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.

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Category:

Howto & Style

Tags:

• photography
• aperture
• aperture value
• lenses
• focal length
• ratio
• nikon
• canon
• camera
• Mark Wallace
• Adorama
• snapfactory

[paulschilly]

After many years in photography, I have never heard such a clear and concise explanation of f/stop. Many struggle with the concept and are simply left with the instruction to just remember the inverse relationship. Confusion quickly sets in. Your explanation will clear that confusion away for most people for ever.

[darthzeta2]

OMG I finally get this subject!! Thanks

[nasi256]

great vid. But I think there is at least 1 relevant factor that hasn't been tackled: a zoom lens can absorb more or less light at different focal lengths(the position of the magnifying elements in relation to the aperture opening can affect the amount of light that goes through the opening)

manufacturers must incorporate such factors in their specs and thus do not respect the exact definition given in this vid. Which explains values like 70-200 at a constant 2.8 f-stop

[OZTrini]

@ssjgeorge I have the same question but what I reason is, because the aperture physically can't get larger than 25mm, it doesn't "grow" to 70mm, instead the VALUE of the aperture changes. The "2.8" is the APERTURE VALUE. so the new equation now becomes 200/x=25mm where x is the NEW AV. x therefore = 4. The NEW AV is 4. Can someone (Mark or anyone from @snapfactory in particular) confirm this?

[rockandrollvirus]

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

[ssjgeorge]

But how does 70-200mm constant f/2.8 work? @70mm it will be 70/2.8=25mm opening, and @200mm it will be 200/2.8=70mm opening... does that mean that the opening actually grew larger when going from 70 to 200?

Cheers

[ryanshayegan]

Very Useful Video

[Corey4Jesus]

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

[photokandi]

A little confusing to a person with poor math skills. My eyes glossed over after the second fraction.

[burtha3]

This was Brilliant! Cheers for that.