[lesjames]

I own a D60 and 100-400mm IS, I have made several attempts at digiscoping without much success. I am thinking of buying a 2x extender which will effectively give me 1280mm. what are the drawbacks or pitfalls? or should I by a larger lens?

Les

[Andy Bright]

Hi Les, not sure how this slipped through unanswered. I expect you've drawn your own conclusions since you posted.
Anyway, for the benefit of anyone else.
You will be getting considerable focal length with the addition of a 2x converter...but at the price of effectively getting light levels of f11. This will result mean slower shutter-speeds and vibration/camera shake at these magnifications will often be too much for the i.s. system of the lens. In addition your camera's AF will have packed up just past f5.6. So you will need a tripod and switch off the i.s.
The results will be rather soft compared to the bare lens and also lacking in contrast...both can be rectified in-computer, to a limited extent. Only you can say if these results will be acceptable to you.
Get a longer lens or go for a 1.4x tc (image degradation is very minor with a 1.4x tc).
Regards,
Andy