I bought this one https://www.amazon.co.uk/gp/product/B01L1E8S6Q/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1

Fitted first time with no bubbles, very happy with it.

Any Pentax dealer should be able to order one for you. It is a very recent lens, there are not going to be many people with a spare one in their camera bag.

What happened to the one that came with your lens ?

Prices on ebay without a sale are no use at all. It is sale prices that are important. I have found one that sold on PentaxForums last July for $450. That one was described as near mint. https://www.pentaxforums.com/forums/36-sold-items/326931-sale-sold-pentax-k-18mm...

Without being able to see your lens I have no further interest.

Can't see an ebay sale of these recently so can you suggest a price you are looking for ?

Where are you based so the lens can be inspected/tested on camera ?

Just to add to this, I did actually acquire last year a Pentax A 16mm 2.8 fisheye with fungus. It is quite a rare lens. I bought it as part of a job lot and it's net cost to me was next to nothing. The fungus cleaned up nicely everywhere (it was worse in the dial-in filters), except for a small patch that was growing behind the front element in the centre. The technician who cleaned it for me was not able to get direct access to it so despite best efforts there is a small patch still visible.

So even if you pick up a cheap lens there is no guarantee you will be able to clean all the fungus off.

ps. there is a M 40/2.8 on ebay at the moment that comes complete with an insect inside !

I would steer clear of any lens that has fungus unless you intend to have the lens professionally cleaned, or clean it yourself. No idea what the difference is between "light" or "hazy". Perhaps just a matter of degree. Some fungus can actually etch into the glass coatings.

If the price is cheap enough it may be worth a punt.

At 1.7 the eyes are in focus but the ears and the left and right edges of the object are outside the DOF.

On the right hand edge you can make out that it is OOF and blurry and looks normal. On the left hand side you have the same OOF/blurry effect, but a blurred dark line is also apparent.

Look behind the object , you have a black broom handle or something leaning up against the wall. That is your problem.

The first picture "Tranquillity" is stunning. Interesting it demonstrates to me at least how even a small change in composition can change a picture totally. The other pictures of the same boathouse do not convey the same feelings, except perhaps the fourth one too.

The symmetry of the first picture and the placement of the jetty dead centre lead the eye to it and then beyond, and the soft light and still water complete the calming view. Good job those pesky ducks stayed out of the frame for this one!

I have just started seeing this today.