What Is the Difference Between Fisheye and Rectilinear Lenses?

If you are new to photography, you might be wondering about fundamental differences between lenses. Many beginners are drawn to fisheye lenses, which offer a different perspective on the world and the ability to get a massive field of view in one frame. So, what is the difference between a fisheye lens and a more standard rectilinear model? This excellent video tutorial will teach you what distinguishes them. 

Coming to you from Dave McKeegan, this great video tutorial will show you the difference between fisheye and rectilinear lenses. "Fisheye" and "rectilinear" are terms that refer to the projection in use for a lens design. "Projection" is a mathematical term that essentially defines how the geometry of one world is translated to another, such as the real world to a camera sensor. A fisheye lens is one that translates a portion of a sphere onto a flat surface, which is what gives them their distinctive lens, whereas a rectilinear lens is one that tries to preserve straight lines. Because of this, you can't really directly compare focal lengths between fisheye and rectilinear lenses directly. For the most part, rectilinear lenses will be the tool of choice, but a fisheye lens can be a nice occasional creative tool. Check out the video above for the full rundown from McKeegan. 

Alex Cooke's picture

Alex Cooke is a Cleveland-based portrait, events, and landscape photographer. He holds an M.S. in Applied Mathematics and a doctorate in Music Composition. He is also an avid equestrian.

Log in or register to post comments
7 Comments

It would be really interesting to have a single lens that could adjust between rectilinear and fisheye. Maybe an easier solution would be to have one lens with the highest resolution and two lens profiles, one each for the desired effect.

That's a great idea --- The technology is potentially there within mirrorless cameras. Why not have the ability to convert from fisheye to rectilinear image "in-camera" and then you could visualise the final image in the electronic viewfinder.

All ultrawides are a compromise - either the lens has to stretch the corners out (rectilinear) or you do it electronically by stretching pixels in software.

I like fisheyes as they are generally cheaper and smaller/lighter weight than rectilnear lenses of the same field of view. Also - there are great free correction programs such as Hugin to turn the image to rectilinear.

For M4/3 cameras there are already some great inexpensive 10mm "semi fisheyes" and 7.5mm true fisheyes. I make great use of both to get 20mm and 15mm FF equivalent perspectives.

Which one of root word is rectilinear coming from: rectification, rectangular (as described) or both?

Have you considered using Google?

I had and it is saying rectification. That is why I was a bit confused so I asked you, experts, for enlightenment.

Oh I found it. It is from rectus = "straight" plus linea = "line".