Wollensak Fototel 20 inch f6.3 first test

[kymarto]

This is Wollensak's licensing of the De Oude Delft Fototel mirror lens, introduced in 1953. Mine is is nearly mint condition, and appears to be a prototype or first "edition", because within a year they had changed the external appearance. It seems reasonably sharp, and has pretty good contrast. One interesting thing is that it focuses by moving the front lens/mirror, rather than the whole lens like my Nikkor 500mm/f5. It has a very good MFD, and the image does not fall apart close up as the Nikkor's image does. The orange flower image is MFD, the others close to that. I will try it later at further distances when I have a subject. These are SOOC, metered for highlights, just as ACR thinks they should be, although as posted they exceed safe chroma values.

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[Doc Sharptail]

Got a photo of the lens?

Interesting. First came across the Wollensak name with early Winchester rifle scopes- the first "A" series...
Winchester assembled the scopes with Wollensak made lenses.

No slouches as straight up camera lenses either.

-D.S.

[kds315*]

Looks good to me Toby!

Much better than results I saw from other Old Delft Fototel mirror lenses!
This one uses focusing using the secondary (front) mirror, quite common
with astro mirror lenses.

Lucky find this Wollensak version!!

[kymarto]

I just did a comparison with a 150-500mm f5. 6 Tokina I have, which is actually quite decent, comparable in sharpness in the center to my Nikkor 400mm f5.6 in the center. The Fototel is not quite as sharp, but still not bad. I'll be interested to get home and compare with my old reflex Nikkor 500/5

[Oldhand]

[kymarto]

Here is a pic of the lens--big and heavy. Interestingly it has a meniscus lens at the rear to adapt to various different flange distances for the cameras for which it was made, instead of simply changing the depth of the adapter like the T adapters.

[kds315*]

Hmm, interesting but with just one simple meniscus lens, a focal difference cannot be adjusted...it would need some afocal system (?)

That negative meniscus lens usually is used as a field flattener, as without it it would have a convex field of sharpness.

I use another "trick" which they may have used too. Such a mirror lens is very versatile and allows focusing beyond infinity, so if you use a shorter or longer register camera, one simply adjusts using the focus of the lens, the only downside is that the focus distance marks do not fit anymore, but so what...[some mirror lenses have inside a focus adjustment which allows to set the infinity point]

[kymarto]