I've missed taking some shots because I was busy wrangling my camera out from my bag. It's times like this I wished someone had thought of the Cloak Bag earlier. The bottom of the pouch is zippered, so you just have to undo this to reveal the lens. Openings at the side of the holder allow you to access the camera's grip and zoom ring around the optics.
Do note that the bag is only 9.25 inches tall, so not all lenses can be secured within the Cloak Bag. You'll also have to use the supplied camera strap which loops around the bag in order to keep the dSLR in place.
The Cloak Bag is available on Naranja's Web site for $49, which is pretty affordable for a nifty carrier.