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Now that digital SLR cameras or “DSLR's” have dropped below $1,000 US, many underwater photographers are thinking about buying one, instead of a new “prosumer” camera like the Olympus 5060 or the Nikon Coolpix 5400. I regularly see questions in the Wetpixel Forums about the differences between consumer and SLR cameras for underwater use, so I'm hoping that this article can serve as an “upgrade guide.” The aim of this piece is not to influence photographers to switch, but rather to answer questions and explain the differences between the two systems.

Some reasons photographers have given for upgrading are:

• Image quality – lower noise
• Lens choices
• Faster autofocus
• Critical focus through the viewfinder

Size

SLR cameras are inherently larger than prosumer cams. While the camera body is not that much bigger, size can double when a lens is mounted. Naturally this means that housings will be larger. Not including a handle or tray, prosumer camera housings are typically roughly 5” tall by 8” wide by 5” front to back. A typical digital SLR housing might be 8” tall by 10” wide by 6” front to back. Add a lens port and the housing can “grow a nose” anywhere from 5” to 10” in length. Most SLR housings have dual handles affixed directly to the housing, so when making size comparisons, make sure to compare “apples to apples” and include a tray and handles on the consumer camera housing.

Dave Haas at DEMA, showing the small size of the Ikelite D-Rebel housing

Ports and Lenses

If you buy the digital rebel (or the Nikon D70 when it comes out) I recommend buying it with the “kit” lens. On the D-Rebel, this mid-range zoom lens is a great starter, because it has an equivalent field of view of 28-85mm on a film camera. That means that it will take photos with a slightly wider field of view than an Olympus 5050, which means you can get in closer to your subjects. Unfortunately, even at the closest focus, this lens does not have very high magnification so the next lens to purchase is a macro. Based on discussions I have had it seems like the first macro lens to buy is the Sigma 50mm. This lens is similar in quality to the Canon 50mm macro, but it will yield twice the magnification. Shooters who enjoyed using a wet-mate wideangle lens may want to look at buying a Sigma 15mm fisheye for underwater use. This lens focuses close and has a very wide field of view. Because of the sensor crop on the D-Rebel, you probably won't notice much distortion in your underwater photos. Another option is the Sigma 12-24 wideangle zoom which was just released.

The Aquatica D-Rebel housing will include TTL conversion circuitry (Photo Jean Bruneau)

Unlike with a consumer camera, it is impossible to switch lenses underwater with a digital SLR. Wetmate macro lenses are sometimes used, but I have never heard of a wet-mate wideangle lens for SLR's. Lenses can be changed on the boat, but after that they go behind either a flat or a dome port which is fitted to the housing. Many have asked, but unfortunately, there is no “one size fits all” port which will work with all three of the above lens types. A good starting point is to buy a flat port to use with the macro lens and a dome port for the kit lens and the wide angle. Fortunately, the kit lens and the fisheye both work behind Ikelite's extended dome port. The same will probably hold true for the Aquatica housing.

Viewfinder

Because there is a real shutter and a mirror in between the SLR's lens and the image sensor, there is no image preview on the back of the camera. If you are used to composing by looking at the LCD on a consumer camera, the viewfinder on an SLR might seem small. But as another photographer once said “As long as it's smaller than my eye, I won't have any trouble looking into it.” What you'll quickly realize is that with your mask up against the viewfinder, you see what the camera sees, and it's bright and sharp and when you press the shutter, that's what you'll capture. Consumer cameras pass a video feed from the imager to the LCD on the camera back and this video is usually delayed quite a bit and only updates a couple times a second. Because of the limited number of pixels, the LCD screen can't be used for manual focus or even really for judging focus after a shot. On the other hand, the viewfinder on an SLR is excellent for focusing on tiny macro critters. To summarize: it will take some getting used to having to put your mask up against the housing to compose and focus, but in the long run this photographer thinks the advantages outweigh the disadvantages.

The viewfinder and control layout of the Ikelite housing (photo Ikelite)

Strobes

If you already own strobes for a consumer camera, the chances are that they will work with your DSLR. With a few exceptions, most strobes will only work in manual power mode. One piece of exciting news is that the Aquatica housing for the D-Rebel has TTL circuitry built into the unit. The DSLR difference will be that the strobes will be fired using an electronic circuit, rather than a slave sensor. Most DSLR's shoot at a low of ISO100, so required strobe power should be about the same as for a consumer camera.

Cost Comparison

I've put together a rounded off cost comparison. It assumes you already have strobes and strobe arms for a consumer camera.

As you can see, the Digital SLR system will run about $1,000 more than a comparable consumer digicam setup. As an underwater shooter, it's really up to you to decide if the upgrade is right for you. Based on the questions I have been seeing on Wetpixel, apparently, at this price point, it's the right choice for a lot of shooters that are ready for a new camera system

Text by James Wiseman. Photos by Jean Bruneau, James Wiseman, and Ikelite