Guides · Updated 1 November 2026

Sigma 150-600mm for bird photography: the numbers, worked out

What the Sigma 150–600 mm puts on a bird at 600 mm, worked out from the focal length and the sensors of six popular bodies: pixels across birds from chickadee to heron at 10, 25 and 50 m, how far you can crop and still meet iNaturalist and contest sizes, and how much the wingtips blur in flight.

Pixels on the bird at 600 mm: 10, 25 and 50 m

Pixels across the bird from beak to tail at 600 mm on the Sony A6700, Canon EOS R7, Nikon D500, Sony A7 IV, Canon EOS R6 Mark II and Nikon Z8, using the bird lengths in our reach calculator:

“Won't fit” means the bird is longer than the frame is wide at that distance. The sum: the bird's length × focal length ÷ (distance − focal length) gives its size on the sensor, divided by the pixel pitch (Sony A6700 3.8 µm, Canon EOS R7 3.2 µm, Nikon D500 4.2 µm, Sony A7 IV 5.1 µm, Canon EOS R6 Mark II 6.0 µm, Nikon Z8 4.3 µm).

What the camera body changes

The lens puts the same image of the bird on every sensor: at 600 mm, an American robin at 25 m is 5.90 mm long on the sensor. The body decides how many pixels cover that image. In pixels per millimetre of sensor: Sony A6700 266, Canon EOS R7 312, Nikon D500 237, Sony A7 IV 195, Canon EOS R6 Mark II 167, Nikon Z8 230. So on the same lens, at the same distance, the Canon EOS R7 puts 1.87 times as many pixels on the bird as the Canon EOS R6 Mark II: 1,842 against 986 across that robin. The APS-C Nikon D500 and the full-frame Nikon Z8 have pixels of almost the same size (4.22 and 4.35 µm), so they put almost the same pixels on the bird (1,398 and 1,357 across that robin); the Nikon Z8 records a wider frame around it. A smaller sensor adds pixels on the bird only when its pixels are smaller (crop sensor vs full frame).

Which Sigma 150–600 mm these numbers fit

Any version, at 600 mm. The pixels on the bird depend only on the focal length, the distance and the camera's sensor, so the table holds for any version of the lens zoomed to 600 mm. It doesn't say which bodies each version fits: Sigma’s current version, the 150–600mm F5–6.3 DG DN OS | Sports, is made for L-Mount and Sony E-mount, and Sigma lists its TC-1411 (1.4x) and TC-2011 (2x) teleconverters for the L-Mount version only.

How far you can crop and still meet real sizes

Nearly every size rule counts pixels on the long edge. Here is the smallest share of each body's frame width that a horizontal crop can keep for each:

An American robin at 25 m with 600 mm is 1,568 px on the Sony A6700, so you can crop until it fills 52% of the width and still have Audubon's 3,000 pixels; on the Canon EOS R6 Mark II (986 px), 33%. Crop tighter and the file drops below the size; enlarging it to reach the number adds no detail, and the contests that ask for full-size files say so (crop rules and minimum sizes for 11 contests). For the general case, see how much you can crop a bird photo. The rule that always holds: crop from the full-size original, never from a downsized export, and never upscale.

Birds in flight: wingtip blur at 1/2000 and 1/4000

From our shutter-speed calculator, with 600 mm on the Sony A6700, panning with the bird, wingtips measured mid-stroke where they move fastest:

Wingbeat rates for the osprey and bald eagle are estimates (est.), so treat these as close guides rather than exact figures. Holding the osprey's wingtips within 3 pixels at this distance would take about 1/12800; for the bald eagle, about 1/10000. The wings slow to a stop at the top and bottom of each stroke, which is why a burst catches sharp wingtips that a single frame usually misses.

Try it with your own body and birds

The reach calculator and the shutter-speed calculator open pre-set to 600 mm on the Sony A6700; change the body, focal length, distance or bird to see your own numbers. Both run in the browser. For one body in more depth, see the camera guides: Sony A6700, Canon EOS R7, Canon EOS R6 Mark II and Nikon Z8.

BirdFrame for Mac finds every bird in a folder or Photos album and crops each from the full-size original, thousands at once.

Questions

Is the Sigma 150-600 long enough for bird photography?

It depends on the bird and the distance. At 600 mm it puts about 1,568 pixels across an American robin at 25 m on the Sony A6700 and 775 at 50 m; a black-capped chickadee at 25 m gets 882. On the Canon EOS R6 Mark II the same robin at 25 m gets 986. Crop the Sony A6700 frame to iNaturalist's 2,048 pixels and the robin still fills 77% of the width.

Which Sigma 150-600 do these numbers apply to?

Any version at 600 mm: the pixels on the bird depend only on the focal length, the distance and the camera's sensor. Sigma’s current version, the 150–600mm F5–6.3 DG DN OS | Sports, is made for L-Mount and Sony E-mount, and Sigma lists its TC-1411 (1.4x) and TC-2011 (2x) teleconverters for the L-Mount version only.

Does an APS-C body give the Sigma 150-600 more reach?

Only when its pixels are smaller. In pixels per millimetre of sensor: Sony A6700 266, Canon EOS R7 312, Nikon D500 237, Sony A7 IV 195, Canon EOS R6 Mark II 167, Nikon Z8 230. On the same lens, at the same distance, the Canon EOS R7 puts 1.87 times as many pixels on the bird as the Canon EOS R6 Mark II. An APS-C sensor doesn't change the focal length; it records a smaller frame around the same image of the bird. The APS-C Nikon D500 and the full-frame Nikon Z8 have pixels of almost the same size (4.22 and 4.35 µm), so they put almost the same pixels on the bird (1,398 and 1,357 across that robin); the Nikon Z8 records a wider frame around it.

What shutter speed freezes a bird in flight at 600 mm?

On the Sony A6700, with an osprey at about 66 m, wings across two thirds of the frame, the wingtips blur about 18 pixels at 1/2000 and 9 at 1/4000 mid-stroke when you pan with the bird. Holding them within 3 pixels would take about 1/12800, so a burst is what catches the wings sharp near the top or bottom of the stroke. Wingbeat rates for the osprey and bald eagle are estimates.