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creators

Help in understanding lens's.

When I bought my D70 kit it came with an 18 - 70mm lens, my telephoto lens is a 70 - 300mm and my Macro is a 50mm prime lens. What exactly do those mm sizes mean and do?

Also, on the telephoto it says, AF 70 - 300 1:4 - 5.6 LD and Tele-Macro (1:2), on the kit lens it says, AF-S NIKKOR 18-70mm 1:3.5 - 4.6G ED, and on my Macro, 50mm 1:2.8 DG Macro D. What are all those ratios and other stuff about?

Simple answers, if possible, please. Thanks.
hil26

Re: Help in understanding lens's.

creators wrote:
When I bought my D70 kit it came with an 18 - 70mm lens, my telephoto lens is a 70 - 300mm and my Macro is a 50mm prime lens. What exactly do those mm sizes mean and do?

Also, on the telephoto it says, AF 70 - 300 1:4 - 5.6 LD and Tele-Macro (1:2), on the kit lens it says, AF-S NIKKOR 18-70mm 1:3.5 - 4.6G ED, and on my Macro, 50mm 1:2.8 DG Macro D. What are all those ratios and other stuff about?

Simple answers, if possible, please. Thanks.


Simple it is then, as that's what I am,

my understanding

the 1:4-5.6 means the lens will only close aperture to F4 at longest zoom and down to 5.6 at shortest (so short dof), which is why fast lenses are recommended 1:2.8 for example

Macro - is your fastest lens - shorter shutter speeds in darker conditions

tele macro means that if it was 1:1 image would be life size in viewfinder
1:2 means half size

focal lengths well thats another story, over to someone else

(hope I got that right)
creators

Thanks Dave, that all kind of makes sense, though I don't quite understand why they show (the macro for example) as a ratio 1:2.8, assuming 2.8 (which it is) means it's lowest f-stop, what does the 1 mean?

The telephotos lowest f-stop fully extended is f-6 (just had a quick gander), but I get the idea.
Evolution104

Funny you should bring this up now - I was just re-reading How To Improve Your Photography and they have an explanation and chart in the reference section which will do far more justice to your question than I ever could.

The focal lengths referenced below are really for film cameras, so you should consider the values as effective focal length or EFL when comparing to digital cameras.

Quote:
Lens Focal Length

This is the distance between the film [sensor] and a certain location in the lens when the lens is focused at infinity. Use lens focal length as a guide to remind you how a lens will see a scene.

Focal lengths can be grouped into three main categories:
Short focal lengths - 35mm and shorter
Medium focal lengths - 40mm - 85mm
Long focal lengths - 90mm and longer

A short-focal-length lens is also called a wide-angle lens because it has a wide angle of view - it sees a lot of the scene.
Angle of view increases as focal length decreases. Therefore, a 17mm lens has a wider angle of view than a 28mm lens, which has a wider angle of view than a 35mm lens.

A long-focal-length lens, usually called telephoto, has a small angle of view and seems to bring a faraway scene close-up. It magnifies the image more than a wide-angle lens. Image magnification increases as focal length increases. Therefore, a 300mm lens magnifies the image more than a 150mm lens.

A lens in the focal-length range from 40mm to 55mm is called a standard lens because most cameras are sold with this lens.


I found this chart useful:

How Focal Length Affects Magnification *
Code:

Relative Focal Length  Magnification
------------------------  ---------------
          15mm                    0.3
          21mm                    0.4
          24mm                    0.5
          28mm                    0.6
          35mm                    0.7

 =        50mm                    1.0    =

          80mm                    1.6
         100mm                    2.0
         200mm                    4.0
         400mm                    8.0
         800mm                   10.0


* This does not imply that a 50mm lens produces life-size pictures. These magnifications are relative image sizes, using the image produced by a 50mm lens as a reference.
Evolution104

creators wrote:
though I don't quite understand why they show (the macro for example) as a ratio 1:2.8, assuming 2.8 (which it is) means it's lowest f-stop, what does the 1 mean?


Maybe this will help? scratch

Don Baccus wrote:
True macro lenses, as you describe, are optimized to provide best performance when focused close. Normal lenses are optimized to provide best performance when focused at more normal shooting distances.

In order to focus close, the focus helical in macro lenses is much longer than in a normal lens so you can do so without adding an extension tube (you can close focus a non-macro lens by adding extension, though the result might be a tad bit soft compared to a true macro due to the lens not being designed to be close-focused). Play with one in a store, and watch it grow and grow as you focus it closer and closer to 1:1. Modern macros often change focal length as they focus close, which lessens the distance the front element needs to be moved to achieve a 1:1 (or 1:2, depending on brand) reproduction ratio.

The magnification ratio is really a ratio, i.e. fraction. 1:1 may be thought of as 1/1 or just 1 - a lens with a reproduction ratio on film of 1:1 will focus close enough so that the subject will appear on the frame life-sized. 1:2 means the same as 1/2, i.e. the lens focuses close enough to put the subject on the frame half life-sized. 2:1 means 2/1 or 2, i.e. twice life-sized on the frame.

Hope this helps!
hil26

long focal lengths also shorten distances between objects

just look at a marathon race and you will see two runners apparently one just behind the other, but from a different angle they are hundreds of metres apart
creators

Thank you so much John, I shall digest at leisure. I've been hiding away from this because of looking a muppet, and suddenly thought, in a moment of blinding clarity, 'Keith, old chap, you're more of a muppet if you don't ask, how did anyone else learn this stuff?' We learn by learning, this stuff doesn't come with genes and DNA. Ah the folly of human pride, never too old to be a muppet. Very Happy
Evolution104

Regarding the cryptic acronyms...
I never thought it would be so difficult to find some simple information Very Happy


Here's the little I did find:

ED = Extra-low Dispersion glass. Reduces chromatic aberration. Recently, Super ED glass has been introduced.

LD = Low Dispersion glass.

AF-S = Autofocus-Silent. Uses Silent Wave Motor to focus quietly and quickly; similar to Canon's Ultrasonic Motor technology. Introduced in 1996.

Macro D = Not sure, but the 'D' may mean that this lens is compatible with Nikon's advanced 3D matrix metering system.
creators

Brilliant, thank you, I wondered why my other lens were noisy, grinding coffee.
Evolution104

To add to the confusion Shocked

D -- (1992) Adds distance information to the data transmitted to the camera via chip. Distinguished by the D or G after the lens designation.

G -- Removes the aperture ring from a D-type lens. Thus needs to be used on camera with Command dial control of apertures. With some older cameras (N90s, for example), can be used in Program or Shutter-priority exposure mode, though.

Quote:
The first autofocus lenses appeared in 1986. These have a "CPU" built into the lens, but this really is just a fancy way of saying it has an electronic transfer of basic lens information to the camera. Since then, we've had several variations of autofocus lenses: D-type (1992) adds distance information to the data supplied by the lens to the camera, AF-I, AF-S add in-lens focusing motors, and G-type removes the aperture ring (but is otherwise identical to D-type). The main things to watch for are non-D, D, or G. This is found by looking at the aperture designation on the barrel, which would be something like f/2.8, f/2.8D, or f/2.8G for plain autofocus, D-type, and G-type respectively.
Evolution104

This seems to be the most comprehensive information I can find. It still leaves me feeling like I still don't understand all the acronyms, but it's better than most:

Nikkor 35mm SLR Lens History, Terminology and Technology
hil26

hmmmmmmmmmm

but info is brilliant
creators

I am incredibly grateful for your time and trouble, thank you. Shall absorb at leisure, still haven't had any, it being Easter and all that.
Evolution104

Hopefully you'll find at least some of it useful.

I like researching stuff like this because I usually learn something - and it's a bit of an interesting challenge at times Smilie_PDT

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