Least Parallax Point of PL lenses (VR shooting) info

[PatrickFaith]

There a bunch of information on finding the least parallax point for stills photography, but I haven't found much for PL lenses and cinematography. Also most of the info out there is for still photography lenses, I haven't found a single spec for cinema lenses ( I btw try not to use still shots in VR composites).

[background info - the least parralax point, which is sometimes called a entrance pupil, is a point where when the camera pivots, lines in the foreground and background do no shift]

My rigs are fairly large, so would be nice to know the exact depth of the LPP for master primes. Also, I have no idea, but I am hoping that master prime anamorphics don't have a spread characteristic on the LPP (like fisheye lenses do).

I'm basically only doing this for two lenses, 35 mm MP anamorphic and a 21 mm CP2. I'm thinking 21mm is the smallest I should go without getting distortions, but I have a lot of problematic shots with things like moving tree's and bushes in the wind (getting complex stitching on a moving branch just takes me way too much time in nuke).

Also just any helpful hints on VR cinematography are very welcome. If this is interest to anyone I'll post results.

 

[Mikael Lubtchansky]

master prime brochure has the entrance pupil info toward the end... not sure those are anamorphic tho... but the data is out there that's a necessity (altho it can be approximated by trial and error otherwise but can take some time and requires a good head with fine tuning...) :

http://www.zeiss.fr/content/dam/Pho...master_lenses/arri_brochure_master_primes.pdf



edit :

master anamorphic 35 : 179 mm from film plane

https://www.arri.com/camera/cine_lenses/prime_lenses/anamorphic/

 

[PatrickFaith]

master prime brochure has the entrance pupil info toward the end... not sure those are anamorphic tho... but the data is out there that's a necessity (altho it can be approximated by trial and error otherwise but can take some time and requires a good head with fine tuning...) :

http://www.zeiss.fr/content/dam/Pho...master_lenses/arri_brochure_master_primes.pdf



edit :

master anamorphic 35 : 179 mm from film plane

https://www.arri.com/camera/cine_lenses/prime_lenses/anamorphic/

Awesome, so from the weird circle mark on the side of the red, i measure 179 mm to the front. 17 cm is pretty far out there, i wasnt expecting it that far out, i dont think i had enough ranger in my prevoius setup rails. the entrance pupil moves around a lot per lense, i will need to ponder that a bit (i thought rectalinear lenses had fixed mm point across different mm). also i noticed the point is different between the 18mm mp and the 35 mm mpa, which i wasnt expecting. thanks again for finding this, i had skipped over that column for some reason.

 

[Mikael Lubtchansky]

Yes the point position is very depent of the optical formulae of the lens itself so can vary greatly from lens to lens.
It requires a special plate usually to be able to rotate around it and is very useful for any stiching work as you get perfect match without any parallax while panning.

 

[Phil Holland]

Side note, but interesting one from my POV.

Long ago I starting building Sphercial HDRI rigs for on set HDR/VFX image based lighting purposes. The No Parallax Point is mostly known in the panoramic world as the Nodal Point, which isn't exactly ideal, but easy to remember. Entrance Pupil No Parallax Point Alignment is more like it, but meh. Details.

I was in my mid/early 20s when this was heavily going down for me and it also inspired a great deal of experimentation regarding motion picture camera movement.

If you're bored one weekend shoot something with a tilt and pan 4 different ways.

- Just set it up like you'd normally shoot it with your camera (ideally balanced on the fluid head)
- Shoot the same scene on the No Parallax Point
- Then one take positioned well forward from the NPP - like say 4 inches
- Then one take positioned well behind the NPP - try the same offset as above, but reversed

Playback all of those clips and checkout how that effects your camera POV's "character".

This certainly gets exciting on wides and teles and can produce a fairly unique character to the camera movement.

 

[PatrickFaith]

Yes the point position is very depent of the optical formulae of the lens itself so can vary greatly from lens to lens.
It requires a special plate usually to be able to rotate around it and is very useful for any stiching work as you get perfect match without any parallax while panning.

Thanks much for the info, I have one plate that has joy sticks, and another system that has full start/stop sync so I can get repeatable angles after moving the plate.

Side note, but interesting one from my POV.

Long ago I starting building Sphercial HDRI rigs for on set HDR/VFX image based lighting purposes. The No Parallax Point is mostly known in the panoramic world as the Nodal Point, which isn't exactly ideal, but easy to remember. Entrance Pupil No Parallax Point Alignment is more like it, but meh. Details.

I was in my mid/early 20s when this was heavily going down for me and it also inspired a great deal of experimentation regarding motion picture camera movement.

If you're bored one weekend shoot something with a tilt and pan 4 different ways.

- Just set it up like you'd normally shoot it with your camera (ideally balanced on the fluid head)
- Shoot the same scene on the No Parallax Point
- Then one take positioned well forward from the NPP - like say 4 inches
- Then one take positioned well behind the NPP - try the same offset as above, but reversed

Playback all of those clips and checkout how that effects your camera POV's "character".

This certainly gets exciting on wides and teles and can produce a fairly unique character to the camera movement.

I hadn't thought of it this way, but I had started noticing something interesting when I had mapped things spherically and was able to do quick pans. I will do a test exactly how you say, also since I map things spherically in nuke with depth, I can simulate this ... I need to ponder what that means from a story viewpoint. I had to do some of this on moving the virtual camera inside a spherical image, it was harder to detect then I'd though. My gutt feeling is it pulls the viewer in/out of a conversation: if the lens is forward from the nodal point it's like your "in/nosy" the persons space, if it's at the nodal point your emotionally neutral/floating from the conversation, if the nodal point is way to the rear it's like your "out/leaning away" emotionally from the conversation.

edit.

btw in my testing I find it amazing how far out the nodal point is from the camera body for master prime anamorphics. I needed to reconfigure my 19mm rail system to push the camera that far off axis, also it takes a 19 mm rail system for that type of extensions. I doubt anyone has done clean nodal spherical maps with MPA's, but I think they have a amazing feel. Rather then full spherical with MPA's I will doing a 360 cylinder, makes more sense for my story.

 

[PatrickFaith]

Here's btw a shot of my vr camera rig. I just reset it up with the weapon.