Why upgrade? For me, the upgrade path is driven by pain, as in "pain in the rear". Here is the history:
Canon G2 (first digital camera)- Great features
- High resolution for the time (4Mpx)
- Great lens
- Slow AF and slow operation overall (PAIN!)
- Clumsy manual focus (PAIN!)
- Limited closeup capabilities (PAIN!)
- No interchangeable lenses (PAIN!)
Pentax K10D (fix for G2 pain points)
Game changing camera at the time of release with too many plus points to name. The K10D fixed all of my G2 pain points and then some.
- Incredibly practical camera
- Great build and handling and a good fit for my style of shooting
- Great sensor
- Poor exposure metering with vintage lenses (HUGE PAIN!)
- Fast and reliable AF performance with stationary subjects
- Poor AF-C performance and poor AF overall with moving subjects (PAIN!)
- Poor high ISO performance, though typical for the time (PAIN!)
- No external PC flash sync (PAIN!)
- Limited wide-angle options due to APS-C format (PAIN!)
- Relatively loud shutter (minor pain)
Pentax K-3 (fix for most K10D pain points)
Also a game changing camera with multiple points of excellence. The K-3 addresses and fixes most of my pain points from the K10D and adds several features that I didn't know I needed until I actually used them.
- Very nice build
- Fast and quiet operation
- Huge improvement to the AF system including a truly usable AF-C
- Huge improvement in high ISO performance over K10D
- Limited wide-angle options due to APS-C format (PAIN!)
- Soooo many buttons that are soooo easy to push by accident (minor pain)
Hmmmm...still one outstanding pain point. Oh well, I managed with the K10D* for seven years. I can manage until Pentax actually releases a FF camera and I can actually afford the upgrade
BTW...This is only the digital progression. There is a parallel branch of film cameras driven (for the most part) by low price and desire for a larger format. Truth be told, for what I have paid out for film gear in the last five years, I could easily have bought a nice FF kit from Nikon.
Steve
* To be honest, I sort of miss the K10D. Its body, though a little larger than the K-3 had a better shape for a two handed grip. It also had a lot fewer buttons to keep track of.