Rendering a screen aligned quad with Graphics.blit - not working?

Hey everyone,

Basically I'm trying to render a full screen, screen aligned quad with a particular shader to a render texture. After a bit of googling around, it seems it's recommended to use Graphics.blit, with a shader wrapped in a Material. Per the documentation 'Blit sets dest to be active render texture, sets source as _MainTex property on the material, and draws a full-screen quad.'

However...is this working correctly? Is it doing something else in the process? Does it merely render the quad to the render texture or is it also blending in the source texture? When I preview my destination render textures, they are usually corrupted with various bits of video memory in them. When I render a roughly screen aligned plane with the same shader I appear to get correct results, but I have not yet figured out how to align a plane to the camera perfectly and would prefer to use something Unity has built in if I can.

Thanks for any help!