What does the f4 or f8 on canon EF lenses mean?

[Grace2]

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Grace 2

Please can someone explain the f4 or f8 numbers on these lens. Is it merely a model number or something more useful?

 

[Lecter]

more detail gracey.....

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Grace 2

Please can someone explain the f4 or f8 numbers on these lens. Is
it merely a model number or something more useful?

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[Harris Chan]

they are f-stops (aperture settings)

the larger the f no., the smaller the aperture. f4 > f8

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Grace 2

Please can someone explain the f4 or f8 numbers on these lens. Is
it merely a model number or something more useful?

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• Harris

10D, 7E, Canon 20mm 2.8, 28mm 2.8, 50mm 1.4
Rollei AFM35, Manfrotto Junior Tripod

 

[drthomas]

More exact, they are the largest apeture that the lens is capable of. If the lens is a zoom, then generally there are two numbers, the lowest being the f stop atthe widest angle, and the higher the f stop at full zoom

So, if you have a 70.200 F2.8 lens, itcan be used at 2.8 all the way through from 70mm to 200mm, while a 70-200mm F4 lens can only use F4.

If you have a 90-300mm F4.5-5.6 lens, then at 90mm the largest apeture is 4.5, and at 300mm, the largest apeture is 5.6

Hope that helps

 

[Peter Phan]

Canon 28-105 f/3.5-4.5 means that at 28mm, the maximum aperture size is f/3.5. But when zoomed out to 105mm, the maximum aperture shrinks down to f/4.5.

Canon 70-200 f/4 means that at 70mm, at 200mm, and at every focal length in between, the maximum aperture size stays constant at f/4.

It looks like you need a good photography book. This is basic photography 101.

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Grace 2

Please can someone explain the f4 or f8 numbers on these lens. Is
it merely a model number or something more useful?

 

[Grace2]

--
Grace 2

Please can someone explain the f4 or f8 numbers on these lens. Is
it merely a model number or something more useful?

--
Grace 2

Got it! Many thanks to all who enjoy helping a beginner!