Guides · Updated 1 November 2026

OM System OM-1 Mark II for bird photography: the numbers, worked out

What the OM System OM-1 Mark II puts on a bird, worked out from its sensor and the lenses people pair with it: 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.

The tools list the same sensor size and pixel count (17.4 × 13.0 mm, 5,184 × 3,888 pixels) for the OM System OM-1, OM System OM-3, OM System OM-5, Olympus OM-D E-M1X, Olympus OM-D E-M1 Mark III and Olympus OM-D E-M1 Mark II, so every figure here holds for those bodies too. OM System's product page gives the sensor as 17.3 mm wide and its manual as 17.4 mm; these figures use 17.4, and the difference moves them by under 1%.

Pixels on the bird at 10, 25 and 50 m

Pixels across the bird from beak to tail, using the bird lengths in our reach calculator (400 mm: M.Zuiko 100-400mm at 400 mm · 600 mm: M.Zuiko 150-600mm at 600 mm):

“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 3.4 µm pixel pitch. Same lens and distance on other bodies, in pixels per millimetre of sensor: OM System OM-1 Mark II 298, Canon EOS R7 312, Nikon Z8 230, Canon EOS R6 Mark II 167.

Compare all Micro Four Thirds cameras for bird photography: every Micro Four Thirds Micro Four Thirds body with a guide here, side by side on the same 600 mm lens.

Why the OM-1 Mark II's small pixels matter

On the same lens, reach comes down to how many pixels fit in each millimetre of sensor. The OM-1 Mark II packs 298 pixels into each millimetre of its 17.4 mm-wide Micro Four Thirds sensor; the full-frame Canon EOS R6 Mark II has 167. On the same lens, at the same distance, the OM-1 Mark II puts 1.78 times as many pixels across the bird: 1,163 pixels across an American robin at 25 m with 400 mm, against 652 on the R6 Mark II.

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 the OM-1 Mark II's 5,184-pixel width that a horizontal crop can keep for each, and how much of that crop an American robin at 25 m with 400 mm (1,163 px) would fill:

So with this robin you can crop until it fills 39% of the width and still have Audubon's 3,000 pixels. 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 400 mm, 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 1/10000; for the bald eagle, about 1/8000. 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 lens and birds

The reach calculator and the shutter-speed calculator open pre-set to the OM-1 Mark II; change the lens, distance or bird to see your own numbers. Both run in the browser.

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

Questions

How many pixels does the OM System OM-1 Mark II put on a bird?

It depends on the lens and the distance. With 400 mm, about 1,163 pixels across an American robin at 25 m and 577 at 50 m; with 600 mm, 1,758 and 868. The sum: the bird's length × focal length ÷ (distance − focal length), divided by the pixel pitch (3.4 µm).

How far can you crop an OM-1 Mark II photo for iNaturalist or a contest?

A horizontal crop has to keep 40% of the frame's width to fill iNaturalist's 2,048 pixels, 58% for Audubon's 3,000-pixel entries and 68% for Australian Geographic's 3,500-pixel finalist files (2026 rules). Crop from the full-size original and never enlarge a crop to reach a size.

Does the OM-1 Mark II's Micro Four Thirds sensor give more reach than a full-frame camera?

Yes, against a 24-megapixel full-frame body: the OM-1 Mark II has 298 pixels per millimetre of sensor and the Canon EOS R6 Mark II 167, so on the same lens and distance the OM-1 Mark II puts 1.78 times as many pixels across the bird. The 45-megapixel Nikon Z8 has 230, so the OM-1 Mark II's lead over it is 1.30 times.

What shutter speed freezes a bird in flight with the OM-1 Mark II?

With an osprey at about 59 m on 400 mm, wings across two thirds of the frame, the wingtips blur about 15 pixels at 1/2000 and 7 at 1/4000 mid-stroke when you pan with the bird. Holding them within 3 pixels would take about 1/10000, 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.