>>> I read somewhere that the Star in the Pentax lenses stands for >>> APO, so it should apply to the apochromatic lenses. But I may be >>> wrong...
[snip] > As far as I am aware Pentax lenses with "*" designations mean > nothing specific apart from being an indication that they offer > premium performance for their class. So you could argue that like > ED and APO, ASPH lens designations it usually purely a marketing > tool and should be considered in context. I would say that Pentax has been both vague and inconsistent in its use of the "*" designation. Overall, I would say that the "*" lenses have been variously been defined by Pentax as those that: 1. are generally "premium" lenses, sold at premium prices. 2. ~might~ ~perhaps~ be assembled and tested more carefully in small batches. 3. ~might~ sometimes use low-dispersion and/or high refractive index glass. In various (and often undated) "Lenses and Accessories" booklets, Pentax has provided, at times, the following sorts of "*" explanations: 1. "The M* and A* lenses are a new generation of telephoto lens, among the most compact on the market, and they incorporate low-dispersion glass to reduce chromatic aberration." 2. "A* = Called A-star. High-performance, compact lens using special glass elements." 3. "A*/F* = Called A-star or F-star. High-performance, compact lens using special glass elements." Note that ~some~ "star" lenses also have been designated with "ED" (apparently for Extra-low Dispersion glass), but some are not. For example, at the time that Pentax made statement #1 above, the only 35mm Pentax lenses that were designated as "star" lenses seemed to be the M* 300/4, the A* 300/4, 300/2.8, and 600/5.6, but only the 300/2.8 and the 600/5.6 received the "ED" designation (for "Extra low dispersion glass to reduce chromatic aberration"), while the two 300/4's did not - was Pentax making a distinction between Extra-low dispersion glass and "mere" Low dispersion glass? Furthermore, while the M* 300/4 and A* 300/4 lenses are dramatically smaller and lighter than their non-"star" counterpart (the SMC 300/4), probably indicating the use of high refractive index glass, most "star" lenses (in my opinion) do not seem to be overly compact for their focal lengths and apertures, so the use of high refractive index glass might not be found in all "star" lenses. In his book "Camera Test - Pentax LX System" (Henry Greenwood and Company Limited, 1982, originally published in The British Journal of Photography), Geoffrey Crawley makes the following statements about the M* 300/4 lens: "The star after the M is in fact inscribed in green and this denotes that extra low dispersion glass is used in its construction." (Pg. 68) - and - "The green star Pentax lens is of the low dispersion glass type and therefore compares very favourably in cost with fluorite designs." (Pg. 69) I just thought that I'd throw another log or two onto the fire... Fred
