I have recently adapted half stops. I routinely use a minus adjustment on the K-5 and found -0.3EV too little and -0.7EV too much, and -0.5EV just right.

It may be so, and if you change to half steps and find the problem disappears we've found the answer.

That's what I'm saying. I tried it with the two lenses mentioned and both behave the same.

Hope that helps.

The difference seems to be what the aperture is when you first turn the camera on. With the 18-250mm and the 18-135mm if set to f/3.5 then the first click does nothing, the second goes to f/4. If the camera is already on then the first click goes straight to f/4.

It does seem to be related to first operation of the camera and waking the system.

Don't forget that the aperture value changes with zooming with many zoom lenses.

I'm not sure why you have your camera set to wide open all the time? Mine is set to whatever aperture was set when last used - usually between f/8 and f/16. As a consequence, this particular behaviour has never become apparent.

Possibly the first click is just reawakening the camera, or alternatively you are makining the first click before the camera has completed some other action.

It's the sort of question better answered whilst handling the camera. If it's repeatable though, then use two clicks by feel and you'll have a repeatable result.

Ken, you're right. They are delighted and all very nice people. From both sides of the fence, Sue has asked and shot pictures. She has been asked and had pictures shot. It's all meant to be fun.

It was slightly amusing though seeing one group[ of goths providing a pre-agreed pattern for every group of photographers who approached them. They slipped into an identical group pose every time and everyone will have exactly the same pictures. I have some images of this process going on, but I think I'll keep them safely hidden away, just to avoid any embarassment...

If that's the case, I'm not surprised that you adjust all your lenses.

All the threads form a picture of how this sale is progressing. We don't normally delete any for sale thread for this reason.

Here are a few of us, newly arrived around 10.30am.

JAK, what would you think if Pentax adjusted their cameras and lenses by using a hand held test? I'm afraid you have to be precise if you are making measurements. Your adjustment is nowhere near precise.

I only mention it because you are making changes based on some very error prone methodology.

There is absolutely no way we can make any conclusion from a hand held test.

I would wait before adjusting anything and start agin with a sturdy tripod and a carefully aligned subject.