This full rainbow was over my house today after the rain storm.  Pretty heavy rain today for October.  Shot with my cellphone.  At 2MP is has more resolution that the second digital camera I bought 7 years ago.

Not bad for a phone camera.

Holy crap! That's great!!

I've tried taking rainbow pics before, but nothing as good as yours
 

You need to tweak the exposure a bit in Photoshop to match what your eye saw.  In this case I boosted the contrast a bit, and increased the colour saturation 20%, otherwise the image captured looks flatter than the actual, probably because the camera exposes for the houses and not the sky.

There's another one, shot nearly 10 years ago at Noosa Heads.  Camera was a first generation 640x480 Sony Mavica that recorded images on Floppy disks!  Only thing good about this camera was it's 10:1 zoom, so at least you did not have to crop too much as there aren't many pixels to start with.