How to View picture

<h3> Picture Size vs Viewing Distance</h3>

A rule of thumb for viewing a photography is at a distance of D=magnification x focal length of camera.<p> For example, if you have an 8x10" enlarged from Minox 8x11mm camera, then the enlargement factor is about 25x, and the best viewing

distance is 25 x 15mm =38 cm = 15". For 5x7" print from Minox 8x11, magnification = 16, and best viewing distance =10". Since people's reading distance is about 10", so for Minox 8x11 camera, 5x7" photos in an album are usually viewed at the best viewing distance.

<p> Why D=mangification x focal length is the best viewing distance ? Because <ol><li> View at this distance reconstructs the photographer's perspective when the picture was taken.<li> Elimitates 'distortion. This is most pronounced in wide angle lens, a cylinder at the side may look comparess into oval shape. But when viewed at D=magnification x focal length, the 'distortion' disappears magnically.</ol>

For prints from Minox 35mm camera, at reading distance of about 10", the best size is about 8x10"; as 8x10" is 8x enlargement, then D=8x 35mm = 28 cm = 11". For Minox 35mm prints, 5x7" need to be viewed at 7" to get proper perspective.

<p> Larger picture view at greater distance. For example if you have a 20x30" landscape from Minox GT-E, the best viewing distance is 20x 35mm = 70 cm.

<p> Of course, there is no need to be rigid, the rules is a quide line.

<h3> Monocular Vision </h3> <p> Normally people look at their pictures with both eyes. Any one knows that it is best to view a picture with one eye ?

<p> If you don't then try this experiment: take one of your 8x10" picture, and place it at your normal reading distance, close one eye and look at it

with only one eye. Blink a few times and stare at it again, you will suddenly find that the picture in your hand looks more three dimensional ! Open the other eye, and look at it with both eye, you will find the same picture becomes flat again.<p>

<p> It was in Beijing National Library beside the beautiful Bei Hai Park(North Sea Park),

when I was reading a note book by Renaissance painter Leonardo da Vinci,

in which he wrote that when looking at a high relief with one eye,

it looked flat, but when view with one eye a picture of the same relief,

the relief picture looked standing out. I tried Leonardo's method on my photographs, how true ! Picture viewed

with one eye indeed look more 3 dimensional then viewing the same picture with both eyes.

<p> The reason behind this pseudo-3D vision is because the two human eyes depend on image disparity as 3D cue. When you use two eyes to view ONE picture, the images on the retinas of both eyes are the same, as if placing two identical pictures in steroscope viewer, the brain immediately tells you it is FLAT.

<P> However, when you view a picture with only one eye, the retina image is identical to the retina image when you view the real landscape or object with also one eye. Since there is no second eye to tell the brain that "it is 3D" or "it is flat ",

the brain is programmed through several millions years of evolution to

relies on the shadow and light, perspective of objects to interpret the retina vision as 3D, that is why monocular vision of a picture looks more 3D like.

<p> Of course, this is not true 3D, but a pseudo-3D.<p> You may watch your TV or even movie that way for fun :) <p> One can learn a lot from masters like Leonardo da Vinci, he had incredibly keen observation and mind.

A few years ago in Popular Photography 'Letter to editor" column, the topic of viewing picture with one eye was asked by reader and answered by

an editor. ( I can't find which issue )

<h3> Leonardo da Vinci on viewing picture through a hole </h3>

<p> Leonardo suggested let a person stood against a wall, put up a candle light in front, and trace the contour; add the required light and shade.

<p> After that, remove the candle light, and in its place put a piece of carboard with a small hole exactly at where the candle light was; then look throught the hole, and any one would have hard time not to believe that the painted person indeed stood out from the wall.

<p><p> When viewing throught a hole, one is essentially viewing with one eye.

<p> See "Leonardo on Painting" , Yale for full text.

<p>I found that when viewing an enlargement (at Magnification x focal length distance ) with one eye

if you curl your fingers in the shape of a tube, and put it over one eye and look throught it at the picture, you will get a even more "realistic" "3D" look.

This is particularly true when the picture frame is blocked out. (As picture frame hints at flat object, blocking out the frame eleminates one more flat surface clue )