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DPG would like to thank Inon for supplying the Z-330 strobes used in this review. Test images were shot using a Nikon D500 in Isotta housing with the Tokina 10–17mm and Tamron 10–24mm zoom lenses.
 

After announcing the retirement of the immensely popular Z-240 in June 2017—after a decade in production—Inon finally unveiled its long-awaited new strobe: the Z-330. With so few strobe options on the market and several manufacturers facing production issues, the big question for underwater photographers has immediately presented itself: Does the promised extra power and wider light diffusion make the Z-330 a worthy successor? (Or is the new model not much more than a Z-240 replacement?)

Having used Sea&Sea and Inon strobes extensively in my work as a photographer and dive group leader, I was excited to have the opportunity to test the new strobe. The press release painted a picture of a significantly improved version of the trusted Z-240, with a much higher guide number as well as broader light diffusion via an acrylic dome rather than a diffuser plate. And like many photographers familiar with the predecessor’s fiddly buttons and dials, I was more than a little eager to see if the usability issues I have had with the controls have been addressed.

Testing was conducted during an Insider Divers group trip to the Maldives, a late monsoon change providing strong currents and somewhat less-than-ideal conditions in terms of visibility. The two Z-330 units provided were set up in a traditional configuration using ball-and-joint arms, alternating between sync cords and fiber-optic cables. The S-TTL automatic exposure mode was not tested, since, like many photographers, I would never use this feature. Due to the lack of suitable dive sites on this itinerary, only the strobes’ ability to shoot wide-angle subjects could be evaluated, as macro photography opportunities were not available.
 

The new Z-330 succeeds the stalwart Z-240

Inon has been a longtime player in the market for underwater photography accessories, and its strobes are known for their consistent build quality and attractive light distribution. The Z-240 is one of the most commonly used strobes, popular both amongst professionals and hobbyists. Its compact size and light weight, in relation to its wide and even output, are the hallmarks of its success. Some photographers, myself included, would have liked the Z-240 to be a bit more powerful, and this is exactly what the new strobe’s specifications suggest.

The Z-330 provides a punchy guide number (GN) of 33—a huge step up from the Z-240’s GN of 24. The angle of coverage without diffusers is given as 110°, which the Z-240 only achieved with its diffusers attached. The Z-330 maintains its predecessor’s fast recycle rate of 1.6 seconds after full dump.

The new strobe is based on the old design, but efforts have been made to improve it in several areas. Notably, there is now a built-in optically designed acrylic dome to provide light diffusion. Included in the package is an adjustable light shade, which is designed to reduce backscatter in close-focus setups, as well as a diffuser called “Strobe Dome Filter Soft” that reduces the 5500K color temperature to 5400K. Future optional accessories have been promised: 4600K and 4900K diffusers as well as a neutral density filter.

Key differences between the Z-330 and Z-240

The fully adjustable light shade is designed to reduce backscatter in close-focus setups
 

The focus light has also seen an increase in power, from 180 lumens to 220 lumens, and it is now equipped with a Fresnel lens to alter its direction to light the center of the strobe coverage area. Inon has also upped the beam width of the focus light, from 20° to 30°.

The weight of the strobe (out of water) has increased by a marginal 1.9oz (54g), less than 10% heavier than its predecessor, likely due to the dome. The shade and diffuser add practically no weight. The dimensions are unchanged, if the dome is not taken into account.

The option to use Sea&Sea-style sync cords as well as fiber-optic cables remains the same, as does the proven transparent compartment for the strobe’s four AA batteries, which allows users to check the O-ring seal easily.
 

The wider and stronger focus light now aims at the center of the beam (image courtesy of Inon)

At first glance, the Z-330 looks similar to the Z-240—albeit somewhat pimped up through the dome. Inon seems to have made an effort to improve the improvable, while retaining what has proven successful. The layout of the light elements is the same, with their patented T-shape twin flash bulbs in the center and the focus light on the left.

On closer inspection, the differences between the old and new models become clear. The flash bulbs now have mini-diffuser trays mounted above them, and the focus light is now clearly pointed inwards.
 

The mini-diffuser trays mounted above the flash bulbs
 

The acrylic dome, which is fixed permanently to the strobe, is protected by using the diffuser, but is otherwise exposed. Only time will tell how robust the domes are, and if scratches will affect the light quality. After mounting the light shades, I was a little surprised to note that the dome would make contact with a flat surface (albeit by just a couple of millimeters) if one placed the strobe “face down”—maybe something that Inon can fix in the future.
 

Because of the dome’s protrusion, even with the shade attached, the strobe cannot be safely placed on a flat surface
 

The diffuser is attached via a soft-locking bayonet mount. While the choice of a bayonet mount is great from the point of view of accessory options, there’s always the worry that the attachment will “unmount” itself. Unfortunately, this concern was proven on one occasion during my trip, though I was lucky to have an eagle-eyed guide to retrieve my runaway diffuser for me. A lanyard option would be good in my opinion.
 

The strobe with bayonet-mounted diffuser
 

The rear control panel has not changed in terms layout or labeling, but the new phosphorescent background is a handy feature for night dives. It doesn’t last more than about 10 minutes, but one quick shine with a torch brings the glow back.

To my delight, I found that the two main controller knobs are much larger and easier to operate than on the Z-240. The manual power dial also now stops at the maximum setting (–0.5) rather than continuing to rotate to the lowest (–6), as was the case—annoyingly—with the predecessor. Finally, the manual (“M”) setting is now the last position on the main control dial, with the position before it being “FULL”, allowing manual shooters like me to just twist the knob all the way without having to turn one step back to “M”, as on the Z-240.
 

The phosphorescent back panel (image courtesy of Inon)
 

Another nice improvement is that the constant high-pitch charging noise produced by the Z-240 is now gone in the completely silent Z-330. It also seems to me that despite having the same quoted recycle rate of 1.6 seconds, the flash bulbs in the new strobe are ready to fire again perceptibly faster than those in the old strobe.

The strobe is able to sync at 1/1000s, though this is only relevant for compact cameras. In my quick test, the Canon PowerShot G7X Mark II could still capture the strobe light at 1/1000s, whereas the Olympus OM-D E-M5 Mark II took its last usable photo at 1/400s, with the Nikon D500 at 1/320s.

As control placement and mounting haven’t really changed, the ergonomics of the strobe underwater are very similar to those of the Z-240. However, the increased size of the controls, combined with the fact that the power output dial stops at the maximum, immediately made using the strobe in manual mode much easier.

As all my dives were to shoot wide angle, I kept the strobes at around ¾ power (roughly the –2 mark) and switched to full when needed. I found that I could adjust the power quickly, as the dials were both simpler to operate and easier to locate by touch. Overall, changing the mode and power settings was smoother and more comfortable—a huge improvement over the Z-240. The smaller knobs for the focus light and pre-flash are still the same size as before, and for me, no less fiddly, but users with smaller hands than mine might not see this as an issue.
 

A manta cleaning station at Moofushi (25m) (Tokina 10–17mm at 10mm, f/9, 1/200s, ISO160)
 

Initially diving mostly with the diffusers and light shade mounted, I had an impression of pleasing, even light distribution similar to when I first started using the Z-240s. Shooting at 5000K produced excellent results with nice natural colors, and only minimal post-processing tweaks required.

My perception was that the light produced by the Z-330 was very bright in the middle with a gentle fall-off towards the outside of the beam, but a bit harsher than with the Z-240. To test that impression, I shot several images with a single strobe, and the slightly harder edges of the beam were obvious—though the lighting is still very nice and even.
 

A marble ray top-lit with a single strobe at Maaya Thila (35m) (Tokina 10–17mm at 10mm, f/9, 1/160s, ISO160)
 

The increased power of the Z-330s allowed me to shoot subjects somewhat further away than is feasible with the Z-240s—possibly also the positive flip side of the coverage being slightly more centrally focused. I found that the power was so strong that occasionally highlights got blown out, and if one wasn’t careful, there was a tendency to get backscatter at the edges of the frame.

Dome diffusers have been on the market for quite a while, providing strobes with wider beams. The downside is that the wider beam and more diffused light result in backscatter more readily than using strobes with narrower coverage. As with the Z-330s, though, it is quite easy to manage by pushing the strobes further out and at a wider angle from the lens. However, this resulted in sometimes undesirable coverage of a bigger area. While large fans would be extremely easy to light with the Z-240s, I found it more cumbersome with the Z-330s at times. Possibly part of the process of getting used to new strobes, I felt like I had to adjust the position of my strobes more frequently than before.
 

The sharks at Embudhoo Express (37m) are lit even at further distances (Tamron 10–24mm at 24mm, f/4.5, 1/100s, ISO320)

The increased strobe power becomes obvious right away with the first few shots. Even with the diffusers attached, I felt that the strobe light reached further than on the previous model. So how much more power is on offer?

The Z-330 promises a GN of 33, but the use of above-water guide numbers is a bit too scientific for me. Instead, I tested the Z-330 and Z-240 together underwater, and certainly had the impression that the new strobe was stronger. But with the changing conditions underwater, it was hard to quantify. So I set up a controlled environment above water to try to demonstrate the difference in power between the two models.

I set the camera to have a balanced subject lighting with the Z-240 (orange square) at full power and then tested the Z-330 against it. Only after powering the Z-330 down by two stops (bottom-right image, below) was the lighting roughly the same. My conclusion is that the Z-330 has around two stops more power than the Z-240, which—given the 6.5 stops available—equates to roughly a third more power (much like how the GNs of 33 and 24 compare).
 

Power comparison (Tamron 10–24mm at 24mm, at f/22, 1/250s, ISO100)
 

Another aspect of shooting at high power is that when it’s done repeatedly, some strobes briefly become unresponsive in order to cool down, leaving the photographer stranded with no strobe for a couple seconds. With the Z-330, I never experienced this issue: I often captured several series of images at full power and the strobe just kept on firing. This is presumably due to the heat sinking system built around the flash bulbs, which prevents them from overheating.

More power does not immediately translate into better photos underwater. The diffusion of light is important, how wide the light spreads, and the question is whether the new dome concept works to that effect.

Tested in a controlled environment against the Z-240, with the Z-330 powered down by one stop, the difference between the two strobes is moderate, but can be seen. Without diffusers (left-hand side, below), the T-shape twin flash bulbs in each strobe produces a cross-shaped light distribution, clearly demonstrating that both strobes require diffusers. However, in the case of the Z-330, the combination of the mini-diffusers over the flash bulbs and the acrylic dome already softens the light footprint. When the diffusers are mounted (right-hand side, below), the light distribution is comparable, though the light from the Z-330 has a hotter center while that from the Z-240 seems to have slightly softer edges.
 

Light diffusion comparison 50cm from wall (Z-330 powered down one stop) (Tokina 10–17mm at 10mm, f/18, 1/250s, ISO100)
 

Ellaidhoo house reef (25m): Even lighting is a hallmark of the Z-330 (Tokina 10–17 at 10mm, f/8, 1/250s, ISO250)

This trip did not offer much in the way of close-focus wide-angle opportunities, with strong currents and the constantly present floating particles that made it hard to avoid backscatter. I used the strobe light shades on many dives, and in a wide-angle setup, they offer no benefit. A controlled test confirmed that when the strobe arms are in a wide-angle position, the difference in diffusion was not noticeable.

With a close-focus wide-angle setup, the effects are more obvious in a controlled test against a white wall. With the strobes close to the housing, the way the shades reduce the light spread can be clearly seen. Underwater, the benefits of the light shades are also noticeable, but require a lot of adjusting for a satisfying result. When the shades are set correctly towards the camera, the light gets blocked from creating flares on the dome and lighting up particles right in front of the lens. However, there is a risk that when incorrectly set, a shadow can appear in the center of the frame.

My recommendation would be to detach the shades when the action is fast. The shades might be a useful tool for close-up coral shots or stationary subjects like frogfish.
 

With careful adjustment of the light shades, I managed to get a pleasing close-focus wide-angle shot
 

Oriented incorrectly, the shades can create a shadow in the center of the frame

Focus Light

A focus light on a strobe is generally not a particularly useful feature, as your strobes would have to be pointed directly at the subject, something we try to avoid in most cases. However, when considered as more of a backup focus light, the feature has certainly improved considerably on the Z-330. The light is perceptibly brighter and through the diffuser creates a soft overall light in the center. The auto off when the flash fires is also much improved, with the light switching on again much quicker now compared to the delay of several seconds on the Z-240.

Macro, Compact Cameras, and Mixed Strobes

While I didn’t have the opportunity to shoot macro with the strobes, I would like to venture a couple of thoughts. With the wide and diffused light of the Z-330, one can expect that lighting macro critters will be as good as it is with the Z-240. As high power is rarely significant for macro, the increased power is unlikely to bring any benefits. I am looking forward to testing the light shades in a macro shooting scenario, as I can imagine that they could be useful here.

For compact camera users with single-strobe setups, I believe this strobe is as good as any other. While the high power will likely not be used to its full potential, the diffusion is sufficient to light fish and even large fan corals evenly with one strobe. The light shade will be of limited value in this case.

Finally, having tested the Z-330 together with Z-240, I would not recommend mixing the new and old models. The Z-330 would need to be powered down by two stops and the slightly different diffusion could result in uneven lighting in some instances. If one Z-240 needs replacing, I would suggest getting a pair of Z-330s and using the remaining old strobe as a backup.
 

Simon in action framing a close-focus wide-angle shot

The Z-330 is a considerable improvement over the Z-240 in terms of ergonomics and power, while the issues concerning the predecessor’s controls have mostly been solved in the new strobe. The light diffusion is a little more centered than on the older model, but still excellent for creating wide-angle images. Diffusers remain a necessity for producing soft light, despite the new light dome, while the bayonet mount offers the promise of upcoming easily-mountable accessories.

Inon has a reputation for quality and reliability, and for photographers considering their first strobes or looking to switch brands, the Z-330 offers a compelling choice thanks to its powerful output, pleasing coverage, and speedy recycle time. For Z-240 users, it is worth considering the upgrade if there is a pressing need to have more power. However, for most wide-angle scenes, but particularly macro and close-focus subjects, the Z-240 remains a great strobe, and it’s harder to make the case for upgrading.

Overall, among the select number of high-quality underwater strobes on the market, the Z-330 is a great option for both enthusiasts and professionals looking for a powerful strobe for single and twin setups.
 

Rasdhoo Atoll (19m): A midnight snapper having a gill clean-up (Tamron 10–24mm at 24mm, f/10, 1/250s, - ISO400)
 

About the Reviewer: Underwater photographer Simon Lorenz is a regular author for dive magazines around the world. With his travel company Insider Divers, he runs guided group trips, combining unusual dive experiences with photo training. As a PADI instructor, his aim is to further the diving and photography skills of his guests. At his home in Hong Kong, he operates Pool Portrait, the first underwater photo studio in the city. As a member of the advisory board of the Hong Kong Shark Foundation, Simon supports efforts to reduce shark fin consumption in China.

 

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Inon Z-330 strobe	Nikon D500 camera		Isotta Housing for Nikon D500
Tokina 10–17mm zoom lens		Tamron 10–24mm zoom lens