Before I divulge the contents of my camera bag, I probably should share some of my lens philosophy with you, I really like prime lenses. I love that they're so sharp at such wide apertures. I love that they are small, light and cheap. I love that when I shoot them wide-open on my full frame Canon 5D I get some slight vignetting in the corners of the frame. I love that with my prime lenses I can shoot at crazy wide apertures like f2.0 in low-light conditions without having to use a flash.
The lenses I use are specific to a full-frame sensor. If I was shooting with a APS-c format DSLR (Rebel XTi, Rebel XSi, 30D, 40D, etc.), the lenses in my bag would be slightly different (but I would like to have similar equivilent focal lengths.)
For each lens, I've also included a sample photo that best represents the capability of the lens.
Canon 5D: I LOVE the image quality of this camera's huge sensor (I do shoot some stock, and the stock agencies like 5D files). I also love the ability to get extremely shallow depth of field, due to the larger sensor (and the need to be closer to the subject.) ISO 1600 on this body is also 100% acceptable. The 5D is a significant investment, but it's been worth every penny (I paid about $2300 for the camera 2 years ago - after a 20% discount and a Canon $300 rebate.)
Canon 17-40 f4: Ultra-wide angle for landscape. Although I'd actually love to replace this lens with the 24-105 f4 IS, I find myself using the 17mm - 20mm range frequently for landscape shots, so it stays in my bag. (A similar ultra-wide zoom for APS-c format cameras is the Canon EF-s 10-22.)
Canon 24-85 f3.5-4.5: If I can only take a singe lens on a trip (mountain climbing, backpacking), this is the lens I bring. I don't use it that often, because I personally prefer primes, but if I'm trying to keep my weight down and use a single lens, I use this lens. It offers a useful range (including 24mm on the wide end) and it's pretty cost-effective (approx. $325 new). I would love to replace this with the 24-105 f4, but I haven't been able bring myself to spend $1000 for the 24-105 (I can buy 3 nice primes for $1000!)
Canon 24 2.8: Great for low light indoor, wide-angle, hand-held shooting. It's very sharp, even wide open. I use this lens a modest amount.
Canon 50 f1.4: Great for low light indoor shooting. Shots @ 50mm have a very 'journalistic' 'look' to them. I use this lens quite a bit. I switch between this lens and my 24 f.28 for indoor flash-free candids.
Canon 85 f1.8: For low-light sports and indoor portrait work. I recently acquired this lens and I really haven't used it that much, it's a little 'long' for my indoor shooting and I really like my 200 f2.8 for outdoor portraits.
Canon 100 f2.8 Macro: For Macro work. Before I had other primes, like the 200 2.8 and 85 1.8 I used this lens a lot, now I just pull it out for Macro work. This lens is also good for portraits.
Canon 200 f2.8: One of my favorite outdoor portrait lenses. Also very good for low-light indoor sports. Razor sharp wide-open. I love this lens and it's what I mount on my camera if I'm shooting people outdoors.
Canon 400 f5.6: I use this for shooting windsurfing, kiteboarding, wildlife, etc. Anything where I need to shoot things that are far away. This lens is also good for creating 'compression.'
Canon 420EX flash: If I need flash, I mount my 420EX. Canon does not sell this model any more, the replacement is the 430EX. This does not get used very often, but it's a 'must have.'
Cokin z-Pro filter holder: If I need to use a filter, this is my filter holder. I hate carrying the filter holder and filters in my bag because I use them so infrequently, but the ability to mount a ND graduated filter is a requirement for me -- for art-quality landscape shots they are needed in some situations -- and I can never predict when I'll need one.
Cokin graduated natural density filter: If I need a graduated filter.
Cokin 8 stop natural density filter: For generating really slow shutter speeds, usually used in conjunction with f22.
4-5 5D batteries (I buy the cheapy clone versions off eBay.)
Extra batteries for the 420EX flash
A 77mm circular polarizer. Extra 58mm lens cover. Extra 77mm lens cover.
Bag: LowePro Mini Trekker AW backpack: This holds all my gear (barely.) I vowed that I would never carry a bigger bag that this because they are simply too dorky (in my opinion.)
Tripod: Manfrotto aluminum tripod (3001BD with Manfrotto ballhead (486RC2.)
I probably need to consolidate my lens collection, I feel like I'm lugging around too much gear, but I can't bring myself to get rid of any my glass.