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### AuthorTopic: "Nodal Points" and pano's  (Read 7865 times)

#### astanley

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##### "Nodal Points" and pano's
« on: March 12, 2008, 01:00:02 PM »

A quick, if dumb question.

Within a given manufacturer, and a given prime (not zoom) lens, will the nodal point be within a very tight tolerance on all lenses, on a given body?

Translation, couldn't I just go out, measure the nodal point for each prime lens, and publish it -- and subsequently save most photographers oodles of time trying to figure out the exact nodal point of each lens all over again?

Cheers,

-Andrew
thinks he's missing something here
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#### Thomas Krüger

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##### "Nodal Points" and pano's
« Reply #1 on: March 12, 2008, 01:23:15 PM »

http://www.swissarmyfork.com/lens_table_1.htm
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#### DarkPenguin

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##### "Nodal Points" and pano's
« Reply #2 on: March 12, 2008, 01:26:32 PM »

Feel free to do a canon lens one.

You should also be able to do a zoom one but you need to do it at different focal lengths.
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#### 01af

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##### "Nodal Points" and pano's
« Reply #3 on: March 12, 2008, 02:09:31 PM »

Quote
Within a given manufacturer, and a given prime (not zoom) lens, will the nodal point be within a very tight tolerance on all lenses, on a given body?[a href=\"index.php?act=findpost&pid=180883\"][{POST_SNAPBACK}][/a]
Yes, it will. On all bodies. However that's true only for one single lens model at one focusing distance.

Quote
... couldn't I just go out, measure the nodal point for each prime lens, and publish it---and subsequently save most photographers oodles of time trying to figure out the exact nodal point of each lens all over again?[a href=\"index.php?act=findpost&pid=180883\"][{POST_SNAPBACK}][/a]
You could.

However no-one would care. Because nobody would be interested in their lenses' nodal points. [EDIT: ... with the possible exception of some hard-core macro photographers.]

-- Olaf
« Last Edit: March 12, 2008, 02:15:29 PM by 01af »
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#### SeanBK

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##### "Nodal Points" and pano's
« Reply #4 on: March 12, 2008, 02:14:29 PM »

Quote
You could.

However no-one would care. Because nobody would be interested in their lenses' nodal points.

-- Olaf
[a href=\"index.php?act=findpost&pid=180904\"][{POST_SNAPBACK}][/a]

I hate to disagree, but I would like to know the nodal points of my Nikon 17-55 & 80-400 at various settings.   That would help for taking panos.
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#### 01af

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##### "Nodal Points" and pano's
« Reply #5 on: March 12, 2008, 02:18:43 PM »

Quote
... I would like to know the nodal points [...] That would help for taking panos.[a href=\"index.php?act=findpost&pid=180905\"][{POST_SNAPBACK}][/a]
No, it wouldn't. Better check out your lenses' entrance pupils.

-- Olaf
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#### feppe

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##### "Nodal Points" and pano's
« Reply #6 on: March 12, 2008, 02:37:51 PM »

Rotating around the nodal point is completely pointless endeavor for many stitched panoramas. It's only necessary if you have something in the foreground.

#### AJSJones

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##### "Nodal Points" and pano's
« Reply #7 on: March 12, 2008, 03:30:13 PM »

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No, it wouldn't. Better check out your lenses' entrance pupils.

-- Olaf
[a href=\"index.php?act=findpost&pid=180907\"][{POST_SNAPBACK}][/a]

Olaf's point being, of course, that "nodal point" is not the correct term for what the rotation axis in a stitched panorama is called

feppe - I think quite a large number of panorama shooters like to have things close enough in the foreground where parallax and entrance pupils are worth accounting for...
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#### Paul Kay

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##### "Nodal Points" and pano's
« Reply #8 on: March 13, 2008, 04:52:56 AM »

Knowing the positions of the entrance pupils of wide angle lenses is also of use to underwater photographers as dome ports need to be aligned so that the centre of the sphere of which the dome port is a part is aligned on the entrance pupil!

But to answer your question, then yes it will be in the same position for any given fixed focal length lens but will shift during focus - although I doubt that this will matter in practice until you are working at relatively close . Certainly in underwater photography, a few mm discrepancy in lens/port positioning does not seem to cause 'significant' image deterioration and I suspect that this tolerance carries through to many but the most demanding applications.
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#### Panopeeper

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##### "Nodal Points" and pano's
« Reply #9 on: March 13, 2008, 03:25:12 PM »

Quote
Within a given manufacturer, and a given prime (not zoom) lens, will the nodal point be within a very tight tolerance on all lenses, on a given body?

What you are referring to is the front entrance pupil. The location varies between lenses.

Furthermore, the location with *some* lenses depends on the focusing distance as well; this is interesting only when shooting indoor, i.e. when high accuracy is required.

You can verify this easily: mount the lens, stop it down, look "into the camera" through the lens and actuate the aperture. The entrance pupil is there, where you *see* the aperture (note: this is not the physical location of the aperture). Now move the focusing ring and observe if the aperture's location changes.

Quote
couldn't I just go out, measure the nodal point for each prime lens, and publish it -- and subsequently save most photographers oodles of time trying to figure out the exact nodal point of each lens all over again?

Some of us are sharing such information. Which camera and lenses do you have?

Btw, with which accuracy do you think to be able to adjust the camera on the bracket?
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Gabor

#### BernardLanguillier

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##### "Nodal Points" and pano's
« Reply #10 on: March 14, 2008, 09:14:18 AM »

Quote
A quick, if dumb question.

Within a given manufacturer, and a given prime (not zoom) lens, will the nodal point be within a very tight tolerance on all lenses, on a given body?
[a href=\"index.php?act=findpost&pid=180883\"][{POST_SNAPBACK}][/a]

Yes, it mostly will,  but then you have the influence of the position of the moon relative to saturn that is still the subject of heated debates.

Cheers,
Bernard
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A few images online here!

#### astanley

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##### "Nodal Points" and pano's
« Reply #11 on: March 17, 2008, 11:18:56 AM »

Quote
Some of us are sharing such information. Which camera and lenses do you have?

Btw, with which accuracy do you think to be able to adjust the camera on the bracket?
[a href=\"index.php?act=findpost&pid=181170\"][{POST_SNAPBACK}][/a]

First, thanks to all for the clarification of "entrance pupil" versus nodal point.

I'm shooting Canon bodies: EOS-1(V, Ds Mk II) and EOS-5d.  Lenses I'll look to do multi-row panos are the 24/1.4L, 50/1.4, 85/1.8 (for multirows of smaller subjects)

My guess is I can nail it within a mm one way or the other.  While the RRS head is very nice and well designed, I don't think expecting anything less than a mm each way is reasonable...

Cheers,

-Andrew
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#### Panopeeper

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##### "Nodal Points" and pano's
« Reply #12 on: March 17, 2008, 03:32:25 PM »

Quote
Lenses I'll look to do multi-row panos are the 24/1.4L, 50/1.4, 85/1.8

I don't have the 24mm, and I have not used the 85mm with the bracket (my own making).

The 50mm f/1.4 does change the entrance pupil location with focusing.

Measured from the mounting flange (which sits on the body) forward:

10mm @ infinity,

11mm @ 4m

Add to this the distance from the mounting flange on the camera to the center of the screw hole, then you get the distance the camera has to be set back from the center of swiweling (i.e. the center of the tripod column, if there is one).

Quote
My guess is I can nail it within a mm one way or the other

That's my best one too. At longer focal lengths this is a non-issue., for example with the 200mm f/2.8L, three mm more or less does not make any difference. In fact, I am unable to find the location with a higher accuracy, for the difference in effect is practically none.

However, with the 24mm you have to be careful, particularly at close focusing if the location changes with the focusing distance. When measuring the EF-S 17-55mm f/2.8 IS, I looked at the test images in non-demosaiced format in order to verify the result looking single pixels.

Btw, one advise I often need to tell: one can find the approximate location already through the viewfinder, particularly if there is enough light to stop down the aperture and still see objects close and far good enough. However, when you think you found it, then you have to make a test shot and verify it, because *the position of your eye over the viewfinder influences, what you see*.
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Gabor
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