"When should you start carrying by the lens and not body"
On a D50, what is considered too heavy or big for the body when using a big lens and carrying holding by the body? I mean can the D50 handle the 70-200mm vr without supporting the lens with your hand? carrying that is pointed down or hanging around the chest. yes would look silly but still.
"when operating the diopter adjustment control with your eye to the viewfinder, care should be taken not to put your finger in your eye accidently"
#5. "RE: When should you start carrying by the lens and not" In response to Reply # 3
I am fairly confident the D50 will be OK with the likes of a 70-200 dangling around from the neck strap (bayonet in tension). The forces on the mount are considerably higher when the lens is in cantilever and should be supported by hand or tripod. As a side note, I would be more concerned about the lens than the body, given the lens is about four times the price in the UK.