Photo at top: Lesbos Bee-eater (Bijeneter) size 16cm distance 25m equivalent 900mm D300 Nikkor 300mm f/4D total camouflage 1//1000 second f/8 ISO 400. Crop 1500 x 1000. Incredible detail of famous old timer Nikkor 300mm f/4D!
Extra Info: Use F11 of your browser to view pictures full frame!
“Reach”
These three pages, Reach I, Reach II and Reach examples, explain everyting about “reach (bereik)” in lightweight bird photography. They are the most important pages in this blog but also the most hardest. Don’t worry if it takes you some extra time to grasp what “reach” in bird photography really is. This knowledge will definitely pay off particularly when buying your equipment. Some marketeers and photographers may have their own ideas about ‘sufficient’ reach, but as a serious enthousiast bird photographer you should understand everything about “reach” yourself. However this is not simple and at the same time equipment costs considerable money.
Birders use telescopes, photographers have their lenses, converters and camera’s and optimal settings thereof and sometimes use a special combination of all this: digiscoping. However quite a few bird photographers are still using equipment which is far too heavy or unnecessarily expensive given the modern photographic equipment. So grant yourself the time and study those pages about reach and look at the pictures we show. It may take some effort but it will pay off. Bird photography happens to be not easy, at least if you take it seriously and want go beyond the level of “Oh, look what a beautiful bird!”, point your camera, shoot your picture, then ask someone else what kind of bird is in your picture…
Reach and Nikon equipment
Take a close look at the picture of the Bee-eater on top of this page, an example of a picture with marvellous detail created by famous old timer Nikkor 300mm f/4D non-VR. “Reach (bereik)“actually is about sufficiently resolved detail in your pictures. It is not a matter of the bird being in-focus. By tthe way some bird photographers tend to talk about “sharp” pictures. We do so too incidently, however keeping matters well defined in this blog we’ll structurally talk about “in-focus pictures” versus “out-of-focus pictures” and “sufficiently detailed” pictures and about “sufficiently detailed” pictures versus “insufficiently detailed” pictures. To get sufficient reach in bird photography you need high quality, semi pro equipment for shooting sufficiently detailed pictures particularly when photographing small (shy) birds far away.
Over many years we have experienced that Nikon photographic equipment, camera’s, lenses and converters were surprisingly well fit for serious lightweight bird photography. Outstanding examples are:
- Nikkor 300mm f/4E PF VR, uses phase Fesnel technology, is not cheap, but the best lightweight 300mm prime we ever used, the only one of this quality being Nikkor 300mm f/4E PF VR, but extremely light, fast focussing, extraordinary detail.
- Nikkor 500mm f/5.6E PF VR, uses phase Fesnel technology, is not cheap, but the best lightweight 500mm prime we ever used, the only one of this quality being Nikkor 300mm f/4E PF VR, also extremely light, fast focussing, extraordinary detail.
- Nikons top quality aspherical converter TC-20E III.
- Nikons second generation mirrorless camera’s Z50 and Z7 II feature the largest opening for light transmission in the smallfilm world. Although fast, they are not the very fastest. This may improve over time when Nikon gathers more experience in affordable mirrorless autofocus technology. Their Z8 and Z9 already feature extremely fast and reliable autofocus, but are not affordable for medium-budget serious enthousiast bird photographers.
If you want to use only one combination then use one zoom lens preferably 500 or 600mm to avoid frequently switching converters in the field. This choice of equipment is a bit of a dilemma though important. You got to decide about this by yourself.
We also experienced, thinking about sufficient reach, that we needed three “elements”:
- (1) A definition of something like the “bird-image-area“, the minimal rectangular part in a bird picture, that contains all pixels (beeldpunten) of the photographed bird in the picture. This bird-image-area contains a sufficient amount of sufficiently resolved pixels (look at the diagram below).
- (2) A standard measure (maatstaf) of “sufficiently resolved detail” like the standard meter, second, gram, dozen, percentage, etcetera. We will define this standard measure (maatstaf) using a well defined benchmark picture of a Kingfisher (IJsvogel) at 10 meter distance, a rather small bird. We will define this picture below at this page.
- (3) Some formula that quantifies the relationship between “reach”, bird size, distance camera-bird and 35mm equivalent used equipment. These three variables apparently determine the amount of reach of a combination camera-lens-converter.
So let’s try to define these three elements:
(1) Our so called “bird-image-area” in the picture of a bird
The “bird-image-area” in a bird picture contains the complete image of the bird. Naturally not all pixels within this rectangle are part of the bird image itself. However the amount of pixels within this “bird-image-area” rectangle is a reliable indication of the amount of actual “reach”(bereik): the more pixels the “bird-image-area” contains, the more “reach” the used combination camera-lens-converter has got.
(2) Our “Benchmark picture” (maatstaf voor bereik) reach
In order to quantify reach we need a well defined measure (maatstaf) for “sufficiently resolved detail” like mankind ever defined the benchmark “meter” for quantifying length, “second” for time, “gram” for mass, etcetera. So we define the following picture as our “benchmark picture”: a picture of a Kingfisher (IJsvogel), size 17cm, at a distance 30m, photographed using equipment with equivalent 1050mm in clean atmosphere and direct sunlight. This picture is shown below and contains a sufficient amount of sufficiently resolved detail of the subject bird in our view. You can of course define your own benchmark picture or any cropping level as being your standard of sufficiently resolved detail. “Sufficiently resolved” is a subjective qualification.
The height of the upright vertical body of the Kingfisher is about 1/3 (33%) of the total height of the picture. We will use this as an easy and quick way for comparing actual reach in bird photography like we do in Examples reach.
| Our “benchmark picture:” Kingfisher (IJsvogel) in direct sunlight, size 17cm, distance 30m, (EXIF data 29.9 Meter), 35mm equivalent 1050mm, D500 Nikkor 500mm f/5.6E PF VR. Crop 2100 x 1400 pixels. |
(3) Three “quadratic rules” quantifying reach and our “reach-formula”
Reach in bird photography is determined by three factors: size of bird, distance camera-bird and 35mm equivalent of the photographic equipment used. Sometimes reach can also be affected by image sensor quality (not sensor-size!), the amount of available light and the state of the atmosphere. We will review these factors of lesser importance later at this page. Many test pictures of different bird species of different size at varying distance, using all kinds of photographic equipment and 35mm equivalents, consistently showed that the amount of sufficiently resolved pixels (beeldpunten), in other words the amount of detail in the bird-image-area, is quadratically determined by three factors:
1. The size, (width x hight), of the bird (cm): (quadratically proportional).
2. The distance (m) of the bird: (quadratically proportional).
3. The 35mm equivalent (mm) of equipment used: (inverted quadratically proportional).
We combine these three “quadratic rules” in one reach-formula:
| Reach is determined by the amount of sufficiently resolved pixels (beeldpunten) contained by the bird-image-area in a picture. This amount is quadratically proportional to size bird and 35mm equivalent of the equipment used equipment and inversely quadratically proportional to distance bird-camera. |
In this blog we will always use the official bird size (“s” for size” or “length” in most Bird Guides or sometimes “w for wingspan” as reported in Dutch bird guide “De Nieuwe Tirion Natuurgids“). See Literature This is the “size” or rather “length” of the body of a vertically or horizontally stretched resting, swimming or flying bird. It does not include an extraordinary long bill (e.g. Heron, Kingfisher) or legs (Stork, Heron, Black-winged Stilt). If the bird-image-area contains a group of birds, we feel that bird size is not really key.
In our view this benchmak picture contains a sufficient amount of sufficiently resolved pixels of the subject bird. When comparing the amount of detail with other pictures, like in the examples at Examples reach we roughly compare the height of the actual bird with the height of this upright sitting Kingfisher, in bird photography usually including head and feet and excluding extraordinary long tail, bill or legs. In this benchmark picture this height of the birds body is about 1/3, 33% of the total height of the picture.
Estimating actual reach in bird photography is about rounded numbers like 5m, 10m, 15m, …, 50, etcetera and not about about single meters. We always roughly compare the relative height of the bird in an actual picture with the height of this Kingfisher body, which is about 1/3 (33%) of total height of the benchmark picture. In that way we can – finally! – quantify “reach” as a “quality” of any combination camera-lens-converter, telescope-digicompact or telescope-smartphone as follows:
| Actual “reach” of certain photographic equipment in bird photography is: the amount (e.g. 0 – 100%) of sufficiently resolved detail in the “bird-image-area” of a bird picture, as compared to the amount of sufficiently resolved pixels in our benchmark picture, which by definition contains a sufficient amount of sufficiently resolved pixels: a picture of a Kingfisher (IJsvogel), size 17cm, at distance 30m, direct sunlight, clean atmosphere, equivalent 1050mm cropped 2100 x 1400 pixels. The height of the bird in this benchmark picture is about 1/3 (33%) of the total height of the picture. |
Correction factor for different cropping levels
When editing a RAW or JPG picture, you choose the optimal cropping level to get a picture with a sufficient amount of sufficiently resolved detail in the bird image-area of the picture. This is will consolidate the amount and quality of detail in the final picture and determines the final number of dots per square inch (DPI) of the picture. A good bird picture is in-focus and the bird image-area of the cropped picture contains a sufficient amount of sufficiently resolved pixels (beeldpunten).
Picture Kingfiser (IJsvogel), size 17cm, distance 30 meter, sun, D500 Nikkor f/5.6E PF VR, equivalent 1050mm, some crop levels like 3000 x 2000, 2100 x 1400, 1500 x 1000, 900 x 600 and 750 x 500.
Up until now we have always used cropping level 2100 x 1400 at this page about reach, but of course the cropping level also determines the amount of detail in a bird picture, so we have to add a final correction factor to our reach estimate. In our view more cropping would degrade the level of detail of the bird-image area in this picture too much, which might result in more noise and or less contrast and possibly in “soft” pictures. Cropping less would make the bird too small and not really be the main subject in the picture. In this example both cropping levels 2100 x 1400 and 1500 x 1000 would be a good choice. We chose 2100 x 1400 and in that case the height bird-image-area benchmark picture will be about 33% (1/3) of the height total picture. If we would use another cropping level the total amount of pixels in the crop would change and accordingly the relative amount of detail in the bird-picture-area. In order to correct this we have to add one more factor to our reach-formula:
| reach (%) = (size/17 x 30/distance x equivalent/1050 x 2100/crop width)2 x reach benchmark picture. |
The complete reach-formula for quantification of reach (bereik)
This enables us to finally create a complete workable definition of “reach (bereik)” in bird photography. We use (part of) this “reach-formula” in the field and when choosing or buying photographic equipment.
| reach = (size/17 x 30/distance x (35mm equivalent)/1050 x 2100/crop width)2 x amount of detail bird-image-area benchmark picture. |
Gradually you may – like we did – start “thinking” and “comparing” actual situations and pictures you create with this 1/3 (33%) of a Kingfisher at 30 meter-“element” in mind. Thiink about it. You might as well – like we did – give it an official name and quantify reach in so called RU‘s, “reach units“. This simplifies the thinking about and estimating of reach. It may take you a while to get used to it, but it makes estimating reach much easier.
| 1 RU (reach unit) corresponds to “33% (1/3) height Kingfisher at 30 meter when using 1050mm equivalent“. |
An example of “thinking or estimating in RU‘s”:
So for example when trying to photograph another Kingfisher at 20 meter distance – like in the picture above – the height of that Kingfisher in the resulting picture will amount up to quadratic rule (30/20)2 = 9/4 RU’s, resulting in 9/4 x 1/3 = 3/4 height Kingfisher in the actual picture. The relative size in the resulting picture is indeed about 75% of the total picture.
Available light, wheather condition, state of atmosphere also determine reach
The amount of available light, the type of wheather and state of the atmosphere also determine the level of detail of pictures. Direct sunlight in clean air and non polluted atmosphere are the ideal never existing situation but mosttimes we do not account for this when estimating reach. Only in obviously exceptional situations, we add or subtract a certain percentage of the outcome of the reach-formula. Some examples of this kind are: twilight, nearly sunset, exceptionally clean air after total lockdown, light or heavy or fog or mist, smoke of fire or sandstorm (in desert). In exceptional situations we consider to adjust the outcome of the reach-formula by adding a constant Ctotal (percent) like this:
CTOTAL = Csensor+ Clight + Catm
- Csensor: high quality image sensor, in our experience: plus 0%
- Clight: available light: sun, partially cloudy, heavy overcast, twilight, dark, in our experience: minus 100% – 0%
- Catm: atmosphere: exceptionally clean air, smoke, sandstorm, in our experience: 0 – plus 15%.
- CTOTAL = Csensor + C light + Catm: minus 100 – plus 15%.
Summary reach factors:
- Reach is quadratically proportional to size, 35mm equivalent and 1/distance.
- The relative height of an upright Kingfisher at 30 meter using 1050mm equivalent in sunlight, crop level 2100 x 1400 is about 33% of the height of the total picture. We define this picture as our benchmark picture.
- By definition the amount of reach in this benchmark picture (the relative height of the subject bird) is one RU (one “reach unit”).
- Condition of air and state of atmosphere can contribute to reach up to minus 100 – plus 15 % (after sunset – exceptionally clean atmosphere)
These rules help us in the field for example deciding about the use of convertors or lenses in borderline situations like in the example of the black woodpecker down at this page.
Three examples of using the reach-formula (and Reach Units of 1/3 body Kingfisher)
Reach = (17/17 x 30/30 x 1050/1050 x 2100/2100)2= 1.0 x height bird benchmark picture = 1/3 height total picture.
Amount of detail picture is equal to amount detail benchmark picture. No wonder, this is the benchmark picture!
Reach = (17/17 x 30/27 x 1500/1050 x 2100/2100)2 = 2.5 x height bird benchmark picture = 5/2 x 1/3 = 5/6 height total picture.
The main factor in this example is the larger equivalent.
Reach = (35/17 x 30/24 x 1050/1050 x 2100/3900)2 = 2.0 x height bird benchmark picture = 2/3 height total picture.
By the way this is a good example of using Silent Mode Z50. What helped also was that Kestrel female was used to our presence, breeding in our garden year after year.
Many more examples at Examples reach.
