Digital Home Thoughts: Guide to Choosing a Lens: From Macro to Astrophotography

Understanding The Application
Now that you have understand the various concepts in a lens, a quick word about the application. There are a very large number of scenarios for which you can buy lenses. Since lenses are expensive, it is always good to understand the most typical kind of scenario that you will be photographing in, so you can optimize on a few, but the right, set of features from above.

• General - Having a general "do-it-all" lens is a fantastic idea. Usually a good general lens is a 28-80mm lens that basically covers the 35mm within its range and gives about a 3x zoom. I have found that adding image stabilization (unless you have money to throw around) is not really necessary for this kind of lens. Usually, your standard camera lens will be perfect for portrait shots.
  
  
• Panoramic/Wide Angle - If you feel that you will be doing a lot of outdoors landscape photography, ISO is probably not as important as Aperture, Zoom and Focal Length. What you are looking for is more of a wide angle lens. Wide angle lenses give sweeping perspective and better depth of field and reproduction than a standard camera lens. They’re best for covering large subject areas. expanding the apparent distance between the foreground and background, they provide a unique perspective. Their exceptional compactness allows for greater mobility. They have a focal length on the lower side of the standard lens, i.e. around 24mm.
  
  
• Macro - If you’re interested in extreme close-up photography, consider a macro camera lens that allows for extremely sharp focusing at short distances. Macro lenses can uncover detail that would be impossible to detect by the eye and give new perspective to extremely minute subjects such as insects or the petals of a small flower. These lenses usually have a very low focal ratio (around f/2.8 ) and range from 50mm to around 200mm.
  
  
• Tilt Shift - You may think this is a weird category but I list think of this as the sky scraper category. With most lenses, when taking a photo of large vertical (or horizontal) objects with lots of straight lines, you may have noticed that in order to fit the entire object into the image, you take the photograph at a steep angle, which causes all the vertical lines to appear at slant as if they were going to a vanishing point. A tilt shift lens helps with this with shift movements that correct the trapezoidal effect seen in pictures taken of tall objects, so as not to distort the subject.
  
  
• Ultra Wide Angle and Fisheye - The wide angle allows you to bring more area into focus and provides greater depth of field. The images from such lenses usually end up giving you an image where things up close and in the center of the image appear large large and items at the periphery of the image are smaller. The image also appears rounded and bent around the center. A typical focal length rangest between 16-30mm.
  
  
• Telephoto and Astrophotography - As opposed to the wide-angle camera lens, the telephoto camera lens is a narrow angle lens. It appears to narrow the image, which is important when you are not able to get close to your subject. You will find that these lenses and telescopes have very high focal lengths. The longer focal lengths effectively compress the distance between the subject and camera to capture the details and the feeling of a far-off scene. If you are into astrophotography, usually you would want to concentrate on the focal length and aperture. But if you want to do the same in a strongly lit city like New York, you can buy something with a small aperture (since you want to capture less light in any case), and get something with a better focus system. A good telephoto lens is at least 300mm. You head into the super telephoto range at around 500mm to 600mm. Telescopes are usually in the thousands of millimeters in order to focus in on celestial bodies.
  

As you can see, there are many different types of lenses and each category in itself has a very large number of options. So understanding your own scenarios and applications is very important.

Cost vs. Quality
My very first DSLR body itself had set me back so much in my budget that I ended up buying a couple of very cheap lenses. And while cheap lenses will certainly get the job done, you have to realize that there is a difference between the cheap and expensive lenses. There is not only a difference between the durability of the lens and the body that the lenses are housed in, but also the quality of the glass; and I have also found a difference with the speed at which the cheaper lenses get dirty vs. the more expensive ones. The cheaper ones also feel cheap when taking photos -- what I mean is that the wheels on which the inner pieces rotate when zooming and focussing feel light and loose vs. the more expensive lenses feel tighter, smoother and give better control, especially when the changes I want to make are very slight.

If you have a choice between buying two cheap lenses vs. one expensive lens, I would say that you should spend the extra money to buy the one better lens and then save up for the extra few months to get the next one. The reason for this is that you will definitely end up wanting a better lens at some point in the future, and you would rather save your money and use it wisely in the first place than realize that you wanted some of your money. The resale value on lenses (especially the cheap ones) is extremely low so hoping to upgrade after having sold your first set usually doesn't work out as one hopes.

Conclusions
Lenses are expensive, but I think it is worth waiting for a bit and getting a better lens if you can. The lenses I would still buy are a good macro lens and a wide angle lens. And of course, it would be great to play with a tilt-shift lens at some point. I hope the above article gives some of you some assistance when you are out buying your new lens.

Suhit Gupta is a Contributing Editor for Digital Media Thoughts. He is a fan of all things digital media and photography related and when he is not reading or watching movies, he is out with his telescope pursuing his passion for astronomy. He lives in Redmond, WA, USA though yearns to be back in New York City.