Before I even begin, let me start with this: You can use whatever lens you want!
But, hey, I still look up which lenses are appropriate for portraits. Somebody out there might curious about what others use for balloon festivals, right? Maybe. For this article, I'll write about the lenses that I use while on the launch field of a balloon festival, and provide some example images. I particularly use a Tamron 15-30mm F2.8, a Nikon 24-70mm F2.8G, and a Tamron 70-200mm F2.8 VC.
I will be writing about zoom lenses for the most part. If you're a prime shooter, just pick an appropriate lens. I personally am too lazy to switch out lenses often; zoom lenses are just very practical for me.
The ultra-wide lens (anything wider than 24mm) is something that I use sparingly. Just like in landscape photography, I kind of believe that the ultra-wide angle is a trap for newer photographers. Upon seeing fantastic wide-angle shots, we go out and buy our own to just get EVERYTHING into the frame. Only after trying it out for the first time, we notice that getting everything isn't always a good thing.
An ultra-wide angle lens can easily allow distracting elements to creep into the photo or, even worse, distort the figures of people. Got a fast food sign in a corner? Clone it out. Distorting the head of a pilot? Unforgivable. Plus, this focal length tends to give the impression that things are further away than they actually are.
If you're willing to deal with some of the limitations of an ultra-wide, it's a good tool to have in your arsenal. There are plenty of shots that are only possible on an ultra-wide lens.
The Wide to Short Telephoto (or just standard)
This is what I consider to be the 24-70/105mm range. My 24-70mm pretty much stays on my camera 80% of the time. I don't think anyone could argue against the flexibility this lens provides. The only thing about my 24-70mm that I'm not so hot about is that 70mm is the longest it gets. You may find a 24-105mm F4 lens to serve you better on the field.
24mm is wide enough for getting close, and having the whole scene captured, without having the distortion of an ultra-wide lens. Crew on the crown line, and pilots on the burners are scenes that you can look out for. Looking inside of balloons is great for the wide end as well.
70-100mm is a great focal length to take detailed shots of the balloons, or capture balloons in flight before they get too far away.
See the two images below for examples on the wider end (28mm), and short telephoto end (70mm).
If you were to buy a camera today, a 24-70/105mm lens should be a top priority to get. For those deciding between a 24-70 F2.8, or a 24-105 F4 for ballooning. You should consider whether you will photograph balloon glows or not. More on that later.
I always advocate for "getting close" when taking photos. However, that gets to be a bit difficult when the balloons take flight. This is when I consider switching out to a long telephoto lens. The telephoto lens provides an excellent opportunity to capture balloons in flight.
Amusingly enough, the long telephoto end seems to have the widest selection of zoom lenses available. You have 70-200mm lenses, 70-300mm lenses, 100-400mm lenses, and 150-600mm lenses. No one is short on choice for this category, and there is a lens for every budget.
Be wary of your shooting angle though. Aiming at balloons up high can cause neck strain (it happened to me), so look for balloons that are flying lower. Telephoto lenses are also a must if you ever get the chance to fly. At many balloon festivals, balloons don't fly closely together so you may want the reach of a telephoto to get a nice shot.
Lenses for Balloon Glows
Balloon glows occur at night, generally right after blue hour, and this means that you will be shooting in dark environments. For balloon glows, you should be considering an F2.8 aperture lens as the bare minimum. For day time shots, F4 lenses work wonderfully. When things go dark though, F4 lenses can make things challenging for your camera to focus well. It's not just about image quality, cameras need that light to auto-focus! If you have a bright aperture prime lens, this is when they will really shine.
For the most part, wider lenses are very forgiving for balloon glows. Shorter focal lengths grant more tolerance for camera shake if you're using a slower shutter speed to keep the ISO low. The dark environment also eliminates many distractions. If the balloon glow is on "main street" for a small town, an ultra-wide lens may prove useful to capture the town scene with the balloons.
I have seen others use longer lenses but, there's a reason why I never see them post images taken with those lenses afterward. It's difficult to control the camera shake. "But, wait, my lens has superior stabilization!" In my opinion, it's undesirable to slow the shutter too much because everything moves, including the balloons. The end result is just a blurry image either way.
I personally use my 24-70mm F2.8 lens for the balloon glow as I am just too clumsy to swap out prime lenses in the dark. This choice does require me to boost my ISO a bit more though. A 50mm F1.8 lens is an affordable option for those lacking a wide aperture lens.
As I stated in the first line, you are free to use whatever lens you want. If you feel like using a 14-24mm lens for an entire shoot, do it. If you feel like using a 400mm F5.6 for an entire shoot, do it. The sky's the limit. However, I like having all three categories of lenses at the ready in my bag.
I do hope that my images have provided you some good examples of what to expect when you visit a hot air balloon festival. Now, go visit your nearest balloon festivals, and go have fun!