This information is valid if you are using a camera that costs a few hundred pounds right the way up to a camera costing thousands of pounds.
When people come and chat with us about the various cameras available for use underwater, one of the things we stress very strongly is that it is a good idea if your intended purchase will accept a very wideangle lens, this is not just shameless salesmanship on our behalf, to get you to part with extra cash, although it all helps;)
Arguably, a WA lens will make the biggest difference to the overall quality of your shots.

First lets define what we mean by wideangle, when talking about underwater photography.
Most modern Digi-Compact Cameras have a reasonably wideangle lens for on land use, but this is generally not thought to be of a sufficiently wide angle of view for underwater.
So its usually thought that a good starting point for a wide-angle lens that would be useful underwater is around 100degrees or even wider.

If you are using a compact camera inside an underwater housing, the wide-angle lens attaches to the outside of the housing, and can be attached and detached whilst on the dive.
With a DSLR camera the choice of lens has to be decided before the dive has begun, but the principle behind their use remains the same.

Even though my buddy seems quite distant she is actually only around five metres or so away!

All a WA lens does is enable you to get closer to your subject, i.e. imagine your shot is of your buddy, without any lens attached to your camera, or housing combo, you may well find that you are around three to five metres away, depending on the size of your buddy!
So if you were then to attach a WA lens you could reduce that distance quite dramatically.
Even in Gin clear tropical waters this makes quite a profound difference, but becomes almost vital if you are shooting in less than ideal, poor viz conditions.
So cutting down the water column between you and your subject matter but still keeping all of the subject in is the big reason we love wideangle lenses.

In the shot below my buddy is less than two metres away from me.

Wreck photography, large marine life, and reef landscapes are all situations which are benefited, by the use of very WA lenses.

Unless I am solely shooting tiny marine life, I am pretty much always shooting using a very wide angle lens whether its on a compact or a DSLR.
I have put a couple of before and after shots below, so you can see the big difference in clarity and contrast.

Here I had to get back about 10 metres from these boilers on the wreck of the Kingston to get them all in shot.


But here with the lens attached I can get much closer giving me a sharper clearer picture with much better colour.
http://www.oceanleisurecameras.com/panel/assets/php/asset_image.php/185/full/600/407/WideAngleDemo-1.jpg

It’s also worth pointing out that I am using no filters or strobes here, and just a simple function that is available on some cameras called Custom White Balance.
This is not the same as the Underwater Setting which doesn’t work quite so well.

“So, what do I do if I cannot attach a wideangle lens onto my current camera and housing set-up?”

Well, even though OLC is in the business of selling underwater cameras and lenses, we understand you may be a little disappointed if you couldn’t use WA attachment lenses with your current purchase. Or you may not be ready to splash out on a wideangle lens yet.