If you’re planning on buying a fisheye lens, there are three things you need to know before making your purchase. Knowing these three things can save you a lot of money and disappointment, not to mention time wasted.
First, you need to know the difference between a fisheye lens and an ordinary wide angle lens. Many people confuse the two and end up being very disappointed with the results. What’s the essential difference?
Difference Between Fisheye and Wide Angle Lens
Unlike a wide angle lens, a fisheye is not corrected for distortion. Because of this, fisheye lenses have an extreme 180 degree angle of view and an image characterized by “barrel distortion.” A regular wide angle lens is corrected for distortion by adding corrective lens elements. As a result, the angle of view is reduced considerably but with an image that is considerably less distorted.
A wide angle lens will always have an angle of view that is less than that of fisheye lens of the same focal length. Do you want a fisheye lens, or are you really looking for an ultra wide angle?
Right Lens for the Right Sensor Size
Another error many people make is buying a fisheye that was not designed for their camera’s sensor size. The vast majority of DSLR owners shoot with the APS-C sized sensors with a crop factor of 1.5x –1.6x times. For instance, if you bought a Canon 15mm full frame diagonal for your Canon 7D because you wanted to create some cool fisheye images, you would be very disappointed with this Canon fisheye. What you end up with instead is a wide angle lens with an effective focal length of 24mm (15mm X 1.6 = 24mm). To achieve the “fisheye effect” you would need a lens with a focal length of between 8 or 10mm.
Here’s a general guideline: If you’re shooting with a full frame camera like the Canon 5D Mark II or Nikon D700, you need a lens with a focal length of between 15 or 16mm. If you’re shooting with a camera that has the APS-C sized sensor, then you need something in the 8 to 11 mm range.
Buying the Right Type of Fisheye Lens
Another factor that is sometimes overlooked is the type of fisheye lens. There are two distinct kinds of fisheye lenses: diagonals and circulars. The diagonal type of fisheye is the most common type and the most preferred. These lenses map a 180 degree angle of view “diagonally” across your frame’s sensor so that the image area is filled in with pixels. It’s for this reason that diagonals are often called “full frame fisheye lenses.”
A circular fisheye, on the other hand, creates a circular image centered within your camera’s frame. Circulars have a much shorter focal length than the diagonals. If you’re in the market for a circular and you’re shooting with a full frame camera, you’re looking at a focal range of 8–10mm. If you’re using a digital camera that sports an APS-C sized sensor then you need a fisheye lens with a focal range of 4 or 5 mm.
Most of the time fisheye lenses are designated as either circular or diagonal, so just make sure you carefully read the product description of the lens in question.
Have fun shooting with your new fisheye lens!
About the Author
For a more in-depth review of buying the right fisheye lens for your camera and alternative lenses by third-party lens manufacturers with full product reviews and price comparisons, go to http://fisheyelensreview.com.
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