Nodal-point info for canon lenses?

[bombo]

Hi,

Does anyohne know if there exist tables or so, showing the nodal-distances for canon zoomlenses? This is important info for pano's.

I have :
canon 17- 40 L ; 24 - 105 L and 70-200 L all f4

Greetings,
Bombo

[sk66]

Don't think there's a table or anything, But it's easy to find.

Here's a tutorial using pes dispensers, but two of anything in a line will work.

[Doug Pardee]

Originally Posted by bombo

canon 17- 40 L ; 24 - 105 L and 70-200 L all f4

The 24-105 and 70-200 are reported to experience significant differences in the location of the entrance pupil (sometimes incorrectly called "nodal point") at different focal lengths.

The 17-40 is reported to have a fairly stable entrance pupil location.

You can make an "eyeball" estimate of the entrance pupil location by looking in the front of the lens as you operate the DoF Preview button at a relatively high f-number. The location where the diaphragm appears to be is the entrance pupil.

[inkista]

Entrance Pupil Database - PanoTools.org Wiki

is always the first place to check, but since it's built by people like me who shoot mostly cubics with wide angle, I doubt either of those lenses is on there. As Doug says, chances are the no-parallax point is going to move about when you change focal lengths. Hell, it changes with my 8mm fisheye depending on the degree of rotation (I kid you not).

And no, the entrance pupil point may not necessarily be your no-parallax point, either. (sigh).

Best bet, really, is to test for yourself. Just google "how to find the nodal point" (I know, Doug, I know, but it's become the accepted terminology), and you'll find about a gazillion tutorials (I like this one), that essentially boil down to, make sure you've mounted on your panohead properly with the lens centered laterally over your pano head. Choose two vertical targets. Rotate. If the two targets have "moved" relative to each other, adjust for back/forth. Try again. Repeat until you've found it.

The thing is, if you're shooting landscapes outside, chances are good you don't need to be that exact about the no-parallax point and handholding will work just fine. It's only if you're shooting small enclosed spaces with objects near the camera that it gets critical. The farther away your subject is, the less chance you have of introducing parallax error that will prevent stitching.