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Watching bats fly at twilight...binoculars? (1 Viewer)

CharleyBird

Well-known member
England
We've moved to Durham and have a pair of bats, presumably pipistrelles, circling the garden every evening.
What, if anything, do you use to watch bats flitting around in the fading light? Something with low magnification and wide FOV?
 

Mono

Hi!
Staff member
Supporter
Europe
You have hit the nail on the head with low magnification. Some 7x50s would be ideal, but make sure they are centre focusing rather than individual focusing marine ones. I'm not sure you will see much detail, the way bats flit and jink about trying to keep one in view maybe challenge enough.
 

CharleyBird

Well-known member
England
Thanks. Getting on the animal is one thing, following the flight (!) depends totally on the insects they're after, and focusing (!!) another thing completely. A few moments of pre-focussed fleeting view out of minutes of trying is the best I've achieved.
However instead of a black thing flitting, I have managed to see a dark brown recognisable bat shape with wings.
So far my 7x42FL with widest FOV and designed for low light are the least unsuitable :D But the little critters make birds like sand martins seem pedestrian.
I just wondered if bat-lovers had found a solution, maybe with a 4/5x magnification instrument, and lots of practice.
 

Farnboro John

Well-known member
Thanks. Getting on the animal is one thing, following the flight (!) depends totally on the insects they're after, and focusing (!!) another thing completely. A few moments of pre-focussed fleeting view out of minutes of trying is the best I've achieved.
However instead of a black thing flitting, I have managed to see a dark brown recognisable bat shape with wings.
So far my 7x42FL with widest FOV and designed for low light are the least unsuitable :D But the little critters make birds like sand martins seem pedestrian.
I just wondered if bat-lovers had found a solution, maybe with a 4/5x magnification instrument, and lots of practice.
No, they are just really difficult!

A few species are easier to watch. Daubenton's Bats skimming water surfaces - the fact that they are mainly manoeuvring in two dimensions reduces the problem. One of my local pub/restaurants has a millpond where you can watch these with a pint - it works for me! (NB the bats don't skim the pint.) Noctules high over fields and woods are easy to follow a lot of the time. Most of the others are hard and bare eyes are best.

People trying to photograph bats generally limit the bats options by using extant choke points or creating their own e.g. by stringing all of a garden pond except the pathway the photographer wants the bat to follow. Then they use a motion sensor or beam-break trigger so the bat is in just the right place. Not really watching though.....

Low mag night vision works - 1X to 3X gives a wide enough FOV for most purposes. If it hasn't got a near-IR light, forget it.

John
 

Hauksen

Forum member
Hi John,

No, they are just really difficult!

I'd like to point out that when you're able to pick your point of view, increasing the viewing distance might make things easier.

Far off, both the angular velocity of the bats in your field of view and the influence of distance changes are reduced, and while the bats are smaller in the field of view, that might still be as good as being closer and using lower-magnification binoculars.

Regards,

Henning
 

Farnboro John

Well-known member
Hi John,



I'd like to point out that when you're able to pick your point of view, increasing the viewing distance might make things easier.

Far off, both the angular velocity of the bats in your field of view and the influence of distance changes are reduced, and while the bats are smaller in the field of view, that might still be as good as being closer and using lower-magnification binoculars.

Regards,

Henning
Yes, and that's the point I was making by mentioning Noctules and to an extent Daubs. However, many of the other bats feed in close environments and can be difficult to get a long sight-line to. Bats' manoeuvrability compounds the problem as they change direction in a microsecond.

John
 

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