Hi Amy
On the subject of filters:
Updated through experience!
See the attached image at the end of the post, that was one of mine, direct hit on the filter, the broken filter smashed it's way through the front element of an £1,100 L series lens!
Personally, I'd rather not have to replace a front element again and experience has shown that even high impact filters degrade when coated with paint.
Covers:
Personal favourites:
http://www.thinktankphoto.com/products/hydrophobia-70-200-rain-cover.aspx
http://www.lenscoat.com/bodyguard®-clear-back-p-1036.html?osCsid=66971bdf854e5a858993aca9933b1efe
Neither of those are cheap in the UK, I was fortunate enough to get mine in/from the USA avoiding the VAT etc.
Other alternatives can be as easy as cutting the leg/arm of a set of waterproofs, though proofed nylon tends to degrade with time and wear,
Wildlife Watching Supplies make some quality alternatives in the UK, and they are well priced
http://www.wildlifewatchingsupplies.co.uk/retail/acatalog/C80-All-in-one-camera---lens-cover---Reversible.html I've used these too.
I also use proper gaffa tape (not the nasty pound shop or diy store stuff) to tape up mode wheel and the focus buttons and rubber grips on the lenses and add extra protection to the camera body, it may be a little ugly but it's effective. If you use the real stuff, as used in the film, TV and photographic industries, it won't leave a nasty glue residue on your equipment when you remove it but it does save your equipment from the white residues that paint leaves when it dries, or you can spend a lot of time cleaning your equipment.
The bodyguards quieten down the shutter noise and protect the camera from knocks, you can find cheap neoprene pouches on ebay too and modify them if you are on a tight budget.
Some photographers cover their lenses with sweat bands and use a towel to shield them, I don't really like the idea of such absorbent materials soaking up paint, or rain, and then being next to my equipment.
Settings:
Most of the time if using a long lens (70-200 with or with out an extender) I stick to a shutter speed of 1/640 this combats camera shake and freezes the action but you can still see balls blurred leaving the barrel and the splash of a hit. A fairly wide aperture, there is nothing wrong with stopping your lens down to f16 or more, though you might loose some sharpness, most lenses are their sharpest around f8. Most paintball sites make pretty ugly backgrounds, so opening up the lens helps by decreasing the depth of field and throwing the background out of focus. As for ISO, easy option is just to set the mode wheel in manual, select your shutter speed and aperture, then bang the ISO setting on Auto, In the woods, movement tends to be a little slower so you can use a slower shutter speed, especially if there is a handy tree t steady yourself against. I also turn off image stabilisation, it can create havoc all of it's own. Set the shutter to burst mode and the focus mode to AI servo, so you can shoot continuously if following a move, or tale single shots of static players. Be prepared to delete lots of files while you develop your style. Select the focus point(s) that suit your framing and remember that with a mask on you might loose some of the view in the viewfinder, so allow for this when framing.
Lenses:
Your 75-300 is an ideal starting point, I'd recommend a 70-200 if you are looking for an upgrade, the non-IS f4 Canon L-series is a seriously good lens for the money
http://www.parkcameras.com/112/Canon-EF-70-200mm-f-4L-USM.html , don't get trapped in to thinking the longer lens is best, switch to a wider lens and experiment. What ever you use I'd recommend adding a petal style lens hood, it helps protect from stray shots and knocks, as well as raindrops and lens flare/ghosting etc. As it's bound to get dirty and knocked about a cheap 3rd party one off ebay may be a better option than an expensive genuine one.
You may also want spare batteries and a more memory cards plus comfortable strap which also helps save the original one from getting ruined
Clothing:
Goggles, choose wisely, they need to be comfortable and fog free with a good field of view. I have used Protos, but found, whilst the lenses were excellent, they tended to muffle sounds too much, Grillz, were excellent, light and comfortable, but the lenses are anti scratch coated, unfortunately, the eyepiece of the camera rubbing on the goggles lifted the coating and the lenses needed frequent replacement, my goggle of choice are JT proflex, they are light, comfortable (and customisable), offer a good field of view and can be broken down easily to pack away small. I tried the new Virtue KLRs, they were comfortable but the lens is at and angle, so the camera was pointing downwards while I was looking straight ahead. Peaks can be a problem as they tend to get in the way when shooting in portrait.
A good solid pair of boots or shoes you can wear all day comfortably and offer the right grip and waterproofness/warmth for the conditions, I use lightweight hiking boots or astroturf hockey boots mostly as I find these work well.
Comfortable trousers that offer some protection and allow movement, not unsurprisingly, paintball pants are a good choice.
Hoodies, loose long sleeve t-shirts etc. depending on the weather, A decent waterproof jacket for when it's wet out there. Mostly I wear black, I don't want to be confused as a player, so wearing a jersey isn't, in my opinion, a good option, I don't like wearing hi-vis as I think it's distracting to players and it looks awful in the background of photographs, not to mention it's effect on focus and exposure it you are unlucky to get Dayglow Derek in shot, and I certainly don't want to look to players like a referee. Most of my tops are logo'd and have the word photographer printed on them. My goggles are fairly distinctive too. Even then, I swear some players forget to wear their glasses on field mistake me for the enemy.
A beanie style hat, or a hood, or headwrap. headband etc. is a good idea as is a pair of elbow pads to help soften hits to the forearms, gloves, preferably with some padding on the back of the fingers. I don't generally wear a bounce vest of body armour, but it's a personal choice. You'll want somewhere to put spares and cleaning equipment, a backpack or something that doesn't get in the way when shooting. Oh, and a hand towel or cloth to wipe your goggles etc. down quickly.
Some organisers may require you to wear a specific jersey, bib or vest, this may be hi-vis, it's their field and their rules, always ask first.
Positioning:
You are going to get shot, and it stings more than when you are playing as it's less expected and the adrenaline isn't pumping. Years of playing helped me with choosing spots where I'd get a decent shot and not be directly in the line of fire. Take a look round the field if it's been played already for paint marks and or paintballs on the ground around the netting, this will give you a decent idea of the spots not to stand in. Learn to shoot with both eyes open, the peripheral vision in your non-shooting eye will help to keep you safe as well as picking up action on other parts of the field, if you can shoot with either eye this helps too. I wouldn't recommend shadowing a ref, they need to move and sooner or later you'll both be looking in opposite directions and collide, but do get to know the refs and make them aware of where you are going to be if needs be. Don't get involved in decisions, stay neutral and don't do anything that may influence the game, likewise, don't fraternise with players on field too much.
Achieving the shots you want.
This takes practice, trial and error, a good eye, talent, and standing around on a muddy field getting shot, some of it is learnt through experience, some can be taught, some is down to talent and an awful lot is down to luck. It helps to have some idea what you are working for rather than just shooting loads and ending up with a ton of similar shots. Players love the attention and are often happy with mediocre shots if they are in them, but you need to take shots that you are happy with. Don't be afraid of a little post, adjusting levels, cropping and straightening, etc, adding filter effects doesn't polish a turd though. As above, be perpared to delete/discard loads of shots. Your 550D is more than adequate, you may desire a faster burst speed, but getting splash shots is mostly down to luck, you'll probably get as many with a 550 as you would with a 1DX!
Hope that helps.
