Re: Kiev fisheye (was: Re: IR spherical panorama)

[Marco Pauck <pauck@xxxxxx>]

Clive Warren wrote:
> 
> At 10:24 pm +0200 16/10/00, Marco Pauck wrote:
> >
> >Clive Warren wrote:
> >[...]
> >>  Was interested to read your comments on the Kiev 30mm W-J.  Have you
> >  > tried out one of these lenses?
> >
> >  > Are we talking true fisheye here?  When you say "full frame" is this
> >>  a circle touching the sides of the 6x6 format, or does the image
> >>  cover the whole of the 6x6 format?
> >
> >The Arsat/Zodiak 30mm is a full-frame fisheye for 6x6 but a
> >circular for 4x5".
> >
> >More info can be found at
> >http://www.pauck.de/marco/photo/stuff/kiev_fisheye/kiev_fisheye.html
> >
> 
> Marco, thanks for the URL - I popped over had a good read.  Your web
> site is looking excellent by the way. I have a few questions for you!
> 
> The edge resolution at 14lpmm is rather poor.  This would translate
> to an easily perceived loss of quality at the edges of the image.

Well, giving a value for the resolution without mentioning the
corresponding contrast is more or less meaningless. Both parameters
are closely related.

> This may well cause stitching problems in any pano. digital
> manipulation. Am interested as to where you found the resolution
> details, or perhaps you measured the performance of the lens yourself?

These are the 'official' values from the factory.
The practical performance of the lens is actually quite good.
The only problem is flare, so I'm thinking about multi-coating it.

> Is this edge value measured for the full frame 6x6 image?

Yes, I guess.

> Anyway, was the resolution test carried out with wide open aperture
> or was this down a couple of stops?  With such a wide acceptance
> angle, closing the iris may cause diffraction problems anyway -
> comments?

I assume that these values are for a stopped down lens.
Diffraction problems will not arise unless you stop down to, say,
f16 or beyond.

> Finally, do you know the size of the fisheye circular image on 4x5 format?

Sorry, haven't measured it.

	Marco
--
Marco Pauck -- marco@xxxxxxxx -- http://www.pauck.de/marco/
For every complex problem, there is a solution that is simple,
neat, and wrong.  -- H. L. Mencken
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