Nodal Point of DVX100A

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Eric01

New member
Hey all,

I'm setting up the DVX to work with an InnerSense system and we're trying to find out the nodal point of the camera.

The info has been difficult to find on the net. Anyone know?

Thanks,
Eric
 
You might want to fire this question to someone over at seriousmagic.com (they make DV Rack) as I am certain that they would know the answer right off the top of their head. If not, you could use a protocol analyzer to interagate the camera directly.
 
Eric,

I am not familiar with the system, but is the idea that you wish to pivot the camera on the nodal point of the zoom lens?

If so the problem is that the nodal point location is different for every focal length (that is is will change as you zoom the lens).

By definition the focal length of the lens is the distance from the nodal point to the image at inifinity. Therefore if you go forward toward the front of the lens a distance equal to the focal length from the image plane you will be at the nodal point.

Because the glass in the beamsplitter affects the image location, for these purposes it is not literally at the green channel chip (straight thru ) which is further back by approx 1/3 the thickness of the beamsplitter than the actual "in air" image location from which you need to measure.

My advice is to make an educated guess and adjust by watching a monitor until you are close enough, but once again, this will change with the focal length.

Bill Turner
Schneider Optics
Century Division
 
Now that I rethink your question, I believe that you are asking about the optical properties and not the electrical characteristics of the 1394 interface, so ignore my comment about asking seriousmagic. Being an EE, I always see things in those light first.
 
if you have a tripod with tha right head for finding nodal point, there is a very easy way to find it..

just put a pipe on top of the table, put the camera in a such position where you can see trough the pipe lets one feet long and 1' in diameter, then start to tilt and pan the camera and check if you can still see trough the pipe, if you can't, move back or forward the camera on your head system until you see trough the pipe in any position when tiltiong or panning, and that is your nodal point. Of course you don't touch the zoom after you find the nodal point!!!! if you change the zoom you can start the operation again.


Mihnea de vries
 
Eric01 said:
Hey all,

I'm setting up the DVX to work with an InnerSense system and we're trying to find out the nodal point of the camera.

The info has been difficult to find on the net. Anyone know?

Thanks,
Eric
Click to expand...
:thumbsup: :engel017:
The great answers you have recieved here provide me WITH AN EDUCATION ON NODAL POINT .
HOWEVER ONE MORE SMALL AND USEFULL TRICK
In cinematography we used nodal point only when we were achieving or trying to achieve a pan along a curved or flatt matt painting of a landscape ,

So my point .
To check achievement of all the above data RESULTING IN A ASSUMED NODAL POINT
JUST set up a small or large magazine layout of a landscape ..Natial Geo or something ... and pan along and see it
the
subject has the look on video of "panning along a" real" landscape '
instead of the feeling that a panel of pictures is curving towards or away from you.
I think this simple test may help you to see if you realy did find the nodal point
It is all about getting results using technology to do that IMHO , SO Try it !!
Another suggestion is to read some data on line regarding Nodal point and panning matt paintings . I think some former guys at ILM including Craig Barron are the vetrans on this subject .Also artical by Dennis Murine of ILM FAME .
Good Luck
Bruce
 
Thanks guys,

I guess specifically what I need to know upon further evalution of this InterSense test is where the CCD is on the camera. In other words, how far back is it from the front of the lens? Info on this seems practically non-existent.

-Eric
 
The nodal point used to be indicated on video camera's by a little line or marking, barely visible. As far as I can tell, the DVX has no such marking, though the Sony VX1000 did.
 
Your looking for the focal plane, not the nodal point, if you want to know where the CCD is located.
A focus chart listing indicates it's at the back end of the onboard light mount.
 
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