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Photography Tips: Understanding DSLR Lenses

Skill Level: Beginner

If you've ever shopped around for a lens, you know that the titles of lenses can get pretty lengthy and confusing. With all the different abbreviations, numbers and labels, the name of a lens can look more like a complex algebraic equation than a product title. So that's why I've decided to put together this blog post to help bring some clarity to the convoluted science of naming a lens.

Here are 2 examples of what a lens title might look like:

I mean really...it's a little ridiculous how complicated those titles are. I'm sure they make perfect sense to the marketing geniuses who came up with all these fancy titles, but to the average person, it's practically a bunch of meaningless letters and numbers. So let's break the names down and look at each part of it individually.

1. Lens Focal Length Range

Starting with the core of the lens title, we have the lens focal length range. The lens focal length is always measured in millimeters and it basically indicates how "zoomed in" the lens can go. Higher focal length numbers (e.g. 300mm) mean the lens will zoom in further, whereas lower focal length numbers (e.g. 20mm) mean the lens will have a wider view. For instance:

On the left: 28mm. On the right: 70mm (full-frame camera).

If the lens has a range of focal lengths, like 55-200mm, then the lens can zoom from 55mm all the way out to 200mm. Lenses that don't zoom are called "prime lenses" and they will be indicated with just a single focal length number - like the Canon 50mm f/1.4 USM.

2. Maximum Aperture

After the focal length range, the title will have an aperture number or a range of aperture numbers. This indicates the lens' maximum aperture. In other words, it tells you what the widest available aperture is for that lens. For instance, on the Canon 50mm f/1.4 USM, the widest aperture you can use is f/1.4 (remember that the smaller the f-number, the wider the aperture).

But then what's the smallest aperture you can use? Well, you'll have to dig a little deeper into the lens specifications to find that out. The minimum aperture for a lens (that is, the smallest opening) is never indicated in the title. Only the maximum aperture is. That's because the majority of customers don't care what the smallest aperture is. Most people want lenses that let in more light, not less. Only us landscape photographers care about the smallest aperture a lens can use.

Alright, now it gets a little tricky, so stay with me...

Some lenses have a range of apertures indicated after the focal length, like the Nikon AF VR 80-400mm f/4.5-5.6D ED lens. In this case the maximum aperture for the lens is listed as "f/4.5-5.6". When you have a range of apertures like this, that means the available maximum aperture will vary depending on how zoomed-in you are. The first aperture in the range indicates the maximum aperture for the short end of the zoom range. The second aperture in the range indicates the maximum aperture for the long end of the zoom range. This is called a "variable maximum aperture."

So in this example, the maximum aperture of the lens when you're set at 80mm will be f/4.5. But when you zoom the lens into 400mm, the maximum aperture decreases a bit to f/5.6. Having a variable maximum aperture like this allows the manufacturer to make the lens more compact and less expensive.

If your lens has a zoom range, but only 1 aperture listed, that means the lens' maximum aperture will be the same throughout the entire zoom range. For instance, on the Canon 70-200mm f/2.8L IS II, the lens can open all the way up to f/2.8, regardless of whether the lens is at 70mm or 200mm.

3. Features and Other Fancy Marketing Terms

All the other letters and abbreviations in the title of a lens will indicate features, quality and other marketing terms. For instance, if the maximum aperture has an "L" after it on a Canon lens - like the Canon 70-200mm f/2.8L IS II - then the lens is classified in its professional line of lenses. That means it'll most likely be weather sealed, the glass will be better quality, the image quality will be top-notch and the overall build will be more rugged.

There are a ton of different labels indicating all sorts of features and specs. Nikon especially has a very convoluted, over-complicated set of designations. Since there are so many, I won't bother defining all of them here, but I will address some of the most common ones. For a complete list of Nikon lens labels, check out this great article at DPanswers.com. For Canon's, here's a good article over at BobAtkins.com.

CANON

  • EF - "Electronic Focus" - This is the designation for all lenses fitting modern EOS bodies
  • EF-S - Same as "EF" except the lens is specifically designed for and will only fit APS-C format DSLRs like the 60D, 7D and Rebel series cameras (in other words, it won't fit full-frame cameras like the 5D or 1Dx)
  • USM - "Ultrasonic Motor" - This is what Canon calls their ultra-fast and ultra-quiet auto focus motor. USM lenses focus quickly, quietly and will typically have full-time manual override
  • IS - "Image Stabilization" - These lenses have built-in optical image stabilizer to help combat camera shake
  • L - This will come after the maximum aperture and it designates Canon's line of professional-grade lenses
  • DO - "Diffractive Optics" - This is a technology Canon uses in a few of its lenses that allows them to make telephoto lenses much more compact
  • Macro - A true macro lens will allow you to focus closer than a non-macro lens - good for photographing close-ups

NIKON

  • Nikkor - This is just Nikon's brand name for their DSLR lenses
  • AF - "Auto Focus" - If the lens has "AF" only (not "AF-S"), then the lens auto-focuses using the AF motor built-in to the camera. In other words, the lens itself has no AF motor. It relies on the camera body to drive the focus. Some Nikon cameras don't have a focus motor in the body, so they can't auto focus with these lenses.
  • AF-I - These lenses autofocus using an internal (that's what the "I" is for) AF motor built in to the lens instead of into the camera body as described above
  • AF-S  - The "S" indicates that it utilizes Nikon's current "Silent Wave" motor to auto focus. This type of AF motor is quieter and typically faster than the older AF-I motor
  • VR - "Vibration Reduction" - These lenses have built-in optical image stabilizer to help combat camera shake
  • D or G - It's kind of complicated. Check out this explanation at DPanswers.com
  • DX - This indicates that the lens is designed for and will only fit Nikon's DX "digital format" DSLR cameras
  • FX - This indicates that the lens will work on full-frame Nikon DSLRs as well as digital format DSLRs
  • ED - "Extra-Low Dispersion" - Indicates that the lens utilizes some special glass to help reduce chromatic aberration
  • IF - "Internal Focus"  - This means that the lens focuses by moving elements inside the lens barrel instead of moving the front element. As a result, the front of the lens won't extend out or rotate when focusing.
  • Micro - Nikon's indication for a macro lens

Canon Announces the EOS 5D Mark III

You know me, I'm not a gear junkie. I've been shooting with a first generation Canon 5D for the past 6 years and I'm the first to say it's the photographer, not the camera. But nevertheless, I thought I'd share the news on a new camera from Canon and create a 1-stop shop for you here on where to get all the details.

Canon EOS 5D Mark III

So in case you haven't already heard, Canon has announced the long-awaited next-generation Canon EOS 5D Mark III, and it has quite an impressive spec list. The new sensor is 22.3 megapixels, which isn't a huge jump over the previous 21 megapixels, but the improvements that shout out to me are the vastly-improved 61-point auto focus system, much-higher 6 fps shooting rate, 100% viewfinder coverage and upgraded weather sealing. Oh, the ISO also goes up to 102,400. Check out the links to follow for more details.

Spec Summary:

- 22.3 Megapixels
- 61-point AF system
- 100% viewfinder coverage
- ISO up to 102,400
- 6.0 fps continuous shooting
- 3.2" LCD
- $3,499 (body only)

Full Specs:

At Imaging-Resource.com

Hands On Previews:

At Imaging-Resource.com
At Engadget

More Information:

CanonRumors.com

Sample Images:

Canon's Website


- Pre-Order the Body Only at B&H ($3,499) -
- Pre-Order Body w/ 24-105mm f/4L IS Lens at B&H ($4,299)

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How Many Megapixels Do You Really Need?

With the recent announcement of the 36.3 megapixel Nikon D800 and D800E, I figured it was high-time I write a blog post about megapixels and how many you really need.

First things first: You should understand that I'm not a gear head. I love my equipment as much as the next guy, but to me, these are just tools in the hands of someone who knows how to use them or not. I don't care about Nikon vs. Canon, I don't need a coffee mug shaped like my favorite lens, I don't want a wrist-band that looks like the lens barrel of my 24-70mm and I'm not about to wear a t-shirt that announces my brand-loyalty to the world.

So when I talk about gear and camera specs, I'm looking at it from a realistic, practical application type viewpoint. No MTF charts, no side-by-side images, no bias towards one brand - I'm giving it to you straight. I'm also trying to talk you out of spending more money, so listen up 😀

Alright, so let's get down to the nitty gritty: How many megapixels do you really need?

To put it simply, it all boils down to how big you want to print. Or better yet, how big you will print. That's a more realistic way to look at it. Because I would love to print gallery-quality billboards, but let's be honest, I'm not going to.

Let's look at some common print sizes and see how many megapixels you'd need to print that size natively (meaning straight out of the camera with no "blowing up" the image). These calculations are done with a 300 DPI print quality for all prints below 20" in the long edge and at 200 DPI for anything above 20" in the long edge. Why? Because that's how photo labs work.

But really, where do most people's images end up? Facebook, email, Flickr, etc. Not many people print very many of their images. It's almost all digital sharing now. So let's look at the megapixels required for some common digital sharing avenues.

So think about all your pictures and where they all end up. How often do you print 24x36? What about 16x24? How about anything above 8x12?

The truth of the matter is most people's pictures rarely end up larger than 8x12. Even fewer go above 16x24. Hardly any print at 20x30 or larger. Of course I'm not talking about professional photographers, but even then, anything above 16x24 isn't the lion's share of their work.

But let's say you do want the ability to print all the way up to 30x45. Does that mean you need a 54 megapixel camera? No! Of course not! 54 megapixels is what you'd need to print straight out of the camera at 30x45 with loupe-worthy detail. You don't need that. With just a little blowing up of the file using software like Alien Skin Software's Blow Up (that's what I use) or Photoshop's built-in resizing tool, you can get great results from 18 megapixels. I know that sounds hard to believe, but I've printed at 30x45 from my 12.8 megapixel camera with results that were good enough to sell as fine art pieces to an art buyer.

The quality of a blown-up file definitely isn't as good as a native 54 megapixel file, but trust me, the difference in quality isn't worth the $31,000 price tag. Plus, you have to realize that larger prints are always viewed from further away. A huge 30x45 print isn't meant to be viewed from 3 inches away. People will look at it from whatever distance allows them to see the entire image. The bigger the image, the further back they need to be. And the further back the viewer is, the better the quality will look.

I print gallery-quality 20x30 prints all the time from my 12.8 megapixel files. That means I blow my files up to nearly double the original size and the results are great!

But if you have the money, why not buy the highest-megapixel camera you can? Well, there are a couple drawbacks to having a ton of megapixels. The first is measurable and obvious: more megapixels means bigger files. Bigger files means more memory cards and more hard drive space. For instance, my 12.8 megapixel camera produces RAW files in the neighborhood of 13 MB. So, I can fit around 79 photos in 1 GB. A 21.1 megapixel RAW file is around 25 MB. So, you could fit 41 images in 1 GB. And the Nikon D800 with its 36.3 megapixel sensor will produce RAW files around 40 MB. That will give you a mere 26 images in 1 gigabyte. That's less than a roll of film!

Given that memory cards and hard drives are pretty cheap nowadays, that might not be a big deal to you. But the other thing that people fail to acknowledge is the extra strain on your computer. Processing 36 megapixel RAW files will take quite a bit more computer power than processing 12 megapixel RAW files. Your computer will act sluggish when you work and you'll have a harder time running multiple programs at once. You may have to get a new computer altogether.

Another drawback to ultra-high megapixels is a little less measurable but, ultimately, much more expensive.

An ultra-high resolution sensor will create ultra-high resolution images that, when viewed 100% on the computer, will reveal every single little flaw in your lenses, subjects and your technique. Your 18-135mm lens that looked great on your 18 megapixel camera suddenly looks a little soft at 36 megapixels. Also, all those little blemishes that make us all human now look like huge blemishes!

This will lead to new, more expensive lenses in that never-ending quest for perfect sharpness and lots of extra Photoshop time removing blemishes. And it will all be for nothing, because although now your 36 megapixel images look great at 100% on your computer, all of your money spent on top-notch lenses and Photoshop plugins will be lost on the 0.7 megapixel file you sized-down for email and Facebook.

So really, don't put down a deposit on the D800 just yet. You probably only need about 18 megapixels at most. No reason shelling out $3000-$4000 so you can throw away half your megapixels with every image you take.