Similar to the the 17-40, focusing on the 16-35 F4 is all internal. This means the end of the lens barrel doesn’t rotate or extend in length when the focal length is adjusted – it’s completely self-contained. Not having the front lens element move forward and backwards while adjusting the focal length ring is advantageous for landscape photographers who frequently use front-loading Graduated Neutral Density filters.
The front lens element does however move forward and backwards within the confine of the lens enclosure, but it doesn’t protrude beyond the end of the lens barrel. As we’ll learn below, this is why Canon on page 2 of their instruction manual says that a UV filter is required to complete the weather-sealing.
The weight of the 16-35 F4 is heavier than the 17-40, yet lighter than the Canon 16-35 F2.8:
The 16-35 F4 has a 9-bladed (rounded) aperture design, which produces 18-point starbursts from specular highlights when using the higher F-numbers – F18 – F22. The Canon 17-40 and Canon 16-35 F2.8 II both use 7-bladed apertures producing 14-point starbursts. Although subjective, I prefer the 18-point starbursts.
77mm has been selected as the barrel thread size on the 16-35 F4, which I’m pretty happy about. I’ve all but standardized all my filters to 77m, as it’s the most readily found on most L lenses.
The Canon 16-35 F4 is constructed of plastic, and when compared to the 17-40, has a matte non-glossy fit and finish. All of the design cues come directly from other L lenses, no real surprises here. The L-series signature plastic red ring is a bit more translucent than other L-lenses, which is entirely aesthetic but it was one of the first things I noticed.
With its weight and balance taken into account, the plastic construction at first may not feel plastic, but it is. It’s size and weight are hefty, so all in all it’s a solid feeling and well built lens.
Solid plastic feel, all-internal focusing is ideal.
Like all of the other L lenses I’ve owned, the 16-35 F4 is weather-sealed against the elements. In my hands-on experience with this lens in the field, the weather-sealing is there and it does actually work, and it works very well. I frequently shoot along the pacific coastline, and it’s unfortunately all too common for rogue waves to break all over the place, getting salt water annoyingly all over everything, lens included. On multiple occasions of getting it completely wet, it has functioned perfectly once shaken off and dried. No moisture has yet to occur on the internals, as would be visible by shining a light down into the front of the lens.
However, although the lens is quote unquote ‘Weather-sealed’ Canon (Nikon and Sony too) recommend protective filters for the purpose of completing the weather seal. “Without a filter, the lens is not dust or water resistant.”, as Canon clearly states on page 2 of their lens user manual for the 16-35 F4. Therefore a UV filter completes the lens weather seal to ensure proper functioning and performance, as well as to simply ensure a long life.
However I’ll reiterate what I’ve so far experienced and illustrated above in the the VIGNETTING / LIGHT FALLOFF section: the 16-35 F4 has inherent light falloff without any filter attached at 16mm of 1 or 2-stops. Although the manufacturers indicate getting one in order to complete the weather-sealing construction, with the 16-35 F4 it’s important to consider the filter frame thickness so as to reduce the light falloff which occurs at filter thicknesses of 4mm or higher, and visibly noticeable at 6mm.
So it’s essentially a weather-sealing feature vs. vignetting feature going on here. If you want to protect the filter and ensure long-life you risk adding stops of light falloff, and if you don’t use any UV filter you risk getting elements inside the lens and in-between the lens element groups.
My recommendation is to find a UV filter with very high light transmittance, high quality MRC and a frame thickness below 4mm. Ideally 3.5mm or lower, and double-threaded.
Durable construction means this lens can stand up to even the harshest of elements, given a UV filter is used to complete the weather-sealing.
With regards to functionality, the 16-35 F4’s focusing ring operates at a much higher threshold than the 17-40; that is to say that the image is either IN FOCUS or OUT OF FOCUS over a smaller distance on the focus ring, making it easier (and faster) to get critically sharp.
The focus ring is smoothly dampened. Even a delicate focus adjustment is smooth and finely pitched, allowing for very precise focus adjustments.
The focal length adjustment ring is likewise well dampened and smooth, with about twice the dampening inertia as compared to the focusing ring. And again, adjusting the focal length does not increase or decrease the size of the lens – it remains fixed in physical size regardless of whether the lens is at 16mm or 35mm.
FOCUS & ZOOM SUMMARY
Focusing ring feels the same as all the other L-lens focusing rings, yet it has a better and more sensitive focusing threshold than the 17-40.
The 16-35 F4’s AF is powered by Canon’s fast and power efficient Ultrasonic Motor (USM), which also allows for manual focus adjustments to be made at any time, intelligently allowing the photographer override AF control. The manual focus ring on the 16-35 F4 is also larger than the Canon 17-40, making it easier to get grip on the focus controls no matter what position you’re in.
In short, no surprises here – another solid USM lens.
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