Nikon Z Telephoto Lens Noise With Continuous Autofocus

[birdbrainz]

I have not seen the subject of lens noise mentioned anywhere recently as lenses have got faster and quieter to human ears, but I wondered if with the current continuous automatic autofocus everywhere whether they are disturbing wildlife with some ultrasonic noises which we can't hear.
I am suspicious because recently I am noticing a lot more birds seem to be disturbed almost instantly in their not too near perches when I point the camera and it starts to autofocus. It may be a coincidence, but it never seemed to happen with an older camera.
They seem to get twitchy and start to move off as soon as the camera starts to focus.
I don't believe it is the visible movement that is disturbing them as they seem OK when I first approach, but it may be just a bit early in the season. I don't think it's the flash from the lens as I am mostly on the sunny side (if there is any) and I always have focus assist etc off.
Has anyone else noticed this with modern Nikon Z lenses.

 

[ajrmd]

Interesting question! My understanding is that birds' perception frequencies are generally more limited compared to humans which depending on species could be as little as 1000-5000 Hz or nearly as dynamic as humans, though they are better at distinguishing tones and rhythms even in noisy environments. Some birds as you know can distinguish vibrations extremely well and given that in most photography situations, the distances are likely great enough that any tones or vibrations would not be appreciable, I always thought that the reasons the birds spooked was related to the sudden movement and/or reflection off the larger front elements (sniper glint).

 

[Warren D]

Most birds are more visual than auditory so I'd say it's not a factor unless you are photographing owls. I think it has more to do with pointing that big, single predator eye (aka the front lens element) at them. I've noticed less of a reaction with mirrorless than I had previously with dslrs. I mostly shoot raptors and have long suspected (in the case of the dslr) that their incredible eyesight might have been seeing through the lens and seeing my eye when it was up to the viewfinder.

 

[Steve]

Most birds are more visual than auditory so I'd say it's not a factor unless you are photographing owls. I think it has more to do with pointing that big, single predator eye (aka the front lens element) at them. I've noticed less of a reaction with mirrorless than I had previously with dslrs. I mostly shoot raptors and have long suspected (in the case of the dslr) that their incredible eyesight might have been seeing through the lens and seeing my eye when it was up to the viewfinder.

I agree -I've noticed this phenomenon for years. I too think it's more about that big eye pointed their way. The moment the animal thinks the attention is on it, the alarm bells go off.

 

[birdbrainz]

I am noticing this even more lately (I always use mirrorless) and it must be the lens glass that they are seeing, but I almost always have the sun behind me and the birds are pretty distant. I prefer to shoot raptors, but have less trouble with them, probably because they are usually more distant and often flying.
It is the small birds that are the most nervous.