Buying A Fisheye Lens - Three Things You Need To Know Before Buying Your First Fisheye Lens
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 buying being very disappointed with the results.
What's the essential difference? The Difference between a Fisheye Lens and a Wide Angle.
Unlike a wide angle lens, a fisheye is not corrected for distortion.
Because of this they 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 when they buy a fisheye that was not designed for their cameras sensor size.
The vast majority of digital SLR 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 your shooting with a full frame camera like the Canon 5d Mark II or Nikon D700 then you need a lens with a focal length of between 15 or 16mm.
If your shooting with a Camera that has the APS-C sized sensor, then you need somthing in the 8 to 11mm 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 frames 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 cameras frame.
Circulars have a much shorter focal length than the diagonals do.
If your in the market for a circular and your shooting with a full frame camera then your looking at a focal range of 8-10mm.
If your using a digital camera that sports an APS-C sized sensor then you need a fisheye lens with a focal range of 4 or 5mm.
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!