Good question! I didn't see anything mentioned, equipment wise, but he said it woke him up with its screeching, so maybe there was already some existing light outside his home/campsite.

The little bit of light in the eye doesn't make it look like it got blasted by artificial lighting, and the whole area isn't washed out, but it does look well lit. Perhaps a smaller light source and a longer exposure?

Lighting nocturnal animals is a constant debate, and there are better and worse ways of going about it. I don't know photography stuff, but using less intense and less focused beams is gentler, and using a flashlight where you can sweep the subject with the beam gives their eyes time to adjust, as opposed to the instant burst from a camera flash. There are also infrared, red, and combo LED lights that can provide gentler light. And yeah, some people just blast them with spotlights. But I try not to share that kind of stuff.

From Discover Wildlife

10 key questions to ask before using additional lighting

1. What’s the species’ general temperament?

2. What’s the individual animal’s general temperament? A captive animal may be more used to ‘unusual’ external stimulus.

3. What’s the species’ normal sensitivity to light? Consider whether they are primarily nocturnal or diurnal.

4. What’s the species’ colour-spectrum perception and sensitivity? Diving animals may be more sensitive to blue light. 

5. Will the animal’s eyes be open or closed when you take the photograph?

6. How much additional light are you adding? A flash used during the middle of the day is probably less noticeable than at dusk or night-time, for example.

7. Will the light be harsh or soft light?

8. Will the light be directly illuminating the animal’s eyes? Consider whether it will be front-on, back or side lighting.

9. How many times and how long will you be using the additional lighting? Consider whether it be a quick, one-off, single attempt, or there will be multiple attempts over a prolonged period.

10. How significant are any potential negative consequences versus the real benefit in taking the image this way? A slight temporary stress impact might be justifiable if the image will be used for an effective conservation purpose.

(The rest of that article is pretty good too, as far as I can tell.)

Barn Owl sees all! Knows all!

Yes... Especially that!