Photo at top: Holland May 2023 late evening, high tide North Sea, heavy overcast, backlight, Cormorant (Aalscholver) size 90m distance 75m equivalent 1500mm Z50 Nikkor 500mm f/5.6E PF VR APERTURE Mode Birds Reach 1/500 f/11 ISO 1400 +1.0EV standard camouflage.
Extra Info: F11 full screen
Quadratic effect of distance
You may never really use our reach-formula as such in the field. We use one or more of our “three quadratic rules” all the time, particularl the rule that amount of detail is quadratically proportional to distance camera-bird. The pictures of an SD card photographed at successively 16.5 meter, 15 meter and 13.5 meter, illustrate this substantial effect:
(click -> open picture, > < next/previous picture, i -> info & settings camera & lens, “Full size” -> full screen, x-> Exit picture)
Plus or minus 10% distance results in significantly less or more detail! (size card is about size small birds head).
You can find many examples of estimating reach with our reach-formula at Reach examples. They may give youa some idea of reach in bird photography and the effect of one or more quadratic rule in the field.
The “30 meter border” in bird photography
During many years of bird photography we found that, using modern photographic lightweight equipment, over 30 meter the amount of reach gets progressively lower, especially when photogaraphing small birds. Over larger distances the amount of dust, air pollution, humidity, mist or haze probably accumulates and progressively blocks the light in between bird and camera. For instance photographing birds like Wren, Bearded Tit, Kingfisher, Shrikes or Bee-Eaters in direct sunlight is all right up to about 30 meter. At larger distance pictures become less detailed. One typically needs equipment with 35mm equivalents over 2000mm, including digiscoping.
Shooting pictures of large or extraordinary large birds
When shooting pictures of large or extraordinary large birds the primary concern sometimes is: “Will this large bird fit in the picture frame?” for example when expecting or hoping that a certain bird will soon arrive at the scene. Look at this example. We were expecting the Woodpecker near its nest soon (they often loudly announce from a distance their arrival We but had no idea whether this large bird would “fit” in the picture frame using 1050mm 35mm equivalent. However we did remove the 1.4 converter, equivalent 1050mm => 750mm, and we shot this picture: we had made the right decision.
Crop 2400 x 1600. @dik redit qm
Reach = (51/17 x 30/35 x 750/1050 x 2100/2400)2 % => 2.5 detail benchmark picture = 2.6 x 33% = 85% detail benchmark picture
The Woodpecker fitted in the picture frame!
“Does sensor size contribute to reach?
Does a camera with a full frame sensor have more reach (bereik) than a camera with for example an APS-C type sensor? In other words: “Does a Nikon full frame camera have more reach when operating in what Nikon calls “FX mode” (full frame format 36 x 24 mm) compared to working in “DX mode” (APS-C format 24 x 16 mm)? This type of question continues to create confusion. Some may feel inclined to answer this question positively but the answer is No!
A full frame camera in DX mode will “cut”, “hard crop”, a 24 x 16 mm image area (APS-C format) out of the full frame sensor area (by the way at the very centre of this sensor). However you can also, using software like Lightroom, “soft crop” any area of 24 x 16 mm (APS-C format) out of the full frame image area when you switch this camera in full frame FX Mode, at any position you wish, centre, corner, along a side, anywhere. Any APS-C size “soft cropped” portion will always have exactly the same resolution of (24 x 16) / (36 x 24)Megapixels = 4/9 part of the total amount of pixels of the full frame sensor. So your crop will always have the same resolution (pixels/square millimeter) as any picture created by this camera either in DX mode or in FX mode. Conclusion: “Full frame” does not necessarily mean more reach but it means: camera output may contain more pixels (to optionally select an APS-C format area from). Try it if you want to be sure.
However – and this is something essentially different – using a camera in full frame mode, “FX mode”, will give you a larger, 9/4, amount of detail and also a larger field of view in your camera viewer, which is extremely welcome when photographing fast flying birds, because they stay longer in the “full frame view”. Amongst other features like two card slots and two processors an usually higher sensor quality this may be a sound reason to, sooner or later, go for a full frame Nikon MLC like Z7 (II) or Z6 (II) if you can afford it.
Only when you normalise the output of a digital Nikon camera to a 24 x 16mm APS-C format image area, you can compare the contribution in megapixels to reach of Nikons full frame Z7 II. Nikons mirrorless System 1 CX, Nikons mirrorless Z camera’s like Z50, APS-C type D300, D500, full frame D800, etcetera. You can see this APS-C-normalised contribution to reach of some Nikon camera’s used in lightweight bird photography in the informative diagram below. It may help you decide which camera you should buy if you consider reach to be a priority.
