Re: IR spherical panorama

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

On 16 Oct 00 at 8:44, Ben Kreunen wrote:

> 
> >What brand/model of 8mm?
> > > Film was Konica IR,
> >
> >Aha, mine was EIR, that makes comparing our shots a bit more
> >difficult.
> >What type of filter btw?
> 
> Sigma, manual focus f4..  only a #25 (internal filter).

I can make you both a #89B and #87C too, internal/circular foil 
filter, to be attached between the standard (UV) screw filter and the 
barrel....still have the cutting dies laying around....;))
(the only practical use right now is for cutting polaroids....also 
recommended....:))
 
> >(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).
> 
> Not a great problem for me as these panoramas are usually shot on a tripod, 
> but I wouldn't go sticking an extra filter inside the lens.  a BTFR filter 
> would be useful though if I wanted to go for the extra IR effect. An opaque 
> filter in front of the lens wouldn't bother me either as I don't actually 
> need to look through the lens since I'm photographing everything.  I also 
> don't use the full 185° since there is plenty of overlap between the images 
> so a filter in front of the lens may be possible. Since this would screw 
> onto the lens shade it would also be practical for changing between bodies 
> but I'd have to test just how much cut off there would be.
> 
> >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-))
> 
> It's definitely radial and as there was no sun that wasn't the problem.. 
> The software I'm using can compensate for it a bit but it wasn't as gentle 
> a fall off as normal lenses so the edges were still quite dark.  It was 
> noticeable on a single scan (oops, trashed everything so nothing to show) 
> and it's not obvious on your images. In the second panorama the nadir is 
> quite dark for example, due to all three images meeting at the edge at this 
> point.  I also shoot an image pointing straight down to patch any defects 
> in this area and this image was quite light.  It was easier to darken the 
> light image than to try and lighten the area it was slotting into.

And you are sure this has nothing to do with the fact that you 
possible used the ring-shade? I always use the full angle, so I never left 
it on....
 
> I've been quite impressed with the way the lens copes with lens flare and 
> it doesn't really produce anything that can't be corrected.

My Kowa 19mm/f4.5 circular fisheye for 6x6 is heaps better....but
that one is from a different era; 'quality and damn the
cost/weight/size'....with camera attached (not the other way
around!) it weighs 4kg....I guess I am one of the few blokes on
earth who ever suffered muscle ache from a circular fisheye....8-)) 
(the Nikon 6mm/f2.8 is not much more rare than this one....;))

--                 
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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