Why null transform when cropping?

[angelleye]

Pretty much everywhere I've seen a guide on how to crop your video says to insert the Null Transform filter and then set the cropping via the 'cropping' button under the filters window.

However...I one time forgot to do it that way...I simply added in the Deinterlace filter as well as a resize filter...the cropping button is already there and ready to use so I just click on it with the resize filter highlighted and set it there...leaving out the null transform. It works great.

Why use null transform?

[celtic_druid]

What happens if you weren't deinterlacing and cropping? Still got access to the crop function? There is your answer.

That said, why not just crop with AVISynth before VDub?