Who is this idiot who invented Aperture...lol

Surfsquish · Feb 7, 2011

Just wanted to Thank you guys for the advice. Used a high aperture which is a smaller F Number, a low ISO and fired up shots with the AV mode.

much better than the previous pictures...

Anyway, why this guy who invented aperture couldnt make a high aperture with a higher number.

Ok, let's try this one more time.

A high aperture is a smaller number which results in a bigger hole....to catch the most possible data in the picture.

subscuck · Feb 7, 2011

The f number is actually a fraction, but it's not written that way. f 1.8 is actually 1/1.8, f 3.5 is actually 1/3.5. That's why a smaller number is a bigger opening. 1/2 (f 2) is bigger than 1/4 (f 4). See?

Josh66 · Feb 7, 2011

It makes more sense if you think of it as a ratio (which it is).

f/2.8. The "f/" part is what makes 2.8 bigger than 8. Same as how 1/2 is bigger than 1/4.

o hey tyler · Feb 7, 2011

Aperture is the size of the lens diaphragm, and represents a fraction. Lets say you have a 50mm f/1.4 prime lens, and you're shooting at f/2. That is a large aperture, what it represents is 50/2. 50/2 = 25, therefore the size of the of the lens opening is 25mm. If your aperture was set to f/1.4 the lens opening would be 35.7mm.

So when you're thinking of aperture don't think of it as a high aperture as a small number, think of it as a large aperture. f/2.8 and larger are considered "faster" lenses. With a large aperture you get a shallow depth of field, which can work against you if you have a moving target or a slow AF system.

Using a large aperture doesn't effect how much data is collected, it effects how quickly it is collected. It's a bottleneck of light to your cameras imaging sensor.

I believe most of this post to be accurate, however if there's someone more experienced with the math of aperture they will most likely chime in.

dxqcanada · Feb 7, 2011

Yes, it is not about how much data ... that has to do more or less with extreme under or over exposure.

Aperture controls the depth of field ... which equates to the circle of confusion ... which really means how much stuff is in focus.

A smaller aperture (higher f stop number) increases the depth of field ... which means more foreground and background objects will be within acceptable focus.

Aperture also controls the volume of light coming into the camera.
Shutter speed controls the duration of light exposure into the camera.

mjhoward · Feb 7, 2011

I think the sensor in your camera is tilted :lmao:

Surfsquish · Feb 7, 2011

mjhoward said:
I think the sensor in your camera is tilted :lmao:

Seriously...lol my wife dropped the camera once....lol

Surfsquish · Feb 7, 2011

dxqcanada said:
A smaller aperture (higher f stop number) increases the depth of field ... which means more foreground and background objects will be within acceptable focus.

Aperture also controls the volume of light coming into the camera.
Shutter speed controls the duration of light exposure into the camera.

I think this is the easier explanation I have heard so far. I gotta memorize these two sentences...

wlbphoto · Feb 7, 2011

:scratch:

Boomn4x4 · Feb 9, 2011

subscuck said:
The f number is actually a fraction, but it's not written that way. f 1.8 is actually 1/1.8, f 3.5 is actually 1/3.5. That's why a smaller number is a bigger opening. 1/2 (f 2) is bigger than 1/4 (f 4). See?

It is a fraction... but it is wrong to replace F with "1". If f 2 = 1/2 and f 4 = 1/4, then you should say that f4 is half the size of f/2.... but its not.

F = Focal length.

Using a focal length of 50mm as an example.

f/2
replace f with the focal length of 50
50/2 = 25 mm diameter.
Area of a circle formula = pi * r^2
25 / 2 = radius
Radius = 12.5mm
3.14 * 12.5^2 = an opening with an area of 491mm.

f/4
50/4 = 12.5
12.5 / 2 = 6.25
3.14 * 6.25^2 = an opening with an area of 123mm

an aperture of f/2 is closer to being 4x's larger than f/4

f/2.8 is one stop up from f/2.
50/2.8 = 17.9
17.9/2 = 8.9
3.14 * 8.9^2 = an opening with an area of 249mm.... which is apx twice the size opening as an f/2.0

To simplify it, think of 1 second of 1 mm = 1 light unit.

A 1 second exposure using a 50mm lens with an aperture of f/2 lets in 491 light units.
A 1 second exposure using a 50mm lens with an aperture of f/4 lets in 123 light units.
A 1 second exposure using a 50mm lens with an aperture of f/2.8 lets in 249 light units.

KmH · Feb 9, 2011

F/4 has 1/2 the diameter of f/2 at any specific focal length.

The area of the lens aperture is what determines what portion of a 'stop' a lens aperture change is. Consequently to let in 1/2 (or 2x) as much light, a full stop, the lens aperture area must be doubled (2x more light) or halved (1/2 as much light) so the ratio of the focal length to the lens aperture has to be changed by 1.4142, the square root of 2.