Digital Photography 1 on 1: Episode 14: Aperture Values

In this episode Mark explains why f/2.8 is a large aperture opening and f/22 is a small aperture opening. Mark also discusses the meanings of the numbers on many lenses.

[MrJazAfonso]

The more videos I see the more clear it gets, he is a fantastic tutor,

[CoreyJesus]

I have yet to hear anyone explain this subject this great. Thanks for sharing this info. God bless!

[drbrar]

Mark...Thank you for simplifying it. I am not a pro...but I always wondered what these values mean. You are an awesome instructor.

[dwt]

I've heard aperture explained before, but never in a way so easy to remember. Thanks.

[ky]

you were brilliant man, just the quality of this presentation and your delivery made me subscribe to learn more.

[sarg]

By far the best explanation on the web. Thank you so much for this video..

[NoSoldatu]

this is the first time i've seen aperture explained so thuroughly, excellent job!

[steinoboy]

Great tutorial - now i have the basic understanding of the importance of different types of aperture values !!

[matthewkeisling]

Wow. Some oldies but goodies showing up on my feed. Good explanation. I use some of the same pie metaphors and simple math concepts when I teach some photography technicians in my work.

[sajinakamal]

Hi Mr. excellent and easiest mode of beautiful explanation that you have given.... Many thanks and hearty regards....

[Claggy]

@vannabie The weird numbers represent the focal length divided by the size of the opening (the aperture), which is what gives you those weird aperture values. It all depends on the size of the current aperture of the lens. Those weird numbers also tell you how your depth of field will appear in the photo, where the smaller f-numbers will give you a shallower depth of field, and the larger numbers will give you a larger depth of field.

[burtha]

This was Brilliant! Cheers for that.

[nasi]

the idea is that the factors u need to include to know how much light is coming through your lens are both the opening of the barrel and the focal length: clearly a bigger opening would allow for more light to go through, but a bigger focal length also equates to a smaller cone of light (smaller amount of light rays being allowed through the lens) because the focal point is farther from the lens. So what will determine the exposure is ultimately the ratio between the 2, which is the f-stop value

[falsaai]

Thank you Mark, I finally got the idea about it.

[blackamericanlesbianprofes]

Thank you so much! I understand the mm and the ratio of the aperature opening. So cool, the mathematics is not difficult either. :)

[slayerettem]

Wow...I totally get it now.

Great job!

[acidnaught]

A big THANKS to you for this great explanation.

[nikusre]

I love math. Thanks for the great explanation Mark.

[bwoogie]

gonna have to watch this a few more times to understand it but i think it helps

[AgnostosGnostos]

Most lenses have specific maximum aperture values like f/1.4, f/2, f/2.8, f/4, f/5.6
That it is not accidental.
These values are the multiplication of the square root of 2 √2
For example
1 X √2 = 1.4
1.4 X √2 = 2
2 X √2 = 2.8
2.8 X √2 = 4
4 X √2= 5.6
5.6 X √2 = 8
8 X √2 = 11
11 X √2 = 16
16 X √2 = 22

But what does these mean
A lens with an aperture value f/2.8 sends double the volume of light to the sensor than a lens with an aperture value f/4.
The same in the case of a lens with an aperture value f/4 sends double the volume of light to the sensor than a lens with an aperture value f/5.6.
It doesn't matter if these lenses have different focal lengths.

It is a little complex. With the shutter speed and ISO the differences of volume of light are much more clear.
Also the real sizes of focal length and aperture diameter rarely corresponds exactly to the physical size of lens.

Also the aperture value is very relevant to the shutter speed. For example check the internet for: sunny f/16 rule
Also check for: Looney f/11 rule.