Lenses Help

[Demilith]

Hey, can someone help me out with lenses and their types and such? I've looked at some of the stickies and they didn't really help much..

What would be some good lenses to start with? I'd take mainly objects, maybe the occasional landscape, some street & blah. Doubt I'll take any portraits. Are prime lenses any good? What one should I get? I've seen some people mention 35mm and 50mm, but I don't understand what the millimeters suggest. Of those two, which is better?

[OsmosisStudios]

Lenses are measured in mm (millimeters) as a focal length. What this means is that the distance in mm is the distance from the front element of the lens to the point at which the light focuses. That's simple enough.

Smaller distances mean a wider angle of view. Longer distances mean a narrow angle of view.

So if you have a 15mm and a 500mm lens, theyre going to see VERY differently. A 15mm lens will be used for landscape shots, vehicle shots, etc. 500mm is pretty much reserved for 2 things: Sports and wildlife.

Different lenses also show the subject differently. Wide angle lenses (like the 15mm above) will exaggerate the distance from the front to back of a scene. Telephoto lenses (like the 500mm above) will compress the background and your subject into what seems to be a 2D plane. This is why portrait lenses are NOT wide angle lenses (generally) because they distort the face and limbs.

You can use any lens for any subject: it just depends on what youre trying to achieve.

Zoom lenses (strictly speaking: varifocal) are expressed as a "xx-yymm", and this means that at one when the lens is "xx"mm and at the other it is "yy"mm. This is great because it means you can get several focal lengths (views, compressions, styles) in ONE lens. The downside is that there are compromises to image quality.

Prime lenses don't zoom. They're a single focal length (eg. 50mm). This can be limiting (no space-altering capabilities) but it can also be a good stylistic choice. These lenses are also designed and optimized for that focal length, so theyre, generally, MUCH better than their zoom counterparts over the same focal length. This last bit is important because a 50mm lens is useless if you need 400mm.

Lens codes also express another vital part of the lens construction: aperture. You'll notice on lenses (like a kit lens for instance) that it says "18-55mm f/3.5-5.6" then a bunch of letters. The other letters are important, but not right now. The f/3.5-5.6 is the maximum aperture (largest opening) the lens can have at both ends of the zoom. So, just like the focal length is expressed as "xx-yy", the aperture is expressed as "aa-bb", so in this case the maximum aperture at "xx" focal length is "aa", and the max aperture at "yy" focal length is "bb".

In the kit lens example: the maximum aperture at 18mm is f/3.5 and at 55mm it's f/5.6

You can go smaller than these (f/8, f/11, etc) but you cant go larger; at least not on this lens. Another area where primes shine is that they allow for VERY large apertures. In the 50mm example given above, the aperture is usually f/1.8 (the most common). They can get down to f/0.95, but those are both rare and expensive. What's the difference between f/3.5 and f/1.8? 2 stops. What this means is that at f/1.8 you can shoot a shutterspeed 4 TIMES FASTER than at f/3.5. So, if you're indoors in poor lighting shooting 1/15s @ f/3.5, you can open up and get 1/60s @ f/1.8

Of course, as with the explanation above: if you need 18mm then a 50mm lens is useless, regardless of aperture.

When you start out, you generally get a "kit" lens with the camera. It's often something like the example i posted above. That's a great starter lens because it gives you some zoom and helps you learn about all the bits and bobs before stepping into new lenses. ONLY get new lenses when you feel that the lenses you have now aren't doing something for you. Not enough reach, too much reach, not enough aperture, etc.

Prime lenses are very good, but you have to be aware of their limitations. I personally LOVE prime lenses because theyre so sharp and, generally, much smaller. That means no worries about bringing a camera bag with 8 lenses: if they only weigh as much as one zoom combined, im golden.

35 and 50mm lengths are bandied about rather commonly. 50mm on FILM (and full-frame digital) is considered to be equivalent to what the eye sees. It's also what used to come with almost all old film SLR cameras as a kit lens before zooms became popular. On digital crop bodies, however, 50mm acts more like a 85/90mm lens, and is a bit long for many people. 35mm lenses, however, act like 50/55mm lenses on digital, which gets you back to the 50mm "ideal".

One of the big reasons 50mm lenses are so popular is that they have wide apertures (as explained above) and are usually cheap as chips. For both Nikon and Canon, these are the least expensive lenses in their lineup.

Both 50 and 35mm lenses are great, it boils down to preference. I prefer my 50 because it gives me that little bit more working space for portraits.

Ultimately, much of lenses comes down to what YOU need, what YOU want and what YOU can afford! Try some out at a camera store, ask to borrow a friends, anything. But learn what you like, what you dont like, and buy accordingly.

I'm quite happy with my lens selection. It gives me good/very good image quality across the range, I have a vast range covered and I've rarely found myself needing something I don't have.

Nikon 10-24mm f/3.5-4.5
Nikon 18-70mm f/3.5-4.5
Nikon 70-300mm f/4.5-5.6 VR
Nikon 50mm f/1.8

[RichardTaylor]

This intro to lenses thread of mine may help.

Flickr: Discussing (1) Intro: Lenses: in Richard_Taylor