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There are 4 variations with respect to the naming:
Rokkor-PG
Rokkor-X PG
Rokkor
Rokkor-X
"X" denotes export lenses that were marketed in different places than the non-X. It does not denote anything "Xtra". According to Rokkorfiles.com "In line with Minolta’s practice of labeling products differently in different markets, the lenses were labeled “Rokkor-X” in the North American market, and “Rokkor” throughout the rest of the world. It is noted that apart from this minor cosmetic change there is no difference between the Rokkor and Rokkor-X version of the same lens. "
"PG" Denotes the lens formula of 7 elements in 5 groups.
First Letter (no. of groups): T=3; Q=4; P=5; H=6; S=7; O=8; N=9.
Second Letter (no. of elements): C=3; D=4; E=5; F=6; G=7; H=8; I=9; J=10; K=11; L=12.
The practice of including the lens formula was dropped in the third generation of Minolta MC mount lenses. Hence, this third generation would have the label "Rokkor" or "Rokkor-X" depending on what market it was destined for.
The older, all metal versions are all "Rokkor-PG" but there are also some rubber-gripped "Rokkor-PG", and some rubber-gripped "Rokkor-X PG". "Rokkor" and "Rokkor-X" are all rubber-gripped.
They are all multi-coated, right from the 200xxxx series right up to the last ones. I know this for a fact because my 200xxxx and 2 other 200xxxx copies that I have had all had green/blue, pink/purple and yellow coatings. The question is, which surfaces of which elements where multi-coated and how did that change over time? Nobody knows for sure.
The multicoating almost certainly changed over the years, but this is not correlated with serial numbers or body style as far as I can tell. Take any one of them and tilt it in the light and you'll see various colours. However, it is believed that coatings on the MC 2nd and 3rd generation lenses are generally better than those on the earlier 1st generation lenses. This is only a generalization because the coatings were undergoing continual development during this period, and accordingly the break from “old” coatings to “new” coatings was progressive, and it is actually likely that there were multiple improvements throughout this period.
One other notable difference is the presence of thorium (radioactive) glass in the first few runs. Lenses with serial numbers 200xxxx, 250xxxx, 255xxxx, and at least some of the 256xxxx have this. Lenses from 257xxxx through 27xxxxx series do not.
They are all excellent lenses (although there certainly is some sample variation after all this time), but the one I kept over many others is a 200xxxx Rokkor-PG.
The conversion process to EF mount is identical for all of them.
Edited on Nov 08, 2009 at 10:04 AM · View previous versions
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