Your best bet is get the hell away from green mode altogether and start to use the camera. I am a K-7 user and can assure you that you will get much better results by not using green the K-7 almost always over exposes simply because it will always try to use the widest aperture it can thereby letting in too much light and your highlights will be blown (no detail)

Start with P and learn what happens when you change your aperture (F number), watch what happens to your shutter speed. Then press the green button on the back to get you back to where the camera wants you to be and change the shutter speed and see what happens to your aperture.

I highly recommend buying a nifty 50, preferably fully manual and learn to use it, you will learn more about your camera in one evening than you will learn in a month using green. And read the manual (RTFM) from cover to cover again and again. Try the things it talks about, eventually you will set the camera up the way you want it.

Personally I use TAV mode an awful lot simply because I want to control aperture and shutter speed, and let the camera sort out the ISO.

But the most important thing is shoot, shoot, shoot and shoot some more, it costs nothing with a digital camera.
Oh, and another thing, enjoy yourself.
Good luck

This is how much I enjoyed the K-7

What camera are you using it on and what settings, how dark is it? All these things have to be taken into account. Try a well lit environment, make sure the lens is wide open f2.8 in this case and also try it with live view to see if there is a difference.

And trust A.N.Other with your precious sensor, I'd definitely take more care of it.

That's great news Smeggy because, like me, you are a serial in the field lens changer. I know because we've had a similar thread in the past.

An interesting question, that's why I bought an Arctic Butterfly. You don't have to touch anything as it attracts the dust with static and I figure if I keep on top of it by cleaning after every shoot I should stay relatively dust free.

I'll have me a bit of that, if the lot hasn't gone?
You have a PM

The DA 35 f2.4 is amazingly good for a plastic fantastic lens, well worth the money

I will look into selling my DA*16-50 (which incidently hasn't skipped a beat) to help pay for it.
I've got an annoying gap in my focal lengths between 50 and 70, this will fill that perfectly.

Ah, OK

Link would be nice