21 - Nodal Offsets¶

▶ 21 - Nodal Offsets — Watch on YouTube

[Music] [Music] when we were talking about lens setups when we were talking about lens setups when we were talking about lens setups on the bolt we mentioned that the nodal on the bolt we mentioned that the nodal on the bolt we mentioned that the nodal offsets on the Milo were different offsets on the Milo were different offsets on the Milo were different differently orientated due to the rear differently orientated due to the rear differently orientated due to the rear mounted camera mount rather than the top mounted camera mount rather than the top mounted camera mount rather than the top mounted camera mount this means that my mounted camera mount this means that my mounted camera mount this means that my nodal offsets for buy lenses when I nodal offsets for buy lenses when I nodal offsets for buy lenses when I mounted on the Milo mounted on the Milo mounted on the Milo are X that way why this way and this way are X that way why this way and this way are X that way why this way and this way the modal offsets if one is using the modal offsets if one is using the modal offsets if one is using relatively simple moves are not that relatively simple moves are not that relatively simple moves are not that important but when one comes to do important but when one comes to do important but when one comes to do precision work or transfer to CGI or any precision work or transfer to CGI or any precision work or transfer to CGI or any export of the data of the movement then export of the data of the movement then export of the data of the movement then you need accurate setup of your lens and you need accurate setup of your lens and you need accurate setup of your lens and your camera this involves not only your camera this involves not only your camera this involves not only getting the nodal point distance from getting the nodal point distance from getting the nodal point distance from the center of the pan and tilt correct the center of the pan and tilt correct the center of the pan and tilt correct but also where the measure hook is where but also where the measure hook is where but also where the measure hook is where the camera itself is actually mounted the camera itself is actually mounted the camera itself is actually mounted and other such measurements all those and other such measurements all those and other such measurements all those are part of the standard then setup when are part of the standard then setup when are part of the standard then setup when we have done these measurements of the we have done these measurements of the we have done these measurements of the modal offset the one uncertainty we have modal offset the one uncertainty we have modal offset the one uncertainty we have is where exactly is the modal point is where exactly is the modal point is where exactly is the modal point within the lens and there is a setup we within the lens and there is a setup we within the lens and there is a setup we can do which we're going to do in a can do which we're going to do in a can do which we're going to do in a moment to prove exactly where that nodal moment to prove exactly where that nodal moment to prove exactly where that nodal point is and this uses the capability of point is and this uses the capability of point is and this uses the capability of panning winning Cartesians in order to panning winning Cartesians in order to panning winning Cartesians in order to use parallax effects to align the modal use parallax effects to align the modal use parallax effects to align the modal point exactly point exactly in order to verify that our nodal point in order to verify that our nodal point measurement is absolutely correct we're measurement is absolutely correct we're measurement is absolutely correct we're going to look at our lens setup this going to look at our lens setup this going to look at our lens setup this particular lens is the arrow macro 40 particular lens is the arrow macro 40 particular lens is the arrow macro 40 millimeters and we have a figure there millimeters and we have a figure there millimeters and we have a figure there 4x nodal offset to illustrate this I'm 4x nodal offset to illustrate this I'm 4x nodal offset to illustrate this I'm first of all gonna go and set that to 5 first of all gonna go and set that to 5 first of all gonna go and set that to 5 centimeters I know this is wrong but it centimeters I know this is wrong but it centimeters I know this is wrong but it will illustrate what I'm trying to show will illustrate what I'm trying to show will illustrate what I'm trying to show you in order to be able to correctly set you in order to be able to correctly set you in order to be able to correctly set this up so we'll apply that I'm now this up so we'll apply that I'm now this up so we'll apply that I'm now going to go to this position and this going to go to this position and this going to go to this position and this position contains two pencils very position contains two pencils very position contains two pencils very carefully lined up on axis of this carefully lined up on axis of this carefully lined up on axis of this camera we are focused at a point midway camera we are focused at a point midway camera we are focused at a point midway between the two so we have reasonably between the two so we have reasonably between the two so we have reasonably good focus within the depth of field of good focus within the depth of field of good focus within the depth of field of the lens we are using and from this the lens we are using and from this the lens we are using and from this position we're going to go into position we're going to go into position we're going to go into Cartesian view and we're going to use Cartesian view and we're going to use Cartesian view and we're going to use Pam as we pan we are panning modally Pam as we pan we are panning modally Pam as we pan we are panning modally because we are in Cartesians and if our because we are in Cartesians and if our because we are in Cartesians and if our nodal point is incorrect the pencils nodal point is incorrect the pencils nodal point is incorrect the pencils will shift with respect to each other will shift with respect to each other will shift with respect to each other on screen if you can see those pencils there if you can see those pencils there they've shifted apart on screen on that they've shifted apart on screen on that they've shifted apart on screen on that side and then I go on to the other side they've shifted apart in the other they've shifted apart in the other direction this illustrates that the direction this illustrates that the direction this illustrates that the nodal point is incorrect because we are nodal point is incorrect because we are nodal point is incorrect because we are panning around a point that is not the panning around a point that is not the panning around a point that is not the nodal point I'm now going to turn off my nodal point I'm now going to turn off my nodal point I'm now going to turn off my Cartesians I'm going to go back to my Cartesians I'm going to go back to my Cartesians I'm going to go back to my first position and I'm going to set my X first position and I'm going to set my X first position and I'm going to set my X nodal offset to something but the other nodal offset to something but the other nodal offset to something but the other extreme going back into my Cartesian extreme going back into my Cartesian extreme going back into my Cartesian view and panning again I find now my view and panning again I find now my view and panning again I find now my pencils separate but they do show in a pencils separate but they do show in a pencils separate but they do show in a different sequence here my front pencil different sequence here my front pencil different sequence here my front pencil is moving less my rear pencil is moving is moving less my rear pencil is moving is moving less my rear pencil is moving more this means my nodal point is more this means my nodal point is more this means my nodal point is further away from the film plane in this further away from the film plane in this further away from the film plane in this way I can see what is wrong with my way I can see what is wrong with my way I can see what is wrong with my modal point and I can adjust it modal point and I can adjust it modal point and I can adjust it accordingly accordingly accordingly so I'm out of Cartesian view go to my so I'm out of Cartesian view go to my so I'm out of Cartesian view go to my position one let's put in a figure that position one let's put in a figure that position one let's put in a figure that I know is correct which is zero point 1 I know is correct which is zero point 1 I know is correct which is zero point 1 1 so that is 11 centimeters forward of 1 so that is 11 centimeters forward of 1 so that is 11 centimeters forward of the intersection of the pan and tilt I'm the intersection of the pan and tilt I'm the intersection of the pan and tilt I'm going to apply that go into Cartesian going to apply that go into Cartesian going to apply that go into Cartesian view again and pan and my pencils stay view again and pan and my pencils stay view again and pan and my pencils stay perfectly lined up as I move across the perfectly lined up as I move across the perfectly lined up as I move across the screen in this way I can check and by screen in this way I can check and by screen in this way I can check and by iteration find the exact nodal point for iteration find the exact nodal point for iteration find the exact nodal point for this camera position having set my modal this camera position having set my modal this camera position having set my modal offset I can also measure again my offset I can also measure again my offset I can also measure again my measure optical offset measure optical offset measure optical offset and if necessary my measure offset in and if necessary my measure offset in and if necessary my measure offset in order to verify that the camera is order to verify that the camera is order to verify that the camera is actually in that position before doing actually in that position before doing actually in that position before doing accurate filming this has been a Mark accurate filming this has been a Mark accurate filming this has been a Mark Roberts motion control training video Roberts motion control training video Roberts motion control training video thank you for watching thank you for watching thank you for watching [Music]