1. Skill - you can set yourself up in locations where the light is good and the angle is good and pick appropriate settings to maximize the image quality. Knowing how high of a shutter speed you need and how to track something that’s moving and keep it in focus are absolutely learnable.

2. Patience - i could never be a wildlife photographer since i’m just not willing to sit long enough. I’ve got some good shots by chance, but you can’t really wake up and decide - today i’m going to take a great shot of an eagle.

3. Equipment - long fast lens, sensors with excellent high ISO performance

4. Post Processing - digital tools have gotten really good for sharpening and increasing the resolution on images.

Silent high speed shutter, also really sharp long focal length lenses.

You take a lot of photos.

Try and retry.

You get one with the best “moment”.

It is always a skill to know “when” it is the “moment” to take the photo. One which you get by trying over and over again, then you “feel” when it is right.

That’s about it.

Practice, time and skill. Gear can help too.

Get close to the subject and use a very long lens. Use a shutter speed that doesn’t sacrifice sharpness. Shoot in good light where you can keep the ISO low.

I owned a Canon 400mm 2.8L IS and let me tell you that using expensive glass makes crisp shots a LOT easier. But good wildlife shooters spend many hours in the field and take many shots to get THE ONE shot.

I used to struggle with this but this year I upgraded to a camera with AI focus & animal eye focusing. This has made it very easy to get sharp images when combined with a good lens and fast enough shutter speed.

perfect light, lots of light aka luck as well

A combination of very expensive gear, considerable skill, enormous patience and the fact that you aren’t seeing all of the missed shots that went before.

1. Years of experience - in most cases, decades worth.
2. Professional lenses that cost North of $12,000
3. Planning and patience so they can…
4. FILL that frame.

You think they gear up in camo from head to toe, crawl into a pup-tent at 3am to shoot through a tiny hole cut in the side whilst dousing themselves in stanky deer piss because any of that is fun?

You should watch some of the BTS for the camera operators that did the various BBC “Planet Earth” shows. What they do to get the shot in some cases is insane… but given the quality of the footage they brought back, absolutely required.

If you’re just heading down to the local lake and strolling around with a $300 lens attached, well, you’re not going to get what they get.

Simon d’Entremont is another good YouTube resource with lots of non-gear centric advice but yeah the answer seems to be pro body (probably mirrorless), one of the expensive prime 400 or 600’s, a shit ton of prep and forethought, and a shit ton of pictures and time waiting.

They focus stack. They take 4-10 shots at small apertures on a tripod with the focus set from front to back. Then they merge them, so the entire image is in focus.

If you are asking this because you want to do it, one good budget option is to purchase a chair and a bird feeder. You can usually sit 8-10 feet away from the feeder and they’ll still come. It is good practice, and if you are quick or careful with the framing, you won’t have the feeder in every shot. For camera settings, google the following and see what other people are doing:

• [your camera model] birding settings
• [your camera model] BIF settings
• [your highest quality telephoto lens model] sweet spot (you are looking for the aperture setting where the lens starts to become very sharp, and the one where it starts to lose sharpness again. If its a zoom, this may vary across the zoom range)

Just as an example, I usually photograph birds with a 300mm f/4 lens that is sharpest from f/5.6-f/8. Settings are - shutter speed a little over 1/1000s, aperture in the sharpest range, and ISO set to auto. High speed burst always.

For lens choice, you are really going to be limited if you don’t have anything 200mm+ and good quality. But if all you have is a 50mm lens or something, just move the chair closer. This is for feeder photos - for actual walking around, the longer the better. But try whatever you have. I have photographed hummingbirds with a 70mm lens and a 100mm lens - some animals just don’t care what you are doing as long as you aren’t moving aggressively towards them.

Expensive lenses, lots of practice and opportunities, good post editing skills.

Good glass, fast speeds, predictability of situations, sometimes a tinge of flash, stabilized lenses and above all, a lot of experience.

That’s pretty much it.