The decisions that go into a purchase are different when you're a hobbyist vs. a working photographer, but it sounds like you're a hobbyist like me so my response will speak to that end.
People take advantage of favorable credit terms for snowmobiles, jet skis, hunting trips or gear, cars, tractors, scuba, airplanes and all sorts of other "hobby equipment" all the time and no one lifts an eyebrow. And, these assets lose value more quickly and are harder to re-sell in a bind than camera equipment. But, when your hobby is photography and not power sports or some other expensive hobby, folks (especially on this forum) look down their nose from their high horse like you're some sort of irresponsible juvenile when you talk about using credit for camera gear.
The key is simply not to allow yourself to become overextended with this purchase combined with your other obligations. Do that, and who is anyone else to tell you how to use your money? If you can't manage that, then sure - you're better off just saving.
Credit cards are fine for 1-2k purchases with a plan to pay off in a few months or a year. Even worst case with a high APR and making no payments for the entire year (not recommended!), you're only out a couple hundred bucks - a bargain compared to renting for the same time. Best case, the actual interest paid amortized over a year with a good rate is going to be much smaller and well worth it for some to own (and play) now.
But, credit cards are probably not the best route for a big purchase like a 400 2.8II unless you're taking advantage of a promotional rate of some sort. If it were me, I'd be looking at loan secured with some other asset with a free title - a motorcycle, a car, a snowmobile, etc. that has been paid off already.
Just my .02 - not trying to encourage bankruptcy, just offering another point of view that includes managing credit responsibly. FWIW, this is how I purchased all my gear and right now my credit card is paid off - using credit is not an indicator for bankruptcy or irresponsibility.