Originally posted by biz-engineer
To change the camera OVF screen for one lens only and mess up AF on other lenses, that 45mm lens much be really really good. And there is already a Samyang 50 1.4 K mount, many other 50mm manual focus vintage lenses. I sold my Sam. 85 1.4 not only it wasn't that sharp in perfect focus, but manual focus was hit and miss, and in addition it had focus shift when aperture is closed. There is a Pentax AF lens , super sharp, excellent coatings, who would want to mess up with an equally expensive 45mm manual lens. For Pentax there is also the 43 ltd, also AF, very close to 45mm.
FYI my AF is not messed up. My improvements from the focus screen extend to AF lenses as well during Quick Shift/Fine tuning. The only draw back is with slower glass as the OVF gets dimmer as you stop down (hence why I suggested those whom are fans of fast glass to consider this option).
I enjoy the replacement focus screen for all lenses (even slower ones), even FA ltds when I am not choosing to use AF (such as being more discreet such as weddings).
I'm not suggesting someone replace a focus screen for just
this lens

, that would be ridiculous. I am just merely pointing out a significant benefit as I see it that would assist the user with the experience of this lens should they choose it (the benefit as well extending to other lenses in their collection). FWIW I wish the FA43
had WR as well, but it does not, again I would suggest one of the strengths of this Irix line up is the apparent WR capabilities. There is a Samyang 50/1.4, but again it has no WR.
I suspect this lens will do very well, for those that cannot afford the DFA 50, nor need the AF it provides, but want something of high quality (which the Irix line up has a reputation for) with a reasonable price tag in conjunction with WR. If Pentax actually released or re-released lenses with WR then yes this lens does seem a little unneeded, but it's actually surprising to see just how few lenses for Pentax that are WR.
The only primes that have WR offered by Pentax
Weather Sealed Prime Lenses | PentaxForums.com
So yeah, a 45/1.4 WR prime for Pentax is welcome, even if it is only MF. I merely suggest an option to improve that experience. Good day