So much in technology changes so fast, it’s a great mental relief when you encounter an absolute 
rule that will never change. You know, like, "Whatever you buy today will look overpriced and underpowered next year."
Two such longstanding rules have just come tumbling down in the world of inexpensive digital SLR, or single-lens reflex, cameras. Digital SLRs are bigger and bulkier than the pocket cameras that most people buy, but they are photographically superior in every regard. They turn on instantly; take stunning, magazine-quality photos; have zero shutter lag; can fire three shots a second; offer infinite manual control; accept a catalogue of lenses and go for days or weeks on one battery charge. Review: A focus on digital SLRs - Business - International Herald Tribune