graham_buxton_smither

The Yashica C/Y mount Auto Tele Converter 2x lens is a bit of an odd-ball in that it was introduced quite some while after Zeiss produced the Mutar I & II (and a later III which was a 1.4x) - possibly recognising there was a demand and seeking to avoid compromising the quality of Yashica's primes through the use of sub-standard tele-converters. It was multicoated like the ML series and as has been mentioned, it is cosmetically identical to the ML lenses; in other words, like the DX 50 f2 C/Y lens, a ML in all but name. The build quality is also high. I have never seen a ML-marked Tele Converter; looking at available literature, the tele-con seems to have appeared around the end of the 1980s. I have just acquired one and so will test it against the Mutar I but I have no idea as to its optical formula - if I can find a damaged one, I'll take it apart and report back. The YUS version seems to have the same multi-coating as the DSB 50 f1.9 and pre-dates the Auto Tele Converter 2x; perhaps the success of the YUS version encouraged Yashica outside the USA to introduce one under its own branding. To answer Jeff Adler's 28 Feb question, the Mutar I was pretty much the universal 2x tele-con as the more complex Mutar II was specifically designed for the telephotos (as was the Mutar III 1.4x) and couldn't couple with most of the other Zeiss/Yashica lenses.