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This is the place for Gigapan.com members to offer peer-to-peer support for exchanging tips, ideas, comments, etc.

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Forums » General Gigapanning » Finding Nodal Point in Canon 100-400mm

 
Finding Nodal Point in Canon 100-400mm
Fred Jones Fred Jones
Total Posts: 5

Hi there!
I’m newby in this of Gigapans, so I’m having some doubts about this.

First of all I want to know how to figure it out the Nodal Point with a Gigapan Epic Pro, Canon T3i and Canon 100-400 mm?

I know that it’ll change while I change the zoom.

Thanks in advance, I hope your answer!

Evan Matwijejko Evan Matwijejko
Total Posts: 1

This video is pretty good at explaining how to do it your self.

https://www.youtube.com/watch?v=zEgLgReARxs

Its pretty simple hope that helps.

Aloysious A Gruntpuddock Aloysious A Gru...
Total Posts: 29

That is the way I like to do it, very simple. You can always mark the slide (paper strip?) when you have found the correct point for a particular zoom setting so that you can go straight there in future.
Can give surprising results – my Fuji S95900 ended up in front of the pivot at max zoom!

Charles Davis Charles Davis
Total Posts: 15

That video is terrible! Over 11 minutes to explain and show how to do something simple [he was more interested in impressing than w/ actually helping viewers do it, IMO].

There are also many errors in this thread. The first is the name, “nodal-point”, which is a misnomer. The correct term is “entrance pupil”…it’s just the place where the incoming light rays appear to converge as they come into a lens.

One very simple way to locate this “pupil” is to simply look into a lens [preferably w/ the iris/diaphram stopped down]. You will see the opening in the iris. You can judge where it is located [since most of us have two eyes, we perceive depth]. Just move the camera until the entrance pupil looks like it is centered on the rotational axis of the GigaPan. For all work where the subject is at a distance, this is adequately accurate.

If you have objects in your images that are close to the camera [less than about 30 feet], you may need to be more accurate. Here is a very simple process that accurately locates the entrance pupil:

http://www.1derful.info/Tools/PanoHead/LensNode…

Modern lenses can be strange. The exit pupil can be in front of the entrance pupil. The entrance pupil can be behind the lens and/or camera. Don’t let that distract you. Just put the entrance pupil near the two axes of rotation of the GigaPan and you’ll be OK.

Mosley Hardy Mosley Hardy
Total Posts: 141

Try this video, which explains the same method that Gigapan recommends:

https://www.youtube.com/watch?v=3JkbZ1KehNo

Start at 3:31

bkaylor bkaylor
Total Posts: 29

I have your points for the Canon EF 100-400mm f4.5-5.6L IS USM lens.

I used a T2i body, but since the flange to sensor distance is 44mm for all Canon EF mounts this should apply to any Canon DSLR.

Charles, I tried the paper method. The minimum focal distance on a 100-400 is 1.8m, so I couldn’t even see the paper before it was several feet away, and if you’ve ever tried looking down a 400mm lens to guess at the entrance pupil, it’s like looking down a well.

Assuming you use the mount ring that comes with the 100-400:

400mm:
Bad news, visible parallax but the camera needed to move forward beyond what the gigapan platform would allow. Slide the mounting platform as far forward as it will go and pray to the stitching gods.

200/300mm:
Between 200-300mm there was no obvious parallax with the platform all the way forward at “0”.

100mm:
Moving the mounting platform back to “60” appeared to give good results examined at 10x zoom on Live View.

Vertical Height:
Adjust the vertical tabs so the arrows are halfway between the upper and lower curvers of the lens barrel, I eye-balled this at about “65” on the Epic Pro scale.

Conclusion:
Unless you are shooting shorter than 200mm, you can leave the mounting plate all the way forward at “0”. If you need to shoot with foreground objects, stick to 300 or less.

These are my own observations, and I’m happy to share my testing method if anyone wants to check my numbers.

bkaylor

lelapinblanc lelapinblanc
Total Posts: 3

Here is how I set the entrance pubil/nodal point (whatever you want to call it) of a Canon EF 100-400mm on the Gigapan Epic Pro with a Canon Rebel t4i.

First, I found the nodal point when the lens is at 400mm zoom is behind the camera body just maybe a bit less than an inch from the back of the camera body.

Well, you can’t set that up with the normal configuration of the Gigapan Epic Pro. So, I took the slide off, turned it around, and put it back on, now the camera mount is at the front of the Gigapan not the back. Then I turned the mount around on the lens and mounted the lens and camera back on the Gigapan. After that I moved the slide forward until end of the slide was about 1/4 inch past the end of the clamp. That’s a bit convoluted to describe so here is a picture of the setup and the left/right shots of a distant light and the aluminum bar of the window:
http://i45.tinypic.com/dxe82e.jpg

I hope the motor can handle all this weight forward of the axis of rotation.

lelapinblanc


Forums» General Gigapanning » Finding Nodal Point in Canon 100-400mm