
And then, this is the Pentax FA20-35mm F4 Ultra Wide Zoom:

And then, compare the above two and then also against the Leica Summilux 21mm Prime below:

Via: http://www.dchome.net/forum.php?mod=viewthread&tid=1215807
(in Chinese)
It is not difficult to notice that, as the OP has pointed out, the optical designs of the three lenses are quite similar, especially for the Tri-Elmar and the FA20-35. So, who copied whose optical design? :-o
I have also checked the optical formula of the DA21 F3.2 Limited lens, it can be seen that the optical design could still be similar, although it is somehow simpilfied:

(Diagram Source: http://kmp.bdimitrov.de/lenses/primes/ultra-wide/DA21f3.2.html)
Nonetheless, as Pentaxians, we are of course glad to learn that we have Leica's optical formula embedded right inside our Pentax glass! So, Pentax could really be the poor men's Leica! ;-D
Uncle Vova · 605 weeks ago
As I know, the Pentax FA 28-105/4-5.6 IF, for example, is a really Tamron lens not only by optical design, but even in lens body design. So, dear RiceHigh, could we say that the Pentax is the rich men's Tamron? ;)
RiceHigh 110p · 605 weeks ago
Uncle Vova · 605 weeks ago
RiceHigh 110p · 605 weeks ago
Uncle Vova · 605 weeks ago
not a PF fan · 605 weeks ago
Yoku · 604 weeks ago
As for DA21 - the difference is huge. Open your eyes, Rice.
Yoku · 604 weeks ago
FA20-35/4 has 20, 24, 28 and 35 mm (main focal length), but it's real to put intermediate length.
M mount and K mount have absolutely different flange focal distance...
What are you talking about, Rice? It's pure water bull shit.
As for DA21 - only cretin could draw a conclusion that DA21 and Leica Summilux have the same optical design.
There are a lot of lenses in the world with similar optical design, there are classical optical design like Planar, for example, and a lot of variation of Planar. It doesn't mean that somebody stole the optical scheme of lens.
But, this TWO examples are not correct at all.
RiceHigh 110p · 604 weeks ago
Yoku · 604 weeks ago
Pentax has 10 elements in 8 group.
Minimum Focusing Distance - 1 meter. Pentax - 0.3 meter. The both lenses were started to produce in 1998.
DA21 is hard to compare with Summilux 21 - different optical formula, aperture blades, filter size. Summilux is FF lens. DA21 can't cover even APS-H sensor.
LEICA Summilux-M is 21mm f1.4, LEICA SUPER-ELMAR-M is 21mm f/3.4 ASPH. Maybe you mean 21/3.4? But this lens is different too.
There is also LEICA ELMARIT-M 21mm f/2.8 ASPH.
BUT this 3 lenses are retrofocus lenses.
Did you post this stories for idiots?