Does the fast-twist Euro-style focus have anything to do with focusing scopes for different distances at high powers?

I was a bit non-plussed when my buddy started cranking the one on my 4-16 Nikon at the range on Sunday. I had always understood that with the old fine-thread adjustment, it was all to do with the reticle focus - and once you found the proper setting it was not meant to be fiddled with by others. With variables going much over 6x, however, I guess some focus analogous with that on binoculars must be needed. I would have thought that would be done with parallax adjustment but my mate swore the occular adjustment was needed to see holes in the target.

The obvious answer is that his focus is not the same as mine but it got me thinking. Could the reason for fast-twist focuses having no locking provisions be because they do need to be adjusted for different ranges at high powers?

No thoughts on this before I reset the focus and wrap it in tape to keep water, bumps and others from messing with it in future?

My Zeiss and Leica scopes are more or less set at fokus at 100 meters.
I seldom need to re-focus, but at high powers/ longish range (+200m) I usually have to adjust a tiny bit.

Also when hunting low light dusk and dawn from stands or blinds at medium or high power, I somethimes tweak a tiny bit to get the clearest possible picture.
Hunting in daylight on less than 150 meters I just leave the setting as it is.

Thanks Arild.
Do those late/long-range adjustments remain valid when you look next time in good light? If so, maybe they are in fact the true focus and a clue to all who focus their scopes. If not, maybe I'm back where my query started.

Don't mix up image sharpness with parallax adjustment. To obtain the best reticle (and image) sharpness, aim the scope at the sky or any othet lighted but empty background (details will only distract your attention away from the reticle), adjust until the reticle is as sharp as possible and you're done. If parallax adjustment is present, then the image will blurr over distances and the image has to be refined using parallax control (not reticle/image shrapness !). One last word about Euro or U.S. scopes. Their respective reticle adjustment differ solely in the threads of the ocular ring to be turned. Fine U.S. threads take longer to adjust than coarser Euro ones. Of course, the same as with binos, each individual needs to adapt sharpness/reticle to his personal eyesight.

So, Andre, do you think Arild was using the focus to tweak a matter that should have been sorted out with parallax adjustment or left alone if there is no side or knurled-objective adjustment for it?

This is not a question of parallax, but to focus the scope at any given distance.

During low light hunting (dusk and dawn), the adjustment is not thouched.
But in broad daylight I might tweek the focus a tiny bit especially on longer shots.

For me it works sort of like focusing a binocular.
Changing wiew from looking at the birds on the feeder 10 meters away to a ship 500 meters away demans a bit of adjusting the binos.

But that said regarding the scope, in 95 % of the hunting situations I leave the setting as it is (targeted at 100 meters).

That's exactly what I was wondering about, Arild.

Does anyone in the trade have an opinion on the matter?

Not in the trade, but Arild describes how I set the focus ring on my scopes. When I first mount it and take it to the range I set the scope to the max magnification and am careful to focus at 100 yds. Then I mostly leave it alone. When I was peering through a recently acquired 3x18 Swarovski I took some time to refocus at 200 yds. The focus adjustment seemed more noticeable to me at the higher magnification (none of my other scopes are higher than 10x). Regards Paul.

Thanks Paul,
we seem to be seeing a pattern in the responses here that differs from focusing the reticle oblivious of everything else.

Does anyone remember how the method for fine-thread focusing with an SLR camera went? Also, did it require a finite background?