On 2012-05-24, Jon Anderson wrote:
On 5/23/2012 1:56 PM, DoN. Nichols wrote:

Did you do what is recommended for mirror lenses -- make a cover
for the front, with a small (say 1" diameter) hole off center so your
actual aperture is significantly smaller that f/11. That might have

[ ... ]

BTW -- any idea where the multiple rings on the thin side of the
image came from?

I am not sure, might be an artifact of the design, or perhaps light
reflecting off the back of the welding lens? I know this type of lens
does strange things with out of focus highlights, one gets little rings
of light instead of smooth bokeh.

Right -- donut bokeh because of the missing part from the
center.

I bought the lens because the price
was certainly right. I saw a couple listed on ebay shortly after I got
it, for over a grand, though in the month I watched them, they didn't
sell. It's a great lens in the right application, but I'm going to
sell/swap it and for an ultra wide angle.

Hmm ... it might be multiple reflections from the front surface
of the lens and the rear surface of the filter. Or -- if the filter is
multiple layers, and they were not parallel you would get multiple
reflections from that.

[ ... ]

One thing about the Perkin-Elmer lens, is the optics consist of one
solid piece of glass, hence it's name, the Solid Cat. Not sure what
might damage it, unless excess heat on the secondary mirror could damage
the coating. But it survived!

I think that it would be that the heat would soften the typical
adhesives used to attach the center secondary mirror to the back of the
lens. In your case, it appears to have been vacuum evaporated onto the
back, so there is no problem.

BTW You are thinking of parting with the lens you said? What lens
mount? And what are you asking for it?

Enjoy,
DoN.

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