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Thread: Nodal Point of Sigma 8mm 1:3.5 EX DG Fisheye Lens

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André

Posts: 8
Location: Klerksdorp, South Africa
Registered: 21 Aug 2008
Nodal Point of Sigma 8mm 1:3.5 EX DG Fisheye Lens
Posted: 21 Aug 2008 at 15:52 GMT
Can somebody assist or help me on how to find the Nodal Point (Entrance Pupil) of my Sigma 8mm EX DG Fisheye Lens, please? Or maybe tell me where this point is on the lense? blush

The equipment that I use: Canon EOS 40D camera, Manfrotto 303PLUS pano head and Manfrotto 525MV tripod.

I will appreciate all your assistance regarding this very much.

Thank you.

André
acjoubert@koshcom.co.za
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Nick Fan
[NodalNinja]

Posts: 289
Location: Hong Kong
Registered: 26 May 2006
Re: Nodal Point of Sigma 8mm 1:3.5 EX DG Fisheye Lens
Posted: 21 Aug 2008 at 16:08 GMT
the nodal point is 90.5mm in front of the tripod socket on 40D.


nick
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André

Posts: 8
Location: Klerksdorp, South Africa
Registered: 21 Aug 2008
Re: Nodal Point of Sigma 8mm 1:3.5 EX DG Fisheye Lens
Posted: 21 Aug 2008 at 16:28 GMT
Hallo Nick

I appreciate your reply vey much but not sure what you meen. I'm still new in this and still a lot to learn so sorry for all this questions! blush

Is this point then 90.5mm from the front of the lens bacward which is the point that must be above the center of the tripod Nick?

If I am wrong, I have a picture that I have downloaded of the web which I can email to you on which you can make a line or point with MS Paint which will be very helpfull. If you can sent me blank email I will email it too you.

Thanks for your help Nick!

My email acjoubert@koshcom.co.za
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Nick Fan
[NodalNinja]

Posts: 289
Location: Hong Kong
Registered: 26 May 2006
Re: Nodal Point of Sigma 8mm 1:3.5 EX DG Fisheye Lens
Posted: 21 Aug 2008 at 16:43 GMT
measure from the tripod socket to the direction of the lens. the distance is about 90.5mm. Sorry I don't have photos, the figure is taken from here
nodalninja.com/nodal_ninja_3_camera_settings.html

nick
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André

Posts: 8
Location: Klerksdorp, South Africa
Registered: 21 Aug 2008
Re: Nodal Point of Sigma 8mm 1:3.5 EX DG Fisheye Lens
Posted: 21 Aug 2008 at 16:58 GMT
Thank you Nick. I have a look at the web site and it helped!

Thanks again and keep well! smile
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John Houghton

Posts: 2317
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
Re: Nodal Point of Sigma 8mm 1:3.5 EX DG Fisheye Lens
Posted: 21 Aug 2008 at 17:33 GMT
90.5mm should be fine for 4 shots around. This will minimise parallax at the horizontal level but not necessarily at the zenith and nadir, since the entrance pupil is not at a single point. See these links:

www.panoramas.dk/panorama/fisheye-NPP/parallax.ht...
www.johnhpanos.com/epcalib.htm
www.rosaurophotography.com/html/technical7.html

Also, since your head is not a spherical head, you should consider tilting the camera upwards by 7 degrees or so, to close the zenith hole that would otherwise occur.

John
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