So, I decided to finetune the search parameters for recent Pentax patents and used the following query string:
Code:
AN/"Hoya" AND AGT/"Greenblum" AND CCL/"359"
on
Patent Searching Database
with sort order "Chronological".
Note that categories 354 to 359 all relate to cameras.
Then, a number of known lenses pop up:
-
DA 35 Ltd.
-
DA* 300
BTW, one is learning that the DA*300 is 290mm f/4.1 and Table1 applies a crop factor of 1.00. It isn't the FA*300/4.5 as the patent describes an 8 element in 6 groups lens. The FA*300 has 9 elements, the A*300 has 8 elements but 7 groups. And the original patent is from April 2007, a year before the DA*300 was released.
So, we now may
officially learn from Pentax that the DA*300/4 is a full frame lens.
You may find other interesting patents, like
Camera system and interchangeable lens
which explains how an SDM lens switches between screw drive and ultrasonic. Some may want to check it out because it may answer the question if a lens with broken SDM would still be useable with screw drive.
Others may look at the 61 entries of the list and find more gems ...
P.S.
The "HIGH ZOOM-RATIO ZOOM LENS SYSTEM" is missing from the list although the search parameters fit (bug...).