Sunday, April 28, 2013

F/4 OR F/2.8? THE NIKON 70-200MM LENSES COMPARED!

Since the advent of professional grade zoom lenses, the 70/80mm to 200mm f/2.8 has been a favourite and a must have for all kind of photographers, be they PJ, sport, nature, travel or landscape shooters. All major manufacturers have been offering such a lens for many years; leaving prototypes aside, Nikon in particular is producing a 80-200mm f/2.8 since 1982 and it's on their 8th iteration of this design, the last two covering a 70 to 200mm range and including VR (Nikon's image stabilisation system). But what about a slower, constant aperture, professional grade 70-200mm, one that would be smaller, lighter and less expensive than the classic f/2.8, while still offering great image quality - a lens that would be ideal for travel and landscape photography?

Once upon a time, Nikon offered the capable 70-210mm f/4 (1986-1988); after discontinuing that lens, however, apparently they decided that the Pros would only need the constant f/2.8 version, while everyone else would have to do with - in order of appearance - lenses such as the 70-210mm f/4-5.6 (1987-2000), 75-300mm f/4.5-5.6 (1989-1998), 70-300mm f/4-5.6, 70-300mm f/4.5-5.6 VR (2006). In the meantime, Canon offered a 70-200 f/4 since 1999 (today in the form of the 70-200mm f/4 L IS USM and 70-200mm f/4L USM, respectively with or without image stabilisation), a lens much loved by Canon shooters and much envied by Nikon users, forced to always carry around their 70-200mm f/2.8.

Until now. In 2012, Nikon finally released the Nikon 70-200mm f/4G ED VR, a professional grade lens featuring all of Nikon's most advanced wizardries to date. A full specification list is available on Nikon's website; let me just point out here the most significative technologies featured in this lens:

- Nano Crystal Coating & Super Integrated Coating;
- 3 ED elements, 1 Super Refractive element;
- VR III (the first lens to feature it, by the way) for a claimed 5-stops advantage;
- 9-blade diaphragm;
- AF-S silent autofocus with instant manual override;
- Internal Zoom and Internal Focus (barrel length never changes and the front of the lens doesn't rotate);
- Minimum focus distance of 3.28ft (1 mt).

Curious to see how this new lens would perform and compare to the legendary 70-200mm f/2.8G ED VR II, I ordered one as soon as possible: luckily, the lens arrived in time for my departure to Death Valley in late January. I immediately adjusted focus for my D800E and brought it with me to put it through its paces in the field (see REAL WORLD SAMPLES at the end of this review), which is the only thing that really matters to me when I evaluate equipment to create images for VIERI BOTTAZZINI FINE ART PHOTOGRAPHY. So how did the new 70-200mm f/4 perform and how did it compare with the 70-200mm f/2.8? Read all about it after the break!

The Nikon 70-200 f/4G ED VR

ERGONOMICS, BUILD AND IN-USE
In short, the 70-200mm f/4 is ergonomically near perfect. Much lighter and quite a bit narrower than the 70-200mm f/2.8, it sits perfectly in my hand (I am 6'1" and have quite large hands) and can be used for hours without fatigue. The focus ring is well damped and has a shorter throw compared to that of the 70-200mm f/2.8; the zoom ring is also well damped, offering slightly less resistance than the 70-200mm f/2.8's. With the lens hood reversed on the lens, however, you cannot reach the focus ring, while on the 70-200mm f/2.8 you can - sort of - operate it by reaching through the scalloped petals of the hood.


Build quality is very good, the lens feels solidly built and operates smoothly; however, it doesn't feel like it would be able to take the same amount of abuse the 70-200mm f/2.8 would.


On the lens barrel, you have the usual control cluster:

- A/M-M, to switch between AF with instant manual override and manual focus only;
- Full / Infinity-3m: to limit the focus range to 3m (the 70-200mm f/2.8 has a slightly more useful 5m);
- VR On-Off and Normal-Active, to set your VR preferences.


All my AF-S lenses are set up with the first control on A/M; unless you are dead set on using MF only, this setup offers you the best of both worlds, and even more so if you set "AF-ON only" for focus activation on camera bodies that support this feature: this way you'll get total control over focus, with your AF activated separately from the shutter and instant manual focus override at your fingertips when you need it.

On the 70-200mm f/4, I'd leave the focus limiter on "Full" for general travel / landscape photography since: a. the difference in speed between the two modes is negligible; and b. Murphy's law will ensure that when you'll encounter a situations where you might need the full range, you'll have the limiter on. On the other hand, I would definitely move it to "Infinity-3m" when you know for sure that your subjects will never get closer than 3m (i.e. for sports or wildlife), since AF locks more resolutely and hunts a bit less in this configuration.

Nikon claims that the new 70-200mm f/4's VR III will give you an extra 5 stops shutter speed; in use, I'd say that you gain an average of about 4 stops, 5 at the wider end and if your technique is good to start with. This is very impressive indeed, allowing you to get handheld shots that you wouldn't be able to bag without VR. According to Nikon, you can leave VR on even when the camera is on a tripod, but I'd not recommend it for critical work; you can leave it on when the camera is on a monopod though.

One note on the very different claims of 3, 4, 5 or whatever f-stops gains that you see online: reviewers tend to measure the effectiveness of VR subjectively, shooting at something while hand-holding the camera at different shutter speeds. While this is possibly the only approach that makes sense if you want to know how a lens behaves in the real world, how someone else's results will apply to you obviously depends on how steady or shaky your hands are to begin with and, especially, on the movement's pattern and range of your hand-shaking. My hands are pretty steady and I spent years working on my technique; however, your hands might be steadier or shakier and your technique might be better or worse than mine, and therefore the results you'll get may vary accordingly. See the (uninspiring) sample below for a hand-held shot at 200mm, 1/20 sec. and a 100% crop:

Nikon 70-200m f/4 @200mm, 1/20 sec. @ f/8

Nikon 70-200m f/4 @200mm, 1/20 sec. @ f/8: 100% crop

As you can see, VR works indeed very well: being able to get such a sharp image at 1/20 sec. at 200mm is remarkable.

If you shoot your 70-200mm f/4 with your camera on a tripod or a monopod, I'd recommend to use a tripod collar, even if it is lighter than the 70-200mm f/2.8. With it:

- Your camera/lens combination will be better balanced on your tripod, and a steadier camera/lens combo means less vibration and thus higher image quality; even more so if you use lighter, non-pro bodies;
- You'll put less strain on the camera's lens mount, which is important especially for non-pro bodies with a less solid lens mount assembly;
- You'll be much faster in turning your camera/lens from landscape to portrait orientation.

Unfortunately, Nikon got stingy and didn't include a tripod collar with the 70-200mm f/4; so, if you plan to use it on a tripod or a monopod, Nikon asks you to spend $169 US to get the Nikon RT-1 collar (B&H prices as April 27, 2013). Another option, especially if your tripod head is Arca-Swiss compatible, is to skip on the Nikon collar and get the Kirk NC-70-200 instead; is $10 US cheaper and comes with a built-in Arca-Swiss compatible plate. I ordered one but haven't got it in my hands yet; however, by looking at Kirk's product images it looks like it will provide better stabilisation than the Nikon's: I will review it as soon as I get it (it will probably be next month). ReallyRightStuff is also in the process of making a collar for the 70-200mm f/4, but they are asking $195 US for it and they are still in the pre-order phase - as in, you cannot even see how it will look like yet to get an idea.

On a personal note, thanks to Nikon not shipping a tripod collar with the lens and not having one available for me to buy at the time, in Death Valley I lost a lot of good images to camera/lens vibration: even using mirror lock-up and a remote release, the D800E's shutter slap was strong enough to generate micro motion blur, especially in the central section of images shot in portrait orientation at speeds between 1/4 and 1/15 sec. While this is something you might not notice if you just look at your images at web resolution or even on small prints, for my VIERI BOTTAZZINI FINE ART PHOTOGRAPHY business I need to print my images very big, and that tiny motion blur was enough to ruin a lot of images for me. So, if this sounds close to the way you'd use this lens or the way you plan to use your images, follow my advice and get a tripod collar, you'll be glad you did.

IMAGE QUALITY: THE GOOD, THE BAD AND THE UGLY
As I mentioned before, for my particular work I need the lens to perform flawlessly into the corners on a FF body, and particularly on the D800E which - as users of this camera well know - puts a lot of strain on the optics you pair it with. So, how good is the 70-200mm f/4 on the D800E, and how does it compare with the legendary 70-200mm f/2.8?

In short, the 70-200mm f/4 is a very strong performer at all focal lengths, and especially so in the centre of the frame. Sharpness and micro-contrast are very high; chromatic aberrations are well controlled; bokeh is very pleasant. However, no lens is perfect: let's examine its performance more in detail, so you can see with your eyes if this is the lens for you or not.

Sharpness
Let's starts examining sharpness; the following quick test features the very uninspiring building across the street (its small tiles make for a good test scene). The D800E was on a sturdy Series 5 Gitzo tripod; camera position wasn't changed during lens swapping; 3 sets of images were shot for each frame, refocussing each time, and the best shot of the three has been chosen for the comparison; all files were shot in A mode w/remote and processed in Nikon Capture NX 2; the same WB was applied on all files in a same set; Landscape picture control was used; all software corrections were set to off; Capture's sharpening was set to off, and files were all equally sharpened slightly using my usual routine.

The test scene first:

Nikon 70-200m f/4 @70mm, uncorrected

Let's start with 100% center crops (click to enlarge):



Both lenses are excellent performers here, showing amazing sharpness wide open and very good micro-contrast. Performance is consistent stopping down, until some softening due to diffraction kicks in at f/8 and is definitely visible at f/11.

100% lower left crops (click to enlarge):



In the corners, the 70-200mm f/2.8 takes very clearly the lead: slightly soft wide-open at f/2.8, it becomes already very good at f/4 and shows an amazing performance from f/5.6 through f/11 where diffraction start taking its toll. The 70-200mm f/4, on the other hand, is quite soft at f/4 and while it improves a bit at f/5.6 through f/11 it never gets really sharp at any aperture.

The relative performances stays the same over the zoom range; the 70-200mm f/4 improves its performance in the corners a little bit, but they never get quite as sharp as the excellent centre-frame at any focal length.

Let's see now how both lenses perform at 200mm, starting with the (uninspiring as usual) whole frame: 70-200mm f/4 first, followed by the 70-200mm f/2.8. As you can see, at this distance the 70-200mm f/2.8 "focus breaths" a bit, meaning that is a bit wider than its declared 200mm:

70-200mm f/4 @200mm, f/4

70-200mm f/2.8 @200mm, f/2.8

100% center crops first (click to enlarge):



As you can see, the new 70-200mm f/4 is at its best wide-open, where is indeed very sharp; stopping down, performance degrades slowly until, at f/11, diffraction definitely renders the image too soft for critical use. The 70-200mm f/2.8 is quite impressive wide open, and is at its best at f/4 and f/8. At first, I couldn't explain why the lens was slightly softer at f/5.6 than both f/4 and f/8, so I re-did the test three times to rule out user error. However, the results didn't change: after examining the corner crops, I concluded that the culprit could be field curvature (see below).

100% lower left corner crops (click to enlarge)



At 200mm, confirming the trend seen over the whole zoom range, the 70-200mm f/4 never gets really sharp in the far corners; best performance is seen at f/8, before diffraction starts to kick in at f/11. The 70-200mm f/2.8 is already pretty sharp wide open, and is at its best at f/5.6 which in the corners is better than both f/4 and f/8; as I said above, this could be a sign of field curvature - why it is so evident only at f/5.6, I guess only Nikon engineers know.

Vignetting
As expected, the 70-200mm f/4 has quite a bit of vignetting wide-open; stopping down, it cleans very quickly and while still visible at f/5.6, vignetting is completely gone at f/8. The 70-200mm f/2.8 shows about the same amount of vignette at f/2.8 as the 70-200mm f/4 does at f/4, however vignette cleans up slower on the faster lens, and traces are still visible at f/8. This behaviour is consistent at all focal lengths. See the samples below, uninspiring as usual, shot both at 70mm and a 200mm:



The samples above, shot seconds apart in A mode and processed exactly in the same way, shows us the differences in colour and contrast rendition between the two 70-200mm: the 70-200mm f/4 is a bit warmer than the 70-200mm f/2.8, and while the camera returned the exact same shutter speed for each pair of images shot at one given f-number, the histogram of the 70-200mm f/4's images is pushed about half-stop towards the highlights compared to those shot with the 70-200mm f/2.8.

(If Blogger doesn't allow you to expand them to their full size, please CLICK HERE to download the full set of images above and compare them at your leisure at %100 on your computer)

Distortion
To put it bluntly, the 70-200mm f/4 has a lot of distortion; much more so than the 70-200mm f/2.8, especially at the wide end, where the 70-200mm f/2.8 is basically neutral. At telephoto, both lens show pincushion distortion, with the 70-200mm f/2.8 being a bit better corrected.

If you plan to use it uncorrected, I definitely wouldn't use the 70-200mm f/4 for architecture or for any other application where keeping straight lines straight is important, i.e. seascapes featuring the horizon prominently in the frame: at 70mm barrel distortion is very evident, as is pincushion distortion at 200mm; as always, mid-focal lengths are better, but the lens is never neutral. You can get away with it by framing your images accordingly, trying to place straight lines as close to centre frame as possible (however, self-imposing such limitations is not always conducive to good compositions); if you really want or need to use this lens for such work, the better solution to preserve your artistic freedom is to compose a bit loosely and leave room for software correction in post-processing - be aware, however, that fixing distortion in post-processing lowers your image quality and might introduce some digital artefacts as well. Nikon Capture NX2 offers the option to automatically correct distortion, and as you can see below the corrected image is definitely better than the uncorrected one (with the caveats above):

Nikon 70-200m f/4 @70mm, uncorrected

Nikon 70-200m f/4 @70mm, corrected in Nikon Capture NX2

Nikon 70-200m f/2.8 @70mm, uncorrected

As you can see, the 70-200mm f/2.8's uncorrected image is better corrected than the 70-200mm f/4's corrected image, which in turn is better than the 70-200mm f/4's uncorrected one.

At 200mm, as you can see from the uncorrected images used for the vignetting test above, both lenses show evident pincushion distortion, with the 70-200mm f/4 being a bit worse than the 70-200mm f/2.8.

CA and flare
Both lenses suffer of "bokeh CA", showing magenta cast in the foreground and green cast in the background, with the faster 70-200mm f/2.8 being more prone to this effect. Stopping down cures it easily, and the effect is gone on both lenses by f/5.6. Both lenses uses Nikon's Nano Crystal Coating which should take care of flare and haze; indeed both lenses behave very well with the sun in the frame. With the sun just outside the frame, the 70-200mm f/4 can show some haze (loss of contrast) on the opposite side of the sun.

THE 70-200MM F/4 VS THE 70-200MM F/2.8: DIFFERENCES
So, what are the main differences between the 70-200mm f/4 and the 70-200mm f/2.8?

- Obviously, the 70-200mm f/4 is one stop slower than the 70-200mm f/2.8 and therefore offers slightly less DOF control;

- Weight and bulk: the 70-200mm f/4 is narrower, shorter and 690 gr. lighter than the 70-200mm f/2.8. As a Landscape / Fine Art photographer, I travel a lot and I do a lot of walking / trekking / hiking to get where I need to be while carrying all my equipment. While for what I shoot f/4 is plenty fast, 850 gr. vs 1540 gr. can make quite a difference after 3-4 hours of carrying a camera bag around. Just to give you an idea about what 690 gr. means: all new Nikon AF-S primes in the 24 to 85mm range are under 660 gr., and even the heavy 14-24mm f/2.8 AF-S is "just" 969 gr. Replacing the 70-200mm f/2.8 with the 70-200mm f/4 frees enough weight in your bag to carry one, two or even three extra lenses (if you'll decide to carry the 28mm, 50mm & 85mm f/1.8 AF-S, for instance), without any weight penalty: something to consider when weight and bulk are a concern;

- The 70-200mm f/4 focuses as close as 3.28ft or 1m vs 4.6ft or 1.4m for the 70-200mm f/2.8;

- The 70-200mm f/4 is a 200mm at all distances, while the 70-200mm f/2.8 suffers of "focus breathing", meaning that its actual focal lens changes with the distance you focus it at; the 70-200mm f/2.8 at minimum focussing distance is really a 70-135mm, while at infinity is a 72-192mm; you can see in my sharpness test image above how the 70-200mm f/2.8 is a bit "wider" at the 200mm than the 70-200mm f/4;

- The 70-200mm f/4 has a lot more distortion than the 70-200mm f/2.8 at both ends of its range, with a generous amount of barrel distortion at 70mm and pincushion distortion at 200mm, while the 70-200mm f/2.8 is almost neutral at 70mm and has just a bit of pincushion distortion at 200mm;

- The 70-200mm f/4's VR III is about one stop more effective than the older VR II featured in the 70-200mm f/2.8;

- The 70-200mm f/4 use 67mm filters, vs. the 70-200mm f/2.8 77mm;

- The 70-200mm f/4 doesn't come with a lens collar, while the 70-200mm f/2.8 has one; this will set you back another $160-170 US, but on the other hand allows you to skip the Nikon RT-1 if so you desire and choose a different solution, like the Kirk NC-70-200 with its built-in Arca-Swiss style release clamp;

- The 70-200mm f/4 is exactly $1.000 US cheaper than the 70-200mm f/2.8, lens only (B&H prices as April 27, 2013); if you want to add a lens collar, getting the slower lens will still save you $830 US.

CONCLUSIONS
I used both versions of the legendary Nikon 70-200mm f/2.8G ED VR for years, my only complains having been focus breathing, weight & bulk. When the Nikon 70-200mm f/4G ED VR was announced, I was among those who rejoiced at the news: finally Nikon gave us a 70-200mm designed around the needs of Travel / Landscape photographers. Small, light, professional-grade build & features, together with the promise of extra-high image quality: I was ecstatic. The first reviews confirmed me that Nikon was really onto something with this lens, despite a few claims of possible weakness on the wider end; naturally, I was eager to try it myself in the field.

In use, the new lens proved a joy to use, outputting sharp and pleasant images at all focal lengths; except for a healthy amount of distortion and some softness in the corners, the 70-200mm f/4 proved very difficult to fault optically on the D800E, which is a very demanding camera when it comes to lens quality.

The closest competitor to the 70-200mm f/4 is of course Nikon's own 70-200mm f/2.8: a tall order for sure, but one that the new 70-200mm f/4 met for the most part. Now, which lens to get?

RECOMMENDATIONS
I generally avoid recommending a lens over another without knowing what use one will do with it: however, in this case I'd recommend both the 70-200mm f/4 and the 70-200mm f/2.8 without hesitation. Which lens to choose depends on what you need and value the most; how much the difference in price, weight, lens speed, close range performance, distortion and so on are worth to you; finally, it depends on which lens better suits the subjects you shoot, your shooting style and needing. Only you can answer that, but the good news is that Nikon now offers us a choice in this very important range, a choice between two exceptional performers, each with different strengths and each answering to different needs. Once you make up your mind on which lens is the one for you, basically you can't go wrong with either 70-200mm.

In short:
- Those who either need f/2.8, need tack sharp corners or need the least possible amount of distortion and use a D800 or D800E, should get the 70-200mm f/2.8;
- Everyone else, especially DX users, can get the 70-200mm f/4 without losing anything and spend the extra $1.000 US on a trip to put their lens to a good use!

One last question: for my work, will I keep the 70-200mm f/4, the 70-200mm f/2.8 or neither?

The good thing is that when I set out to the field I now have three different options: the 70-200mm f/2.8, the 70-200mm f/4 or a combination of the 85mm f/1.4 AF-S + 135mm f/2.0 DC or 180mm f/2.8D. Either of these last two combinations are lighter than the 70-200mm f/2.8, but of course they lack VR, range, the possibility of using tele-converters and the flexibility of a zoom; in exchange for that, I'll get to squeeze a bit more image quality out of my camera, I'll get more speed and more DOF control (plus the DC feature if I choose the 135mm). I am generally more of a prime guy; however, both the 70-200mm f/2.8 and the 70-200mm f/4 are so good that they provide excellent alternatives. Truth is, for my work if the 70-200mm f/4 had less distortion and especially if it had sharper corners the choice would have been immediate; unfortunately this is not the case, so since at least one of the zoom will have to go I think I'll hold onto the 70-200mm f/2.8 and, sadly, I'll see the 70-200mm f/4 go.



REAL WORLD SAMPLES - DEATH VALLEY, 2013
Some images shot with the 70-200mm f/4 last January in DEATH VALLEY:

Badwater's reflections, I (Nikon 70-200mm f/4 @70mm, 1/2 sec. @ f/8)

Devil's Corn Field and Mesquite Dunes
Devil's Corn Field and Mesquite Dunes

Devil's Cornfield (Nikon 70-200mm f/4 @200mm, 1/250 sec. @ f/8)

The Golden Dome (Nikon 70-200mm f/4 @70mm, 1/8 sec. @ f/11)

Plug: high-quality, signed, certified and WARRANTIED Fine Art Prints are available for sale of my VIERI BOTTAZZINI FINE ART PHOTOGRAPHY website, and on the new DEATH VALLEY gallery as well.

OK, this is about it for my comparison of the Nikon 70-200mm f/4 AF-S VR & the 70-200mm f/2.8 AF-S VR II! Thank you for reading so far, and stay tuned for more...

Now for the technical stuff (click to go to the related product page): all test images taken with the 70-200mm f/4 AF-S VR & 70-200mm f/2.8 AF-S VR II, as well as all DEATH VALLEY images, have been shot with a Nikon D800E. Product shots in this article have been shot with my trusty Nikon D3x, equipped with the Nikon 85mm f/2.8D PC-E and the Nikon 135mm f/2.0 DC. Lighting for those shots has been provided by two SB-700 Speedlight, controlled via PocketWizards MiniTT1FlexTT5 & AC3. For support I used a Gitzo tripod equipped with an Acratech GP-s ballhead; last, but certainly not least, in DEATH VALLEY I used Singh-Ray filters, including a polarizer & various ND filters. All photographs have been developed in Nikon Capture NX 2 and finished in Adobe Photoshop CS6

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