Rokinon 8mm vs. 10mm vs. Sigma 8-16mm vs. Pentax 10-17mm Ultra-wide Showdown

Flare and Starbursts

Imperfections in an optical design can lead to aberrations such as fringing, lens flare, and ghosting, all undesired symptoms of having a strong light source enter your field of view.  When used in conjunction with a lens hood, modern glass coatings do an excellent job of suppressing lens flare, and some better than others. Pentax has been widely regarded as having some of the best coatings in the industry, a reputation built over decades through their "Super Multi Coating," largely known via the iconic SMC, and most recently with their improved HD (High Definition) coating.

Due to the inherent relationship between flaring and the production of starbursts, especially with ultra wide angle lenses, we combined the two on this page to compare them during both the day and at night. The following page will be dedicated to chromatic aberration, particularly in the form of purple fringing.

Going into these comparisons, the mystery we wanted to solve was this: despite being the oldest lens of the four, does Pentax's coating prowess handle flare well, or have the third party contenders caught up? Especially Rokinon with its latest nano-coating in the 10mm prime, let's find out!

Comparison One - Angular Sunlight

We wanted to see what happens when you place the sun at the extreme corner of the frame. Not only is this much more common compositionally than centering the sun, but it's very stressful to an optical design thanks to the angle the light rays strike each piece of glass within the lens and refract.

All of the shots for this series were taken using the below settings:

The full set of 31 RAW images can be downloaded here (681 Mb).

Comparison Two - Community Center at Night

For our second flare and starburst stress test, we waited for the sun to do down and planted our tripod in the sand outside a beach town's community center on the night of a full moon.

All of the shots for this series were taken using the below settings:

The full set of 27 RAW images can be downloaded here (524 Mb).

Verdict

Regarding flare, the venerable SMC does a great job holding its own, effectively mitigating all forms of flare that we could see. The only lens that struggled was the 10mm prime, which was surprising because it's the newest optical design and features Rokinon's latest nano coatings.

At the end of the day, though, all the lenses should be commended. They all did better than we initially thought going into the first comparison regarding mitigating massive swaths of flaring, which honestly wouldn't be unexpected considering just how much light is being bent inside these ultra wide lenses. More of an issue than actual flare was chromatic aberration at the source of these bright spots, which all but the Sigma had trouble with controlling regardless of the aperture.

On the other hand, we found the starbursts to generally be sub-par and less than "mind controlling" as the SMC DA 15mm F4 Limited is known to be with how it handles light sources. Once the lot of lenses really had any attractive starbursts, they were already beyond the point where diffraction was taking its toll on resolution.

On the next page we look at how fringing is controlled by three of the four. And the fourth lens, well, not so much...