Binoculars for ornithology
Enlarging the vision
For bird watching, a popular choice is binoculars with 8 to 10 times enlargement. (We here are not talking about spotting ranges because that is a separate story. Enlargement of more than 10x times provides a very narrow field of vision and an image that is difficult to stabilise. That makes it more difficult to follow birds in the air. Binoculars with enlargement under 8 x do not bring the image close enough.
The objective's diameter is important because it defines the light and vision experience of the user (larger is better) and on the other hand the weight and size of the binoculars. It therefore is a compromise between image quality and weight and size.
Binoculars with a diameter of 42mm are very popular with bird watchers. That size is considered a good compromise between image quality and size/weight.
Width of the field of vision
To observe a bird in flight a wide field of vision is required, otherwise you will lose sight of the bird quickly.
The field of vision depends on the enlargement, but also the construction of the binoculars. Pay attention to this.For 8x42 binoculars a field of vision of 130 metres at 1000 metres distance is good and a field of vision of approx. 140 metres is very good.
For 10x42 binoculars a field of vision of 115 metres at 1000 metres distance is excellent value.
Colour fastness, sharpness and other optical features
If you wish to enjoy nature, a good image quality is of course important. Colour fastness and sharpness are important optical features for binoculars used for ornithology.
Edge sharpness is often mentioned as a quality feature of binoculars. But you should be careful here. Edge sharpness should always be evaluated in relation to the width of the field of vision. In binoculars with a narrow field of vision it is not difficult to achieve high edge sharpness and there even are manufacturers who integrate an edge that foolishly cuts off part of the image to achieve edge sharpness. Producing binoculars with a wide field of vision and good edge sharpness is a true challenge.
For a bird watcher it is very important that the binoculars focus quickly to see a bird in flight sharply. In some binoculars the focus button must be turned a few times to set the focus from close to far whereas for other binoculars like our Eden Quality ED and HD 8x42 binoculars, one turn is enough.
It takes some getting used to, but once you are used to the fast focus you will not want anything else.