Re: IR spherical panorama

["Willem-Jan Markerink" <w.j.markerink@xxxxx>]

On 15 Oct 00 at 15:09, Ben Kreunen wrote:

> At 10:25 PM 10/14/2000 -0500, you wrote:
> >CONGRATULATIONS Ben.  What a fabulous image.
> 
> Thanks Keith
> 
> Although personally I think it could be a lot better with some decent 
> light. It was about as flat and overcast a day as they come so it can only 
> get better ;-).
> 
> One problem that I have found though is that I was getting some 
> considerable light fall off towards the edge of the images.  I'm shooting 
> with an 8mm circular fisheye, one of the benefits of which for this sort of 
> work is that there is no light fall off with normal films. With IR film 
> however, it appears to be quite pronounced.   The sharpness across the 
> image was consistent. If anyone has any ideas??? or am I stuck with it.

What brand/model of 8mm?
You might want to check a few 8mm IR circulars in my personal 
gallery, I never noticed light fall off, but then again I never 
looked for it either....

http://www.a1.nl/phomepag/markerink/mainpage.htm 
(or /thumnail.htm directly)
 
> Film was Konica IR, 

Aha, mine was EIR, that makes comparing our shots a bit more 
difficult.
What type of filter btw?
(these circular fisheyes are *the* prime candidate for BTFR-filters 
(between the film rails), as one cannot attach filters to the front 
of the lens (and the rotatable filters inside on some models only 
offer #25 red at most, while internal screw filters (old Sigma) or 
rear slot filters are also a mediocre solution with darker IR filters 
(unless you commit yourself to a tripod).
Many years ago, my Sigma 8mm was the starting point of fabricating
these BTFR-filters....there was no other way with an opaque #87C
filter, when shooting at a steep ski-slope, in -20C weather, and
changing between 3 bodies and 3-4 lenses (that alone made fiddling
with normal filters a big no-no too....neither ergonomic nor
foolproof....8-))

> stupidly shot handheld as I was testing a new method of 
> aligning the camera. (1/8sec @ f4, hence some of the blur) I've added a 
> second panorama to the page and you can see on this one how the density 
> differences at the edge of the image show up the vertical seams between 
> images. I can correct this a bit better than I have done here but it's a 
> lot of work I'd rather avoid.

Is the light fall off mathematically from center to edge, or does it 
depend on the direction of the sun?
With circular fisheyes, flare gets a whole new meaning....8-))

PS for those interested: I still have a brand new/never used Sigma 
8mm/f4.0 for sale, in Contax/Yashica mount, with possible conversion 
to EOS....US$400 vs US$550....
(I use the same lens in Nikon mount myself, through a Novoflex 
Nikon->EOS adapter....I could be persuaded to sell this one for 
slightly less (it's in mint condition), instead of the C/Y mount, 
where it not that the C/Y version is no longer made (unlike Nikon and 
other AF mounts), so I rather leave it intact, IOW: a C/Y owner is 
preferred....but not at all cost or course....mail me privately if 
you are interested....;))

--                 
Bye,

Willem-Jan Markerink

      The desire to understand 
is sometimes far less intelligent than
     the inability to understand

<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]
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