Dioptre adjustment and manual focus

I've just discovered something that has made my manual focusing a lot quicker, so I thought I'd share it.

I'm lucky enough to have good uncorrected eyesight, and looking through the viewfinder, everything in focus has always looked good and sharp. However, I was idly playing about with the camera just now, as one does, and it happens to have a MF lens on the front of it. I noticed that although the viewfinder image was sharp, my eye didn't feel as relaxed as it might (it felt as if it was working to focus, as it were), so it occurred to me that I might have accidentally moved the dioptre adjustment.

So I adjusted it, and sure enough, I could then see the viewfinder image sharp, with my eye relaxed - focused wherever it does when relaxed.

Now, all this isn't very interesting so far - the number of people wandering around with wrongly adjusted viewfinders must be legion, and I was just one of them.

However, what I then noticed, was that I can now focus manually, and get focus confirmation much, much quicker than before.

Before, it was "turn the ring, looks sharp, no confirmation, turn it backwards and forwards, eventually get confirmation, recheck image, yes, still looks sharp". It always annoyed me, but I put it down to the lack of old-style split-prism focusing.

Now it's "turn the ring, looks sharp, focus confirmation comes up". No messing.

So, why?

I reckon that while my dioptre was set wrong, it wasn't wrong enough to stop my eye being able to focus on the viewfinder image.

So with an AF lens on the front, it would focus, and I would then see the image sharp. I'd only have to look at it for a moment, and then I'd take the picture. So I wouldn't notice the effort my eye was having to go to.

With a MF lens on the front, though, it starts off not sharp, and my eye would be try to focus... meanwhile, I'd be turning the focus ring, and that would change what my eye was trying to focus on. This iteration would eventually stop when the lens and my eye were both correctly focused. But it took an annoyingly long time.

Presumably with the dioptre adjusted right, the effort required by my eye is less, so the iteration is much quicker.

It's certainly a dramatic improvement.

I'd be interested if anyone else finds a similar improvement, if they discover that their dioptre is set wrong - not by much, but enough to require the eye to work a bit, to get its own AF lock .

Greetings all,

Page 60 of the K10D manual describes the procedure for setting the dioptre adjustment.

As a variation to this, I did it by taking the lens off and then pointing the camera at the sky. I found it a bit distracting doing it with the lens attached as the cloud detail was catching my eye.

As a spectacle wearer, I still enjoy the focus confirmation in the viewfinder having used a manual focus SLR until last year.

Regards

Peter

I would think that everybody would benefit from correct diopter adjustment.

As another eyeglass wearer, I found that the diopter adjustment on my K100D has enough range to compensate for my glasses. So I adjusted the diopter to provide a sharp rectangle in the viewfinder without glasses.

I know it's a nuisance having to remove the glasses before taking a picture. But it gets me closer to the viewfinder, which again shuts out stray light and makes it easier to see the info in the bottom part of the viewfinder. The image appears crisper and it is much easier to use manual focus.

I can't speak for people with glasses, of course, although I struggle to take pictures with sunglasses on.

My situation was that I thought that my VF was already adjusted correctly - because everything was perfectly sharp when the image was in focus.

I'd just encourage people to check - since for me at least, a small adjustment has had a very welcome and unexpected side effect.

It's a very good point.

Users of old cameras with no dioptre adjustment (or diopter if you prefer!) can buy adjustment lenses for the viewfinder.

Alternatively, glasses wearers who use reading glasses may find that these are ideal for viewing through older SLRs. The focusing screen has an optical distance of around 1 metre (meter....)