Hello Guest it is July 20, 2019, 11:15:52 PM

Author Topic: centering cross hairs on video camera  (Read 4064 times)

0 Members and 1 Guest are viewing this topic.

Offline jimpinder

*
  •  1,233 1,233
  • Wakefield, West Yorks, UK
    • View Profile
centering cross hairs on video camera
« on: November 20, 2008, 06:05:27 AM »
I dismantled my PC theatre orgen and moved the PC to the workshop. Took the laptop off the machine and substituted a desktop (with 1.5 gig of ram ). Tried the video camera and lo and behold, it worked !! (something it would not do on the laptop)

I spent this morning machining a holder for the camera, then mounted it in the milling spindle. I had drilled a target hole with a small drill, and the cross hairs on the video feature do not line up with the hole. If I turn the spindle by hand, the picture turns around the target hole, showing my fixture is accurate,

Therefore, it would seem, I need to move the crosshairs, to coincide with the target - how do I do it, please, I can't find any instruction(s)

Not me driving the engine - I'm better looking.

Offline RICH

*
  • *
  •  7,342 7,342
    • View Profile
Re: centering cross hairs on video camera
« Reply #1 on: November 20, 2008, 07:17:20 AM »
Hi Jimpinder,
I don't know if you can electronicaly adjust the crosshair (been a while since i fooled with it ).
I would have added adjusting screws ,three of them, so you could adjust the crosshair to the viewed target.
Adjust using the screws till on target,rotate and repeat until croshair dosn't move off target. If the cosshair dosn't
stay on target then your seeing the spindle runout.  But that would only be good for that particular distance.Could be all wet here.

A mirror may make a better target, as the reflection from the mirror back to the camera could be infinity and adjustment then would be more accurately centered. I have to think more about that one as an image is not
being projected from the camera. hey it's early in my neck of the woods. :)
RICH

Offline jimpinder

*
  •  1,233 1,233
  • Wakefield, West Yorks, UK
    • View Profile
Re: centering cross hairs on video camera
« Reply #2 on: November 20, 2008, 10:23:14 AM »
Rich -
 Yes - I've thought about this - AND - as far as I see it, the problem in machining the housing is that you could be off centre with it. My housing fits in the milling/drill chuck. So > I put a small drill in first, and drilled a target hole in the workpiece, then swapped the drill for the camera.

The picture I get is the target hole, but the cross hairs on the screen are  off to the left  (not a long way - but say 5mm - it is a bit hard to tell becasue I don't know the magnification).

If I spin the chuck manually with the camera in, the picture turns - not about the cross hairs - but about my target hole. Therefore my camera seems to be aligned with the spindle, but the cross hairs are not. If I move the camera, it won't be aligned with the spindle, it seems to me that it is the cross hairs I need to move - but how.

Jim

Not me driving the engine - I'm better looking.
Re: centering cross hairs on video camera
« Reply #3 on: November 20, 2008, 11:02:54 AM »
Rich -
 Yes - I've thought about this - AND - as far as I see it, the problem in machining the housing is that you could be off centre with it. My housing fits in the milling/drill chuck. So > I put a small drill in first, and drilled a target hole in the workpiece, then swapped the drill for the camera.

The picture I get is the target hole, but the cross hairs on the screen are  off to the left  (not a long way - but say 5mm - it is a bit hard to tell becasue I don't know the magnification).

If I spin the chuck manually with the camera in, the picture turns - not about the cross hairs - but about my target hole. Therefore my camera seems to be aligned with the spindle, but the cross hairs are not. If I move the camera, it won't be aligned with the spindle, it seems to me that it is the cross hairs I need to move - but how.

Jim



Jim,

The problem *is* absolutely that the camera is off-center relative to the spindle.  The fact that the cross-hairs rotate around the actual center point is proof of this.  The solution is as someone pointed out - you need to add three adjusting screws, that will allow you to move the camera to where the cross-hairs are aligned with the true center.  In fact, you need two sets of these screws, so you can not only get the cross-hairs centered over the spindle center, but also get the axis of the camera perfectly aligned with the axis of the spindle.  Otherwise, when you get the cross hairs centered, then move the head up or down, the cross-hairs will move off-center.  If you try this right now, I bet you'll find the distance by which the cross-hairs are off is a function of the head height, which, proves the camera axis is not aligned parallel to the spindle axis.

Regards,
Ray L.
Regards,
Ray L.

Offline jimpinder

*
  •  1,233 1,233
  • Wakefield, West Yorks, UK
    • View Profile
Re: centering cross hairs on video camera
« Reply #4 on: November 20, 2008, 02:39:23 PM »
Yes - thanks Ray - now you have said that, I've had another think   ;D ;D
Not me driving the engine - I'm better looking.

Offline zarzul

*
  •  317 317
  • Wyoming, USA
    • View Profile
Re: centering cross hairs on video camera
« Reply #5 on: November 20, 2008, 03:01:32 PM »
If you need a idea on how to make it adjustable check out the bargain basement under my machining camera. 

Then to calibrate it.

What you do is make a target mark, (i like to scribe a X on some scrap)  position your camera by moving the table so the crosshairs are over the target mark.

Then turn the spindle 180.  You will probably find the scribe mark moves off from the crosshairs.

Now adjust your camera mount adjusting screws so the crosshairs move 1/2 way back to the mark.

Then move your table again until you line up the mark under the crosshairs.  repeat these steps until the mark doesn't move from the crosshairs, it just rotates directly under it.

Offline jimpinder

*
  •  1,233 1,233
  • Wakefield, West Yorks, UK
    • View Profile
Re: centering cross hairs on video camera
« Reply #6 on: November 23, 2008, 04:07:19 AM »
Thanks gents, I've got it all sorted now. As Ray said, it was off so I moved it by hand until the crosshairs lined up with my target, and it was spot on, even when turned round as Zarzul says.

My vertical movement is limited (a milling attachment on a lathe), so I simply mixed some araldite, and glued the camera into the housing - (adjusting for centre before it set) - with the camera at it's highest point (about 2.5 inches).

It certainly makes it easy (and much quicker) to centre the spindle at the start (0,0) position of programs - put in the camera, jog to the start position, zero the DROs and away we go.

Thanks for the help - Jim.
Not me driving the engine - I'm better looking.