Agfa Colostar N 77/4.5
Heliar lens fitted to Colormator rollhead printers, Variograd belt copying machines and other Agfa industrial imagers. Optimised for 3.5x magnification. Low serial, all silver versions have same tooling/casing as Steinheil enlarger lenses. High serial versions have large black aperture rings. Commonly mis-spelt ‘Colorstar’. No aperture markings.
|Focal Length (mm)||
|Max Aperture (f)||
|Min Aperture (f)||
5 / 3
|Flange-Focal Distance (mm)||
M39 x0.5, M42
This lens was also available in M42 mount for bellows use, and it certainly behaves like a short-distance specialist, scoring 82% for f5.6-f8 average close-up, but dropping off conspicuously to 78.3% at middle distances, and sinking even lower at infinity. In some respects this is typical of a five-element enlarger lens (see also the otherwise Gold-worthy Meopta Meogon-S 80/2.8 and Leica Focotar II 100/4.5). It was a close decision whether to promote this to a Silver award or demote it to Bronze: it’s right on the cusp. On balance, though, its optical virtues are just positive enough to squeak over the line into the finer company it barely deserves to keep, rather than slum it among the Bronzes where it doesn’t quite fit either.
Users of the Colostar-N 77mm are left to guess at the selected aperture: five clicks span the diaphragm’s operation, closing it to a presumed f22. At maximum aperture there’s quite strong spherical aberration and at no point will you see Zone 3 recording a score close to 8.0. That’s Delta-speak for ‘soft corners’ (on a 35mm full frame, at least). The image circle is roomy enough for shift movements of up to 8mm (which means it covers a 645 sensor), but Zone 4 looks increasingly aberrant. Focus shift is more than average but in common with most enlarger lenses of this focal length, geometric distortion and CA are minimal.
The single coating and relatively exposed front element combine to make flare a problem: without a hood, or a front filter thread, the Colostar N 77 is prone to dramatic contrast-loss without much provocation. However, bokeh is smooth – typical for Agfa lenses with circular apertures. Colour is more muted than vivid and the balance is neutral. These ingredients combine to give the Colostar-N 77 an appealing look: somewhat subtle and understated. This Colostar doesn’t bring fireworks to the party, but its sponge-cake is OK.