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How to Choose a Lens for SLR Cameras

July 21, 2011

After reading a dizzying amount of reviews and tutorials on different camera lenses, I knew others may have similar questions and concerns about choosing a lens that I had. So here is a summary of what I learned, although it’s mostly just the basics to get you going in the right direction.

What Kind of Photography are You Into?

Close-ups, food, landscape, portraits, sports… the list goes on. Determine what you wish to use your lens for the most and keep reading to figure out what lens will fit your needs.


{Clearly we know what I prefer to take pictures of. But my current 18-55mm lens can do a lot more than just food close ups….}

Picking a Focal Length

If you’ve looked into lenses before, or are just getting started, you’ll notice different numbers, or ranges of numbers before the abbreviation mm. For example, right now I shoot with an 18-55mm lens. These numbers refer to the focal length.

This number dictates how wide of an image the lens will capture. 50mm is comparable to the human eye and is a good place to start if your going to be taking a wide variety of shots, anything less is considered a wide angled lens and anything more is considered a telephoto lens.

The lower the number (such as 35mm) the wider the angle and more of a scene you can capture. For example you would use a wide angled lens to capture a vast landscape of a large group of people.

The higher the number (such as 200mm) the more narrow the angle and less of a scene will appear in your shot. This is good for capturing detail from further away and great for sports, portraits, and details of nature.



Fixed vs. Zoom Lens

You can buy a lens with a fixed focal length (such as 35mm) or one with a zoom range (such as 18-55mm). Zoom lenses are convenient for getting a variety of shots and everyday photography, but usually produce a lesser quality image than a fixed lens. Of course there are very expensive zoom lenses that are top quality, but as a general rule of thumb fixed lenses can let in more light and perform better.

You can find wide angled zooms (15-35mm), telephoto zooms (100-300mm) or more of a mix (such as 24-70mm).


{My zoom lens can reach a variety of focal lengths…}


Picking an Aperture

The next number (or two numbers on a zoom lens) you’ll see is the widest aperture or range of apertures that the lens can ahceive. For example my current lens is an 18-55mm f3.5- 5.6. This range tells me the widest or maximum aperture that the lens is capable of at each end of the zoom. So when the focal length is positioned to 18mm my lens can reach a 3.5 aperture at the widest and when it is positioned to 55mm, my lens can only acheive an aperture of 5.6 at the widest. Some high quality zoom lenses can still have a fixed aperture such as 17-55mm f2.8.

Generally a lower f number (meaning a wider aperture) is a higher quality lens. A lower number also means a faster lens that can capture better images in lower light situations.  A lower f number also means you can achieve a more blurry background. Now you can see why a low number translates to a higher quality lens.

I just purchased a 35mm f/2 which is an upgrade of aperture from my current f/2.8-5.6. This will help me shoot pictures when the lighting is not always adequate and will allow me to achieve more blurred backgrounds behind my subjects.


{See the wide aperture and blurred background that my lens can achieve. (f/3.5). My lens can also achieve a wide angled landscape view with a smaller aperture (f/16). }



If your looking to shoot ultra close ups of certain subjects such as insects or nature, you may want to consider a macro lens. They are usually between 50 and 100mm in focal length which can capture more detail and allows you to get closer to the subject.


What Camera Body Do You Have?

You must purchase a lens that is manufactured by the same brand as your camera body. If you shoot with a Nikon you must buy a Nikon lens and so on. Only the same brand lens will be able to mount on to your camera body except for a few third party lens manufactures. But to keep things simple you should stick with the same brand.



 Putting It All Together

Are you looking for a convenient lens that you can use for a variety of pictures? Start at a 50mm and consider buying a zoom lens so you can achieve a variety of focal lengths and detail.

Are you looking to take ultra close-ups or nature, bugs, or food? Consider a longer focal length to capture more detail, and a wide aperture (lower number) to achieve that blurred background look (narrow depth of field).

Are you looking to take vast landscape photography? Look for a wide angled lens, such at 28mm or lower to capture a wide image. A wide aperture is not as important with taking full landscape pictures.

Finally, consider your price range because lenses can get upwards of $2000. You can also find quality lenses for much less. Do your homework, go to a local camera shop, test out different models, and make an informed decision!

When my new 35mm f/2 lens arrives I will do a full review and comparison shots to put some of this knowledge to practice!


What is your favorite kind of photography to take or look at? If you shoot with an SLR camera, what lens do you use?

6 Comments leave one →
  1. July 21, 2011 4:25 pm

    Great post and tips. I’m so interested in photography but it can be really confusing. I have been shooting with my dad’s SLR but I’m not sure which type of lens we have.

  2. July 21, 2011 10:08 pm

    In response to your question about the lens I was using in today’s post, I use a 18-55 most of the time with a reverse lens mount for my funky macros. I use this lens the most because it is versatile but sometimes I break out the others. I need to really dig the 100mm macro out.

  3. July 22, 2011 9:49 pm

    This is a great post for anyone, especially those new to buying lenses and trying to decipher what ALL the numbers mean.

    Focal length, aperture, zoomed and not zoomed, so many #’s and it’s easy to get overwhelmed.

    I recently bought the canon 24-70mm f/2.8 Love it. I never take that lens of!!! 🙂

  4. July 24, 2011 1:09 pm

    When I got my first fixed focal length lens it took getting used to as I was so accustomed to zooming in and out with my other one! It does take great pictures though.

  5. July 24, 2011 2:26 pm

    Awesome post Katie. I use an 18-105mm on my Nikon D 3000 and love it.

    • Katie permalink*
      July 24, 2011 7:10 pm

      That sounds like a really versatile lens, I bet it’s great!

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