The telephoto zoom limit is listed at 45mm on the Panasonic vx100 and 72mm on the Sony PD170. That sounds like quite a big difference. Is it? Does anyone have any real world examples that could illustrate the difference? I do enough outdoor videography where I have to zoom in to capture various things.

I assume you mean the Panasonic DVX100, Bill?

The DVX100 is definitely not a wildlife shooter's camera, with only a 10x zoom lens. The PD170 also only has a 12x lens. This could be supplemented by a tele adapter.

If you think you need a longer lens you should look at a GL2 (20x optical Flourite) or an XL1s (16x standard lens).

The DVX is 4.5 to 45mm.

The PD150 is 6 to 72mm.

The DVX is quite a bit wider on the wide angle, the PD150 is much longer on the telephoto end.

If you add a 1.6x teleconverter, it would bring the DVX's long range up to match the long end of the PD170 without a teleconverter. (of course, you'd have to put a .7 wide-angle adapter on the PD170 to get it to match the wide-angle capability of the DVX), so really, you pick your preference.

If ultimate telephoto is your goal, the PD170 will be more capable because not only does it start at 72mm, but you can add teleconverters to that.

The XL1's 16x lens goes to 88mm, which is longer still.

For the difference between 45mm (DVX max) and 72mm (PD170 max, or DVX with 1.6 teleconverter) check these pictures:

DVX at 45mm:
http://www.icexpo.com/dvx100/No_teleconverter_full_zoom_240x160.JPG

DVX at 72mm (45mm + 1.6 teleconverter):
http://www.icexpo.com/dvx100/Century_teleconverter_full_tele_240x160.JPG