Cool cameras and other stuff

Canon WP-DC21 Waterproof Housing

Written by Digicamhelp Editor

Review of the Canon WP-DC21

waterproof housing by a professional photographer. Great insights and tips for anyone who wants to use their camera near or under water.

I always have a camera with me. Greater photographers than I can be quoted as saying that you can’t take pictures if you don’t have a camera.

Canon WPDC21 & the G9

But, when it rains or if I go to the pool or the beach, the camera has always had to stay in the bag or better yet in the truck. I couldn’t stand having to put the camera away at the first sign of rain, so I started looking for a waterproof housing for my Canon 5Dmk2.

I was shocked. They start out at $1600.  This prompted me to look at smaller cameras. After a bit of research I settled on a Canon G9 and the Canon WP-DC21 waterproof housing.

In short, I love this set.

Waterproof to 133ft. And it floats or not.

WPDC21-frontRather than a soft bag the WP-DC21 is a dive-rated hard case.  The manufacturer rates the case to be waterproof down to 133ft.  A soft bag style case works fine in wet weather or in shallow water but as depth increases so does pressure, and the water pressure will actually press the buttons for you, but not the way you want.

The case with camera installed is a bit less than neutrally buoyant so it floats, but Canon sells a set of weights that screw on to the bottom to make it easier to handle for diving.

Handling the WP-DC21. Real buttons.


All of the cameras controls are duplicated on the outside of the case, except the main control dial on the back.  Not sure why Canon left this off but I had no problem without it.

The controls are well spaced and easy to find.  In fact, the case feels good to hold and use. However, practice is a good idea, as the labels for them are embossed in the same clear plastic as the case.  Printed labels would be nice.

Quality of photos taken with the WP-DC21 underwater housing

The photos taken with the WP-DC21 housing are as good or better than without.

The front optic is the same as any high-end filter, high quality glass and multi-coated to reduce or eliminate internal reflections.  Also, the part of the case the houses the lens has a black rubber lining which acts a hood, so less lens flare.


The sound on the video is somewhat odd and muffled and the sounds of your hands on the camera are amplified.

Under the water with the Canon WP-DC21

White balance

Underwater photo by Brett TurnerThe G9 has an underwater white balance setting that is very useful for both stills and video. This setting will remove most of the blue cast in photos but will render scenes above the water very red.

It is worth mentioning that water absorbs the red section of the light spectrum so the deeper you go the less red light exists.  This is when the cameras built in flash is useful and effective.

Flash range

The effective range of the flash while under water is reduced dramatically.  (There are many companies who sell underwater flashes most of which are triggered by a sensor which detects the firing of the camera’s built in flash.)

Salt water

After using in salt water it is a good idea to soak the case (before opening) in fresh water so that salt will not build up in the controls.

Swim with a digital camera without worry

I first used this set in a pool and it was great being able to swim with a camera without worry.  The following week was vacation at the beach and then the water parks at Disney.  At the beach I could have used a different camera or simply used the G9 without the housing, but even with out going into the water I would have used the housing just to avoid the salt spray. The best use was at the water park.  The cast members never stopped me from using the camera on slides.  So I was able to take video while on the rides.

What I like about the Canon WP-DC21:

  • The combined cost of the housing and the Canon G9 is significantly less than a hard case underwater housing for a DSLR.
  • Protects a camera from the elements such as sand, dust and water spray.
  • Waterproof to 133ft.
  • The case floats with the camera in it but you could weight it to be neutrally buoyant.
  • Lightweight and well-made.
  • The controls are easy to use.
  • Included flash diffuser.
  • Included adjustable wrist strap.
  • All camera functions including video and flash work any time any where. Even on a water slide.

What I dislike:

  • Having to re-grease the O-Ring.
  • Probably no more impact resistant than the camera would be with out it.
  • Some what bulky but less so than a DSLR.

Some concerns from the manual

The WP-DC21 manual indicates that the O-Ring that has to be cleaned and re-greased each time the housing is used.  It says a even a bit of lint can lead to a leak.

Also the housing should never be left in the sun.  It will act like a green house and given enough time, cook the camera. However, I have carried it around in the sun for 8 hours and had no problem. The camera was quite a bit warmer than it would have been normally. If you will be in the sun, carry a bag or a light colored towel to cover the case when not in use.

Humidity is also a concern with any waterproof housing.  If the case is loaded and closed in a high humidity environment and then you dive in cold water the case could condense water on the inside. Either load in  low humidity like an air conditioned room, or buy some descant to put in the case.

Underwater cases are available for the Canon G10 and many other digital camera models.

Click images to enlargeClick images to enlarge


  • About using the flash underwater: there is a water characteristic called a “blue barrier”. This is the distance at which all the usable light has been absorbed – regardless of the light source strength! In the clear seawater it is something like five meters. The first meter will filter out the red part of the spectrum! Then the rest of the warm part goes, after which only the blue remains. So if your object is, say, two meters from the camera / flash (never mind whether built-in or remote), the whole path from the lightsource to the object and back will be near the borderline of the “blue barrier”, which is nearly useless. The object will be cast in blue, colors will be gone, and the intensity will be too weak to mention. Regard the u/w use of the flash useful only if your theme is not further than about 1 meter,preferably less. It is an useful rule-of-thumb.
    The most attractive u/w photography is in the shallows, and then mostly panoramic wideangle shots and macrophoto. Use flash to fill-in the shadows if you shoot against the Sun (very attractive!), and w/a lenses let you come much closer to your theme, which in turn makes for less water and floating sediment to mar the scene, combined with superior depth-of-field. Anyway, there is no real substitution for a sunlight, and in the shallows there will be plenty of it to use without the flash.
    Flash units also eat a lot of battery power… and there is probably no greater frustration than having to carry a dead camera amidst all those underwater wonders down there…
    My 2 cents… 🙂

  • Let me add some info. You do not grease an O-ring to seal the casing port, but to allow the building water pressure to move the ring symmetrically toward the zone of lesser pressure, i.e. toward the iside of the casing. Thus, you don’t have to use lots of grease, because it won’t work better. It will just attract sand and other sediment particles. But don’t forget to ever so lightly grease the space where the ring lies. Check and re-grease when you see the grease washed off the ring; otherwise just pull the ring trough fingers to “re-shine”. If the ring is properly greased, you’ll see an uninterrupted equally thick line where it presses against the casing.

  • All under water housings or bags put something front of the cameras lens. In some of the bags it is just clear vinyl. And yes any time you add more glass to a lens system there is some compromise but in this case it is negligible if not undetectable.

    The likely hood is that the glass on the housing is as good or better than the glass Canon used to make the G9’s lens. While the rest of the case is made of hard plastic the font optic (port) is just like any top quality UV filter you could buy for a lens. If it cuts light transmission at all it is below the cameras ability to measure.

    As for zoom and other functions they work just as they do with out the case. The lens port is long enough to allow the camera to zoom from full wide (approx. 28mm equivalent) to full telephoto (approx. 200mm equivalent) with out vignetting. You can’t add on accessory tel extender or super wide converters as they will simply not fit in the case. Remember that when viewed through water any image is magnified so you will likely use the wide angle setting while under water. In a kayak use whatever you want. You will find a loss of light the farther you go under water but that is from the water not the case.

    The white plastic piece on the end of the lens housing is, as you guessed, a flash diffuser. It is removable. It snaps on and is tethered by some nylon cord so as to not lose it in the water. When it is loose it is a bit annoying as it can float in front of the lens. Functionally it does two things. First, to a small extent, it diffuses and softens the light from the flash. The second and more important function is to prevent the lens area of the housing from casting a shadow. The diffuser redirects the light from the flash and sort of wraps it around the lens. I thought it was a bit of a joke when I bought the housing but it works surprisingly well. I have even used it for macro shots out side of the water. Usually there is no need to change flash exposure to compensate for the diffuser as the camera will figure it out with no problem.

  • Thanks for posting this.  I go kayaking and am not really looking for underwater shots, but don’t want my camera getting wet.  I have 2 questions

    1) Are the camera’s functions affected?  There is still full use of the zoom?  Is there additional glass to go through that will affect the light getting through (resulting in wider aperture or slower shutter speed)?

    2) What is the piece of plastic attached to the end of the section where the lens goes? Is that a defuser for the flash?  Is it removable?