Paul,
In general the Rikenon / Sears 50mm F2 lenses were single coated, I believe they have a yellowish cast to the coating. The 50mm F1.7 & F1.4 lenses are multi-coated and have a purple cast to the coating.
For my own use I've broken down the Rikenon / Sears lenses in the following patterns -
First Generation XR Rikenon / Sears - 52MM filter, traditional lens barrel markings with a separate rubber focusing ring.
Second Generation XR Rikenon / Sears - 52MM filter, minimalized lens barrel markings with a molded into the barrel plastic focusing ring.
Third Generation XR Rikenon P - 52MM filter, minimalized lens barrel markings with a molded into the barrel plastic focusing ring, P lens mount contact and setting on the apeture ring.
I remeber that at least one of the Sears lenses I owned was a Yellow cast coating ( F2 Single coated.) as was the XR Rikenon 50/2 that I had. ( It's been a couple of years and my memory isn't what it used to be. )
I know one of the ones I had was a Sears 50MM F1.7 Second Generation lens. I took a series of pictures of one of my former employer's Semi-Trailer Trucks on the first day that I had the lens. It was in good light and the trailers we were using had a lot of our vendor's logos on them, so there was a lot of detail to look at in the slides. I ended up enlarging one of the slides I took that day to an 11 x 17, framed and presented it to the president of the trucking company at his retirement party.
I was happy with the way it turned out, and he loved it.
Mark
