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Samyang Fisheye parameters

PostPosted: Thu May 03, 2012 12:02 pm
by hermer-blr
I just bought a Samyang fisheye (Nikon AE version) and I would like which lens correction settingsI should use for it. Until now, with my wide angle lens, I had put every parameters to "automatic" and it worked fine !

PostPosted: Thu May 03, 2012 12:25 pm
by mediavets
As I recall this lens does not provide lens details in the EXIF?

If that's the case with the AE version then you need to specifiy a focal length of 9mm (people say that's best for this lens) and change the lens type to Fisheye and check the Crop circle.

PostPosted: Thu May 03, 2012 1:25 pm
by gkaefer
isnt it labeled with 8mm?
(I allways was satisfied using 8mm & fisheye & setting correct crop factor...)

and take care to set the NPP ... the golden ring.... 1mm or 2mm from golden ring in direction to the camera
you've to test the values for your camera&lens combo. even 2mm placed wrong and you get a lot of postproduction work to do to solve stitching errors.
Georg

PostPosted: Thu May 03, 2012 2:24 pm
by mediavets
gkaefer wrote:isnt it labeled with 8mm?
(I allways was satisfied using 8mm & fisheye & setting correct crop factor...)

Some of the branded clones are labelled 6.5mm and 7mm I believe.

I have read that PTGui users seem to thing that 9mm works best for them.

I don't think it matters so much with APP/APG because as I recall the focal elngth for FE lenses is just used a as 'guide' and the software computes a value for FE lenses.

PostPosted: Thu May 03, 2012 6:03 pm
by hermer-blr
Thanks for those answers. I note from your comments that 9 mm (while the lens is labelled 8 mm) may be worth testing..

But my question, in fact, was not this. In the APG settings, you have to define your lens CORRECTION settings. Until now, I set them to automatic and it worked fine with my wide angle lens.

What should I do with the SAMYANG fisheye, especially for the distortion model ? I think that keeping focal calculation and distortion calculation to automatic will be fine. Does that however make sense if distortion calculation is set to automatic to set up a specific distortion model ?

Reference: optimization tab - Lens distortion correction (focal calculation, distortion calculation, distortion model)

PostPosted: Thu May 03, 2012 7:14 pm
by gkaefer
hermer-blr wrote:Thanks for those answers. I note from your comments that 9 mm (while the lens is labelled 8 mm) may be worth testing..

But my question, in fact, was not this. In the APG settings, you have to define your lens CORRECTION settings. Until now, I set them to automatic and it worked fine with my wide angle lens.

What should I do with the SAMYANG fisheye, especially for the distortion model ? I think that keeping focal calculation and distortion calculation to automatic will be fine. Does that however make sense if distortion calculation is set to automatic to set up a specific distortion model ?

Reference: optimization tab - Lens distortion correction (focal calculation, distortion calculation, distortion model)

to be honest - I never cared - it allways worked with the default values - never used lens correction in APG with Samyang lenses (also not with the 85mm)
Georg

PostPosted: Thu May 03, 2012 10:14 pm
by Jeremiah
I have a samyang (branded rokinon) and a canon t2i. The defaults work fine.
The only thing I have to change is manually telling it that the images are fisheye since the lens doesn't talk to the camera.
I've mentioned my setup before (http://www.kolor.com/forum/p94459-2012-02-01-19-49-18#p94459), but since you have the AE version of the lens I expect that you will probably be able to stitch without changing anything at all from the defaults.

PostPosted: Sat May 05, 2012 10:18 am
by hermer-blr
Thanks for support.


I can confirm that having the AE version of the lens the fisheye is automatically recognized by APG, based on....

...the fact that I have incorporated the lens in the lens database (it was not there).