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dandantheadminman

F-Stop?

Hi, bit of a noobish question, but o well, I'm still relativey new to photography

whats teh f-stpo thing mean? is it the rating given with teh lense? like, 50mm, f-2.6-3.6 or whatever? what does it mean? what does it do? how does it affect the pictures,etc..?

thnx
duncan_g

The f/stop regulates how much light is allowed through the lens by varying the area of the hole the light comes through.
Good ol' google! http://www.uscoles.com/fstop.htm
dandantheadminman

oo thnx, now this is dif to aperature right?
Hamish

No. The f-stop is a measure of the aperture. Big aperture = small f-stop = shallow DOF & vice versa. Confusing at first but you'll get used to it.
dandantheadminman

yeh i know all abotu aperature, and coresponding f/so and so, but what does this mean when quoted on the lense describition?
Hamish

?????????

It means that the maximum aperture of the lens is what is quoted.

50mm f1.8 has a maximum aperture of f1.8 and will go down to f22, as will most lenses (some go down further but you won't ever use that taking biking pics)

Where there's a range quoted, such as 18-70DX f3.5-4.5, then it means that the maximum aperture changes as the focal length increases. At 18mm you'll get f3.5 but at 70mm you'll only be able to use f4.5.

In order to buy a zoom lens with a constant maximum aperture ( e.g. 70-200 f2.8 ) then you need to spend a lot of money.

Does that help?
dandantheadminman

oo thnx,

yeh that cleared it up for me Very Happy

thnx buddy
duncan_g

Same! I had little knowledge too
Roo

As one of the links says, the numbers do actually mean something, say you have a 50mm f2 lens, 50 divided by 2 = 25, so the actual size of the aperture is 25mm, not very useful but good to know. Also as you may have noticed, there is a patten in the main apertures you double the number and you get the next but one, aperture, so they go

f1.4 f2 f2.8 f4 f5.6 f8 f11 f16 f22 f32 f45 f64

if you are serious about photography you should know those off by heart as well as the shutter speeds, e.g.

4" 2" 1" 1/2 1/4 1/8 1/15 1/30 1/60 1/125 1/250 1/500 1/1000 etc...

the gap between every one of those shutter speeds and apertures is known as a "stop" and stops work on the doubling and halving scale, so f4 is half the light of f2.8 and double the light of f5.6. ISO of course also comes into this

100, 200, 400, 800, 1600, 3200

each gap again is a stop, this may seem overly complicated but can be very useful. if you are given an exposure of 1/60 @ f5.6 @ ISO200 and for some reason you get told to use f16 but you have no exposure meter or TTL then you work out the exposure by stops, the gap between f5.6 and f16 is 3 stops, so you need to open up 3 stops on the shutter speed, so 3 stops brighter on the shutter speed from 1/60 is 1/8. Alternatively, you could leave the shutter speed at 1/60 and up the ISO by 3 stops, from 200 it is then 1600.

Oh, one last thing to confuse you in case you use a light meter f4.8 is exactly the same thing as f4 1/2 or maybe shown as f4.0 5.

As I said, if you are serious, that should all make sense.

Lesson over Smile
fozzybear

Hamish wrote:


In order to buy a zoom lens with a constant maximum aperture ( e.g. 70-200 f2.8 ) then you need to spend a lot of money.


No sheet... it does.. about £1200.. weighs a blooming tonne too (well nearly 2 kgs..)

as Hamish says you want higher F.stop lenes ideally for action photography but this comes at a cost.. that cost is price..
Hamish

Roo wrote:
Also as you may have noticed, there is a patten in the main apertures you double the number and you get the next but one, aperture, so they go

f1.4 f2 f2.8 f4 f5.6 f8 f11 f16 f22 f32 f45 f64

if you are serious about photography you should know those off by heart as well as the shutter speeds


I've just remembered that for every 1 stop increase/decrease then you just multiply/divide the aperture by 1.4 wherease shutter speed & ISO are doubled/halved.

Does that mean that I'm serious as well? Wink
dandantheadminman

Roo wrote:
As one of the links says, the numbers do actually mean something, say you have a 50mm f2 lens, 50 divided by 2 = 25, so the actual size of the aperture is 25mm, not very useful but good to know. Also as you may have noticed, there is a patten in the main apertures you double the number and you get the next but one, aperture, so they go

f1.4 f2 f2.8 f4 f5.6 f8 f11 f16 f22 f32 f45 f64

if you are serious about photography you should know those off by heart as well as the shutter speeds, e.g.

4" 2" 1" 1/2 1/4 1/8 1/15 1/30 1/60 1/125 1/250 1/500 1/1000 etc...

the gap between every one of those shutter speeds and apertures is known as a "stop" and stops work on the doubling and halving scale, so f4 is half the light of f2.8 and double the light of f5.6. ISO of course also comes into this

100, 200, 400, 800, 1600, 3200

each gap again is a stop, this may seem overly complicated but can be very useful. if you are given an exposure of 1/60 @ f5.6 @ ISO200 and for some reason you get told to use f16 but you have no exposure meter or TTL then you work out the exposure by stops, the gap between f5.6 and f16 is 3 stops, so you need to open up 3 stops on the shutter speed, so 3 stops brighter on the shutter speed from 1/60 is 1/8. Alternatively, you could leave the shutter speed at 1/60 and up the ISO by 3 stops, from 200 it is then 1600.

Oh, one last thing to confuse you in case you use a light meter f4.8 is exactly the same thing as f4 1/2 or maybe shown as f4.0 5.

As I said, if you are serious, that should all make sense.

Lesson over Smile


thnx again roo, you've taught me alot there Very Happy
sassycat11736

Roo wrote:
As one of the links says, the numbers do actually mean something, say you have a 50mm f2 lens, 50 divided by 2 = 25, so the actual size of the aperture is 25mm, not very useful but good to know. Also as you may have noticed, there is a patten in the main apertures you double the number and you get the next but one, aperture, so they go

f1.4 f2 f2.8 f4 f5.6 f8 f11 f16 f22 f32 f45 f64

if you are serious about photography you should know those off by heart as well as the shutter speeds, e.g.

4" 2" 1" 1/2 1/4 1/8 1/15 1/30 1/60 1/125 1/250 1/500 1/1000 etc...

the gap between every one of those shutter speeds and apertures is known as a "stop" and stops work on the doubling and halving scale, so f4 is half the light of f2.8 and double the light of f5.6. ISO of course also comes into this

100, 200, 400, 800, 1600, 3200

each gap again is a stop, this may seem overly complicated but can be very useful. if you are given an exposure of 1/60 @ f5.6 @ ISO200 and for some reason you get told to use f16 but you have no exposure meter or TTL then you work out the exposure by stops, the gap between f5.6 and f16 is 3 stops, so you need to open up 3 stops on the shutter speed, so 3 stops brighter on the shutter speed from 1/60 is 1/8. Alternatively, you could leave the shutter speed at 1/60 and up the ISO by 3 stops, from 200 it is then 1600.

Oh, one last thing to confuse you in case you use a light meter f4.8 is exactly the same thing as f4 1/2 or maybe shown as f4.0 5.

As I said, if you are serious, that should all make sense.

Lesson over Smile


Mr teacher!

And what if you're serious AND have dyscalculia Rolling Eyes

I try to memorise the numbers by asscociating them with images that i've taken in settings where i've used them.

Try taking a photograph of a scene using various settings and recognise how the images come out after they react to the different shutter speeds, ISO settings etc.

This is VERY helpful if you have problems with numbers guys, it might not be the most professional way to go about things but if you're retarded with figures try it- and if it helps do it. Embarassed
dandantheadminman

thnx for the tip nikki

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