I seem to have 70 mm eyes - how weird am I?

[steve welle]

55mm on my 1.6x crop camera = 88mm. Oops, another "freak".

Thanks for letting me know Andre. I did some more research and it turns out we are not freaks. I totally forgot about viewfinder magnification factors. With my 6D the magnification is 0.71. Magnification is how large the viewfinder scene looks using a 50 mm lens compared to using the naked eye. Therefore I have to use a focal length of 50/0.71 = 70 mm to make the viewfinder scene look the same as what I see with my eye.

I gave my cropped sensor T2i (550D) to my daughter so cannot check it out, but the spec sheet indicates a magnification of 0.87. This number is misleading because the magnification is not just from the viewfinder but also from the 1.6 magnification associated with the crop factor. So my eye should have matched the viewfinder at 50/.87 = 57 mm, which would be equivalent to 91 mm full frame. So my memory was fuzzy about the exact numbers but I did remember correctly that I always had to go much higher than the 50 mm full frame equivalent for the viewfinder scene to look as large as what I saw without the viewfinder.

Of course this does not explain the issue of subjective perspective differences looking at photos taken at different focal lengths. I do believe that 70 mm looks about right to me, but as indicated in previous post the difference between 50 and 70 in perspective is subtle and the review of the photos was totally unscientific.

[AB26]

I did some more research and it turns out we are not freaks.

Thanks Steve:
I was about to book my place in the loony bin instead of an old age home.

[ajohnw]

John, thanks for the information and link.

It's a pleasure Steve. I like to keep things factual. One fact often missed is that 35mm is a fairly recent format. There are others and the so called standard lens is always based roughly around the diagonal, usually a touch longer and really is reckoned to match the eyes field of acute vision. One way to check that is to put say a box with writing on it on a table or where ever and slowly look to the side of it and see how far you can go and still read it. :-) You may well say I wish I had eyes that good but distance and size come into it as well. The perspective aspects have the same sort of problem. Use that lens in shorter total depth and also distance situations and it has a different type of effect. The word more dramatic has been used to describe that in the past.

John
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[jcuknz]

Whatever the experts may say I say they are completely wrong and actually the human eye is a 400mm or more telephoto lens which takes many images and the brain assemble them to give the accepted impression that people see with a 50mm lens eye.

So I think you are wrong as well and my eyes see, with the keyboard sitting on my lap, just a single key.... true I have excellent perifial viewing ability which means I perceive the whole room.

The monitor is a bit further away at about 450mm and at that distance I see 'whole room'

[steve welle]

Whatever the experts may say I say they are completely wrong and actually the human eye is a 400mm or more telephoto lens which takes many images and the brain assemble them to give the accepted impression that people see with a 50mm lens eye.

So I think you are wrong as well and my eyes see, with the keyboard sitting on my lap, just a single key.... true I have excellent perifial viewing ability which means I perceive the whole room.

The monitor is a bit further away at about 450mm and at that distance I see 'whole room'

That's an interesting take on this that I have never heard before. So you are saying that even when I think I am not moving my eyes to scan a scene they are actually moving involuntarily so that I can put together a 40 degree angle of view from a bunch of images equivalent to photos taken with a 400 mm lens? Is there a publication or web site I can check out to learn more about it?

[ajohnw]

Whatever the experts may say I say they are completely wrong and actually the human eye is a 400mm or more telephoto lens which takes many images and the brain assemble them to give the accepted impression that people see with a 50mm lens eye.

So I think you are wrong as well and my eyes see, with the keyboard sitting on my lap, just a single key.... true I have excellent perifial viewing ability which means I perceive the whole room.

The monitor is a bit further away at about 450mm and at that distance I see 'whole room'

I don't have any problem seeing 5 keys clearly when it's closer than it would be if on my lap. I have seen the keyboard many many times and that fact comes into what we see as well. What you actually see is a sort of sketchy view of the whole room. If you then look at a particular point in the room the detail will be a lot clearer - particularly if you were looking at a monitor 450mm away. Odd things happen if you have looked at something many many times - the brain will fill in detail for you. One famous example of that is not being able to see car keys if for some reason a person puts them in an unusual place by mistake and forgets. This usually causes problems if a person is in a rush to get out as the brain can fill in the view less the car keys as they aren't usually there.

The eye / brain is sensitive to movement in peripheral vision - good job too. It helps with survival.

I've never checked it before but just set up an m 4/3 lens to 25mm and I would say the comment matches acute vision is more or less correct but at the distance I checked it at acute vision is a bit of an over statement.. I would say roughly 1/3 / 1/4 of the field of view is truly acute and the rest might be described as clear.

Don't give a monkies frankly though as since the diagonal plus a bit is similar to human vision goes way back I'm prepared to accept it and if some one wants to draw some other conclusion that's fine by me. No comment at all on 400mm. There eye problems and certain drugs that can make the eye tremble but people don't see that way/

John
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[jcuknz]

When you 'see' more than one key, or five as John says, you are not really seeing more but the start of perifial vision. I accept that my eyes with age or whatever reason may have narrowed down their comfortable Angle of View, but I think many are confusing the pleasing perspective with what they see if they are critical as I expect a photographer to be.
Whatever it is one of my pet soapbox subjects and I'll step down now