What is a fisheye lens? Is an ultrawide-angle lens that produces strong visual distortion intended to create a wide panoramic or hemispherical image. (Wikipedia) Ok let's create it 'virtually'.
What this tutorial is based on is in taking a 180x180°-squared panorama, and when seeing it flattened (not spherical 360-180°) creates a fisheye look.
Download Photosynth app from the App Store, it's free and has no ads. Read the in-app quick tutorial to know how to use it, it's really simple.
How to get the best fisheye effect: Closer subject or straight lines looks better when 'fisheyed' // Take a 180x180° panorama (left-right-up-down) without moving your body // Has to be a squared pano
This is the original image exported from Photosynth. I've tried to make it squared, and it's about 180x180° (a bit less), but it's ok.
Using any photo editing app (I use and recommend Filterstorm) I've cropped it squared and improved it a little bit using two masks of levels and curves.
And I gave it a dramatic look with some adjustments and the Sutro Instagram filter. That's the final picture.
Note the visual distortion on the sideway buildings, improving the fisheye effect. This is because the original image derived from a spherical image (partial 360x180°) that became flattened.
Also note that a simple camera capture would be like that, about 1/8 or less of the final fisheye image, so it's what a fisheye lens does.
Any questions or suggestions, just ask or leave a comment ;) I'm albertruefoto on Instagram.
Another example I took some days ago.