1.4x Teleconverter vs Cropping on 5Dmk2

[futureal33]

Hi all,

I am aware this topic has been covered to death, but I was just talking to a very keen wildlife photographer who has mentioned something that got me thinking.

His opinion was that teleconverters CAN be good.. but only in a situation where there is already detail - allow me to explain.
He said that if you add a 1.4x TC to your lens with the intention that it will bring something that is miles away a little nearer, then you will be disappointed. However, if you add a 1.4x TC to your lens and shoot a subject that is relatively close, and it just allows you to fill the frame better, then it will be very good.

His argument was that a lens can only resolve the detail that is there in the first place. So if you're shooting something 300m away, then obviously the fine accurate detail of that subject will be limited, and sticking a 1.4x or even 2x TC on wont make things any better at all, it will still be the same detail, just with slightly higher magnification - which might not look any better than just a crop would have done.
However, if that subject was just 20m away, then the detail will be much higher at that range, but if it still doesn't quite fill your frame at that range, then in that situation adding a 1.4x TC on will be using the TC for its intended purpose.

This was coming from someone with a Nikon (boo hiss) D700 (12mpx IIRC)

I just wondered how this would relate to a Canon 5DMk2 user, which has 21mpx and therefore a lot more cropping potential.

Thoughts?

 

[hollis_f]

His argument was that a lens can only resolve the detail that is there in the first place. So if you're shooting something 300m away, then obviously the fine accurate detail of that subject will be limited, and sticking a 1.4x or even 2x TC on wont make things any better at all, it will still be the same detail, just with slightly higher magnification - which might not look any better than just a crop would have done.

Yes, the detail will be limited. But, as long as the lens can resolve that detail then a TC can magnify it. Now, with some crappy lenses, or with decent lenses used improperly, the resolving power of the lens would be so poor that there is no extra detail that can be brought out by magnification. With a lens like that a TC would be no help.

But just about all lenses can resolve much more detail than the camera can capture. So the only way your friend is correct if if their technique is poor enough to screw up the lens's resolution.