A bit tongue in cheek, but it does have some basis in the real world in some situations.
Sar and I took some photos of some tiny birds yesterday, an Australian bird called a Double Bar Finch which is about 4 inches long from head to end of tail, so, very small! They were at a nature reserve where they feed them seed in a plate and they are very flighty and so getting close to them was a bit difficult, but we managed to get about 3.5 meteres from them sitting on the ground staying very still and then they would return to the plate to feed. This was as close as they were going to let us get and any slight or sudden movement and they were off!
Using the D800E with 300mm f2.8 VRII + 1.4x TCII attached and handholding, I managed quite a number of shots and here is an example of the resolving power of the D800E, not to mention the superb resolution of the 300mm f2.8 VRII + 1.4x TCII attached. As you can see, I still had to crop quite heavily from the original image to what I actually wanted to end up with. The cropped image that I ended with up was 4065 pixels wide from the original 7138 pixels which is 43% linear crop! So, I would need a lens of about 600mm, but with a close focus of 3.5mts! I could have used my 2x TCIII, which would have allowed the close focus of the 300 bare, but I do not think the result would have been better and possibly would have been worse.
Captured in RAW, converted in Capture NX2 and tweaked in Photoshop. These are all 1800x1200pixels, so to see their full potential, you will have to click on the images and expand them to the full size.
D800+ 300mm f2.8 VRII + 1.4x TCII, @ f5.6, 1/200sec, ISO900, handheld.
Image I was aiming to end up with:
Here is an even tighter crop to show off the incredible detail. This is cropped to about 2100 pixels which is about a 70+% linear crop!