Monday, August 18, 2014

Nikon AF-S NIKKOR 24-70 F2.8G ED Review (Mostly on DX)


"Real pros don't use normal zooms."

 Pish-tosh.

It would be a brave event shooter who didn't have a AF-S NIKKOR 24-70 F2.8G ED in his/her camera bag; after all, few would dare juggling with primes during a wedding shoot. The truth is, even if photographers end up specializing on specific focal lengths, the versatility of he Nikon 24-70mm speaks for itself; hence, one of Nikon's best-selling FX zooms.

Another reason why that ascertain doesn't seem to ring true is because of the sheer cost of this lens; maybe it's true that the majority of shots are done between 24mm and 70mm, but the truth is that the majority of people don't have, can't afford or are saving up for the 24-70mm lens. Though its practically a bargain compared to the price that Canon is asking for their version of this lens, it still tends to occupy a lot of Nikon shooter's wish lists.


On a DX Body 



There is a temptation for DX owners to try to slowly accumulate FX lenses for an eventual jump to an FX body. The accompanying illustrations depict the downside to this strategy: the 24-70mm is a long lens, the longest of the 24-70mm full frame lenses made by any manufacturer for any mount, in fact. It's as long as a consumer-level zoom lens, and is in fact heavier. The reason for this is because it was designed to excel as a professional-tool; portability takes a back-seat to optical performance.


This means that carrying the 24-70mm on a DX body entails some compromises. The weight and size won't require the most substantial of camera bags, but you will likely need something better than entry level. Of course, there's the crop factor to contend with; 24mm only gives the FX equivalent of 35mm field-of view, which limits this lens' versatility indoors.

There can be a lot to be said to describe the optical performance of this lens, but it can be simply described as generally excellent, though not without weaknesses with the aperture held wide-open or with the lens set to its widest position. Chromatic aberration is on the high side, but not out of keeping for a fast aperture lens. As with many of the other contemporary professional-grade lenses, sharpness is fairly consistent throughout the zoom range.

DX Bokeh



Because lens optical performance is a complex topic, the objective description of such is beyond the scope of this blog. Though there are many aspects to quantify (resolving power, field curvature, distortion, aberrations, etc.), a general sense of a lens’ character can be determined without resorting to lab testing. The following is one aspect; bokeh and apparent background blur with the subject at short distances.  

Bokeh at 24mm


The following was shot on a D7100. Bearing in mind that 24mm and f/2.8 on a DX body is the equivalent of 35mm at f/4, there isn't much opportunity to develop meaningful foreground background isolation. However, that shouldn't the be-all and end-all of using depth of field. You don't have to obliterate the background to convey a sense of depth. Though the 24-70mm isn't a bokeh champion, the background rendition is generally smooth enough that it can keep the busy background in this sample under a semblance of control. Because this is DX and we are looking through the central portion of the lens, the image rendition is clean even at f/2.8 and almost free of an distractions like vignetting and spherical aberrations. 

24mm, f/2.8
24mm, f/2.8 (100% crop)

24mm, f/4
24mm, f/4 (100% crop)

24mm, f/5.6
24mm, f/5.6 (100% crop)

24mm, f/8
24mm, f/8 (100% crop)

Bokeh at 70mm


On DX, bokeh is more useful on the longer end of the lens where the the increased focal length also magnifies the background blur relative to the subject. Because it's DX and because the lens only opens up to f/2.8, there isn't the outright defocus that you would see with either a 50mm or 85mm prime. However, a lens of this type on a crop-sensor camera acts like a more flexible version of a portrait lens, and you are essentially trading bokeh for focal length flexibility. 

70mm, f/2.8
70mm, f/2.8 (100% crop)

70mm, f/4
24mm, f/4 (100% crop)

70mm, f.5.6
24mm, f/5.6 (100% crop)

70mm, f/8
24mm, f/8 (100% crop)

The take home message is not to expect miracles with a f/2.8 standard-zoom on a DX body, but that if you do get to use one, the optical quality that this lens produces is better than a DX-specific lens at equivalent focal lengths.

FX Bokeh


Of course, the 24-70mm was really designed for the FX bodies. The following were shot with a Nikon D610. The focus distance is similar to the above samples, but the sets aren't directly comparable because of the different background distances. However, you can get a visual sense of how much more room you have to play with in terms of bokeh and foreground-background subject isolation.

Interestingly enough, just because you have a lot of "bokeh power", it does not mean that you will automatically produce a smooth looking image. In the f/2.8 example below, there's an odd shadow-lattice pattern that predominates across the image. It's not actually produced by one particular thing, but instead, is the sum of the blur from the regularly repeating  patterns of the tiles and the trim beneath the green kiosk.

70mm, f.2.8
70mm, f/2.8 (100% crop)


70mm, f/4
70mm, f/4 (100% crop)

70mm, f/5.6
70mm, f/5.6 (100% crop)

70mm, f/8
70mm, f/8 (100% crop)

There's very little to complain about in the above sample. One note about the handling; even on a D610, this lens still feels long and  front-heavy. It never quite reaches a comfortable balance until it's home on a either a D800/D810 or a D4/D4s.

Concluding Thoughts




If you are doing paid work, then you probably know whether or not you need this lens.

Many amateur photographers look for f/2.8 lenses to help with low-light shooting, and are then disappointed to discover that lenses like the AF-S NIKKOR 24-70 F2.8G ED don't have image stabilization. Though it would benefit from it, it actually doesn't need it. The problem is that on a non-professional setup, the handling is a slight bit off, but when you attach this lens to a D810 or D4s, the balance is just right. The sheer mass of the setup is its own version of image-stabilization; though its heavy, the camera and lens sit still in your hands.

Speaking of image stabilization, the Tamron 24-70/2.8 VC is a natural choice to consider. For its price, the Tamron is good value for the money, but it lacks the outright optical quality of the Nikon. Chromatic aberration is lower, but vignetting is higher and  the general quality of the bokeh is more nervous than with the Nikon. Despite having a plastic/composite body, the Tamron feels sturdy and is only a modest bit lighter than the Nikon.

Though it would be a brave choice for any manufacture to do so, the most helpful feature that is missing from the Nikon 24-70mm is a tripod collar. The manufacturers would never do such a thing; it's just not used on a standard-zoom lens. However, the problem with tripod works is that the mass of the lens imposes quite a bit of leverage because the mounting point is on the body. This requires a sturdy tripod head, and the problem with that is that most tripods/heads that can support this lens/camera combination tend to be pricey. The same challenge also applies to using this lens on camera-stabilizers for video work. This is yet another example of how the cost of acquiring FX equipment is not just in the camera and lenses alone.

Though one of the better selling FX lenses, the 24-70mm isn't traded as often as would be expected on the used market. The lens covers a usable focal length range, is of high quality and has a generally good reputation. A good percentage of these lenses are bought with protective front filters, usually of a higher quality to match the performance of the lens. $200 USD or more is a lot of money for something that slightly degrades your image quality, but its a price that many are willing to pay to protect a lens that sells for over $1600.

If you are looking for one on the used market make sure that you try one extensively before completing a purchase. These are extremely rugged lenses that have been known to survive not only merely bumps, but actual drops. Aside from obvious physical wear, make sure that the zoom and focus rings turn smoothly without any points of increased friction during operation. Autofocus speed should be near instantaneous in all circumstances. Marked hesitancy or slow autofocus is a sign that the lens needs the service attention.



With thanks to Broadway Camera

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