Snell’s window is a phenomenon by which an underwater viewer sees everything above the surface through a cone of light of width of about 96 degrees [From Martin Edge: Underwater Photography].
During my last Gapapagos Trip there was a bit of an issue in terms of photography subjects, in essence most of them were fairly big like sharks, turtles, eagle rays and of course divers.
After a while shooting or trying to shoot those uncooperative models I had the idea to try and do different things such as silhouettes and Snell windows. You can also combine both as we did in this case.
So what do you need to shoot image of a Snell window:
1. A lens that is wide enough, you need a bit more than 96º field of view to take the whole window
2. Something interesting on the surface (if you have calm water you can see right through)
3. An interesting subject as silhouette to contrast the clear water if there are waves and you can’t easily see through.
A normal flat wet wide angle lens for our compact camera is not sufficient to capture the snell’s windows as in this example
Take into account that even with a fisheye lens on an SLR you can’t capture the Snell’s window on the vertical axis as the field of view will fall short a few degrees.
With a compact camera a semifisheye lens will capture the edges of the window if correctly aimed on the diagonal and horizontal dimensions and will fall short on the vertical.
I am reporting some of the calculated field of view for the most popular lenses at present for compact at 3:2 image format
|Wet Lens||Diag FOV||Hor Fov||Ver FOV||Flare/Ghost|
All those lenses will take a good Snell’s window I have not tried the UWL-28 and I have some concerns this lens may flare as it usually does but I do not know for sure.
Both the Inon lenses produce sharp images with no defect.
In general small sensor cameras like the Canon S series will work fine with the fix/idas lenses and should produce good results also of normal shots through the water.
Using the UWL-04 or UWL-28 with large sensor cameras like the RX100 there could be a sharpness issue a larger apertures so make sure you close that at f/8 or smaller instead of using the shutter speed to balance exposure if you want to go through the water.
Snell’s windows are uncommon with compact camera shooters as they are considered an advanced subject but they can be taken. I will be taking more in a next trip to Egypt I hope for calm surface conditions so I can go through the surface with the shots. Failing that this is very easy to practice in a swimming pool.
Have fun shooting snell’s windows!