Foto at top: Holland sun Kingfisher (IJsvogel), size 16cm distance 30m, Z50 Nikkor 500mm f/5.6E PF VR equivalent 1500mm substantial camoufllage.

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Reach (bereik) is by far the most important, never and nowhere quantified, rather undefined factor in bird photography. Reach (bereik) depends on several factors. We developed a usable definition that really works for us every day in the field bt also when we are buying photographic equipment like camera’s or lenses. For that reason we always report distance to bird and 35 mm equivalent used in this blog. Once you can quantify actual reach (bereik) in more or less difficult situations you can better decide whether you will make or leave a certain shot or whether to optimize settings or equipment before you do so.

Our “working definition” of reach (bereik) is:

Reach (bereik), in meters, is the number of Megapixels of sufficiently resolved detail, per square millimeter in the uncropped digital image of the photographed bird.

Reach (bereik) depends on the following factors:

• 35mm equivalent in millimeters of used equipment (squarely proportional)
• sensor resolution Mpixels per square millimeter (proportional)
• distance camera-bird in meter (inverted squarely proportional)
• amount available light (some factor 0-100%: deep shadow, heavy overcast, cloudy, light cloudy sun)
• quality atmosphere (some factor 0-100%: light fog, hazy, fog, clear air)
• size of bird (“size” in centimeter in ANWB Bird Guide or other Bird Guide)
• some subjective personal judgement of “sufficiently resolved”: We shall define this defining a benchmark-photo of a Kingfisher (IJsvogel) at distance 30 meter using Nikon D500 Nikkor 500mm f/5.6E PF VR. This is our benchmark for what we call “sufficiently resolved” in bird photography.

35mm equivalent = focus distance (mm) x magnification factor converter x crop factor camera (mm).

For example: 35mm equivalent D500 NIkkor 500mm f/5.6E PF VR TC-14E = 500 x 1.4 x 1.5 = 1050mm.

Note that reach is also dependant on the size of the subject bird you are photographing. A small Wren (Winterkoning) must be pretty close like 5 -10 meter in order to produce an acceptable detailed picture whereas a Grey Heron (Blauwe Reiger) can be at 50 meter and yet produce a fine picture.

You have to develop a good understanding of what your actual reach (bereik) in meter is of your sets of equipment in different situations when photographing different species of birds in varying circumstances at certain distances. You need this knowledge when buying or choosing equipment. You also need it in the field when deciding to photograph a certain bird at a giving distance, certain available light, your current equipment, the settings thereof, etcetera. Quantification of actual reach (bereik) may seem difficult – and it is! – but it is one of the keys to succesful lightweight photography. Many photographers, even sales people or “experts” don’t have the foggiest idea of what quantified reach in bird photography really is.

Reach (Bereik) depends on:

• 35mm equivalent equipment used,
• size bird,
• distance equipment – bird,
• amount of available light,
• quality atmosphere.

Reach (Bereik) is squarely proportional to the 35-mm equivalent of camera-lens-converter combination.

and

35mm equivalent = focus distance (mm) X converter factor (1.4, 1.7, 2.0) X crop factor

Crop factors are for example: Nikon DSLR D300, D300S 1.5

• Nikon DSLR D500 1.5
• Nikon Full frame D800 1.0
• Nikon System 1 MLC 2.7
• Nikon MLC Z Series Z5, Z50 II 1.5
• Nikon MLC Z Series Z7, Z7 II DX mode 1.5
• Nikon MLC Z Series Z7, Z7 II FX mode 1.0
• Panasonic camera’s 2.0.

This means that for instance a picture of a Great Spotted Woodpecker at 14 meter has only about half the amount of detail (resolved pixels) of a picture taken with the same combination at 10 meter (1.4 x 1.4 = 1.96), at 17 meter 33%, at 20 meter 25% detail.

If you invert this rule you see that, going from 500mm to 700mm equivalent by using a 1.4 converter on a 500mm lens, you achieve a 1050 mm 35mm equivalent and this is good news! (although at a loss of 1 stop light).

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Some examples of pictures with rather small, average or quite large reach (bereik) may demonstrate the use of this working definition of reach (bereik) in the field: these examples show you how to quantify your chances on sufficiently detailed pictures in different circumstances using various sets of equipment by applying these “quadratic rules” in the field:

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