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The Lens You Can’t Do Without…

January 22nd, 2009 · 3 Comments

A lot of people are into photography. With the price point of good digital SLR cameras coming down in recent years, there is a definite move towards these cameras over point-and-shoot types by people who want a little more “do-more-ability.” When people find out that I’m a photographer, I get a lot of technical questions from the people who have an interest in the art. One of the most common ones is: “What lens could I get that would help me improve my photographs?” My answer is always the same: “Get a 50mm f/1.4!”

[i]Image Copyright Nikon USA[/i]

Image Copyright Nikon USA

This stubby little guy is all you need. Really. “Where’s the zoom?” you ask? It doesn’t have one. This is a fixed focal length lens, also known as a prime lens. There is no zoom, unless you count the zooming you’ll do with your feet to get close enough (or far enough, depending) to the subject to fill the frame.

Let’s get into the nitty gritty of what this lens is (skip this if you’re familiar with the terminology). This might also be a good primer on lens basics for those of you who are somewhat new to SLR photography.

50mm refers to the lenses focal length. On a standard 35mm film camera and some professional-level DSLR cameras with full-frame image sensors (which are the same size as 35mm film), this lens is roughly equal to the diagonal dimension of the film or sensor (a normal lens). On consumer level DSLR camera, you will find the smaller-format APS-C image sensor. Because the image sensor is smaller on these cameras, they see a smaller part of what the lens is actually projecting. For that reason, a multiplier is used to determine the lens’s equivalent focal length, also known as crop factor. Speaking Nikonian (other makers are slightly different), you need to multiply the lens’s focal length by 1.5x to get an idea of how it will look through the viewfinder of a consumer-level DSLR. In this case, a 50mm lens will act like a 75mm lens. In other words, with the 50mm lens, you’ve got a mild telephoto lens in your hands!

Now, let’s talk about the lens’s f-number. Defined technically, the f/1.4 rating refers to the lens’s focal length divided by its maximum effective aperture diameter. That definition means precisely jack squat to most, of course. What the number really relates to is size of the hole (aperture) and the amount of light that can be passed through the lens in a given length of time. That’s what we call lens speed. Just remember that the smaller the number, the bigger the hole, the more light gets in. So with an f-number of 1.4, you’re going to let more light through the lens and onto the sensor in one second than you will with an f-number of 22.

But there’s a tradeoff to the wide-open f-stop! You will greatly decrease your depth-0f-field by opening up the aperture. This means you will have a narrower band of in-focus subject, and you’d better be careful about where you focus your camera to make sure you’ve got what you want in focus! Here’s an example (hover your mouse to see f-numbers and shutter speeds, and click to see larger versions):

In the first image, I’ve set the f-number to f/1.4 and focused on the middle figure’s face. As you can see, the face is about all that is in focus. There is a very narrow range of distances from the camera’s lens that are in focus with such a wide open aperture (shallow depth-of-field). As you stop down (decrease the aperture size), you can see how the depth of field increases to include a greater range of distances from the camera’s lens. The middle image is at f/4.5 and the right hand image is at f/16. It is plain to see that as your aperture size decreases (f-number increases), your depth of field increases as well!

You should also take note of what happened to the shutter speeds in my depth-of-field demonstration above. With the lens wide open at f/1.4, the shutter speed was fast (1/50th of a second) because so much light was being let in by that big opening. At f/16, the shutter speed was very slow (2.5 seconds) since very little light was getting through the lens to the sensor. With the 50mm lens, any shutter speed slower than 1/50th of a second will be difficult to take sharp pictures with while hand-holding the camera. In general, you can apply the rule that shutter speeds equal to or faster than your lens’s focal length will give you less possibility that camera shake will cause the image to blur. So if you’re shooting with a 200mm lens, your hand-held minimum shutter speed should be somewhere near 1/250th of a second to keep your photographs sharp.

Now that all the technical stuff is out of the way, let’s get down to what this lens will do for your images versus the kit lens that came with your camera. A knowledgeable photographer will be able to control depth of field and use it to his advantage when capturing images. For instance, you can take more artistic-looking portraits by using a big aperture, making subject appear to “pop” out of the background and foreground by taking advantage of that shallow depth-of-field! Just be sure to focus on the subject’s eyes!

Notice how the foreground and background are out-of-focus?

Notice how the foreground and background are out-of-focus?

With the power that little 50mm f/1.4 puts into your hands, you can also take pictures in very poorly-lit areas. By opening up the aperture and increasing your camera’s ISO a little bit, you can often take images without a tripod where other cameras would fail.

No flash here!

And that’s not all this little gem can do! By adding a couple inexpensive accessories (like a lens reversing ring or a set of extension tubes) you can turn your little 50mm prime lens into a very powerful macro lens!

The 50mm f/1.4 as a macro lens.

The 50mm f/1.4 as a macro lens.

Its versatility is the reason why I recommend the 50mm f/1.4 lens to anyone who asks which lens they shouldn’t be without. This lens gives you superbly sharp, distortion-free, high contrast images for around $300. Nikon has two versions of the 5omm f/1.4 (a standard and the new G-type lens with the silent wave motor which is slightly more expensive, but will work on Nikon’s newer bodies that have no internal focusing motor). Canon has one as well. For off-brand, Sigma makes a good lens as well. If you truly want to improve your images, give yourself the gift of CONTROL and get yourself one of these lenses for your kit bag! You won’t be sorry!

Tags: Gear · Lenses · Photography · Tech/Geek

3 responses so far ↓

  • 1 Bob // Feb 7, 2009 at 2:09 pm

    Nice, comprehensive article. You make a good case for the versatility of the 50mm. One thing you didn’t talk about is common shots – those indoor group pics. Is the 50mm good for that? Is the length right to get a relatively wide shot without the distortion of say, an 18mm? Or is the 50 too long, and, say, a 35mm better?

  • 2 gcalvin // Feb 7, 2009 at 7:27 pm

    Thanks, Bob. Glad you liked the post.

    You can pretty much take what I’ve said and apply it to more commonly taken photograph types, since just about any lens can take indoor group pics relatively well (from varying distances depending upon group size and focal length).

    But here’s the thing: having the power of f/1.4 at your fingertips can be just as big a burden as it is a boon. Indoors with low light and no flash, a less-savvy photographer might be tempted to open the aperture all the way up for that group shot. He focuses on the middle face in the middle row, the picture is shot, it looks great on the camera’s screen, and then when the photographer gets home to print out what he’s taken, he finds that only the faces in that middle row are perfectly sharp. Everyone in the row in front or the row behind is slightly out-of-focus because of that very shallow depth of field that you get at f/1.4

    So to avoid this problem with a large subject like a group of people, you’re going to have to stop down to f/8 or so and use a flash anyhow. Of course, the 50mm will still take a great photo in this setting, and it will be SUPER sharp at f/8. But if you know you’re going to be taking group photographs, I’d say take along a 28mm prime or a good all-around lens like the 18-200mm wide-angle telephoto zoom that Nikon makes. The wider focal length will allow you to get closer to your group subject (which makes working in smaller rooms a lot easier) while still getting everyone in frame.

  • 3 Chance // Mar 5, 2009 at 3:30 pm

    Great article. Nice progression, and hitting all major aspects, with examples. I think that is most important, so I can better understand…I like to see it. The lens and its reasonable price sound like a must. I will add it to my wish list.

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