Originally posted by Timd Put another way, there is no legacy lens with FOV on FF that the 10-20 has on the K5
Why legacy? Yes, the traditional FF ultra-wide for SLR has been 20mm. Shorter lenses were made for the format,
but not retrofocus and not compatible with the mirror being up[B] but are rare with many being non-retrofocus and unusable on SLRs without mirror lockup. The ongoing issues have been and continue to be designing to minimize barrel distortion, poor edge performance, and vignette. What's more, ultra-wides were considered to be a niche market and both pricing and production numbers reflected that.
If you want a zoom at a similar price/quality point with similar FOV, your point is well made. The Sigma 10-20/3.5 is a good performer at a moderate price and is fairly unique in both regards. The D FA 15-30/2.8 is in another league in both price and performance. If you can settle for a prime and mostly just want a FF lens at the wide end, I would suggest the Samyang 14/2.8 or Venus 15/4.
As I noted in my comment above, I have been looking for APS-C wide angle solutions for nearly a decade with only mixed success. For ultra-wide, I actually prefer a circular (fisheye) projection over rectilinear and if fishy doesn't cut it, a stitched image provides straight lines without the volumetric distortion common to all rectilinear ultra-wides in preferable IMHO.
In regards to APS-C, K-mount rectilinear lenses in the 10mm range, the current options offer reasonable quality and won't break the bank, though the choices are not extensive in those that are readily available:
- Sigma 10-20/3.5 $499
- Samyang 10/2.8 $399
- Tamron 10-24/3.5-4.5 $499
There are no premium K-mount offerings in this space. It is hard to tell how long both Sigma and Tamron will continue to offer their short APS-C zooms. If those lenses fall out of the lineup, the Samyang remains as the sole APS-C ultra-wide.
Steve