Originally posted by Douglas_of_Sweden Follow the link I gave you and from there you have links to the patents.
As for the FA77ltd and A*85 you only need to compare the lens designs side by side to see that the 77ltd is just a slight mmodification of the A*85. It is true that Jun tweaked the A*85 into the FA77ltd, but to my knowledge it didn't result in a separate patent. At the same time Jun presented a 31/2.4 and the 43/1.9. Only the 43mm made it into production, as Pentax wanted all three FA ltds to be sub f2.
As for the DA ltds, I of course meant them used on an APS-C DSLR where the combined smaller size is a considerable advantage in some situations. Besides that, they are more modern design and suffer less need for post processing to get rid of optical abrevation etc. But I love them and own all the limiteds, except the 20-40 zoom.
Edit:
A*85/1.4
FA 77/1.8 limited
If you look carefully there are small changes on the 3rd to 6th elements, but it is clear he built it on the A*85. The drop in speed is logical as the A*85 is rather soft there. Why 77mm? Japanese number magics??
Funny how we can look at the same two less designs, you say one is copied from the other. But if the designs are accurate, only in the type and places of the elements. ON the other hand, saying all he did was tweak it...that would imply that to be truly his design he would have to redesign the wheel and do a completely new original design. SO I'd have to hear from a lens designer how original the 77 is. But then I'm looking at the actual curvature of the glass elements.
I would completely reject that it's not Hirakawa's design.
How can you say "he copied the deign but the changed a few things.?" The crux of the matter being , how much do you have to change something to make it your own? Given current copyright standards, very little. And yes, the 77 did have it's own patent. It was posted and linked to on the forum numerous times. And Jun Hirasawa's name was on the patent. There is no mention of any other designer.
A similar number of elements does not make a design similar. Or every 9 element lens would be a copy right infringement of the first 9 element lens.
Without examining every lens with the same number of elements, I personally would have no idea how original the design is. For all I know every lens with the same number of elements looks pretty similar. And it's surprising you don't know about the patent for the 77. I've quoted it many times, because of the phrase Jun HIrakawa used in the description. " A lens designed for the way people take pictures, not for the test charts. " is a rough paraphrase.
It's playing pretty loose with the facts to bas your whole opinion on a few lens diagrams.
Here's another link discussing the FA ltd.
https://www.dpreview.com/forums/post/53451224