On 26 Dez., 11:58, namklim <[email protected]> wrote:
> The focal length of the Samyang is very nominal at 8mm (and the
> Vivitar version is labelled as 7mm). Older versions of Hugin optimised
> it to about 9.5mm and I set the lens to that before any CP detection.
> However, I suspect the latest version may still try to use the EXIF
> focal length as well in optimisation? The nadir image really needs to
> be declared as a different lens otherwise the optimisation gets
> confused and tries to optimise all images with a shorter than optimal
> focal length. Perhaps that nadir image should be deleted before you
> run any basic tests?

Hi!
I also use the Samyang 8mm on a Canon EOS 450D, so this isn't a full-
format sensor, but 1.6 crop. Let me mention a few things I've found
using it:
- I think it's best to do 6 around in portrait orientation, one up one
down to have enough overlap
- don't do the zenith straight up but tilted up at about 60 degrees,
that way you get more overlap with the 6 around and still have enough
in the up shot to get the sky right
- same thing for the nadir; just tilt it down 60 degrees, not straight
down.
- for the optimization to work out right, you want lens type
'stereographic'.
- you also want to calibrate the lens carefully. I came up with
lens.ini values like
v=98.6965
a=0.0215261
b=-0.0839417
c=0.0349003
- as long as the hfov is right, I think the precise focal length
doesn't matter.
- and you should optimize for d and e every time.
- use the same lens setting for all shots, just make sure it's well
calibrated

> It is possible to use the lens for four rather than round and only one
> up and one down.

I think 6+1+1 is better.

Give it a shot, maybe it sorts out your problem.

Kay

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