Never too old to learn a new trick! (tip about Dioptre adjustment)

[Astro]

I went out with a friend and her 13 yr old son for a walk yesterday. I had my Canon Eos R mirrorless camera with me and Luke who is becoming rather keeen on photography, 'took over' my camera almost immediately as we walked.

He is at that stage of being enthusiastic and shooting everything in sight! After a lens change I suggested a particular shot, at which point he complained he could not focus and the image seemed blurry in the viewfinder (up to this point he had been using the back panel display. I rarely do, being 'old' )

I took a look and saw nothing wrong .... the clicked... of course, I am old and the dioptre adjustment was for my eyesight! So I explained and showed him how to adjust for his vision.

About 20 minutes later he said he thought the view was still off and then, looking through the viewfinder proceed to adjust the diopre setting while continuing walking...
I suggested he stand still and make it easy on himself. He informed me he didn't need to. He had brought up a preview image of an ealier capture and was using that to adjust the setting.

Admittedly I rarely need to readjust the dioptre setting but when I have, I usually set the camera on a tripod because it is so fiddly holding the camera while trying to twiddle the adjustment wheel and focus on something moving around the frame.

Looking at a preview image in the view finder it is easy, even hand held because (of course) the preview image never moves

When I told him it had never occured to me to use a preview image, and that he had taught me something I didn't know, he went off with the biggest grin to shoot a whole load more images!

Pity is I still have to stick to the old method for my 5DsR.

[pschlute]

I always do the dioptre adjustment with the camera pointing at a plain white wall. or even with no lens on the camera. I concentrate on getting the viewfinder grid lines (or other focus screen overlay) sharp. You are then not dependent on the lens (or preview image) being focussed correctly.

[xpatUSA]

I always do the dioptre adjustment with the camera pointing at a plain white wall. or even with no lens on the camera. I concentrate on getting the viewfinder grid lines (or other focus screen overlay) sharp. You are then not dependent on the lens (or preview image) being focussed correctly.

Wow, Peter, works like a charm on my old no-live-view DSLR !!!

I had not realized that the adjustment has nothing to do with the scene or distance thereof! I used a sheet of letter-size paper about a yard away under a fairly bright desk-lamp.

Thank you so much ...

[Manfred M]

I usually shoot with my glasses on, so have never really bothered with the diopter adjustment.

I have been slightly nearsighted for most of my life, but when it comes to corrective lenses, my biggest issue has always been fairly severe astigmatism. That is something that the diopter setting does not compensate for so I do need the correction to read the camera data in the display.

The add-on lenses corrective lenses sold by the camera makers do not correct for astigmatism and in theory it is possible to go to an optician and order custom ones. I expect that this would end up costing a lot of money (I looked at this approach back in my scuba diving days for my dive mask and the costs were prohibitive, so I wore contact lenses on dives). Unfortunately, I shoot in horizontal and vertical orientation in roughly equal amounts, so having a fixed diopter adjustment will be in the wrong place for about 1/2 of my shots.

The main downside of my technique is my glasses get quite smeared after taking a few shots, but I always have a microfiber cloth in my camera bag, so there is a simple fix and I end up cleaning my glasses a lot.

[pschlute]

Like Manfred I also suffer from near-sight and astigmatism. I am very near-sighted (always looking over the top of my distance glasses when viewing a review image on the lcd. I have only minor astigmatism in my left eye which is my dominant one. So I am a right handed, left eye shooter.

I find it quite fascinating that I use my distance glasses to focus a viewfinder image on a SLR camera. It demonstrates the distance the light travels from the focus screen via the prism. I have never tried a mirrorless with electronic viewfinder display but suspect it would not be the same view

[DanK]

I too had substantial problems with astigmatism. The problem I have shooting with my glasses on is that I can't see both sides of the frame at once.

One of the few advantages of getting older is that you can get rid of astigmatism when you get rid of cataracts. Instead of a standard lens, you can get what's called a toric lens implanted, one that counters the share of the eye itself to correct astigmatism. I had them implanted. There are two drawbacks. One is that depending on your health system, it may cost you. On my insurance plan, standard lenses were covered, but the (considerable) extra expense of toric lenses was not. The other is that when the eye heals, it can change shape enough to re-introduce a modest amount of astigmatism. that happened with one of my eyes but not the other.

I don't understand the optics of this at all. When I had my lenses implanted, I had one set for distance and one for about 75 cm (30 in.), which is roughly the distance to my computer monitor. In other words, the former is no longer nearsighted and shouldn't need a diopter adjustment, while the other is still nearsighted. When I look through the viewfinder of my DSLR with the diopter adjustment set to 0, focused images at even a short distance, say 3ft/ 1 m, are definitely far clearer with my distance-focus eye. When I focus at a few inches with a macro lens, that difference goes to nearly zero, but not quite. It's still very clear with my eye set for distances. There is nothing in the system that is far from my eye.

[pschlute]

I am no expert on this , but i think the point is with a SLR camera you are viewing the distance between the eye to the focus screen through the prism. I estimate this to be between 1 and 2 feet.

[xpatUSA]

I am no expert on this , but i think the point is with a SLR camera you are viewing the distance between the eye to the focus screen through the prism. I estimate this to be between 1 and 2 feet.

Feet? Not inches?

By the way, the "trick" also worked with a 1.34X magnifier attached to the viewfinder.

Thanks again, Peter.

[Manfred M]

One of the few advantages of getting older is that you can get rid of astigmatism when you get rid of cataracts.

I still have my own lenses and if I take after my father, who had cataract surgery in his early 90s, I'm still going to be stuck with my own for another 25 years...

When I was actively scuba diving I wore a contact lenses. My left contract lens was for correcting presbyopia (so that I could read my dive instruments that I wore on my left wrist) and a toric lens in my right eye to correct for the astigmatism and near sightedness. It felt a bit weird when if first started with that combination, but my brain figured things out pretty quickly.

[revi]

I am no expert on this , but i think the point is with a SLR camera you are viewing the distance between the eye to the focus screen through the prism. I estimate this to be between 1 and 2 feet.

I'd expect the system to include a loupe, effectively putting the viewfinder image at infinity. Easy enough to check, when you can keep both eyes open: a far away object should be sharp for both eyes (only works for near-sighted people if they wear their glasses).
The pathway from the focus screen to the eyefinder in a traditional SLR would be in the order of a few inches, certainly less than one foot...