My first digital SLR was a Canon Rebel and I used it for a long time till the camera exceeded its life expectancy as far as use. So I upgraded to a Canon 50 D which was a terrific upgrade with new features that expanded my skills as a photographer. This upgrade had given me a better frame per second burst and a much larger ISO sensitivity rang. And by staying with the same brand of camera I could use my lenses I purchased for my old camera on my new camera. So when you find technology is far beyond what your current camera will do, you might think about making that upgrade.
Another reason to make that upgrade is if you’re freelancing and depending on just one camera to get by with, this could eventually be a problem. Not having a backup camera could leaving you as they say “holding the bag” and could give you much grief with potential customers. I actually bought my second camera about a year after I upgraded because I wanted to have a full frame camera to photograph landscapes. At that time the Canon 5 D Mark II had just been released and it being a full frame camera, having many features that professional cameras of twice its price; made it as good a time as any to make a second upgrade. This gives any photographer a peace of mind when going out on a photography shoot one or both those cameras will do the job.
But when you go to upgrade, don’t wait too long and let technology pass you by, because you can always use the current camera for a backup. You also want to look at the cost of switching camera brands if you have several lenses from the previous camera; you don’t want to purchase new lenses if it’s not necessary. If you’re going to spend lots of cash on this new camera you want to make sure it fits comfortably in your hands. Holding a camera that’s uncomfortable can make for a long day of shooting photos. But the best reason to make an upgrade is to enhance your ability to create photographic art.
When not to upgrade is if you have a bad case of technology envy because your recent purchase might not have some bell or whistle that just come out after your purchase. Don’t get caught up in a bigger; newer digital SLR will make me look more professional, that’s determined by the photographs you take. From experience I would wait at least a year or two after my upgrade to take advantage of the newer cameras unless a fantastic deal comes along.