# I am not sure if i am asking the correctly. But I would like to learn how to calculat

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#### macasuero

##### New Member
Hi Guys!!

I'm a neophyte here. I just found this question from a particular but no answer..:dunno:

this is the question:

I am not sure if i am asking the correctly. But I would like to learn how to calculate new shutter speed base on F stop increment or decrement? for example, 1/60 after 1-stop decrement = ?.

#### catchlights

##### Moderator
Staff member
very simple

+ one stop is double,

- one stop is half.

Staff member
30 sec
15 sec
8 sec
4 sec
2 sec
1 sec
1/2 sec
1/4 sec
1/8 sec
1/15 sec
1/30 sec
1/60 sec
1/125 sec
1/250 sec
1/500 sec
1/1000 sec
1/2000 sec
1/4000 sec
1/8000 sec

get it?

#### macasuero

##### New Member
Thanks for the quick reply bro!! yeah i got it but how about the aperture? I've read some articles that there are some settings which is equal exposure to the different settings, in relation with shutter+apperture. I'm confused...

#### ST1100

##### Senior Member
Thanks for the quick reply bro!! yeah i got it but how about the aperture? I've read some articles that there are some settings which is equal exposure to the different settings, in relation with shutter+apperture. I'm confused...
In photography lingo, one stop is half or double the amount of light.

Opening the shutter twice as long increases the exposure by one stop, reducing the shutter speed by half decreases the exposure by one stop.

Opening the aperture to twice/half its area lets in twice or half the amount of light, and hence increases/decreases the exposure by one stop.

The f-stop number is the ratio of the lens' focal length to its aperture. Eg f4 means the aperture's radius is 1/4 of its focal length, f2 means the radius is half the focal length. Every change of 1.414x (square root 2) in the f-number changes the exposure by one stop. f2.0 to f1.4 is an increase of one stop, f2.0 to f2.8 is a decrease of one stop, also known as "stopping down".

For any particular exposure, changing the shutter speed by n stops and changing the aperture by the same number of stops in the "opposite direction" results in the same exposure. For example, f1.4-1/4s is the same exposure as f2.0-1/2s (stopped down), and is also the same exposure as f1.0-1/8s.

#### calebk

##### Senior Member
List of full f/stops:

f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/44, f/64 (and I don't think you'll see anything beyond this on a SLR system anyways)

There are intermediate f/stops, depending on your camera. They may be in 1/3 stops or 1/2 stops, for instance

1/3-stops: f/2, f/2.2, f/2.5, f/2.8, or
1/2-stops: f/4, f/4.5, f/5.6

#### Dream Merchant

##### Moderator
Staff member
What Catchlights said.

Also, Google EV or Exposure Value and look at the old school EV/Exposure meter dials. That's everything ST1100 said at a glance.

This will help :

#### Rashkae

##### Senior Member
I just found this question from a particular but no answer..:dunno:
Did you try searching? Your question is the very basics of exposure, and is detailed, described and in many cases even charted all over the web and in many photography books.

#### catchlights

##### Moderator
Staff member
just for the fun......

f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/45, f/64,

f90
f128
f180
f256
f360
f512
f720

FIY, after f90, most like you will only see pinhole cameras has such small aperture.

#### Octarine

##### Moderator
Staff member
Thanks for the quick reply bro!! yeah i got it but how about the aperture? I've read some articles that there are some settings which is equal exposure to the different settings, in relation with shutter+apperture. I'm confused...
Read this Newbies Guide first, no point asking endless questions if you don't know much about the very basics. It needs 3 parameters to define exposure: shutter speed, aperture and ISO. Changing one requires also changing the other one or two in order to keep the exposure correct (correct amount of light to capture the image).

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