SEALUX CD7100 housing

++ April 2014 ++ Review ++ by Werner Fiedler

SEALUX CD 7100 The underwater housing for the Nikon D7100 camera

Nikon’s current top reflex with DX sensor is a good camera for ambitious photographers. For the divers among you SEALUX have developed a suitable housing. Werner Fiedler now presents this interesting product and its features.

From the model number alone one can guess that the D7100 is the follow-up version of the D7000 and not of the former DX top-of -the-range D300 or D300’s. There are quite a few who were hoping for a “D400” as their logical improved successor, but obviously, Nikon’s product strategists must have had different ideas. All those disappointed at first find sufficient consolation in the new experiences with the new camera and the laboratory tests carried out and published by relevant photo magazines that are coming to the surface, given that they attribute outstanding features to the new DX flagship (with Nikon the term DX stands for the sensor format APS-C) that meet semi-professional requirements at least. Consequently, thousands of D7100 owners have made the right choice, but still need an underwater housing which is also up to their expectations. To start with, by researching the relevant market the CD7100 from SEALUX absolutely merits their attention.

The housing

Just the same as all SEALUX models milled from a solid block, this product also shows similarly clear lines. Once the two housing halves have been machined, that is, provided with the port mount, the necessary holes for the control window and the viewfinder as well as all perforations and screw threads, said halves are hard anodized in black for additional protection. The inner surface is left uncoated to attenuate any stray light. The outside features an additional silver-metallic powder coating to make it look shiny, in contrast with the mat black controls and the moulded handgrips. Apart from the housing itself, all component and accessory parts are resistant to any form of corrosion, too, as they are also made of a seawater resistant electroplated aluminium alloy, of tough plastics or stainless steel. For the compact D7100 reflex camera SEALUX have been able to design rather a small housing, which appears a little higher only because the flipped-open interior flash reflector needs to be fitted inside, too. The vertical partition of the housing runs approximately through the middle, resulting in two halves about the same size. There are practical reasons for this design, making it extremely rugged. Two spring-loaded quick-release locks hold the front and back cover halves together, so that the housing can be opened and locked again quickly.

A relatively large diameter O-ring acts as a reliable main seal. An interior continuous retaining lip largely prevents any splash water getting onto the camera when the housing is opened before it has completely dried off. The ample diameter port mount takes up the largest part of the front surface. It features a seal face for the O-ring and the tried-and-tested bayonet lock with stop. This solutions allows a quick change of the
port, which, as underwater photographers know, needs to match the camera lens used in each case. SEALUX have a wide range of ports with flat and dome-shaped lenses made of mineral glass. Among them are the fisheye mini-dome or the macro port with conical body to better illuminate small objects. Also worth mentioning are the various viewfinders: The LD viewfinder, a Galilei optical system, is the basic low-price version. Likewise, the more comfortable GD viewfinder offers a direct view with a larger viewfinder image. The GV150, which allows comfortable viewing of the reflex image at a 30º angle, is suitable not only for macro photography close to the bottom. What is special to all viewfinders is their small frame diameter which does not encroach upon the view of the monitor. The underwater photographer needs to choose one of these versions, given that the viewfinder is fitted by the manufacturer with no intention of easy interchangeability. Of course, it can be replaced with another model afterwards.

From the position alone of most of the controls on the housing you can guess their function. This is particularly true for the keys on the back which directly act on the equivalent camera keys. So, anyone who knows his camera well enough, will soon be able to use it without any problems under water, too. As most function transmission devices are adapted, all necessary adjustments can easily be made by pressing the equivalent keys on the housing. In principal, the housing can be extended by fitting two flash units (for example, for the Nikon system flash unit SB-910, SEALUX can supply a special housing). There are T-pieces fitted to the rail above both handgrips to mount the flash arms. On the upper surface of the housing you find two standard sockets for fibre-optic cables to ensure optoelectronic synchronization with the internal camera flash, whereas the standard model comes with an N5 flash socket. Optionally, the manufacturer can supply an additional socket, and a moisture alarm can be installed inside the camera housing as extra, too.

In action

Before inserting the camera inside the housing a number of function transmission devices need to be put in specific positions (see operating instructions!). Still outside the housing, the camera is mounted onto a slide provided with stops using the tripod bolt, and then the slide is pushed precision-guided into the housing where it is finally locked. This way the camera will always remain in a steady position, where it can remain in order to change memory cards or if you need to have access to interface connections such as USB or HDMI. Only for recharging or changing the battery would it be necessary to unbolt the camera from the slide. When opening or closing the housing it is recommended to operate the two locking levers from the top, since they swivel past the handgrips so closely that your fingers would not fit in between. The interchangeable lenses are always attached to the front of the camera inside the housing.

All function transmission devices are made to the usual SEALUX standards of quality. Reliably working long-lasting cogs and friction wheels, levers, forks and
buttons are employed as adapters. Ergonomic considerations played an important role during the design stages of the housing. This can be seen, for example, from the attachment of the pleasantly curved grip rail which features elongated holes for the mounting bolts to adapt it to the photographer’s finger length. His hands can hold the anatomically shaped grips while his fingers can comfortably reach nearly all controls that need to be accessed quickly.

Among these are the shutter release button on the right, the lever for storing the auto focus and exposure values and the control dials at the front and back. The left hand can comfortably access the focus switch, the AF mode-key and the control knob for zoom selection or for manually focussing the fitted lens. An extra long right-hand thumb would be an advantage only to operate the multifunction selector. However, to move these transmission devices further away from direct key access positions would have an impact on the price of the housing. The same applies to placing a greater distance between other tightly positioned keys on the back, where thick neoprene gloves can be a slight handicap. This modification would not represent a technical problem. In this regard, the realized solutions without radial arms represent a compromise in consideration of the funds available to hobby underwater photographers. Apart from that, the push-buttons on the outside are easy to operate, and the control levers offer a good grip, all shafts are double sealed, and the keys even four times. Two control windows at the top allow you to look at the adjustments of the function selector wheel and the display at any time. Those who wish to shoot videos have to adjust the individual function g4 on the D7100 in such a way that for this purpose the shutter release instead of the key for video recording can be used.

Under water the housing shows a slight downward pull which varies only a little, depending on the lenses and their corresponding ports used in each case. This welcome balance is maintained even when the equipment is enlarged by the flash system unit SB-910 inside its own housing made by SEALUX. Therefore, the diver has perfect control of his equipment under the most varied of diving conditions. The CN 7100 appeals just by its attractive surface coating and its unassuming design without any frills, in line with practical requirements. The aluminium shell has a flawless finish. The manufacturer has generously provided the housing with solid function transmission devices which will certainly work with high precision and absolutely trouble-free over a long period of time. Nothing rattles, wobbles or has more play than necessary. With such qualities one can recommend it as a top quality housing which will enable you to shoot excellent photos or videos. But of course, their quality is also determined by the capability of the diving photographer.

SEALUX CD7100 Review Technical Data

Material seawater-resistant aluminium alloy
Surface black-anodized, silver-metallic powder coating
Ports with flat and domed mineral glass lenses
Locking devices 2 quick-release locks with safety catch
Hand grips detachable grip rail
Viewfinder LD (standard), GD or GV150
Control/function windows 3
Function transmission devices 26 (standard) + 3 (optional)
Fittings for accessories 2 T-pieces on grip rail, 2 M6 threads
Sync chord socket 2 optical flash sockets; 1 flash socket N5 (standard) 2nd flash socket optional (also optional spring-loaded N5 sockets or S6 sockets)
Dimensions W x H x D 232 x 184 x 147 mm
Weight about 2.8 kg (without camera and port, with grip rail and LD viewfinder)
Buoyancy almost neutral, depending on port
Tested maximum depth 90 m