With a F-Stop of 1.7 or 2, is the shutter speed slow or fast?

Answer 1

Fast. The smaller the f stop number, the wider open the aperture is, so the faster the shutter speed is.

Answer 2

That really depends on what you're shooting and the available light. If you take the same subject with the same lighting and change the aperture size, the shutter speed has to change too in order to avoid over or under exposing the picture.

As the aperture gets larger (lower f number), the shutter speed has to increase (for example 1/100 to 1/250)

Also as the lighting on the subject is reduced, the aperture needs to open up in order to maintain the same shutter speed OR the shutter speed has to slow down in order to maintain the same aperture size. That is a decision you have to make, based on the type of film you're using, the depth of field you want and whether you're using a tripod or not (so you don't shake the camera).

One other thing: the aperture size determines your depth of field, which is the range in which things will be in focus. With a lower f-stop, you have a shorter depth of field, which means things that are closer to you and further from you than the primary object will be more out of focus. A larger depth of field allows you to have objects close and far still be in focus.

Answer 3

Inside your lens is a diaphragm made up of thin metal blades which open or close to form the opening called the f-stop (aka aperture). The size of the opening determines how much light is admitted to expose our film or sensor. The smaller the number (f1.4, f2), the larger the opening. If your lens is at f1.4 it is said to be "wide open" and admits all the available light; at f16 its "stopped down" and admits very little light.

The shutter determines how long the light is allowed to expose the film or sensor. As less light is admitted by smaller and smaller f-stops the shutter has to stay open longer and longer.

ISO is a measurement of the sensitivity to light of a light-sensitive surface, whether film or sensor. The higher the ISO the more sensitive to light our light sensitive surface is.

Here is a hypothetical example of the aperture/shutter speed relationship. Its a sunny day and we're using ISO 100.

f1.4 @ 1,000
f2 @ 1/500
f2.8 @ 1/250
f4 @ 1/125
f5.6 @ 1/60
f8 @ 1/30
f11 @ 1/15
f16 @ 1/8

And if we used ISO 200?

f1.4 @ 1/2000
f2 @ 1/1000
f2.8 @ 1/500
f4 @ 1/250
f5.6 @ 1/125
f8 @ 1/60
f11 @ 1/30
f16 @ 1/15

As you can readily see, ISO 200 is twice as sensitive as ISO 100, which is 1 stop. For ISO 50 our shutter speeds would be 1/2 (1 stop) as fast as the ones shown for ISO 100; at ISO 400 our shutter speeds would be twice as fast as at ISO 200 -again 1 stop.

Since we know that f1.4 is admitting all the light available, the question is now "How much light is admitted by each successive f-stop?" The answer is 1/2: f2 admits 1/2 as much light as f1.4; f2.8 admits 1/2 as much as f2; f4 admits 1/2 as much as f2.8, etc. With less light to expose our film or sensor the shutter speed must be slower to allow correct exposure.

NOTE: I was amused by one answerer who asserted that:
"... but no one using these f-stop of 1.7 or 2 for outdoor photography under sunny day, it must be crazy actions or something wrong with this person..."

For the record there have been times when I shot wide-open on a sunny day to achieve either a certain effect I wanted or to make certain any motion was frozen.

Answer 4

F stop is different than shutter speed. F-stop has to do with the aperture (how wide the hole is that allows the light in). A smaller f-stop is a larger aperture.

A faster shutter speed usually requires a larger aperture, which is a smaller f-stop.

Answer 5

the f-stop determines aperture size, not shutter speed. 1.7 or 2 is a fairly large aperture, which means the lens would let in more light.

edit: although the comment above mine is correct, if you're not using a manual camera--in this case, the camera will set the shutter speed for you and it will need to be fast in order for a good picture to be taken.

Answer 6

Fast shutter speed,but no one using these f-stop of 1.7 or 2 for outdoor photography under sunny day,it must be crazy actions or something wrong with this person,mostly use f/8 or f/11,the background will be automatically blur by itself either using Tele-lens or Zoom lens.

Answer 7

Depends on the light level and the ISO.

In a dark room the shutter speed might be slow; outside on a sunny day, fast.

Hope this helps.