Is it always better to just buy now and ignore marketing hype, announcements, and speculation? If I always wait for the next model, I will never buy anything.
What about buying the cheapest thing now as a stop-gap, and waiting until after the next big photo-show? Or renting equipment until I find something I really like working with? (Won't that get expensive over time?)
What do you do when you want to get new kit?
I would really like to hear how best to make the decision to buy or to wait.
Does it do what I need now?
That's the key one. There'll be another better one in 6 months or whatever, but in the mean time do I want to miss 6 months of photos I could be taking?
You have touched on a surprisingly difficult question we all face. Mostly we intuitively feel our way towards the right answer but it can be very helpful to parse out the influences we factor into our decision.
My advice is to carefully think about each of these items and ask the question, does this support my decision to re-invest? There is no magic formula but you will have examined the problem from all angles making it likely that you will make the right decision.
It all comes down to one last question. Will this really make me a better photographer? Is it worth the cost?
Buy now. Enjoy using your gear in the meantime. I held back on buying a 5D for a long time waiting for the 5D mkII, then ended up getting a mkI anyway when it was released (the specs of the mkII were not what I'd hoped given the price)!
There will allways be new models as you say. Also when new cameras are released the price starts very high, there are are often problems with supply, firmware bugs and other issues that are noticed by early adopters which take time to fix. It's much better to wait a while until all the faults are ironed out and a user base develops, helping evaluate the camera.
The only exceptions are truly game changing features such as Nikon's first FX camera (and perhaps video). That's the only thing I would take into account, asking myself "does this new camera do something that was impossible before?", if not why wait.
Renting is an option, if you only expect to shoot infrequently, though this is a better approach for lenses. With camera bodies it pays to really learn all the features and get used to using it, which takes time. It's nice to sit and home and play in your spare time, not try and learn it three days a month when actually shooting.
If you know a new announcement is coming (ie. around Photokina) it might be better to wait a few weeks (or a few months), if your primary concern is budget, because you may find older models being reduced in price as their replacements are announced.
For instance, in August, I decided that I wanted to get a D90, but knowing that its replacement was expected to be announced in September, I decided to wait. And, although the D7000 has impressive specs, the D7000 body costs the same as what the D90 kit used to cost. Since the announcement, the D90 has dropped dramatically in price (over $250 in Canada anyway).
I ordered my D90 this morning.
On the otherhand, if you need the camera now, then now is the time to buy!
Like many consumer electronics, you can easily be paralyzed by perpetually waiting for the next, best thing to come out. Unlike most other consumables, though, photo equipment comes with a couple additional factors to consider:
Compatibility. No matter what sort of setup you're buying, you're going to end up picking up a ton of accessories. In the case of a DSLR, obviously, this includes lenses, but even for a P&S, you're likely to accumulate bags, batteries, tripods, flashes, memory cards (this could go on for a while), and so on. If you're buying into a system, your purchase is pretty important, and you should be looking at the whole system -- not just the unit you're drooling over.
Resale value. Unlike many other consumer electronic items, used cameras hold their value fairly well, and lenses hold their value even better. Therefore, you can pick up today's equipment (or even yesterday's equipment) and have a good chance of getting most of what you paid out of it if and when you want to upgrade (which makes upgrading much more budget-friendly).
To the extent that you can pick a system and buy stuff that's compatible with that system, you've got a lot of flexibility to swap pieces and parts, and you'll be able to make better decisions about the stuff you're buying because you're taking pictures!
There will always be "something better" released in the future; I'd advocate not getting too hung up on whether the next model will solve world hunger or not as rumours of what it may (or may not) support are merely rumours.
Some sites share an opinion on whether it is a bad idea to buy or not, based on their predictions, for example, for Canon gear, there is this site, which currently doesn't think any of the Canon bodies are due to replaced imminently (with a 1Ds replacement 6-12 months away).
I'd always recommend upgrading when there is a feature that you need, and instead invest in lenses, as you can reap the benefits sooner.
Personally I think it's best to use your current equipment until they either break or it's clear that you are limited by your equipment - and then upgrade the parts of your kit that are limiting to less limiting ones. Just buying newer model because reviews tell it's greater than the old ones does not make your pictures better.
So, if you know what's limiting you right now and there's a fix available on market - go for it. If you hear the fix is coming, but not available yet, waiting makes some sense.
And like others said, camera body is less often the limiting factor, as long as it's DSLR. The other parts of your equipment like lenses, off-camera lights, tripod etc can equally well be the restriction.
For example, if your problem is lack of light when taking photos out of people, a speedlight at hands distance away with some softening can make pictures a lot better than camera body with better high ISO performance.
My approach is to borrow kit to get me started, or to try out for a holiday. My first DSLR was a fairly old one second hand off a friend to dip my toe in the water and see if I really liked it.
Once I was sure I did like using a DSLR, and was frustrated by the limitations of the kit (lack of top LCD and second dial on a Canon 300D) I looked around for what was coming up and bided my time.
In the end I bought a 40D just after the 50D came out - the 40D price was cheaper than the 500D at the time I think, and the big new feature on the 50D was video which doesn't interest me.
