| Heliar | moderate to slow (e.g. f/2.8, f/3.5, f/4, sometimes f/2), except for the 50mm f/1.5. | simpler designs (often 5-element or fewer), vintage-style corrections | soft to “gentle” look; lower contrast wide open; smooth transitions; pleasing falloff | smaller, lighter, lower cost (relative) | when character, nostalgia, “vintage” rendering or compactness matters |
| Ultron | fast to moderately fast (e.g. f/2, f/1.7, sometimes faster) | more aggressive correction, use of aspherics or more complex elements | sharper than Heliar, more contrast and punch; more modern rendering while retaining some “character” | moderate complexity, size, and price | as an all-rounder “working” lens: good balance of sharpness, usability, and compactness |
| Nokton | “fast” / “super-fast” (e.g. f/1.5, f/1.4, f/1.2, even f/1) | Some lenses are more corrected than others, but usually aberration, coma and distortion is quite controlled | subject isolation, creamy bokeh, sometimes more pronounced aberrations wide open (character) | tends to be bigger, heavier, more expensive | low light, portraiture, where maximum aperture / “speed” gives a creative edge |
| Color-Skopar | slower to moderate (e.g. f/2.5, f/3.5, f/4) | simpler, compact designs; modest correction | clean, efficient rendering, less “look” but good sharpness especially stopped down | minimal size, simpler construction, lower cost | travel, street, compact prime, when size & weight are priorities |
| APO-Lanthar | moderate (often around f/2) | apochromatic correction, use of exotic/low dispersion glass, often many elements | extremely low chromatic aberration, high resolution, high contrast, very clean, neutral rendering | high complexity, more elements, bigger size, higher cost | critical work, high resolution sensors, when optical performance (especially chromatic control) is a top priority |
