Re: IR spherical panorama

[Ben Kreunen <ben@xxxxxxxxxxxxxxxxxxxxxxx>]

>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).

>(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.

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.

The weather is better today so I'll go out at lunchtime and try some 
more.  It was only one film so it may be possible that I did something else 
wrong... time will tell.

Cheers

Ben

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