Full frame vs Crop sensor (good info)

[fokker]

You lose reach moving to FX. Whether or not that matters to you depends on what you shoot, what you own for glass now, and how much you are willing to spend to recover that reach. A lot of people would rather keep using their 400mm as a ~600mm on a quality crop sensor than spend money on FX and then spend a lot more money regaining that 200mm that just disappeared.

This is only partly true; if you're comparing say a 5D mk2 with a 40D then the 5D (21.1 MP) has greater pixel density than the 40D (10.1 MP), which means you can crop the image down after taking it and still have the same field of view while retaining even more detail in the remaining area.

I think he was referring to Nikon sensor since he mentioned FX. So in that case it's technically true but then again, if you can afford it, just go with a bigger telephoto. And if your shooting requires 300, 400, 600mm prime telephoto, then I'm pretty sure your a professional. In that case, spending money on your gears to make you more money shouldn't be a problem.... just my 2cent =P

Nikon or Canon, the point remains valid if you keep pixel densities in mind.