[RKKS08]

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I remember I saw this lens in shops long time ago (early seventies?)
I never knew anybody owning it, and it is the first time for more than 3 years I saw it on eBay:

AUTO FOCUS 50mm f2 RIKENON PRIME LENS FOR PENTAX VERY UNUSUAL & RARE | eBay

The seller claims it can be used on digital bodies, but from the pictures I think it would fit on the K-01 only (flash may prevent mounting). It seems to use infrared distance measuring, or is it sonic like the polaroids?
Some of the Ricoh 2/50s had a reputation to match Zeiss and Leitz lenses (and being sharper than the SMC-M 1.7/50), specially used fully open and in respect to border resolution. Is this lens one of these?

[THoog]

Dunno about the glass, but I think it would be a bit later, maybe 1980~83? All the pictures I found indicate it is pre-Ricoh pin. From what I could google, the AF system is Honeywell Visitronic technology, which was not active (infrared or ultrasonic), but a passive optical system using one fixed and one moving light sensor. The moving sensor would pivot until the signals from both sensors matched, and it would calculate the range from that.

[RKKS08]

Thank you.
Eighties is possible.
I'm getting in contact with the seller to find out whether it would fit to DSLRs. And what he would charge for sending it to Germany.
And what kind of batteries it uses.

I am considering to bid. Of course it looks clumsy, but could be a cheap alternative to the FA 1.7/50.
The late Ricoh 2/50 was known to be at least as sharp.

[RKKS08]

Just for the record.

I asked the seller and was told there is about 6mm leeway between the box and the mount. With my K200D, the penta mirror/flash unit protrudes >14mm, so it cannot be used.
It needs 2 AA batteries.

[THoog]

Too bad - what little I found made it sound like dSLRs with long flash overhangs might have problems. Like you said, the K-01 is probably the only thing that would work. Now, that would be an interesting blocky combo!

[stevebrot]

Eighties is possible

Fall of 1980, just a few months before the Pentax ME-F. The technology was a passive IR rangefinder if I remember correctly.


Steve

[post_eos]

Like you said, the K-01 is probably the only thing that would work. Now, that would be an interesting blocky combo!

I wonder if it would focus faster