If you want to take your sports photography to the next level, especially if you shoot any sport where having a second camera remotely can add a lot to what you can cover in a game, like football (soccer) or basketball, then you'll need a wireless remote shutter release.
Let me preface this by saying I'm not a tech geek, but it doesn't take a rocket scientist to operate these units - the "manual" provided with it is so small you might not even notice it.
Not all of us can afford Pocket Wizards, so we turn to the cheap alternatives. This is where the Yongnuo RF603C II (C stands for Canon, there is also the Nikon version) comes in. There are many other brands out there just as cheap, but I've had good experiences with Yongnuo (I have 2 Yongnuo flashes) that's why I picked them. These units can also remotely trigger flashes if that's what you're after, but I'm not gonna cover that here.
The most obvious difference between the Yongnuo and Pocket Wizards is the price. The Yongnuo RF603C II comes in at around 25£/29€, and the Pocket Wizards are almost 10x more expensive, so that's a huge deciding factor for those of us on a budget.
They operate on 2 AAA batteries, mount on your flash hotshoe, and use a cable (very important to get the right one) to connect to your camera's remote port. To trigger the shutter, you can half press to focus - though if using it remotely, it's likely you have set your camera to manual focus - and you fully press it to fire the shutter. These also work in bulb mode, you just need to press and hold the button for as long as you wish.
They don't require line of sight, and the range is quite insane for such cheap units. It says the range can go up to 100 meters (109.3 yards), though in my experience I wouldn't say it went that far. To be fair though, I don't need it that far anyway, when shooting on a football field (90-120 meters from end to end depending on the pitch), I always set the remote behind one of the goals, and I go near the corner, or up the field a bit, but nowhere near midfield (which would be 45-60 meters).
The only "con" I see with the Yongnuo RF603C II is that you have to press the shutter yourself on the 2nd unit (the one you have with you), so you'll have it on your left hand, while the right hand operates your main camera; it will not fire if you mount if on your main camera, as Pocket Wizards would. That being said, it's not necessarily a bad thing, as this way you only press it when the action is near the remote camera, and you won't end up with a lot more pictures.
If you're thinking about purchasing the Yongnuo RF603C II, the Pocket Wizards, or anything else, consider using the Amazon links provided below, it costs you nothing extra, and I get a tiny kick back for referring you to Amazon, which helps this channel.
Yongnuo RF603C II
PocketWizard 433MHz Plus III Transceiver
PEDCO Ultra 2 Camera Tripod
Eneloop AAA Rechargeable Battery