Saturday, January 28, 2012

[UV] Transmittance of the Minolta TC f4 135mm Triplet Lens

I tested some bellows lens heads the other day and the (expected) surprise was, how well that older and overlooked Minolta TC f4/135mm bellows lens head performed (teal and pink line), nearly identical to the Noflexar 35mm (red line; only about 0.2 stops less at 365nm). [I'm not sure if later made models may have the same good transmittance, as the coating may have been changed]

[click on image to see a larger one]

Here now a quick photographic test of that lens, which shows quite some focus shift in UV, the triplet lens design it is.

The micro structure that gets visible on the left petals looks promising, so quite a useful lens I have to say. Btw. it also comes mounted on a focusing helicoid for Minolta mount, sold under the same name, but the lens head can be unscrewed as it has a Leica thread mount (M39 x 26tpi) which is the standard enlarger lens mount.

Outside tests will have to be performed to see if it is free of hotspots, how free of flare it is etc.

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site