What do the numbers actually mean?

D.S.

D.S.

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Ok so for example I have an AF-S VR DX 55-200 mm Lens

Breaking this down AF-S = Auto focus (whats the -S stand for?) VR = Vibration reduction DX = ?Product line? 55 - 200 = focal length

Its the 55 - 200 I dont really get, is this the distance between lenses within the lens? How does this translate to the distances i'm trying to zoom / photograph?

I want to get a wider angle lens for landscape and other types of shot. I have been pointed towards a Sigma 10-20mm f4-5.6 EX DC HSM.

10-20mm = (same questions as above) f4-5.6 = (No idea what so ever???)

What makes it wide angle?

I have seen lots of questions relating to speed, is this the shutter speed, or focusing or what exactly?

Sorry if these have been asked before, I haven't really found a thread that answers them. :bonk:

Thanks very much.
 
The distance in mm is the focal length of the lens.
The smaller the number the wider the angle.
The longer the number the longer the zoom.
Prime lenses are fixed and have just one focal length
Zoom lenses have a range.

The f numbers relate to the widest aperture the lens can achieve. Cheaper zoom lenses cannot maintain constant maximum aperture over the whole lens range so you have maybe f4 - f5.6 - this means it can achieve f4 at the short end and f5.6 at the long end.

The smaller the number the 'faster' the lens.
 
55-200 is the focal range of the lens - on a 35mm frame.

Nikon DX format cameras have a multiplication factor of 1.5x - because they only use part of the 35mm frame (APS size sensor). The maths for this is easy, your 55-200 is effectively a (55 x 1.5) = 82 - (200 x1.5) =300.

So the magnification effect means you are actually shooting with an EFFECTIVE
82-300mm.

The S in the AFS stands for "silentwave" - it is the type of autofocus motor the lens uses. Other lenses have helicoid drives and are much slower.

f stops (f5.6 for instance) is a ratio of the diameter of the "hole" the light comes through in the lens to the diameter of the front lens element and the focal length. Depending on how you set the lens diaphragm (the blades that create the "pinhole" the light comes through) the f-stop alters.

I am falling over myself now.

If we use a 300mm f2.8 lens as the example - f2.8 is the ratio between the frontal element and the focallength = 300 divided by 2.8 = 107mm. That is the size of the front elemnt. The bigger the front element the more light can be channeled through the aperture in the diaphragm. Make your aperture hole smaller and the ratio goes up, which is why the number gets bigger.

A 300 f4 has a front element of 75mm diameter (300 divided by 4).

basically, the bigger the hole, the smaller the artio, so the smaller the number - and from a picture taking point of view, the more light you can get through.

You can think about taking pictures as filling a bucket with water.

Your shutter speed is how long you turn the tapon for.

Your aperture is how big a bore the tap has.

The "correct" exposure is a combination of these things that fills the bucket exactly to the rim, no more, no less. So you can fill the bucket faster with a bigger tap - it needs to be turned on for less time.

Use a smaller tap, and you need to leave it on for longer.
 
Lensflare, just what I was after thanks very much!

& to all the other replies as well
 
Lensflare said:
55-200 is the focal range of the lens - on a 35mm frame.

Nikon DX format cameras have a multiplication factor of 1.5x - because they only use part of the 35mm frame (APS size sensor). The maths for this is easy, your 55-200 is effectively a (55 x 1.5) = 82 - (200 x1.5) =300.

So the magnification effect means you are actually shooting with an EFFECTIVE
82-300mm.

The S in the AFS stands for "silentwave" - it is the type of autofocus motor the lens uses. Other lenses have helicoid drives and are much slower.

f stops (f5.6 for instance) is a ratio of the diameter of the "hole" the light comes through in the lens to the diameter of the front lens element and the focal length. Depending on how you set the lens diaphragm (the blades that create the "pinhole" the light comes through) the f-stop alters.

I am falling over myself now.

If we use a 300mm f2.8 lens as the example - f2.8 is the ratio between the frontal element and the focallength = 300 divided by 2.8 = 107mm. That is the size of the front elemnt. The bigger the front element the more light can be channeled through the aperture in the diaphragm. Make your aperture hole smaller and the ratio goes up, which is why the number gets bigger.

A 300 f4 has a front element of 75mm diameter (300 divided by 4).

basically, the bigger the hole, the smaller the artio, so the smaller the number - and from a picture taking point of view, the more light you can get through.

You can think about taking pictures as filling a bucket with water.

Your shutter speed is how long you turn the tapon for.

Your aperture is how big a bore the tap has.

The "correct" exposure is a combination of these things that fills the bucket exactly to the rim, no more, no less. So you can fill the bucket faster with a bigger tap - it needs to be turned on for less time.

Use a smaller tap, and you need to leave it on for longer.
Click to expand...


Interesting analogy:)
 
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