Lens protection filters are little more than a scam. For every tale of one saving a lens there's another of one damaging a lens by the shards of the protection filter scraping the glass of the lens. A hood will do far more to protect a lens from knocks and spray plus adding flare protection and thereby increasing the image quality, rather than decreasing it.

Ffordes will give you a refund but only for the value of the item, not for the extortionate amount they charge for delivery. Factor in what it would cost for a professional clean and it becomes probably the most expensive M 85mm f/2 I've seen.

Excellent shots - great composition and bring together a nice medium format depth of field with FP4+'s superb tones.

Can I ask how they were scanned?

Around that budget a used 18-135mm or a Tamron 17-50mm f/2.8 should meet your needs. The Tamron would provide a faster max aperture (for low-light shooting or narrow depth of field) and is almost certainly sharper while the 18-135 would provide weather resistance, an in-lens focus motor and more range, while losing a small amount at the wide end.

How many adapters you buy depend on how you're going to use the lens. If I put an adapter on a K-mount body I usually go out only with M42 lenses and switch them on and off as required, leaving the adapter on the camera. However, some people like to use M42 lenses interchangeably with K-mount ones, and they may prefer to get one adapter per lens and leave them on.

If you choose the latter then getting genuine Pentax adapters will be costly - they usually sell for around 25 to 30 GBP each for good used copies. The main problem with cheap ones is that they can get stuck on the camera, so people remove the little locking mechanism, but that leaves a risk of the adapter plus lens falling off.

The risk of getting stuck is very real so I don't touch non-genuine adapters. I have a total of three genuine ones which I use without any problem, and that's what I'd recommend for a trouble-free experience.

As for using M42 lenses on K-mount bodies, there isn't much to it. Make sure you set it to "M" (manual) mode on the lens so that the aperture responds to changes on the aperture ring. You may want to focus wide open, then stop down, meter the scene and take the picture. I find metering to be inaccurate so I usually set the exposure manually (which becomes quite easy with practice) and you can always shoot in raw format to leave yourself a few stops of leeway for adjusting exposure in PP.

What's your first M42 lens, out of interest?

The A 50mm f/1.7 is notorious for this problem. It's caused by bits breaking off the inside of the aperture ring (which is made of brittle plastic) and getting stuck, preventing the ring from moving properly.

It's not worth fixing. The only thing I can suggest is keep trying to move it and if you can get it into A mode and leave it there, it'll be fine for use on a DSLR.

Looks like an effective combo.

Are you using it in one of the three custom settings? Custom settings have to be purposefully saved in the menu system otherwise they will revert back to the saved ones when the camera is switched off.

There is also a setting somewhere in which the user selects which settings are saved and which ones aren't.

I think the most recent model is the Q7. I'm not sure it's been discontinued, though the whole Q system has been languishing without any updates for a couple of years.

If it as problems then the aperture ring will feel gritty when turned. The volume of the click is irrelevant.