The bodies are different. I have both in front of me. The D is smaller and has more controls and a smaller screen. It is a lot nicer to hold and to use. It also has a 'green button' which is missing from the DS (it isn't really but you need to know to use the 'ae'l' button instead). Both nevertheless take great pictures. You might not think to attach an F* 300mm to either but it works a treat!

You certainly don't want to fall in there! We hear about such excess rainfall (or snow melt) but we are rarely shown the results of it happening unless a disaster strikes.

On the topic of battery terminals, Do clean them with (e.g.) a pencil eraser but also, make sure they are bent upwards (outwards?) so that they will press firmly on the battery caps when the door is closed. Frequent use tends to depress them over time until they can barely make proper contact, when things like 'depleted battery' can appear when you know they are freshly charged. It drove me crazy until I realised what was happening.

Apart from the last firmware update (that simply allows use of some monstrously expensive lens) mine is up to date. I think it is a mechanical fault rather than an electronic one. I will try the LV button next time it happens.

I had a Sigma 150-500 that I used with a K1. It quite turned me against all things Sigma. I didn't realize it preferred being matched to a K3. Neither did I know about the enforced noise reduction with later marques of Pentax cameras. Hey, the value of a forum like this one!

Since we are talking about 'unknown' things and K1s in particular. I have two K1s. Both exhibit the same problem. Leave them unused for a while and turn them on and when you first press the shutter release you get a very non-usual noise and the whole shebang locks up. The only remedy is to turn it off (behold, the display on the LCD remains, no matter what you try, even though it's 'off'!). Remove the battery, The display goes off. Replace the battery and turn it on. You get a loud Ker-LACK! noise and it all works perfectly thereafter. Watching events without a lens in place, the mirror goes up and stays there. On viewing the photos you have taken, there is one black frame, representing the glitch, so it thinks it has, indeed done something - when it hasn't.

I just live with this now but I am always in fear of a total catastrophe of some sort. Anyone else had this problem?

Sad innit?
We, of our generation have invested heavily into learning how to use a DSLR but the younger generation find them clunky and almost incomprehensible. They, for their part have invested heavily into learning the use of multiple buttons and fancy software on tiny, handheld devices that we find increasingly incomprehensible with each new iteration. Would that there was a common, middle ground but the two seem to diverge faster and faster.

What do each of us want from a photographic device? I want the ability to create a work of art from the fusion of an antique lens and the controlling possibilities of a 21stC camera. They seem to want a whizz-bang box of gimmicks to render their endless selfies sufficiently well to post on social media sites, accepting the fact that their efforts will be forgotten before the week is out. There is but one of me vs. thousands of them, so which way do you expect the camera manufacturer to go?

Like I said, it's sad. So keep posting images and comments on here. Otherwise our hosts will be faced with the same problem.

The second one is wonderful, provoking all sorts of questions and evoking so many similar memories. It is also technically excellent.

I have both istD and DS and I love working with both of them. The DS has the advantage of accepting both TTL and PTTL flash protocols. Both are capable of fantastic results but don't get carried away by modern facilities (which we tend to take for granted). They are NOT weatherproof and their high ISO results do leave room for improvement. Use them within sensible limits and they are super cameras.
This one is from an *istD - view it larger.

I can't speak to the 50mm/1,2 but I was disappointed with the 1.7A when comparing it to the Takumar 55/1.8 - there is no comparison. But here you will find the beauty of vintage FF glass. Superb lenses are there for the having! People are so hung up on the latest mega whatsit thingies that 'old glass' is completely ignored. ...
Their loss, your gain! You buy an M42 for £10 and you don't like it? Resell it. You find a wonderful copy? Great! The K1 was made for these so do take the plunge. You won't be disappointed.

The Tamron 90 will produce stunning macros too but there is a (slight) caveat. The older, adaptall version was never intended for digital use and can leave an annoying purple circle in the middle of the image at times due to internal reflection off the rear element. Those with an 'A' setting won't do this and can produce absolutely stunning images. I often take my Tamron 90 and a K1 on holiday, knowing that my entire needs will be met.

So, "Yes". Go for it but do invest in the fun of experimenting with old glass.

There are indeed some superb photos - and more to the point, some are from people who have not been regular posters until now. Just keep it up guys!