Guides · Updated 30 October 2026

Is 400mm enough for bird photography?

Yes, for most birds, as long as you can get reasonably close. Taking “enough” to mean at least 1,500 pixels across the bird, enough for a sharp 8 × 10 inch print, a 400 mm lens covers a 14 cm songbird such as a European Robin out to about 8 to 9 m (25 to 29 ft) on a full-frame camera, and 10 to 13 m (34 to 42 ft) on APS-C or Micro Four Thirds. Bigger birds give you more room: a heron gets plenty at 30 m. Further away, a small bird shrinks to phone-screen or record-shot size, and 600 mm, 800 mm or getting closer is what helps.

What “enough” means here

Reach comes down to pixels on the bird: how many of the sensor's pixels the bird's image covers, which is what's left after you crop. This guide uses two yardsticks, both for a crop in which the bird spans half the picture's width:

• 1,500 pixels across the bird gives a crop 3,000 pixels wide: an 8 × 10 inch print at 300 ppi (3,000 × 2,400 pixels).
• 1,000 pixels across the bird gives a crop 2,000 pixels wide, more than a Full HD screen (1,920 pixels) shows.

Fewer pixels still work for a phone, social media or an eBird or iNaturalist record. The figures assume a sharp frame and a bird side-on. A soft frame, heat haze or a bird facing you all mean fewer useful pixels (how much you can crop for prints and screens).

A 14 cm songbird at 400 mm

Pixels across a European Robin (14 cm, 5.5 in) with a 400 mm lens on six popular cameras:

Bold: 1,500 pixels or more. 5, 10, 20 and 30 m are about 16, 33, 66 and 98 ft. Megapixels are the size of the image each camera saves. Open these in the calculator: Canon EOS R7 at 20 m, 892 pixels; Sony A7 IV at 10 m, 1,139 pixels; OM-1 at 30 m, 564 pixels.

At 10 m the APS-C and Micro Four Thirds bodies still clear 1,500 pixels, and the full-frame ones give 1,139 and 1,327: plenty for a screen. By 20 m every camera is under 1,000 pixels, and at 30 m the robin is 369 to 622 pixels across, a record shot. The smaller sensors win because they pack more pixels into each millimetre: 312 on the R7 against 195 on the A7 IV, so the same image of the bird covers more of them (crop sensor or full frame, compared).

How far away can the bird be?

Run the same sums backwards and you get the furthest distance, in metres, at which a 14 cm songbird still gets 1,500 pixels:

For 1,000 pixels, enough to fill a Full HD screen, the 400 mm distances stretch to 11 to 13 m on full frame and 15 to 19 m on APS-C and Micro Four Thirds. A 24 cm American Robin gets 1,500 pixels out to 13 to 15 m on full frame and 17 to 21 m on the smaller sensors.

Bigger birds: robins, kingfishers and herons

Pixels across three more birds at 400 mm, on a full-frame Sony A7 IV and an APS-C Canon EOS R7:

Bold: 1,500 pixels or more. Too big: the bird is longer than the frame is wide. In the calculator: Grey Heron, Sony A7 IV at 30 m, 2,480 pixels; Common Kingfisher, Canon EOS R7 at 20 m, 1,019 pixels.

At 400 mm a Grey Heron only fits across the frame from about 11 m (36 ft) on a full-frame body and 17 m (57 ft) on the R7. For big birds 400 mm is plenty, and a zoom that goes wider is often more use than more focal length.

400 mm, 600 mm or 800 mm?

The harder case again: a 14 cm songbird at 20 m (66 ft).

Bold: 1,500 pixels or more. Compare two lenses side by side in the calculator: Canon EOS R5 at 400 and 800 mm, 650 and 1,327 pixels.

A 600 mm lens puts about 1.5 times as many pixels on the bird as 400 mm, and 800 mm about twice as many; the distances in the table further up stretch by the same factors. Getting closer works the same way: 400 mm at 10 m puts exactly as many pixels on the bird as 800 mm at 20 m (1,139 on the Sony A7 IV).

When 400 mm is enough

• Gardens, feeders, hides and known perches, where you can work within about 10 m (33 ft) of small birds.
• Birds the size of a robin or bigger. A 24 cm American Robin at 20 m gets 956 pixels on a Sony A7 IV and 1,529 on a Canon EOS R7; herons, ducks and birds of prey get more.
• Birds in flight, where a lighter lens and a wider view make the bird easier to find and follow.
• APS-C and Micro Four Thirds cameras, which put about 1.4 to 1.7 times as many pixels on the bird as a 33 MP full-frame body with the same lens.

When it isn't

• Small birds you can't approach, or across water or a mudflat. At 20 m a 14 cm bird is 558 to 940 pixels across, and at 30 m 369 to 622.
• Big prints of small birds, unless you can get within 8 to 13 m.
• 24-megapixel full-frame bodies, which pack fewer pixels into each millimetre: a Canon EOS R6 Mark II puts 478 pixels across the robin at 20 m.

Getting more from a 400 mm lens

• Get closer. Halve the distance and you roughly double the pixels across the bird, with no light lost. A hide, a car or a quiet wait by a feeder often beats a longer lens.
• Add a 1.4× teleconverter, if your lens takes one. It turns 400 mm into 560 mm, and the songbird at 20 m on the R7 from 892 pixels into 1,259, for one stop of light.

To check your own camera, lens and birds, try the free bird reach calculator.

Cropping a whole trip from the full-size originals

At 400 mm the bird is often a small part of the frame, so nearly every keeper needs a crop. That's easy for one photo and slow for a thousand. BirdFrame is a Mac app that finds the birds in a whole Apple Photos album or folder, including small, distant and half-hidden ones, and crops each one Tight, Balanced or Wide. It crops thousands of photos in one go, so there's no cropping by hand.

Every crop comes from the full-size original: nothing is downscaled, upscaled or generated, so each crop keeps every pixel your lens put on the bird. It reads JPEG, HEIC and RAW files, runs on your Mac with nothing uploaded, and is free for up to 50 photos per run. A one-time $29.99 unlocks bigger batches, and it needs macOS 15 or later.

Questions

Is 400mm enough for birds in flight?

Usually. Birds in flight are often bigger or closer than a perched songbird, and a 400 mm lens is easier to swing and shows more sky around the bird. A 55 cm Red-tailed Hawk at 30 m gets 1,451 pixels on a 33 MP full-frame Sony A7 IV and 2,320 on a Canon EOS R7.

Is 400mm on Micro Four Thirds the same as 800mm?

For framing, roughly: 400 mm on an OM System OM-1 shows about the view of 800 mm on full frame. For pixels on the bird, not quite: the OM-1 puts 851 pixels across a 14 cm songbird at 20 m with 400 mm, where a Sony A7 IV with 800 mm puts 1,139. Its 20 megapixels sit on a sensor with about a quarter of the area.

Is a 100-400mm zoom enough for bird photography?

At 400 mm it puts as many pixels on the bird as any 400 mm lens, so these tables apply; how sharp they are depends on the lens. The shorter end helps with big or close birds, such as a heron, too long for the frame at 400 mm within about 11 m on full frame.

Should I get a 600mm lens instead?

If most of your birds are small and more than about 10 m away, yes: 600 mm puts about 1.5 times as many pixels across the bird. If you work from a hide or a garden, photograph birds in flight or bigger birds, or mostly share on screens, 400 mm and a careful crop is usually enough.