They both have their merits but I would go for the first one because of the potential to zoom in even closer to those lovely droplets.

If it has inspired just one person then it was worth sitting up at night writing it. Thank you Adam and get your camera out. Stick an M42 adapter in there and enjoy your old glass.

Right. Without wishing to derail the thread (it's sold now) ! .....

The OP stated they were unused to old glass - there is no need (or possibility of??) calibrating an old lens. You get what you get.

With 'old glass' you can fall into one or two traps. The first is reliance on the image, as snapped - it will likely be uninspiring. The next is the modern desire for SHARPNESS. Modern glass delivers razor edges, old glass rarely does. And you need to stop down to avoid all manner of ills associated with a particular lens. Let's address each of these:

A snapshot is just that. But if you treat it as the basis for something remarkable .... If you are Photoshop savvy or able to utilise RawTherapy then great. If not, get a (free) copy of Faststone Image Viewer and you will quickly elevate that snapshot into something else! If you have pots of cash then Topaz AI will transform mediocre into stardom. In short, you have to process those images (sensitively) and nearly all platforms will deliver the goods to greater or lesser extent.

Is sharpness the be-all and end-all of image-making? Perhaps the absolute subject needs to be sharp, but the rest of the image? Many old lenses are revered for their 'rendering', which doesn't equate with sharpness. It might be how colours are shown, it might be how the background is handled. For example, there are many 135mm lenses available and every one of them is different, which brings us to 'stopping down'. ....

If you present the camera's sensor with a huge hole (e.g. f1.4) then most of the light rays entering the lens have a multitude of potential paths they can take. A very few will be spot on focus, most will miss by a mile because there is nothing to prevent them going where they will. In optical terms, there is a big 'circle of confusion' Consequently, the image can appear way out of focus and you will reject it. The obvious solution is to make the hole (aperture) much smaller, which will cut out the multitude of competing light paths and only let those that will focus to pass. You will need a longer exposure or a higher ISO and lots more of the image will be in focus - and it will all compete with what you hoped would be the subject!.
Now look at it differently. SOME light rays will be in focus - so capitalise on them. Use live view (and magnify it, maybe) to determine the exact focus on the precise detail of your image that matters most - ignore the rest - it will produce amazing bokeh! Additionally, because the aperture is larger you can see the result more easily and focus accordingly. My personal 'baseline' is the closest edge of whatever it might be. Once that is in focus, you can reduce the aperture to admit more or less of what is there into focus. A gut reaction might be, 'set it to f8'! and a great swathe will be in sharp focus when, in actuality, it just needed f 2.8 reduced to f4 to capture the actual subject, leaving the remainder to optical chance.

Wow. That is a long exposition and some of it might be wrong (?)
On the other hand, Old glass is different but it produces the most wonderful images that the Modern stuff cannot compete with.

"OLD GLASS RULES" - Now it's your turn.

Is he seeking absolution or simply making excuses?

I don't know about 'scientific' but in the one case I had with focusing issues I put the camera on a tripod and used a row of iron railings. I stuck some random bit of litter on one upright about half way along and twiddled with the fine focus adjustment until it was right. That was one of my F series AF lenses on the K3ii. Today, while the camera remembers which lens it was I have no idea!

They do serve to bulk up a salad bowl. You pull up the entire plant(s), snip off the root, wash it and chuck it (them) in whole. It's more texture than taste.

Do get on E bay and look for a Takumar 55mm f1.8. It is a magnificent lens.

Hairy cress? .......... You can eat it but it doesn't 'taste', one way or another.

Welcome to the Pentax fold. I hope you have some great experiences here.

Have a very happy birthday and post the pictures you take with it ........ please.