So here's the situation. I am currently shooting an XSi Gripped and a Sigma EF 530 DG Super Speedlight, with only the 18-55 IS and 55-250 IS lenses. (I have other items like wireless shoes, remote shutter, umbrellas, etc; but in terms of basic gear that's what I have.) I feel I am pushing the 55-250 as far as I can and am looking to move beyond the quality I can get from either of these two lenses. I shoot a wide variety of objects from indoor sports like volleyball and basketball - all with the 55-250 and a flash to light things up - to daylight and night outdoor sports like softball and football. Obviously I have the most trouble with football, but he stadium is lit well enough for me to shoot 1/200 wide open and usually with ISO 1600. I also shoot portraits, wide landscapes (less often), interiors and specialty projects. Basically right now I shoot everything from Bees to Birds, lol.
I have budgeted myself $1500 at the beginning of the year to make a fairly significant upgrade. I was going to add to my range and pick up the 100-400mm ƒ/4-5.6L IS USM lens. But I had the opportunity to shoot the 100mm ƒ/2.8L Macro IS USM lens the other day and was able to see a 1:1 comparison of my shots at nearly the same focal distance and doing so I saw the obvious improvements from better glass. So now I'm less convinced that I should extend my range with the 100-400 and thinking my best solution is to replace part of that range with a versatile and high quality zoom lens. Which the 100-400 kind of does, but I think of it as being more of a reaching tool vs shooting on the short end.
My basic requirements are that the upgrade is an upgrade, not a side grade, or something that is purpose specific like a 10-22mm. I like that lens (and the Tokina 11-16 better) and will get one, but that will be a separate upgrade. For now I want to see significant improvement in quality and usability. This puts me in a conundrum. I can strap an 800 prime on my camera and it will reach out and slap ya; but if you put that same lens on better body, it can reach out and slap ya, then tickle your ear and maybe sign an autograph. Basically the XSI will still have the same limitations within the camera no matter what I have attached to it. I don't mind going to a FF camera, but honestly I would rather upgrade into a better crop frame like the 7D first, then move to a FF after I have more L glass. Having said that, I know great glass looks great on the lil ole' 450D...
My first instinct is to go with the 70-200mm ƒ/4.0L IS USM. As a flat aperture I know I can draw in more light at the higher end, but I do give up 50mm. Then I thought, maybe I should consider the 70-300mm ƒ/4-5.6L IS USM. But, I'm still going to be fighting with light and I need to be able to gather light better then I can now. However, I also know that the newer body's do a much better job of reducing noise in high ISO settings. I can ONLY go to 1600 with the XSi, and even then I have to remove noise in LR. So a better body would allow slower glass by pushing the ISO up higher.
A few people loosely mentioned going with some faster zoom lenses from Sigma etc. but most did not have image stabilization, which is a deal breaker for me; or the quality just wasn't as good as the Canon 70-200 (and I know the f2.8 is even better but way beyond my price range). So now I'm sitting here trying to figure out what is my best move. I wont give up IS, and I don't want to give up range but would give that up before IS. Maybe a new body makes the most sense, but I feel pretty confident that I would see a bigger improvement OVERALL with a better lens. And I am trying to look at the big picture...which leaves me overwhelmed at the moment trying to decide what to do.
I'm open to suggestions that keep me under budget, and improve the "potential" of the gear. I know there is no tool which makes you a better shooter, so I'm not looking for a magic fix; I'm just looking to open the door further and position myself to be able to expand my abilities. If I were to pull the trigger today, the 70-200 ƒ/4 IS would be the call I make. And it may be the right call. But if anyone has a suggestion of what would be a better decision, please let me know. There is one caveat though, I will NOT be selling any of my gear. So selling this and that to give me a bigger price range is not an option. I would also prefer new, but I am certainly willing to consider used options especially with glass.
Thanks and I look forward to hearing your suggestions!

