Back in July, I spent a couple of weeks with the Nikon 500mm f/5.6 PF lens (to be precise the Nikon 500mm f/5.6E PF ED VR AF-S NIKKOR Lens). I rented it from Lenses for Hire to use at the Shuttleworth Collection and RIAT for aircraft, and on Skomer and Oare marshes for birds (I got a nice discount from them for visiting their stand at The Photography Show - thanks!). There have been quite a number of reviews of this lens – in fact, I think it's one of the more reviewed lenses that I'm aware of – but I've seen very little about its use with aviation, and there are one or two points also about bird photography that I don't think have really come out, especially in relation to its use with small birds.
The great thing about the 500mm f/5.6 PF lens is that it is much smaller and lighter than the classic f/4 lens (1460g Nikon 500mm f/5.6E PF ED VR AF-S NIKKOR Lens vs 3090g Nikon AF-S NIKKOR 500mm Lens f/4E FL ED VR), although it comes with a one-stop penalty for both light grasp and potential for subject isolation. However, at about half the weight and almost a third of the price new, it does give the appearance of a compelling option.
If you want to see comprehensive reviews, those from Richard Peters, Thom Hogan, and Backcountry Gallery are all excellent. If you want MTF measurements have a look at Ephotozine’s review. The full specifications are on the Nikon website.
This piece will be about my impressions of the 500mm PF lens after a couple of weeks of usage in relation to my practice and my expectations of what a good lens should be able to do. There have also been a lot of comments on various forums about potential limitations of this lens so I'll mention a couple of them as well as we go along.
Why am I interested in a 500mm lens for aircraft? For about a decade, I've been using the 200-400mm lens with success: it got me my ARPS, after all. Since the Shoreham air crash, aircraft generally fly further away from people, and where 400mm was fine in the past, it can be too little now and lead to excessive cropping. I'm lucky enough to have two cameras (a full-frame D810 and crop-sensor D500), so the combination of 70-200mm, 200-400mm, and 500mm lenses gives me everything and more that I could want. The 200-400 is also excellent for wildlife if you can get close enough, but 500mm gives more options without excessive cropping.
Looking at pictures
The first thing to say is that the 500 PF lens is very sharp, and meets my expectations for a 500mm prime lens. Specific comparisons given in the Backcountry Galleries video shows that it is essentially comparable to the f/4 E lens, one of the sharpest lenses I have ever come across.
Most lenses sharpen up quite a lot as they are stopped down, but this lens can be used wide open without, as far as I can see, any penalty at all. The sharpness is also edge-to-edge when used wide open: this frees you to compose as you see fit (put the subject on the edge of the frame if you want, without worrying that it will lose definition). You can see this in the MTF measurements, too, at Ephotozine.
I've seen some comments on some online forums that they don't like the quality of the out of focus areas (the bokeh) and the way the focus transitions between sharp and unsharp areas. Well, I don't know what the complaints are. There's very smooth bokeh when the background is fully defocused. At the Shuttleworth Collection, I photographed several aircraft against various backgrounds that were not fully defocused, with small details from leaves, trees, and buildings. Under these conditions, my aperture is limited by the shutter speed I want: on a bright day, even at ISO Lo1, getting, say 1/80 may mean that the aperture is well stopped down, so the background is still partially focussed. Perhaps it could be smoother, but overall, it is a non-issue for my taste. The quality of the bokeh does not seem to me to be a problem at all. The focus also degrades reasonably elegantly from sharp to defocused areas, and again I can't see a problem.
Speed of focusing and focusing pickup
A critical factor when photographing birds or planes is the ability of a lens to track focus accurately on a fast-moving subject, and, especially, to pick up focus quickly.
One reason why I would never consider buying the Nikon 200-500mm lens is the issue of picking up focus quickly. I tried one with red kites at Gigrin farm, photographing the fast-moving birds as they swoop in for food. I found it impossible to reliably pick up focus on the swooping birds with this lens on a D810. By comparison, the 500mm f/4 E FL and my 200-400mm f/4 VRII lens both picked up focus extremely quickly. I haven't repeated this with the 500mm PF lens (although I'm very tempted to go back to Gigrin at some point) but I had no problem picking up focus either at RIAT or Skomer.
The instance I was most pleased with the 500mm PF lens was with the USAF F-16 at RIAT. On the Thursday evening, in lowering light, the F-16 approached very low and very fast for a pass along the runway, appearing out of the blue from behind. I caught him coming in about five or six seconds before he came past me: in that time, I managed to raise the lens to my eye, lock focus and pan with him, getting a burst of 22 frames. He was in focus in each one, moving towards me in excess of 500 mph. This enabled me to get a picture I'm pleased with (the opening picture of this piece). So, I've no qualms about the ability of this lens to pick up and track focus on my D500. (This was using AF-C, group area autofocus and back button focus.)
Vibration reduction (image stabilisation)
It is important to me is to be able to photograph aircraft at shutter speeds that are compatible with maintaining the blur on propellers, or motion blur in the background of aircraft taking off/landing. This means that shutter speeds between 1/80-1/160 are critical. Good image stabilisation is therefore essential: the "one over the focal length" rule of thumb would mean that you would not normally expect to be able to use this reliably at less than 1/500 second.
One forum user described experiments with shooting a static target at different shutter speeds and concluded that the VR is very good except at speeds around 1/80-1/100. I have not attempted to repeat that experiment and all I can mention is my general observations.
In general, with moving aircraft you are trying to pan with the aircraft's movement: however, the aircraft might be bouncing on a grass runway; or perhaps, on takeoff, its motion is not only forward, it is also lifting its nose, etc. So in this context, it's highly unlikely that you will get a perfect set of sharp images using a long lens at a slow shutter speed as an aircraft moves past. Nonetheless, I found that in every set of exposures in a sequence there were sharp images between 1/60-1/160. So even if it is correct that the VR is weakest in that exposure range, in practice it did not prevent me from getting the pictures I wanted. I was using Sport mode for this.
Parenthetically, I can also mention that when I went along to a launch event for the mirrorless Z cameras in London last year, I tried a 500mm PF lens on a Z7 with the FTZ adaptor. The in-body and in-lens image stabilisation work together, and (just judging on the rear screen) I was getting sharp pictures at about 1/10 second exposures. Bloody amazing!
Depth of field: Subject isolation vs subject sharpness
One of the biggest weaknesses of the 500mm PF lens compared to its f/4 bigger sister is that the potential to isolate subjects is less. An f/5.6 lens can never provide the subject isolation potential of an f/4 lens. This is a concern for anybody who is trying to shoot wildlife in a busy background, for example, a predator sitting in tall grass or foliage. But, for somebody who enjoys photographing smallish birds, is this always such an issue?
Something that is almost never mentioned in reviews is that when shooting small birds at relatively short distances, depth of field is at a premium. At the moment, there is such a culture of shooting a lens wide open that many people seem to forget that if you want to get all – or even most – of your subject in focus, you need more rather than less depth of field. There are a lot of online depth of field calculators (which, actually, are rather generous in their interpretation of what depth of field really is). Suppose you're photographing a small bird, like goldfinch or kingfisher, at a distance of 5m: the depth of field is 2cm at f/4. Given that kingfisher is around 16cm long, such a depth of field is very limiting on your potential composition. Even at f/11 it's only 6cm. Getting in close to small birds (shooting from a hide or with good fieldcraft) means that backgrounds can usually be completely suppressed, so the issue of f/4 vs f/5.6 is moot.
In terms of my photography, I had a look in my Lightroom catalogue to see how I've used 500mm f/4 lenses in the past (both the Nikon AFS-VR and the new E FL lens). My Lightroom catalogue has 3041 raw images taken with these lenses. Of these, 315 (just over 10%) were shot at f/4. 2067 were shot between f/5.6 and f/16, i.e. about 87%.
So, for me, although f/4 is certainly an advantage – and it is a big deal in low light – it is not sine qua non. Nearly 90% of the time I didn't use it.
One other limiting factor of using an f/5.6 lens is with teleconverters. I have used the TCE-III 1.4 teleconverter with great success on the f/4 lenses: it does not seem to substantially degrade image quality, and it does give really useful extra reach. But, there is a one-stop penalty, i.e. the f/4 lens becomes f/5.6: worse, an f/5.6 lens becomes f/8. Using a 1.4TC with the 500mmPF lens would be very limiting both in terms of light grasp, and the number of focus points that work at f/8.
The thing is, though, that with a 1.4X teleconverter on a 500mm f/4 lens using a full-frame camera, you get a 700mm f/5.6 lens. However, if I use a 500mm f/5.6 PF lens on my Nikon D500, an APSC crop-sensor camera, I get a field of view equivalent to 750 mm, and it is still f/5.6. (Clearly, using a 500mm f/4 + TC on the D500 I would get a much longer lens still, but there are real difficulties in practice of using a 1050mm lens).
In all, for me, given the price and weight differences between the f/4 lens and the f/5.6 lens, in practice the f/5.6 lens is a much more suitable choice.
The long and short of it is that I have decided to order the PF lens. There is a saying that the best camera is the one that you have with you. By the same token, the best lens is the one that you have with you. I found on Skomer that I was happy to carry the 500 PF all day*, and it was no more of a burden than carrying my 70-200mm f/2.8. While the latest version of the Nikon 500mm f/4 lens (the E FL lens) is much lighter than previous versions, it is still heavier and much more cumbersome. The 500mm PF lens is being produced at a very low rate, perhaps 1000 per month for the whole world's demand, which means that there are very long waiting lists for it. I've no idea when mine will arrive, but it may be some months yet**. There may be occasions when I want to photograph something in very low light (for example, an owl at dusk), in which case I can rent the f/4 lens. But I expect that, for my personal practice, the PF lens will meet 90% of my needs.
*If I'm so fussed about small, light kit, you may ask why I would not add an Olympus 300mm f/4 to my kit to use with the GX9 instead of getting the Nikon 500mm PF. It would be £1000 less, and the combination would be lighter, for an equivalent 600mm f/4. (1) I don't think the focussing on the GX9, even though it is good, is in the same league as the D500 for fast moving subjects (2) subject tracking with the EVF and focus blackout between shots is much worse on the GX9. So, why not get an EM1 MkII to complement an Olympus 300mm f/4? That should be a small and light combination with good focusing and a terrific f/4 lens. (1) that would be more expensive in total (2) I'd have to learn a whole new camera system (3) the PF lens is light enough that the D500/500PF combination is not much heavier or bigger than the EM1 MkII/300 pairing (4) I can get much more out of a D500 raw file in extremis than out of a micro-43 file.
**One other thing that follows from this is that this lens is one of those aspects of the Nikon system that keeps me with Nikon despite its comparative unavailability. Sony, for instance, has amazing autofocus in the A9 and A7RIV, and the details of birds to be had from the A7RIV, in particular, are spectacular: have a look at Mark Smith’s recent video. But they have nothing to compare with the Nikon 500mm PF (and I'm pretty confident that by the time the Z cameras are up to version 3, the AF will be as good as the D500, which would suit me fine.)