DA* 11-18mm Full Frame Compatibility Tested
A look at vignetting and dark corners on full frame
By PF Staff in Hands-On Tests on Sep 15, 2019
The HD Pentax-DA* 11-18mm F2.8 is the latest addition to Pentax's lineup of premium APS-C lenses. With an ultra-wide zoom range, a fast aperture of F2.8 throughout, and the latest in optical and lens technology, it's the perfect lens for demanding wide-angle shooters.
As a DA-series lens, the 11-18mm is of course designed for APS-C cameras. But, can it also double as a wide-angle lens on full-frame? You may recall that we recently posted a comprehensive test of all DA lenses on full frame. Today, it's time to add the 11-18mm to the list of tested lenses!
In our full frame coverage tests, we assign a simple, qualitative rating at various aperture and zoom settings. An "A" rating implies that a lens is just as good as one designed for full frame, while an "F" rating means that little to no coverage is offered outside of the APS-C frame.
Finally, we give each lens an overall rating, out of three stars: ★★★ (3) for "A" ratings across the board, ★★☆ (2) if there are some "A", or mostly "B" ratings, ★☆☆ (1) if there is at least one non-"F" rating, and no stars otherwise. Most lenses that we've awarded three stars are also officially designated as full-frame lenses; these include the DA* 200mm, DA* 300mm, DA 560mm, and DA* 60-250mm. Lenses with no stars are typically kit lenses. This leaves most other DA lenses in the one- or two-star category.
Without further ado, let's take a look at the overall scores for the DA* 11-18mm.
DA* 11-18mm Full-frame Coverage Rating
"Full coverage at some F-stop and focal length combinations"
Looking at these results more closely, we observe that at 11mm, coverage beyond the APS-C area is minimal: just slighly less than a 1:1 crop frame. As we stop the lens down, the strength of the black corners increases, though general vignetting decreases.
At 14mm, we observe the last remnants of black corners, which still darken as we stop down. 1:1 crop mode is perfectly usable here. However, the mere presence of black corners automatically drops our rating down to "C".
Starting at 15mm the full area of the frame can be used, with slight softness in the corners and moderate vignetting (which is characteristic of the lens in general). Fortunately, after this point, flaws can easily be corrected in post. Note, however, that the hood—which is designed for APS-C—will not be usable (i.e. to help prevent flare).
Select test photos can be found below. For real-world samples, stay tuned for our in-depth review, which we will post shortly.
For now, our verdict is that the DA* 11-18mm doubles nicely as a full-frame ultra-wide lens starting about halfway into the zoom range. This is quite handy if you are an APS-C shooter and could justify this purchase if you are looking for something wide on both systems. However, if you primarily use full frame, there's no reason not to get the D FA 15-30mm F2.8 instead, which costs the same but will deliver sharper corners, less vignetting, and less flare due to the presence of a hood— not to mention a longer zoom range.
Until our in-depth review goes live, you may stop by the lens database to learn more about the 11-18mm.