Lots of questions, so lots of answers coming. At the end of the day, you have to answer these questions for yourself, but some good advice helps...
Maybe true, but it depends on the sport. You mention bike rides and triathalons - generally, spectators and casual photographers at those events can get pretty close to the action - close enough that 200mm is likely plenty of focal length. That might not work for wildlife, possibly for big game on a safari (where you sometimes need a wide angle for wildlife - in Ngorongoro Crater, lions and elephants came within 5 feet of the Land Rover we were riding in), but not for small animals/birds, where even a 400mm lens comes up short. If birds/wildlife is an occasional thing for you, a teleconverter makes sense (more on that below).
Wow does it. Incredibly detailed answers as well.
If/when I decide to go to Africa, taking a seven thousand dollar+ 500mm is on the list. Oh so very on the list. Fortunately, I limit myself to the Australian outback - I don't believe I'll have a massive worry about distance to be honest, most of the wildlife is either tame enough to be captured within the 200mm range (we have wallabies and a massive echidna that love the area below our house). I do however worry if it comes close, as there is an increased likelihood is that it's coming to poison or kill you.
Great choices! The 70-200mm II is a great lens, and I really liked the 10-22mm angle of view (I had one, which I sold when I added a 5DII and 16-35mm f/2.8L II to my kit, giving the same angle of view as 10-22mm on APS-C).
I disagree with the blanket statement that EF-S lenses lose value quickly. Some do - kit lenses and lower end lenses in particular. But three current EF-S lenses deliver optical quality equivalent to many L lenses (when used on APS-C), and hold their value well - the EF-S 10-22mm f/3.5-4.5, EF-S 17-55mm f/2.8 IS, and EF-S 15-85mm f/3.5-5.6 IS. FWIW, after using the 10-22mm for about a year, I sold it for only US$50 less than I bought it for (new from Amazon.com), and that was before the recent spate of lens price increases - selling it today, I likely would have made a profit.
Thanks! I did about two months of research and price comparison before settling on my choices. I heavily considered the 16-35mm F/2.8L, but it really had several issues I wasn't prepared to deal with. Including the 82mm filters which fit nothing else in my arsenal, and the fact that I wouldn't actually have a true wide angle lens on an APS-C sensor. If I decide to upgrade to a FF, I'll look at the 16-35mm then.
I also agree here. I purchase the EF-S 10-22mm at $839 USD. It retails here in Australia for $1360 USD. I have observed the used lens prices from $700-775 on eBay for the past two months. I am very satisfied with the return on the lens and completely disagree that it would lose its value.
For occasional use, a TC is fine. Personally, I would not plan on it for frequent use. More later...
With the 10-22mm in your kit, a 24-xx L zoom would work. You could also look at the 24-105mm f/4L IS - on a crop body, it's a useful focal length for outdoor shooting.
I'd skip the IR filter - dSLRs aren't really sensitive to IR, because the Bayer mask (RGB array) covering the sensor blocks almost all light outside the visible range. There are 3rd party vendors which remove that mask (IR conversion), which would be the way to go if you want to shoot IR on your 450D (after getting a new body, that is, unless you only want to shoot in black and white going forward).
I've heard the quality on the 24-105mm is severely lacking and the QC on the lens tends to be very iffy at best. I may hold off on this lens until I either buy the FF, or I see a new lens that Canon puts out for this range. I'll hold judgement until I can hold and test both the 24-70 and a 24-105 at a store.
Noted. Will skip and keep using Photoshop
Zoom lenses are for convenience and flexibility. For example, you just got a 70-200/2.8, but the 200mm f/2.8L II prime lens gives you the same long end and aperture in a package that's 1/3 shorter and half the weight.
IMO, the main reason to get primes is for the faster aperture - the fastest zooms are f/2.8, but if you need to stop action in low light, f/2.8 makes that challenging. Similarly, if you want to stop action in low light at long distances, those heavy supertele primes (300/2.8, 400/2.8 ) are often used by pro shooters, but with cameras that have better ISO performance than your 450D.
Noted and agreed on both ends. The 200mm isn't practical for the reasons you pointed out - convenience and flexibility on one camera.
Depends on the benefit you want to achieve. For a working photographer shooting events, a second camera is almost a must-have. Are you getting paid for your shooting (you mention charity events, so possibly not)? Cameras fail, and if you're getting paid for covering an event/wedding/etc., 'sorry, my camera broke' doesn't cut it for the client. But if you're just a casual shooter, carrying a second dSLR as a backup is not really necessary, IMO (if you're concerned, bring a P&S).
The one exception to that might be if you're using prime lenses, so you can hang both cameras off yourself and change focal lengths quickly. But that's why you're using zooms...
Answered previously, and also noted and agreed with.
At the point where you feel your camera is limiting your shots (or when you own all the lenses you could ever need/want). Personally, I started with a 500D/T1i, and I did find it limiting. Compared to your camera, the 7D's autofocus system is a dramatic improvement. Compared to your camera, the ISO performance of a 5DII is a dramatic improvement - the 450D tops out at ISO 1600, and you might not even find that useable, whereas the 5DII produces useable images at ISO 3200.
Another limiting feature is AF microadjustment - as you get faster lenses, you might find they are a little off with a thin depth of field. AFMA can correct that (so can a trip to Canon for service, but you need to send in your body and all your lenses). With fast primes, I'll never get a body withour AFMA (my 100mm f/2.8L Macro IS was backfocusing on my 500D, for example, but I worked around that because I shoot mostly manual focus for macro work).
True. I'll see how the 70-200 handles on the 450D, I don't find I have many issues in the manual settings at the moment, but I'm a heavy handed post-production fan, mainly because I did graphics work prior to experimentation with a camera. I do find the ISO settings limited especially when pairing with fast shutter speeds, but I would rather look at a 7D compared to a 5D Mark II until we get specs for the III.
I find the AF across the board on DSLRs pretty terrible. I honestly won't be happy until I can have an option to choose my own AF points, if I want to override the camera. I use the feature on my camera phone (terrible I know), but I've gotten to used to the feature.
That's always a trade off. On a recent trip to China, my photo gear bag weighed in at about 10 kg (all packed in a LowePro Flipside 400AW, which was in turn packed into a Pelican Storm im2500 hard case for a 15 kg total carry-on).
I suspect if you get a decent general purpose zoom (24-70, 24-105), you'll carry that instead of the 18-55mm kit lens - you might need a bigger bag.
The thought did cross my mind that I'm going to need a bigger boat. As mentioned previously though, I'm 103 lbs, I already lug around a 15" laptop and my camera when I travel, and boy is the weight noticeable already. I try to limit myself to the twin kit and the macro when I travel already. Adding in the extra two lenses and dropping the EF-S 55-250mm will just be a nightmare to be honest. I think I'm going to have to buy a pack mule.
The combination of a general purpose zoom and a 70-200mm telezoom would cover most needs. I do disagree with the previous poster stating 24-70 + 70-200 - that would be fine on a FF camera, but on a crop body, 24mm is not even wide angle (38mm FF equivalent). However, an EF-S 17-55mm f/2.8 IS with the EF 70-200mm f/2.8L IS II would cover almost all your shooting needs in a 2-lens kit.
First off, of all the lenses you've mentioned, the only one a Canon TC will work with is the 70-200mm zoom (they are compatible with 135mm and longer L-series primes, the 70-200mm L-series zooms, the 100-400mm but you sacrifice AF unless you have a 1-series, and a few miscellaneous lenses like the TS-E series). You could get a 3rd party TC that would work with other lenses, but IQ is not as good.
Yes, the 1.4x III causes less of an IQ hit than the 2x III.
I really recommend using a TC for only occasional use. For routine use, buy the focal length you need. A possible exception would be the supertele primes - a lens like the 300mm f/2.8L IS takes only a very small IQ hit even from a 2x TC. The 70-200 II holds up pretty well to a 1.4x, and decently to a 2x. There's a whole other thread on the latter, and I also posted a shot with the combo on my 7D. I also have the 100-400mm, and the IQ is definitely better with that - not a lot better, but noticeably better. I got the 2x II for use with my 70-200 II as a weather-sealed alternative to the 100-400mm.
Swapping on and off a TC is a hassle, especially in the field. You'll likely miss shots if you need to do that frequently. For situations where you need to go from short to long quickly, consider the 70-300mm L or the 100-400mm - either would be a lot more convenient than 70-200mm Â± TC, and deliver better IQ.
Yes, you'll lose effective aperture as you know, but that's not the only downside. Less commonly known, but possibly significant, is that AF is slower with a TC - by design, when you put on a 2x TC the camera will slow down the AF by 50% (25% for a 1.4x TC). That might be an issue for fast moving sports (you would notice it compared to the 70-200 II without a TC, yes, but compared to a non-USM lens like the 55-250mm you've been using, even 50% slower on the 70-200 will still be faster than that).
Hope some of those answers help. Good luck with your decision!
Honestly, from what you state here, and from the weight issue, I think I might actually pick up a 1.4x TC. I don't think adding a 100-400 will solve my weight issue and give me the effective 300-400 range. The information about the AF is incredibly helpful, zero posts I've read about the subject mention that, and I appreciate that information . I am not hunting the primes yet, but if I do happen to look at picking up the 100-400mm, its nice to know I can potentially consider using it there.
Thanks so much for your post - its given me a lot to think about and use for the next step