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General discussion Here is the place to discuss photography topics that may not be specific to one of the other board topics on this forum.

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Old 4th November 2015
nrdlnd nrdlnd is offline
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What is a "normal" lens

In July there was the news about a coming Panasonic lens 1.7 25mm corresponding to a 50mm lens for the 35mm film format. I quote the text:

"The 50mm focus distance offers almost the same viewing angle and sense of perspective as the human eye which means users can enjoy shooting a portrait or scenery as they see it."

Is this true? I say no! A "normal" perspective depends on the viewing distance and how big the picture is. Once upon a time the most popular lens for 24x36 was the 35mm lens because when you enlarged the picture to 18x24cm (the most popular format here in Europe) then with a viewing distance of about 25cm then you saw this as a normal perspective. You could not enlarge a picture taken with a 50mm lens that much to get a normal perspective at the same viewing distance otherwise it will look compressed. If you use a even wider lens than the 35mm then if you enlarge the picture enough with the same viewing distance you get a "normal" perspective.

So the above quotation is true if you view the picture on a rather small screen and a tele lens will have a normal perspective on for example a smartphone!

Per
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Old 4th November 2015
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Re: What is a "normal" lens

I've always considered a "Normal" lens provides the same field of view as the eye.

If you look through the viewfinder of a DSLR/SLR/EVF with both eyes open then an object will appear the same size. However most viewfinders have a magnification factor +ve or -ve so the FoV or focal length will be different, depending on that VF magnification.

Of course a "Standard" 50mm lens on the 35mm film will be a wide angle on a Medium Format camera and a short tele on a MFT camera

Unfortunately we do seem to be "stuck" with using 35mm equivalents to describe our lenses and somehow "Full Frame" has become used to describe a sensor of roughly 35mm film dimensions.

Having used half and quarter plate cameras, I still consider Full Frame to be 10"x8"
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Old 5th November 2015
nrdlnd nrdlnd is offline
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Re: What is a "normal" lens

Quote:
Originally Posted by Graham View Post
I've always considered a "Normal" lens provides the same field of view as the eye.
Yes but that was not my point. The perspective when you look at something in the "real world" depends on the distance to the object/objects. Try for yourself! My point was that when you look at a picture it depends on the viewing distance and the enlargement if the perspective is normal as the eyes see it.

My hypothesis was why the 35mm lens for 35mm film was so popular among professionals about 50 years ago was that when it was enlarged to 18x24cm (or Letter format) and viewed at a distance about 25cm it gave a natural perspective.

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Old 5th November 2015
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Lightbulb Re: What is a "normal" lens

Yours is as good a hypothesis as several of the others out there.

I quite like this article, and refer to it when this subject comes up.
http://petapixel.com/2012/11/17/the-...the-human-eye/

I particularly like the bit:

"Studies have measured the cone of visual attention and found it to be about 55 degrees wide. On a 35mm full frame camera, a 43mm lens provides an angle of view of 55 degrees, so that focal length provides exactly the same angle of view that we humans have. Damn if that isnít halfway between 35mm and 50mm. So the original argument is ended, the actual Ďnormalí lens on a 35mm SLR is neither 35mm nor 50mm, itís halfway in between."
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Old 5th November 2015
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Re: What is a "normal" lens

Hence 14. ---- 42mm??
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Old 7th November 2015
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Re: What is a "normal" lens

That's maybe a thumbs up for the Pana 20mm 1.7. I have the mark I and it's a great lens.
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Old 7th November 2015
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Re: What is a "normal" lens

I once had an Olympus 35RC compact with a fixed 42mm lens. I found this to be a lovely focal length that matched my own field of view pretty well. I loved the characteristics of my 35mm and 50mm lenses on my SLR but the 42mm seemed the most natural.
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