Lens Week Recap


Some things about lenses to keep in mind

Original: 6/27/2010 on front page

What is Wide?
June
27 (commentary
)--Lens questions tend to be at the top of the list this time of year, as many of you are trying to figure out your lens kit for upcoming vacations. I'm not going to exactly answer the "what lens" questions in this series of short articles, but instead try to give you some background information to consider. Today, we start with wide angle.

What exactly is wide angle?

To answer that question we have to answer another: what is normal? Some people think that this is the focal length of the eye. That would be wrong. Technically, the focal length of the eye is somewhere around 22mm (FX equivalent). That would be what we generally consider a wide angle lens. No, "normal" usually refers to an aspect of perspective, not angle of view. A normal lens is usually defined as having the same focal length as the diagonal capture (DX: 28mm, FX: 43mm). This produces a "normal sized print" that has a "similar perspective" to what we'd see in real life if we were standing there.

Wide angle lenses for DX currently fall in the 8mm to 24mm range, for FX we have 12mm to 35mm available. Here's the thing to think about with wide angle lenses:

  • If you stand in the same place with a wide angle and normal lens you get a wider angle of view (more things to the sides now appear) with the same perspective.
  • If you stand closer with a wide angle than you do with a normal lens you get a different perspective that exaggerates depth relationships (near/far).
  • If you stand further away with a wide angle than you do with a normal lens you get a different perspective that removes depth relationships.

Most beginning photographers try to use a wide angle lens in the first manner. Most pro photographers use a wide angle lens in the second manner. A few really pro photographers will sometimes use a wide angle in the third manner, because it emphasizes what they're trying to show with the composition.

The problem with the first use is that it tends to remove depth relationships in order to show more "width." But photographs are two-dimensional when presented (at least the vast majority at this point in time). "More width" in a 14" print doesn't really help to make the image more involving; it tends to have the opposite impact. Removing depth clues makes an image look very "flat" and tends to make the viewer feel distant (which is what the pro attempting the third use is probably trying to emphasize).

What I've long taught at workshops is this: the wider the lens you use, the closer you probably should be to the nearest thing in your scene. And there should be a nearest thing in your scene! The classic landscape shot is something like: near flower, middle lake, far peak. How far do you think the photographer is from the flower? The lake? The peak? How about 1 foot, 10 feet, 1 mile+? Yep, there's almost a logarithmic nature to near/middle/far in most pro landscape shots. In most amateur shots, it's more like middle/far/far (10 feet, 100 yards, 1 mile). And the image feels "flatter" when hung on the wall in a frame because of that.

This is not to say that you always frame a wide angle with near exaggeration, but I'd want to hear a clear plan on what you're trying to achieve by removing depth perspective if you're going to try something else, like standing back.

Is there a sweet spot? Yes. Though it has tended to move over time. Back around World War II it was probably enough to use a 35mm lens. The difference in perspective (when used correctly) was enough to distinguish such pictures from those shot at 50mm and 55mm. ("Normal" was a bit longer than it should be during that period because longer lenses were easier to make sharp.) Over time, that has changed, though. By the time Galen Rowell became one of the preeminent 35mm landscape shooters in the 80's and 90's, 20-24mm was where things stood for "wide angle." I'm not sure they've moved beyond that, though. That's because it gets more difficult to find things you can photograph at <6" with things that are near infinity that make any sense. 24mm (FX; that's 16mm DX) is good, when used properly. 20mm (FX, or 14mm DX) produces a bit more perspective exaggeration, but is trickier to get right, and starts to be a problem if there are people in your shot outside the central area. Wider than that generally needs a very specific set of near/middle/far relationships and someone who is clearly manipulating those.

So, let's break this out for DX and FX users.

First, FX: you need a 20mm or 24mm lens to get strong depth perspective changes. Anything wider than that gives you some flexibility in really close or tight quarters (e.g. indoor shooting). So we've got plenty of great choices for wide angle: 14-24mm, 16-35mm, 24mm f/1.4G, and 24mm f/3.5 PC-E come to mind. Just make sure that you have a way to get to a very usable 24mm. Unfortunately, the 18mm and 20mm lenses Nikon produced don't do very well on the digital bodies, so we end up going to zooms in that range over primes.

DX users need at least 16mm. That really only gives us zoom lenses: 16-85mm, 16-35mm, 12-24mm, and perhaps the 14-24mm. The 14mm f/2.8 isn't all that great--I'd rather have any of the three zooms. This once again points out the fact that we don't yet have any usable DX wide primes. Surely someone at Nikon must have noticed that, which means that Nikon thinks you don't need a wide DX prime. That would be a wrong decision, and surveys of Nikon users tend to prove that point.

You can certainly go wider (14-24mm on FX, 10-24mm on DX). But make sure you know how to frame for depth with these lenses and that they're really what you need. I find 14mm on FX and 10mm on DX a much more conditional use than a basic use. On FX most of my wide landscape work would tend to be 20-24mm, on DX 14-16mm.

I should point out that we have some "fun" wide angles, too. The fisheye lenses (e.g. 10.5mm DX and 16mm FX) definitely provide a completely different perspective. They are a bit tricky to master, but using them is almost like playing a game, trying to figure out how to "score" with an image using them.

Almost everyone reading this certainly has a wide angle lens of some sort. Even the kit lenses on DX give you a 28mm equivalent, which is within the wide realm. But here's the thing. Learn just one thing and it might open up a new wide angle world for you: get closer. That's it. Get closer. If you're a wide angle newcomer, just try this: move two full steps closer when you're at 18mm on your kit lens. Resist the temptation to move backwards to "get everything in." (Uh, if you're standing at the edge of a cliff, cancel that move two steps closer order. But you'd find me laying on the ground and hanging a bit over the cliff. ;~) If you're photographing people in front of things, moving closer is going to mean you have to move the people out of the center of the image, too. And note that "get closer" may also mean you need to get closer to the ground. You're not going to get depth perspective enhancement from eye level if the nearest thing is at your feet.

Trust me on this: just try moving closer when you zoom out or change lenses to a wide angle. You'll discover your images are suddenly different, and have depth to them they didn't have before.

Convenience Zooms
June
30 (commentary
)--Returning to our focus on lenses this week (yes, intentional pun), today we want to look at what most of you use most of the time. And that's mid-range zooms and superzooms, the so-called convenience lenses.

Nikon has a long history at trying to perfect the mid-range zoom, and it dates all the way back to things like the 1963 introduction of the 43-86mm f/3.5 zoom (technically that would be a normal-to-modest-telephoto zoom). In the film autofocus era that got started in the early 1980's, some variant of 28 or 35mm to 70 or 85mm gained popularity, as this was within the design capabilities at the time and satisfied the "three in one" aspect most mid-range zooms have to deliver. Almost every maker ended up with more than one variation on this: just enough wide at the one end to be called wide angle, just enough telephoto at the other end to be called telephoto, with lots of "normal" in between ;~).

Tamron was the first to popularize something that went beyond the mid-range zooms, the so-called superzoom (lots of focal length range). Their original 28-200mm was compact and provided pretty much all the focal lengths a user might want most of the time. The lens was so popular, it was the first lens to sell a million units (though I believe that was across a couple of minor model changes).

Most of us called the mid-range zooms and superzooms "convenience lenses" when they first arrived on the scene, and I'd say the same thing today. Most people tend towards mid-range zooms (or superzooms) because it's convenient. You end up with one thing to carry (camera plus lens). You don't have to worry about how to carry more lenses, keeping track of lens caps, worrying about different filters for different lenses, the list goes on and on.

But with convenience comes compromise. Early on that compromise included image quality, though that's largely a thing of the past. Today's convenience lenses (again, mid-range zooms and superzooms) are pretty competent in terms of image quality. But you have to watch out for several types of compromise that sneaks in on your images when you use such lenses:

  • Low light. Except for the big, expensive, and heavy f/2.8 versions of these lenses, one thing you almost certainly give up is fast aperture. It's not uncommon to have f/3.5 at the wide side and already be down near f/5.6 in the "normal" focal length range of such lenses. Certainly by the time you get into the telephoto range you're at f/5.6. This is a bit insidious compared to prime lenses. Consider a 35mm f/1.8 prime lens, a very inexpensive DX lens. It's at least two-and-a-third stops faster than any of the non-f/2.8 convenience lenses. That's the difference between needing ISO 3200 versus 640 in low light.
  • Depth of field. That smaller aperture means that you have a tougher time reducing busy backgrounds to a blur; you may get more front-to-back focus depth than you want.
  • Static perspective. Because you can zoom in or out from any position, you never move position. Need a detail of the plaza? Zoom in. Need the whole plaza? Zoom out. Want your honey standing in front of the fountain? Middle of the zoom range. There, see, you didn't need to move a foot.

One of the reasons why people gravitate to the f/2.8 mid-range zoom (currently the 24-70mm) is the first bullet, above. Some do so also for the second bullet. But the third bullet isn't being addressed as long as you stay put and zoom instead of move. So if you're going to get a mid-range zoom or superzoom, be careful this doesn't make you lazy in your shot selection. If you're zooming instead of moving, you're getting lazy. One thing you can do is to consider your zoom a multi-focal lens, not a zoom. Pick three focal lengths (e.g. 16mm, 35mm, and 85mm for the 16-85mm DX) and only use them. Think of your zoom as a wide angle (16mm), normal (35mm), and telephoto (85mm) and pick the type of lens you want before trying to frame the shot by pre-zooming to that focal length. Then bring the camera up to your eye and use your feet to help frame, not the zoom ring.

A lot of those switching from film to digital did something interesting: they kept using their basically FX mid-range zooms on DX bodies. Thus, I notice a lot of 28-70mm, 28-85mm, and 28-105mm lenses ending up on DX bodies. That makes them really 42-xx lenses, or normal-to-telephoto, not midrange. But this also means that those users don't often have any wide angle capability. Funny thing is, they didn't miss it because they didn't really know how to use a wide angle lens. If I could break photographers from any bad habit it is this: shooting only at eye level and only using a zoom to get closer. These folk are doing both those things. They never shoot at anything other than eye level, and they think that the purpose of the zoom is to simply get the shot without moving their feet. All of you who did my homework assignment during You Week know what I'm talking about here, so I won't belabor it.

Am I against mid-range zooms? Not at all. I've got a few myself, and they are very useful in a lot of situations. For photo journalism and sports, for instance, you often get stuck in a single position, and then the only way you can vary the shot is by zooming. That's not what I often want to do in that situation, but it's all I can do. There's a difference.

And mid-range zooms and superzooms are indeed convenient. All of us like convenience. Just make sure that the convenience doesn't take precedence over everything else. When it does, your images will start to suffer. Note that almost every pro has a convenience camera (usually in their pocket). That's why we all want better, larger sensor, compact cameras. Give me a 24-70mm, DX-sensor, competent and well thought out compact and my convenience camera problems probably get solved once and for all, and I might not need the convenience lens at all.

I am a little more against superzooms than mid-range zooms these days. As good as the Nikkor 18-200mm (DX) or the Tamron 28-300mm (FX) are, their image quality compromises do start to show up when you put them up almost anything else that covers less focal length range. And they aren't as long in the telephoto end as anyone seems to think they are as you start bringing focus closer than infinity.

I'd argue these days that if you want a versatile all-in-one lens that it needs to be something in the 24-105mm range (FX; that's 16-70mm DX). Why? Because, as I noted in the wide angle discussion earlier, as we've started printing larger and as we've been accustomed to the 28mm and 35mm perspective, it really takes 24mm to have full impact for wide angle work these days. An all-in-one lens has to take you from useful wide angle to useful telephoto. 105mm at the telephoto end is starting to get into the detail isolation realm for close subjects. If you go much beyond 105mm, though, the lens itself starts to get a bit long physically, and I think you're just better off getting a dedicated telephoto of some sort (zoom or prime) to get closer.

So what does Nikon have for us? Well, DX users are in luck: the 16-85mm is not only a great lens optically, but it pretty much defines a very useful mid-range. Its only real drawback is the f/5.6 aperture at the long end, but that's the price you pay for convenient, light, and small. We don't really have a great f/2.8 DX candidate, though the 17-55mm comes close. It's just a little too little at each end. The Tamron 17-50mm f/2.8, ditto, though it too is a very fine lens for what it covers.

FX users are out of luck. Nikon hasn't given us what we need. The 24-70mm f/2.8 is wimpy at the long end, and it's big, heavy, VR-less, and a host of other things that make it less the slam dunk than it at first looks. The 24-120mm isn't optically up to what we need these days.

The one good thing about mid-range zooms is this: if no one makes the one you really need, just buy three great primes. All you need for FX is a 24mm, 40/50mm, and 105mm (some might prefer an 85mm if they've got other long telephoto options). Not as convenient maybe, but optically better. Realistically, you probably don't use all the focal lengths of your mid-range zoom, anyway. DX users have less luck here, as they don't have a 16mm prime available or anything that's even reasonably close. But what I'd do is use the 12-24mm, 35mm f/1.8, and 60mm Tamron f/2 as my three "primes."

The thing that's important to realize in these last examples is this: you can build a small, relatively convenient three-lens kit that gives you more performance in most aspects (low light, image quality, focus choices, etc.). The "convenience" you lose by not using a mid-range zoom instead is simple: you have to change lenses from time to time, and you need to move your feet. That really doesn't sound all that inconvenient to me, especially since I'm moving my feet already even if I'm using a zoom.

Lenses--Going Long
Ju
ly 1 (commentary
)--Today we consider the sore spot of most photographers' existence: the telephoto lens. Why is it a sore spot? Because there's a good chance that what you need is big, heavy, and expensive, or that Nikon doesn't make it (or you can't get one because it's out of stock). Yuck.

Let's start at the extreme. Probably the most extreme telephoto use is for birding. Short of being in a blind (and sometimes even then), bird photographers tend to gravitate to the longest lens they can afford and handle. Generally wildlife photography doesn't fall much behind the birding photographer: you don't want to be shooting a grizzly bear with a 105mm lens, unless it's at the zoo and there's something between you and the bear ;~).

Unlike wide angle, where a small difference in focal length number seems to make large differences in angle of view, at the telephoto end the opposite seems to happen: large jumps (100mm or more) of focal length seem to garner only small changes in angle of view. That "little bird" viewed at distance with a 600mm lens seems to look only a tad bigger than it did with the 500mm. Hmm. Maybe an 800mm?

  • 200mm--FX 10° horizontal, DX 6.75°
  • 300mm--FX 6.9° horizontal, DX 4.5°
  • 400mm--FX 5.2° horizontal, DX 3.4°
  • 500mm--FX 4.1° horizontal, DX 2.7°
  • 600mm--FX 3.4° horizontal, DX 2.3°
  • 800mm--FX 2.6° horizontal, DX 1.7°

Someone recently asked me how to calculate subject size to angle of view. Your geometry instructor was right: that knowledge is useful in real life! (Off the top of my head--I'm traveling at the moment and don't have my usual desktop sources to verify--I think it's tan(A) = a/c where a is half the subject width and c is the distance for the subject. A is then half the angle of view, so use the table above. I'm sure there's a better calculation than that, though.)

I have one suggestion to those who are into true wildlife photography, especially where smaller animals are concerned: just bite the bullet and get as long and as fast a lens as you can afford and handle from the start. It's sort of like my tripod article suggests, only with a twist: you can buy a series of lenses hoping that you can sneak up on the goal and maybe find something "usable" that's less expensive and smaller, but it ain't going to happen. You'll buy a 70-300mm VR. Replace that with a 300mm f/4. Replace that with a 200-400mm f/4. Replace that with a 500mm f/4. And eventually decide that maybe the 600mm f/4 is what you really need (all the while wondering how it performs with teleconverters ;~). By the time you're done, you'll have spent a small fortune on lenses and still wonder if you have the right one. Since the exotics keep going up in price, trying to sneak up on the final answer has a cost penalty, too: what you can buy today for US$11,000 used to cost US$7000 back when you bought your first 70-300mm. While you might be able to get most of your money out of the telephoto lenses you bought as you work your way up the focal length ladder, it is by no means assured.

Yes, I understand that not everyone can afford to just go out and buy the "right kit" from the start. Plus spousal buy-in is usually necessary. But trying to sneak up on "the right lens" is just an exercise in frustration and perpetual credit card abuse. The problem with wildlife photography, and especially bird photography, is that the same opportunity you saw this morning might not occur again. So if you didn't have the right lens this morning, you'll never get that shot.

If you have to compromise at the extreme end, compromise on features, not quality and focal length. It's long been my suggestion that if you can't afford a 500mm f/4 VR, for example, that you look for a used 500mm f/4P. Yep, you lose autofocus and VR, but you'll pay US$2500-3000 for a lens in excellent or like new condition versus $8500 for the latest and greatest version. And as I note in my article on VR, you're already turning VR off when you're on a tripod or shooting at over 1/500. Are you really sure that autofocus and VR is worth US$6000?

So, for those of you thinking you have to save up for or sneak up on the exotics, consider these options instead:

  • 400mm f/5.6 AI-S. Small, convenient, sharp.
  • 500mm f4P. Basically the current lens without the Nano, VR, or autofocus.
  • 600mm f/5.6 AI-S. Smaller and lighter than the 500mm f/4, but hard to find.
  • Any of the AF-I or AF-S previous versions of the 400mm f/2.8, 500mm f/4, or 600mm f/4. You won't get VR, but all these lenses have autofocus capabilities that pretty much match the current exotics, will take the current TCs, and product image quality on par with the current versions (only small differences).

Three other things you can consider if you don't have the extreme focal length requirements of the birders and dedicated wildlife users:

  • 70-200mm f/2.8 VRII with the TC-20e. Looks pretty good for a TC'd lens. Certainly a better choice than the 80-400mm to get to 400mm right now.
  • 300mm f/4 with the TC-14e. Gets you to 420mm at a reasonable price, but you won't have VR.
  • 300mm f/2.8 with the TC-14e. Starting to get into the pricey range, but still a reasonable alternative if you're not really trying to get to 600mm (Note: I haven't yet tested the 300mm f/2.8 with the new TC-20e; it might actually be usable, but I don't know yet).

These options still delivery decent image quality. Though not quite at the level of the dedicated focal length exotics, these last three options tend to be better than the 80-400mm, 150-500mm, and 50-500mm options that tempt the "long shooter." But they're also bigger and more expensive than those popular telephoto zooms. Still, I put image quality at the top of the list always when it comes to sports, wildlife, birding, and the other types of uses you need these lenses for. Again, that's because many times the "great picture" opportunity you encounter only occurs once (or at least rarely). You won't be able to duplicate what happened today a few years from now when you can afford the exotic telephoto. Thus, always buy image quality first and foremost for very long telephoto lenses. All features are window dressing.

Of course, you can also consider renting. You can rent a 500mm f/4 for a week's use for about US$500. If your budget is US$2500 and you're only shooting three weeks a year where you need such length, you might be able to get by with just renting for a couple of years. Of course, you won't own anything at the end of that period (other than great pictures, that is!). .

So, if you need a really long lens, don't compromise the wrong thing. You need a long focal length with high image quality. You may not need a zoom, autofocus, or VR.

But most users just need a solid telephoto lens that's a little more modest. The 80-200mm range is something almost every photographer needs covered. Nikon has several reasonable choices here: the 70-200mm f/2.8 VR, the 80-200mm f/2.8, and the 70-300mm f/4-5.6 VR. All are quite good lenses (and you'll find reviews of them elsewhere on this site). Even the 55-200mm f/4.5-5.6 VR is a pretty good lens, and a real bargain, at that. Every Nikon user should have one (or more) of those four lenses in their kit, in my opinion.

Better still, with a CU lens set (usually the Canon 500D) or the right extension tube, the above four lenses can also provide some reasonable macro capability. For the 70-200mm, any of the TC teleconverters can give you an impromptu focal length boost without sacrificing much, if any, performance. (That's true of the VR II version of the lens with the latest TCs. The older 70-200mm is a little less capable with TCs, especially the older TC-20e.)

More on Angle of View
Ju
ly 2 (technique) updated--
Several of you just wanted angle of view calculations for a focal length, not for a subject size (remember, a table of this is in all of my digital eBooks and in the ToGo Guides). While there are plenty of calculators on the Internet you can't always see the formulas behind them. The formula you probably want to use for simple angle of view calculation is 2*arctan (half capture dimension/focal length), then convert to degrees.

Believe it or not, Google can do the heavy lifting for you. Let's say we have an FX sensor, 50mm lens, and want the horizontal angle of view. The sensor is 36mm wide, so half that is 18. The formula is therefore 2*arctan (18/50). Just type that into a Google search bar (plus the words "in degrees" at the end [otherwise you get the answer in radians, which you probably don't think in]) and you get your result (~40°). So far, so good.

Now how do we get the distance to a fixed size subject or the size of a subject at a fixed distance? That's the tan(A) = a/c formula I gave earlier in the week. We now have calculated angle A, which will be half of the value Google generated. So if the distance to the subject is 20m, we want to be calculating tan(20) = a/20, which gives us half the subject size. Google will give you "tan 20 degrees" as ~3.6. So now we multiply both sides by 20 and get 20*3.6 = a. If instead you wanted the distance to a subject that's 20m wide, take half the 20 and you get 3.6 = 10/c. Divide each side by 3.6 and multiply each side by c and you have c = 10/3.6. (Previous versions of this made the common mistake of converted tan(20) as radians, not degrees. Also, for these distance calculations, you can use any units, as long as they are consistent. Thanks to those that pointed out my errors.)

Or you could have asked your teenager who's taking geometry ;~).

A Couple of Lens Week Followups
Ju
ly 2 (commentary)--Some of your responses to this week's articles are worth elaborating on:

  • Establish rules of thumb. One reader noted that they literally use their thumb (extended at arm's length) to judge whether a distant animal subject is going to be large enough when shot with their 800mm lens. But this works for all focal lengths. Figure out what 24mm, 50mm, 100mm, and 200mm are for you. For example, 50mm for me is about double my shoulder width at arm's length. I can extend my arms straight out, move them to double that width apart, and see about what the horizontal angle of view for my 50mm is (FX). Likewise, I can hold my thumb out at arm's length and estimate my 400mm vertical angle of view (it's slightly different than my thumb length, but I've done it enough now that I just automatically make that adjustment). In short, for your critical focal lengths find a shortcut that gets you close to seeing what the lens sees without you having to put the camera up to your face.
  • The 200mm f/2. I omitted the 200mm f/2 in my telephoto discussion. The 200mm f/2 lens works great with the TC-14e, and I think (still testing) it works fine with the TC-20e III. Thus, it's another option if you don't need extreme focal lengths. You can get a usable 200mm f/2, 280mm f/2.8, and 400mm f/4 out of it.
  • Mirror lenses. I omitted any mention of mirror lenses in the telephoto section. Intentionally. While they are low in cost and size, they have a lot of different downsides. They are manual focus lenses, have an unusual bokeh, have a fixed aperture, and many aren't great in image quality to start with. The small fixed aperture (often f/8) and manual focusing make for a tough combination. If you don't like your DSLR viewfinder at f/2.8, you're really not going to like trying to manually focus at f/6.3 or f/8. Live View helps, but in bright light the LCD might not be easy to see, either. Over the years I've tried a lot of mirror lenses. Most are quite usable in a pinch, but I always find myself longing for something will fewer frustrations.


 

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