Pentax DA 21790 55mm

Owners rate this lens 4.8 out of 5 and praise its sharpness and low-light performance, but our database puts its optical score at just the 53rd percentile. The build quality is the real standout at the 78th percentile with full weather sealing. If you shoot Pentax and need a weather-sealed f/1.4 prime, this is worth a look, especially at the EUR 512 end of the price range.

The optical performance is a mixed bag. You get 9 elements in 8 groups with one ED element, plus the Aero Bright and SP coatings. That's a solid recipe, and owners consistently mention razor sharp image quality and beautiful bokeh. But our database puts the optical score at the 53rd percentile, which is about average for this type of lens. The bokeh ranking is actually a weak spot at the 25th percentile, which is surprising given the 9-blade diaphragm and f/1.4 aperture.

Autofocus uses the SDM system, which Pentax claims is smoother and quieter. Our AF score lands at the 54th percentile, so it's fine but not a standout. The quick-shift focus system is a nice touch for manual override. Minimum focus distance is 450mm with a 0.3x magnification, which puts macro performance at the 38th percentile. Not a lens for close-up work, but that's not what it's for.

Stacked against the competition, this lens fights a different battle. The Tamron Di III VC 28-300mm and Sigma Contemporary 16-300mm are superzooms with stabilization and massive focal ranges, which makes them far more versatile. The Panasonic Leica DG Vario-Elmarit and Sony E 18-135mm are also zooms with OSS or similar stabilization. The Pentax has none of that. What it has is a fixed 55mm focal length, f/1.4, and weather sealing. If you need one lens that does everything, any of those zooms beats this. If you need a fast, weather-sealed prime for Pentax K mount, none of those competitors even fit your camera.

Pricing is all over the place depending on where you shop. In the US you'll find it between $647 and $650 across two listings. But in Europe, the spread is wild: EUR 512 to EUR 900 across three listings in Spain, France, and Italy. That's a EUR 388 difference for the same lens. If you're in Europe, shop around before you commit. The CAD listing sits at $1,117, which is a single listing so there's no comparison shopping to be done there. For a weather-sealed f/1.4 prime with this build quality, the lower end of that EUR range feels fair. The higher end does not.

The Pentax DA* 55mm f/1.4 sits in a weird spot in our database. Its build quality lands in the 78th percentile, which is genuinely impressive, and owners give it a 4.8 out of 5 across six reviews. But the optical score is dead average at the 53rd percentile, and the aperture ranking is a disappointing 22nd percentile. That gap between how it feels in your hands and how it performs on paper is the story here.

At 375g with weather sealing and a 9-blade diaphragm, this is a lens built for people who shoot in real conditions, not just test charts. The f/1.4 max aperture sounds fast, but the constant f/22 minimum aperture is an odd spec that drags down its versatility score to the 33rd percentile. Still, for Pentax shooters who want a weather-sealed portrait prime, there's not much else in this mount.

Skip this if you shoot on an older Pentax body and rely on autofocus. The SDM system has documented issues on older DSLRs, and our AF score is only average. Also skip it if bokeh quality is your top priority, since the 25th percentile bokeh ranking is one of the weakest we've seen for a lens with a 9-blade diaphragm. And if you need any kind of stabilization, look elsewhere. The 34th percentile stabilization score means you'll be relying entirely on your body's IBIS, if it has any.

The Pentax DA* 55mm f/1.4 is a lens that owners love and our database is lukewarm on. The 4.8/5 user rating and 85/100 sentiment score tell you real photographers are getting great results. The 53rd percentile optical score and 25th percentile bokeh ranking tell you it's not class-leading on paper. For Pentax shooters who need weather sealing and a fast prime, this is a solid choice, especially if you can find it at the lower end of that EUR price range. Just know that the SDM autofocus has a reputation for being finicky on older bodies.