How many nodal point with a zoom?

For shooting panoramas, how many non-parallax points do you determine for your 24-105, for example?

I'll plead ignorance, but ask the question: do nodal points vary with the focal length? In other words, is the question about the particular lens, or should it be about the focal length used?

tonylong wrote in post #14522949
I'll plead ignorance, but ask the question: do nodal points vary with the focal length? In other words, is the question about the particular lens, or should it be about the focal length used?

Nodal points do vary with focal length. One reviewer said he uses three points on a zoom lens: the minimum and maximum zoom FL's, and one in between. I wonder, in actual practice, if anyone uses more?

A great tutorial on how to find the no-parallax point of you camera/lens combo.

http://www.johnhpanos.​com/epcalib.htm

tonylong wrote in post #14522949
I'll plead ignorance, but ask the question: do nodal points vary with the focal length? In other words, is the question about the particular lens, or should it be about the focal length used?

tony, they vary, but not by much. here's how to find them

http://reallyrightstuf​f.com/WebsiteInfo.aspx​?fc=85

I found this site with dimensions http://wiki.panotools.​org/Entrance_Pupil_Dat​abase but it doesn't list the 24-105.

Does anyone know the dimension for the 24-105 at 24mm? I know there are guides on how to find it but It would save time if someone had already calculated the entrance pupil dimension

Even a zoom lens has TWO nodal points, the front nodal point and the rear nodal point. It is the LOCATION of the nodal point which varies based upon the FL setting of the zoom lens, so it affects multi-shot composite panorama photos. The 24-105mm zoom therefore has 81 different optical node or entrance pupil locations -- you need to ask yourself is how few of these 81 different FL positions you really need to bother keeping separate track of their locations, for the purposes of panorama shooting.

Wilt as the zoom function of the lens is analog surly there are an infinite number of node positions. After all there is no limit to the actual focal length you can set on the lens, between the minimum and maximum values. I guess the question then becomes are you a scientist or an engineer. The scientists answer is above. For the engineer the real question is how accurately can you either measure the location of a nodal point in the real world, or how accurately can you actually measure the set focal length and other parameters necessary to calculate the position of the nodal point, and of course to then set the system up so that rotation is around that nodal point. The answers to these questions gives you the actual number of nodal point locations that you will actually need to worry about.

Personally when doing (very rarely) a pano, I try not to have much foreground detail, and use at least 50% overlap. It doesn't remove the parallax error, but it does help minimise it. Also the last couple of pano's that I did were spur of the moment and I did not have/could not use a tripod anyway.

Alan

Alan, no debate on the points you raised from me! Thinking as an engineer, the best approximation (without an EXIF reader in the field to look at the recorded FL) are the FL indicator marks on the zoom ring, so that should serve as a starting point for how many nodal locations to bother with. That's just me.

The anally compulsive could bring a laptop to look at the EXIF to find out the FL to the nearest integer value, in which case we're back to 81 locations!

With today's software (CS6 or Nik) you can shoot panoramas handheld and it will merge them just fine.

I'm as persnickety as the next guy when it comes to technical details, but... really?

Curtis N wrote in post #15000517
With today's software (CS6 or Nik) you can shoot panoramas handheld and it will merge them just fine.

I'm as persnickety as the next guy when it comes to technical details, but... really?

My thoughts exactly. Just level your tripod, mount your camera with an L plate, and you are good to go.

The nodal point precision might have been important in the past before auto stitching existed, but not any more. I couldn't care less about setting up the nodal point, because all my panoramas comes out perfect anyway.

Osiriz wrote in post #15165342
My thoughts exactly. Just level your tripod, mount your camera with an L plate, and you are good to go.

The nodal point precision might have been important in the past before auto stitching existed, but not any more. I couldn't care less about setting up the nodal point, because all my panoramas comes out perfect anyway.

This is only applicable when there is nothing detailed or close in the foreground. Try doing a panorama inside a room in your house without setting it up nodally and you will have all sorts of issues stitching it together due to parallax