Originally posted by dfp771 I have the Samyang 24mm F1.4. It's a manual focus lens. It's very sharp, very contrasty. Colors are slightly different than Pentax but still a very nice lens.
According to reviews and MTF charts the Samyang should be the best choice at the moment.
Optical performance should be in the same league as the Zeiss 25mm. The build and feel of the lens should not match the Zeiss, though.
I'm waiting to have the Sammy in my hands, I found a second-hand example in the USA that looks like new. Hopefully it will not be decentered...
I already have the Sigma AF Ultra-Wide II 2.8/24mm, I don't know if it has the same optics of the Sigma 24mm Macro mentioned in this thread. Any clue?
I also own the FA 24-90mm and the Tokina AF 20-35mm. The former has never been used on the K-1, but has too wide a range to allow for great expectations, and the latter is quite good but not outstanding.
The best MF lens should be the early K version (3.5/24mm), but I have no personal experience.
The second K and the A versions have the same optics. There are worse 24mm's, many of them, especially older ones, but it's not considered among the best Pentax designs.
Two cheap options are the older Sigma Ultra-Wide (same design as the AF version) and the Tokina/Soligor C/D. Both should be more than fine, but I can't vouch for them because some old pictures on film are not enough to express any meaningful opinion.
The Kiron 2/24mm was at the top of the charts with the best brand names at its time. Though I have no idea how it performs on digital full frame. If it works well on a Nikon FF, it should work more or less the same on the K-1.
Both the FA* and the Sigma EX f/1.8 are expensive, I'm not entirely sure they deserve such important amount of money. So I never pulled the trigger. I have plenty of lenses and if I invest good money in a new one I want to be fairly certain that it would be much better than what I already own.
If I don't mind carrying a bulky, somewhat fragile monster (which is not the case most of the time...) my current go-to zoom, a Sigma EX DG HSM 34-70mm, performs more than Okey even at its lowest focal, and works very well in AF with the K-1.
The Samyang is not exactly small either, but is two stops faster, has no complicated system of cams/sleeves that can easily get out of whack, and is supposedly one step better: stopped down a little should be vignetting-free, have negligible distortion, and show high resolution across the entire frame.
Considering the impressive performance of its 1.4/35mm sibling, I have high expectations. I'm keeping my fingers crossed because there have been consistency issues with Samyang lenses.
I took the risk because it's hard to find a cheap second-hand one in Pentax mount.
If you are fine spending a little more, I'd suggest buying one from a vendor with a no-question-asked return policy.
Cheers
Paolo