Converted Symmar sample

[Ole Tjugen]

Since the question comes up every once in a while, I've dug out an old picture shot with a convertible Symmar 150mm in the 256mm setting. Since it has to be big to show the aberrations, I've put it on flickr:

http://www.flickr.com/photos/71733804@N00/438377619/

[Ole Tjugen]

Addendum: If anyone really wants it, I've got a 2780x2050 pixel version, too. :)

[GPS]

Just curious, Ole - where is this northernmost beech forest in Norway?

[Ole Tjugen]

It's in Seim, Lindås kommune, about 50km north of Bergen.

[GPS]

Correct, that's what I thought. These northernmost things are sometime false, see e.g. the world's northernmost forest (birch forest, Betula pubescens) claimed in Norway near Hammerfest (called Johannes (sp?)forest) which it is not.

[JW Dewdney]

I can't see any aberrations at THAT size...! I CAN, however, see some reflections (I assume it was shot through a window!) Is there a link to the bigger one? It's funny how everyone assumes that the convertibles were somehow compromised and inferior to modern lenses - they were actually QUITE good, IMO - but only some perhaps. I think Schneider were designing them for the prime focal length and noticed, incidentally, that they COULD be used with rear group only, nearly acceptably. I BELIEVE that it was a marketing mistake more than an optical one.

[Ole Tjugen]

No reflections, but a little bit of flare at the top there. It was one of those days with a light cloud cover which makes the light flat but the sky brilliantly white - and it's almost impossible to shade the lens well enough. Even when all the glass is behind the aperture.

I've snipped out a bit from the top left corner. There is a hint of chromatic aberration which could be helped with a coloured filter when shooting B&W, but the astigmatism is greater by far. After taking this picture I dropped all thoughts of using coloured filters with converted lenses - unless I have a better reason than sharpness to do so.

BTW - the sharpness isn't that great. That's not a problem with the lens, but with my Agfa Duoscan T1200 scanner - and my scanning skills!