Which lens for plane spotting? The right focal length for every spot

The Airbus A380 taxis out for takeoff, you raise your camera – and in the viewfinder sits a small white aircraft in the middle of a lot of gray asphalt. Or the other way around: the aircraft comes in on final approach so low above you that wings and tail stick out of the frame. The question of the right lens for plane spotting is therefore not a matter of taste but a math problem. This guide shows you the formula behind focal length, a calculator for your spot, a table with typical distances and the lens classes spotters actually work with at the fence.

The short answer

For most spotters, a telephoto zoom with a 300 to 400 mm long end (full-frame equivalent) is the most important lens. With it, at most observation decks, fences and spotting points, you get takeoffs, landings and taxiing traffic filling the frame. If you often shoot from hills or distant runway ends or like to collect regional aircraft, reach for a zoom up to 500 or 600 mm. An additional standard zoom covers decks with an apron view and approaches directly over your head.

You don’t have to guess which focal length you really need at your favorite spot, though. It follows from three quantities: distance, aircraft size and sensor width.

The formula behind focal length

For subjects that are far away, a simple proportion holds as a good approximation: the aircraft is rendered on the sensor as large as the ratio of focal length to distance. Rearranged, this gives the focal length at which the aircraft exactly fills the frame width:

Focal length (mm) = sensor width (mm) × distance (m) ÷ aircraft length (m)

An example: a Boeing 737-800 is 39.5 meters long. If it taxis past you sideways at 400 meters, on full frame you need 36 × 400 ÷ 39.5 – so about 365 mm for it to fill the landscape frame edge to edge. In practice, you leave some room so the nose and tail aren’t cut off. With 90 percent frame fill, you end up at about 330 mm.

Three conclusions from the formula are important:

• Distance works linearly. Double the distance requires double the focal length. If you get 100 meters closer to the runway, you often save more than a new lens would.
• So does aircraft size. At 72.7 meters, an Airbus A380-800 is more than two and a half times as long as an ATR 72-600 at a good 27 meters. At the same distance, the ATR therefore needs more than two and a half times the focal length.
• Perspective changes the calculation. Side profiles depend on fuselage length. If an aircraft approaches you head-on or at an angle from the front, wingspan is the relevant width – for the A380 that is almost 80 meters, for the Boeing 777-300ER 64.8 meters.

Crop factor: smaller sensor, more reach

The focal length on the lens always stays the same. What changes is the portion of it that your sensor uses. A full-frame sensor is 36 mm wide, an APS-C sensor from Nikon, Sony or Fujifilm about 23.6 mm, one from Canon about 22.3 mm, a Micro Four Thirds sensor about 17.3 mm. This gives the familiar crop factors of about 1.5, 1.6 and 2.

For spotters, that is a real advantage: a 100–400 mm on Micro Four Thirds shows the same angle of view as a 200–800 mm on full frame. In the formula, you simply plug in your camera’s sensor width – then you directly get the real focal length that has to be on your lens.

Calculator: how long does your lens need to be?

Table: focal length by distance and aircraft type

The following values apply to full frame and a side profile that fills about 90 percent of the frame width. On APS-C, divide them by 1.5 (Canon: 1.6); on Micro Four Thirds, by 2.

Aircraft (length)	150 m	300 m	500 m	800 m
ATR 72-600 (27.2 m)	approx. 180 mm	approx. 360 mm	approx. 600 mm	approx. 950 mm
Embraer E190 (36.3 m)	approx. 135 mm	approx. 270 mm	approx. 445 mm	approx. 715 mm
Airbus A320neo (37.6 m)	approx. 130 mm	approx. 260 mm	approx. 430 mm	approx. 690 mm
Boeing 737-800 (39.5 m)	approx. 125 mm	approx. 245 mm	approx. 410 mm	approx. 655 mm
Airbus A350-900 (66.8 m)	approx. 75 mm	approx. 145 mm	approx. 240 mm	approx. 390 mm
Airbus A380-800 (72.7 m)	approx. 65 mm	approx. 135 mm	approx. 225 mm	approx. 355 mm

The table explains why spotters have such different experiences with the same gear. If you mostly shoot long-haul traffic at a hub, you get far with 400 mm. If you collect regional traffic with turboprops and small jets, you hit the limits even at medium distance. The dimensions come from our type profiles; there you will also find the wingspans for head-on shots.

Focal length by spot type

With the formula in mind, typical locations can be sorted quickly. Concrete distances differ from airport to airport – measure them on the map before you set out.

• Observation deck with an apron view. Parked and taxiing aircraft at the gate are close, and a standard zoom is often enough here. For the runway traffic behind, you still need a telephoto. On the observation deck at Düsseldorf Airport or Terrace B in Zurich, it is therefore worth being able to switch between short and long focal lengths – a zoom with a wide range plays to its strength here.
• Elevated spotting points. Hills and platforms get you above the fence and grass, but the distance to the runway usually stays large. At the Munich Airport visitors’ hill or the Zeppelinheim viewing platform in Frankfurt, a long telephoto is part of the basic kit.
• Approach path. Under final approach, aircraft come surprisingly close. Widebody jets then quickly no longer fit in the frame – a zoom with a short start matters more than reach. An extreme example is Maho Beach on Sint Maarten, where landings pass low over the beach.
• Runway end and holding point. This is where aircraft stand before takeoff, often at a long distance. The long end of 400 to 600 mm gets you detail shots of engines and landing gear.

Which end of the runway is in use on a given day is determined by the wind. That makes the runway direction in use often decide more about your focal length than the spot itself: the same position can be ideal for landings and much too far away for takeoffs.

Lens classes compared

Specific models change quickly, the classes stay. These ranges have become established among spotters:

Lens class	Typical use	Strength	Weakness
Standard zoom (about 24–70 or 24–105 mm)	Deck, apron, approach directly overhead, scenes	fast, versatile	too short for runway traffic
Telephoto zoom 70–200 mm	Decks close to the runway, large aircraft	often fast, quick autofocus	too short at far spots
Telephoto zoom 70–300 mm	Entry level, fences, medium distances	light, cheap, common	rather slow at the long end
Telephoto zoom 100–400 mm	All-rounder for most spots	reach at a reasonable weight	more expensive, more conspicuous
Telephoto zoom 150–600 or 200–600 mm	Hills, runway ends, regional aircraft	maximum reach	heavy, haze and shimmer are more noticeable
Telephoto prime (e.g. 400 or 500 mm)	Specialists with a fixed home spot	sharpness, often faster	rigid, impractical with changing distances

At the airport, almost everything speaks for the zoom. Aircraft are constantly moving toward you or away from you, and with a zoom you can adjust the framing several times during a landing. A prime lens is mainly worth it if you always stand at the same spot and know its distances exactly.

Teleconverters: reach with side effects

A teleconverter sits between camera and lens and extends the focal length by its factor. A 400 mm becomes 560 mm with a 1.4x converter and 800 mm with a 2x. Lens speed drops in the same proportion: the f-number is multiplied by the factor. A 1.4x converter therefore costs one stop, a 2x converter two. f/5.6 becomes f/8 or f/11.

Two further effects come with it: the autofocus works with less light and reacts more slowly, and every additional glass group costs a little sharpness. With fast, high-end telephoto lenses, that hardly matters; on a slow zoom, it quickly becomes visible. Also check beforehand whether your lens can be used with converters at all – by no means every model is designed for it.

Cropping is often the better alternative: a high-resolution sensor still delivers images after a substantial crop that are good enough for the web and your collection.

Why more focal length doesn’t solve everything

The formula knows only geometry. Outdoors, two disturbing factors come in that grow with focal length:

• Heat haze: Over heated asphalt, warm air rises and bends the light irregularly. The longer the focal length and the farther away the aircraft, the more of these air layers are in the picture. At 600 mm and 800 meters distance, a summer afternoon quickly becomes a sharpness lottery. In the morning and in winter, the air is much calmer.
• Atmospheric haze: Even without shimmer, images lose contrast and color over long distances. A closer position almost always brings more than additional focal length.

Add to that the direction of the light. A telephoto lens amplifies any backlight – how to visit your spot at the right time of day is shown in the guide Planning sun position, and what still works in backlight is covered in Backlight in aircraft photography.

Long focal length, short exposure time

The longer the focal length, the more any movement of your hands shows in the picture. An image stabilizer helps against that, but not against the movement of the aircraft itself. For jets taking off or landing, you therefore need a short exposure time in any case. For propeller aircraft, the opposite applies: if the time is too short, you freeze the propellers and the aircraft looks parked. How to balance both is explained in the guides on camera settings for plane spotting and shutter speed for propellers.

For night shots, the priority list is reversed: then lens speed matters more than reach. More on this in the article Photographing aircraft at night.

Three setups for three types of spotters

If you are still unsure which focal lengths you really use, you can start with an inexpensive telephoto zoom or a rental lens first. After a few sessions, the metadata of your pictures shows whether you are constantly stuck at the long end – then more reach is worth it. You will find more about cameras and accessories in the gear checklist.

What matters when buying a lens

• Autofocus speed before lens speed. A quickly tracking focus matters more at an airport than one more stop of aperture.
• Assess weight realistically. A heavy super-telephoto that you no longer want to hold after two hours delivers less than a lighter zoom you use all day.
• Check tripod rules. At many decks and spotting points, tripods are unwelcome or prohibited. Plan your setup so you can use it handheld. What is allowed at the fence is covered in the article Is plane spotting allowed?.
• Mind the fence gaps. Some spots only allow photos through chain-link fencing. A lens with a large front diameter doesn’t fit through every mesh – with a wide-open aperture and the front element close to the fence, the wire often disappears anyway.
• Used is an option. Telephoto lenses last long with good care. When buying used, check autofocus, stabilizer and zoom ring in person.

Your own focal length statistics

The best buying advice is in your own pictures. Digital cameras store the focal length in the metadata for lenses with electronic contacts. After a season, sort your successful shots by it, and you immediately see whether you lack reach at the long end or whether a lighter zoom would be enough. Also note for each spot which focal length you used to get which type filling the frame. After a few visits, you no longer have to calculate.

If you are just starting out, the guide Plane spotting for beginners helps you choose your first spots. And if you want to identify the aircraft in your pictures with confidence, you will find the most important features in the guide Identifying aircraft types.

Conclusion

The right lens for plane spotting follows from distance, aircraft size and sensor width. For most spots, a telephoto zoom up to 400 mm on full frame is the best compromise; for distant runways and regional aircraft, up to 600 mm is fine. Smaller sensors bring additional reach, teleconverters cost light and speed. And if it really isn’t enough, a closer position beats any longer lens.