Steve's Digicams Forums

Steve's Digicams Forums (
-   General Discussion (
-   -   new!!!! lens ? (

paintthesky Mar 17, 2008 5:28 PM

hello. i just got a d40 and my dad gave me his lens 70-210mm of course i have no idea what this means or what it is used for!!!!!!!!!!!!!! i'm really new at this! can anyone explain the lens and what i would use it for! i want soem good shots of my son at his first t-ball game. i wont be able to get too close. and then some easter egg hunts that are coming up! can anyone help someone so clueless and dont even know what to ask. i have used the camera several times lately even witht he lens but i just put it on auto and shoot. (easy way out i know) thanks!

JimC Mar 17, 2008 5:33 PM

What brand of lens is it, and what do you see printed on the front of the lens?

Chances are, it's not going to autofocus on your Nikon D40. The newer entry level Nikon bodies like the D40, D40x and D60 do not have focus motors built into the camera bodies.

So, you need to use lenses that do have focus motors built in if you want Autofocus. For example, Nikon's AF-S (Silent Wave Focusing) or Sigma's HSM (Hypersonic Motor Focusing) lenses.

Most other Nikon camera bodies will not have this restriction (requiring a lens with a focus motor built in). The only Nikon SLR or dSLR camera bodies without focus motors are the D40, D40x and D60.

You could probably use manual focus with it. If it's an Autofocus lens, you probably wouldn't have any autofocus with a D40. But, you'd still have metering. With a manual focus lens, you'd lose metering, too (so, you'd have to estimate the settings needed for aperture, ISO speed and shutter speed, "shooting blind", without another meter to measure light).

paintthesky Mar 17, 2008 6:46 PM

thanks. it is a nikon af nikkor 70-210mm under that it says 1:4-5.6 i actually did use it on manual focus and just tried my best~ have alot to learn!~!!!!!! what does the 70-210 mean and the 1:4-5.6 do you know any books for beginners that would be helpful! there are just way too many bells and whistles on the camera (for me)!!!

JimC Mar 17, 2008 7:24 PM

70mm is the focal length at it's widest zoom setting (least apparent magnification, or widest field of view).

210mm is the focal length at it's longest zoom setting (most apparent magnification, or narrowest angle of view)

As for the other numbers, f/4 is the widest aperture setting at the widest focal length (the 70mm end of the lens). f/5.6 is the widest aperture available at it's longest focal length (the 210mm end of the lens).

The aperture scale (in one stop increments) goes f/1.0, f/1.4, f/2.0, f/2.8, f/4.0, f/5.6, f/8.0, f/11, f/16, f/22, etc. With each one stop move to a smaller aperture (represented by larger f/stop numbers), you will need shutter speeds twice as long for proper exposure.

Basically, the f is for focal length, and the idea being (after doing all of the math), is that the area of the hole formed by the aperture iris either doubles or halves as you go up or down 1 stop. So, if you go from f/2.0 to f/2.8 (one stop), half as much light gets through, because the area of the aperture iris is being reduced by one half.

Let's say you have a 50mm lens shooting at an aperture setting off/2.8. 50/2.8 ~= 17.86, where 17.86mm is the diameter of the iris opening.

Or, you can take the focal length, and divide it by the iris opening diameter and get your f/stop (50mm / 17.86mm ~= 2.8 )

That's one of the reasons you see lenses that have different aperture ratings as focal lengths get longer, even though the physical size of the iris may not be changing.

Now, it gets more complicated. The area (not the diameter) of the aperture iris is what is changing by half or doublewith each one stop change.

Here is an article on it that explains it in detail, complete with formulas:

So, a lens with a larger available aperture is desired to get fast enough shutter speeds to reduce motion blur (either from camera shake or subject movement) in many conditions.

Here is achart you can use to get anidea of the shutter speeds required for any EV and Aperture (but make sure to use your camera's metering, as lighting can vary -- this is only to give you an idea of how it works). It's based on ISO 100. So, each time double the ISO speed, you can use shutter speeds twice as fast:

The term "faster" lens is because you can get faster shutter speeds with it.

Of course, nothing is without tradeoffs. A brighter lens is larger, heavier and more expensive.

Here is a handy online exposure calculator that lets you see how this works in 1/3, 1/2 or 1 stop increments (you can change this via check boxes at the bottom). Also, note how the graphics show the aperture iris diameter changing with your aperture settings (to let more or less light through).

A brighter (a.k.a., faster) lens also helps a camera to "see" better for Autofocus Purposes. Many cameras won't be able to focus with a slow lens in some lighting conditions. You often seen complaints of the Autofocus hunting when users try to buy inexpensive long zoom lenses (with maximum available apertures of f/5.6 or f/6.3).

For indoor sports, night sports in a stadium, or similar conditions, you really need a lens with a constant aperture of f/2.8 or larger a better chance at decent shots of non-stationary subjects, even at high ISO speeds using a DSLR model. Otherwise, you'll have motion blur from camera shakeand subject movement.

With zoom lenses, you usually see two numbers listed. One is the maximum available aperture at wide angle, and the other is the maximum available aperture at full zoom. For example, f/3.5-5.6. For higher quality zoom lenses, you may only see one number listed (for example, f/2.8 ). These lenses are able to maintain a constant effective aperture throught their focal range.

For some uses, many users go to faster (f/1.8, f/2.0) primes, since they can getter even faster shutter speeds this way. Some users invest in f/1.4, f/1.2 or even f/1.0 primes for some low light conditions (but an f/1.0 prime is very pricey -- for example, Canon made one for a while, and it's usually $2k plus on Ebay in used condition.

Aperture also impacts depth of field. Lenses with larger available apertures are desired for portraits (or similiar subjects), where you want a shallow depth of field to help your subject stand out from distracting backgrounds.

You can see how Aperture, Focus Distance and Focal Length work together for Depth of Field purposes with this handy online calculator:

Many users make the mistake of buying inexpensive, slow, lenses that are not suitable for many conditions. So, you'll need to pick your lenses carefully for the conditions you plan to shoot in, and the largest available aperture is one of the most important considerations.

A larger available aperture is often preferred for getting a shallower depth of field, too (so that you can make your subjects stand out more from distracting backgrounds by blurring them).

BTW, a lens with a larger available aperture still lets you use smaller apertures when needed. So, if you want faster shutter speeds and/or a shallower depth of field, you can set it to a larger aperture value (smaller f/stop number); or set it to a smaller aperture (larger f/stop number) when greater depth of field is needed (which will result in slower shutter speeds).

The 70-210mm f/4-5.6 lens you have is considered to be a relatively slow (a.k.a., dim) lens. It's worth approximately $100 retail from reputable vendors of used gear, depending on condition. Here's an example:

Nikkor 70-210mm f/4-5.6 AF Lens at

paintthesky Mar 17, 2008 8:02 PM

wow. thanks for all the info ( it was a little above my head) i dont have a fugi. i have the nikon d40. dad has the nikon d70 so he just gave me the lens b/c he doesnt use it. so what lens do you recommend for every day shots (mainly of kids)? i can't afford to buy several different ones (wish i could) thank you tahnk you for taking time to help me!

JimC Mar 17, 2008 8:21 PM

I removed the paragraph regarding Fuji (I copied most of the info from another post).

Short answer:

It's a longer zoom and you may not be able to backup far enough to use it in many conditions.

As for a general purpose "walk around" lens, most people will want something starting out at around 18mm or so.

paintthesky Mar 17, 2008 9:06 PM

thanks so much! im so grateful i found this site!!!

All times are GMT -5. The time now is 12:13 AM.