Lens Operating Ring Layout

While involved in a discussion to use a battery grip or not, I noticed the layout of the focus and zoom rings was reversed on the DFA 150-450 compared to other Pentax Zoom lenses. At first I thought it's to make it more comfortable to use the longer heavier lens, but then the the DA 18-135, hardly heavy or long, uses the same configuration.

So I've got 8 zooms from F35-70 to DA55-300 including a DA*50-135 that have the zoom ring closest to the body and focus ring in front of that. Then the two lens mentioned above the opposite way round.

The question is, why?

Hi Barrie
Could be than the 50-135 is internal focus i.e. It doesn't get longer when focusing

Damn! and I thought they'd got it right

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Don't know Neil.
Looking at the photos for the DFA range and the new DA55-300 they are all focus ring closest and zoom on the end. Do we need a lens designer to explain why?

The newer lenses might use rear group focusing, or it could just be a new way of designing the internals of the lens. It does take a little getting used to, but in the end the important thing is that the zoom and focusing rings operate in the same direction for all lenses. That avoids confusion when using several lenses.