my test mon on the bnc that would normally plug into the fibre driver.

It is weird, as the picture is perfect with this new lens at the camera, but it just does not like the fibre.

dont get it at all. Also, the iris does not appear to be working at all. I put my hand in front of the lens, expecting the iris to open, but nothing happens at all.

what do you think i should do? Customer really needs this lens working.

thanks all

mike

[ilkie]

Have you look at the output of the camera with the new lens fitted with a 'scope?

Ilkie

[mikeald]

nope, used a vista video level meter. and is 1 volt p to p. No access to a scope unfortunately.

any more ideas?

thanks

[spider]

Does the fibre receiver have automatic gain or is it one with a pot to adjust, if manual adjusting type, try adjusting the gain on that, I have been caught with that

[Rich]

correct, I put my test mon on the bnc that would normally plug into the fibre driver.

It is weird, as the picture is perfect with this new lens at the camera, but it just does not like the fibre.

dont get it at all. Also, the iris does not appear to be working at all. I put my hand in front of the lens, expecting the iris to open, but nothing happens at all.

what do you think i should do? Customer really needs this lens working.

thanks all

mike

The fact that the iris doesn't work should give you a clue.

It would help to know what model the camera is, the chances are you have the drive and damping connections round the wrong way, or possibly the camera does not support the lens (unlikely)

One lens has 3 connections +ve, video and 0v the other uses 4 damping + and -ve and drive + and -ve.

If you are powering the camera from one supply and the fibre transmitter uses a diffrent supply, then there could be a difference on the 0v line which is causing your problem, but as you say the lens isnt working, I would check to make sure the camera can support your lens, if it does you need to know how the plug is wired, if damping and drive are round the wrong way that will probably be the problem, or it could be that the plug on the side can take both types and you have not configured the camera to take the different lens type.

So, get the model of the camera.

Find out what each wire does on the new lens

Find the wiring connections of the lens socket on the camera

Make sure that there are no dip switches for the camera that need setting.

Check the camera settings again.

[mikeald]

thank you for your constructive advice, I will re post tomorrow with the technical data.

4 now,

mike