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Review of the Canon EOS R100 in Ikelite Housing
By Matthew Sullivan, May 18, 2024 @ 06:00 AM (EST)

DPG would like to thank Ikelite for supplying the Canon EOS R100, Canon RF-S 18–45mm f/4.5–6.3, Canon RF 15–30mm f/4.5–6.3, and Ikelite 200DLM/D housing for the Canon EOS R100 with dome port, and various accessories used in this review.



Pros: Very compact rig overall, good image quality, competent autofocus

Cons: No back-button focus


  1. Ergonomics, Handling, and the Ikelite Housing
  2. Lens Selection
  3. Image Quality Beyond Expectations
  4. Simple, Reliable Autofocus
  5. Final Thoughts


With the EOS R7—the spiritual successor to the vaunted EOS 7D series of DSLRs—Canon has shown that it is serious about mirrorless cameras with crop sensors. When I reviewed EOS R7, I discovered a camera that very much lived up to its position at the top of Canon’s APS-C lineup. A year after announcing the EOS R7, Canon addressed the opposite end of the range, unveiling a camera that might be thought of as the mirrorless version of the incredibly popular Rebel series—the EOS R100. Boasting a 24-megapixel sensor, a DIGIC 8 processor, and Dual Pixel autofocus, the EOS R100 provided an easy path into interchangeable lens cameras, and for the price—a mere $380 at the time of writing—offered pretty remarkable value.

Of course, the R100 has its limitations, but for those upgrading from a compact camera or a GoPro, does the R100 fit the bill? I’ll cut to the chase: After putting the R100 through its paces, I feel this camera is a great companion for an underwater photographer traveling to destinations with warm, clear, tropical water. The small size is appealing, the image quality is excellent, and as part of an affordable rig like my Ikelite test system, it offers budget-conscious shooters a serious tool for taking their photography to the next level. If you want a competent camera that will blow your compact out of the water, the R100 may be the upgrade you’re looking for. Read on to learn about the R100 and why it has a place in Canon’s lineup—and why it may well have a place in your gear bag, too!

Juvenile honeycomb cowfish (Canon EOS R100, Canon RF 100mm f/2.8 Macro lens, Ikelite housing, dual Retra Flash Pro Max strobes, f/3.5, 1/200, ISO 100)


1. Ergonomics, Handling, and the Ikelite Housing

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The Ikelite R100 housing is extremely compact and lightweight and makes the most of the features that the R100 provides

The R100 is impressively small for a mirrorless camera, and this translates to a very compact and lightweight housing from Ikelite that is a pleasure to carry on long walks to the water and easy to shoot one-handed underwater. Depending on what strobes you are using, the rig itself requires almost no flotation.

The R100 features two dials rather than the three you typically get on an interchangeable-lens camera. There’s the usual mode dial for choosing between program, shutter priority, aperture priority, and manual photo modes, video mode, and so on; and there’s just one main dial for adjusting settings. In the manual exposure mode you use in underwater photography, the main dial adjusts shutter speed by default. If you want to adjust the aperture, you have to push the +/– button once and then you can set aperture with the main dial. If you push the +/– button again, you can use the main dial to adjust exposure compensation.

My preference is to use back-button focus—removing AF from the shutter and assigning it to a custom button—but there’s no dedicated control for this on the housing, so I had to adapt my shooting style accordingly. Of course, if you don’t already shoot that way, you won’t miss it. On the other hand, if you can’t do without this functionality, you’ll want to look at moving up to the EOS R10 in Ikelite’s housing.

The test rig: Canon EOS R100 in Ikelite housing (including 6-inch dome port & zoom gear) with tray with dual quick-release handles, and dual Ikelite DS51 II strobes. Note the fiber-optic connection—see explanation below

Ikelite made its name (“Ike’s lights”) producing a range of high-quality strobes. As well as being among the best on the market, they are distinguished by their rivals by being triggered electrically out of the box, or fiber optically using converters. Ikelite housings ship with their preinstalled electrical bulkhead and manual hotshoe, so if you have Ikelite strobes or any strobe that can be electrically triggered, all you need to start shooting (in manual flash mode) is a single sync cord.

Now, if your preference is for fiber-optic triggering, or you have strobes that can only be fiber-optically triggered, you can add Ikelite’s new TT5 Canon TTL Fiber Optic Transmitter, which supports both manual and TTL strobe exposure. This combined LED flash trigger and bulkhead opens up lots of lighting options for Ikelite users, including strobes like the Backscatter Mini Flash 2 and the Retra Flash Pro Max. In order to test this new product alongside the R100, Ikelite supplied the housing fitted with the TTL Fiber Optic Transmitter (but note it does not come with the housing), and I was able to shoot the Retra Flash Pro Max strobes with the R100 rig, which I would not have been able to do otherwise. The TTL Fiber Optic Transmitter performed flawlessly, even when shooting bursts. The R100 maxes out at 3.5fps with AF, which is adequate for most action underwater.

A young scorpionfish hidden in sponges. The fiber-optic transmitter allowed me to use the Retra Flash Pro Max strobes with the R100 seamlessly (Canon EOS R100, Canon RF 100mm f/2.8 macro lens, Ikelite housing, dual Retra Flash Pro Max strobes, f/3.2, 1/200s, ISO 100)

Ikelite also supplied a pair of DS51 II strobes—their entry-level models—which, of course, are designed to be hooked up to a housing via electrical sync cords. However, just as Ikelite have equipped their housings with the ability to trigger strobes fiber-optically with their new TTL Fiber Optic Transmitter, the company also allows Ikelite strobes to be triggered via fiber-optics. To convert the electrical bulkhead of any Ikelite DS strobe into a fiber-optic port, you can just add the RC2 TTL Receiver, which allows you to use the TTL Fiber Optic Transmitter and enjoy the same rock-solid automatic strobe exposure you get with Ikelite’s TTL converters using electrical triggering.

Thus, in our R100 test rig pictured above, you can see DS51 II strobes connected to the housing via fiber-optic cables by way of the TT5 Canon TTL Fiber Optic Transmitter and an RC2 TTL Receiver for each strobe. This setup worked very well, allowing me to switch back and forth between the Ikelite strobes and the Retra strobes. The TTL Fiber Optic Transmitter is powered by two CR2032 batteries. While these batteries last a very long time even with the trigger left on, it is best to turn it off at the end of each dive day to maximize the batteries’ lifespan. The small on/off switch is on the part of the transmitter that mounts to the inside of the housing.

Again, keep in mind that a typical Ikelite setup—Ikelite housing plus Ikelite strobes—will natively be connected electrically, allowing manual strobe exposure “out of the box.” If you want the option of automatic strobe exposure, you just need to add the appropriate Ikelite TTL converter for your camera—there are TTL converters for all the major camera brands.

A striated frogfish lurking in the muck: The rectangular flash tubes and relatively harsh light of the DS51 make it a good macro strobe for those who want a beam that is easier to control (Canon EOS R100, Canon RF 100mm f/2.8 Macro lens, Ikelite housing, dual Ikelite DS51 II strobes, f/13, 1/160s, ISO 100)


2. Lens Selection

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Ikelite offers an R100 housing set up for the 18–45mm f/4.5–6.3 with a dome port, which will allow you to capture a good variety of subjects

In the good old DSLR days, it was easy to recommend the Tokina 10–17mm Fisheye for wide angle and the Canon EF-S 60mm Macro for close-ups. If you own these lenses, then go ahead and buy Canon’s EF-EOS R mount adapter and get on with it. If you don’t, things get a little tricky, since both of these lenses are now unfortunately discontinued.

For wide-angle subjects, one option is the optically excellent Canon EF 8–15mm Fisheye with EF-EOS R mount adapter. This fisheye lens can be used with the same dome port that comes with the housing kit; you just need a different zoom gear.

Ikelite offers an R100 housing set up for the 18–45mm f/4.5–6.3 with a dome port, which was what was supplied for review. This standard kit lens is comparable to other kit lenses in its class, and the 29–72mm full-frame equivalent focal range combined with the minimum focusing distance of 7.9 inches allows you to capture a good variety of subjects—even if you’ll struggle with big animals and macro critters.

Another wide-angle option, which Ikelite also provided for the review, is the Canon RF 15–30mm f/4.5–6.3. At almost double the price of the 18–45mm, it was significantly better optically. Performing surprisingly well behind Ikelite’s relatively small dome port, the 15–30mm was sharper in the corners, focused a little closer, and suffered less pin cushion smearing or distortion. With a 24–48mm full-frame equivalent focal length range, it is a great midrange lens, though again, on its own, it is not conducive for true wide angle or true macro subjects.

The optically good RF 15–30mm is best for midrange and medium-sized subjects that aren’t too big or too small, like the prow of this sunken boat (Canon EOS R100, Canon RF 15–30mm f/4.5–6.3 lens, Ikelite housing, dual Retra Flash Pro Max strobes, f/13, 1/200s, ISO 100)

Second-hand market aside, for Canon’s mirrorless mount, your macro options are the RF 24mm Macro, RF 85mm Macro and RF 100mm Macro. The last one, the macro lens used for this test, would be my recommendation. On the R100, it is still fast and snappy and produces beautifully sharp and detailed images. Admittedly, it is more than twice the price of the camera itself, but it is such a good lens, it is worth spending the money on.

The discontinued EF-S 60mm Macro is a fantastic option. I did not use it on the R100 but I have used it in the past and it works well with the EF-EOS R adapter. It is speedy, sharp, and excellent value. While I haven’t personally tried the RF 85mm Macro, Ikelite has an excellent review that demonstrates the quality results possible with this lens.

Cushion stars are quite large. This one was about a foot across and this shot shows the minimum focus distance with the 18–45mm lens at the narrow end. There is a fair amount of pin cushion distortion and smearing around the edges of the frame (Canon EOS R100, Canon RF 18–45mm f/4.5–6.3 lens, Ikelite housing, dual Ikelite DS51 II strobes, f/10, 1/160s, ISO 100)

Another large cushion star (this one feasting on a fish carcass), photographed with the 15–30mm. The edges of the frame are somewhat better than with the 18–45mm (Canon EOS R100, Canon RF 15–30mm f/4.5–6.3 lens, Ikelite housing, dual Ikelite DS51 II strobes, f/10, 1/160s, ISO 100).


3. Image Quality Beyond Expectations

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As with most modern crop-sensor cameras, the R100 is capable of producing beautiful pictures, and your lenses have a far more significant impact on image quality than the sensor

The most important feature of a camera to me is image quality. The R100 impressed me in this regard, and it is in this area that I really do feel it performs much better than its modest price tag would suggest. The 24-megapixel sensor matches or exceeds most other Micro Four Thirds and APS-C sensors in terms of resolution, and it is more than enough for the vast majority of shooters—myself included.

With good-quality glass, the R100 produces very appealing, surprisingly malleable files. Shadows and highlights are controlled well and detail can be pulled from each in post. At well over three times the price, the R7 is appreciably better, but the gap between the two cameras is much narrower than in other areas.

Having said that, even as the technology advances, there is only so much low-light performance that can be squeezed out of the R100. Noise creeps in quite quickly, and while there are many processing tools to remove noise these days, it is still important to bear in mind that this camera is best shot at the lowest possible ISO settings.

A beautiful lined seahorse. With a high-quality lens like the RF 100mm Macro, the R100 is capable of producing wonderfully detailed images (Canon EOS R100, Canon RF 100mm f/2.8 Macro lens, Ikelite housing, dual Retra Flash Pro Max strobes, f/10, 1/200s, ISO 100)


4. Simple, Reliable Autofocus

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The R100’s autofocus system is comparable to autofocus implementations in cameras well beyond its price bracket

Canon has enjoyed a reputation for producing cameras with good, solid autofocus—even if not necessarily the best on the market. Canon’s reliable Dual Pixel autofocus system has made its way into the R100, and although its an older generation version of that system, for the most part it does the job.

The R100 features subject and eye tracking, and while eye detection AF wasn’t too reliable, I did find the subject tracking modes to be surprisingly adequate. The R100’s system doesn’t quite match that of higher-end cameras, but it is comparable to autofocus implementations in cameras well beyond the R100’s price bracket.

Despite the subject tracking modes being decent, I preferred to rely on the tried-and-true center-spot AF and recompose as needed, since I found this to be the most accurate and snappy. If a subject was in the center of the frame in the autofocus box, the R100 locked on beautifully and did so regardless of light levels.

A longarm octopus sitting at the entrance to its burrow. I trusted the center-spot autofocus most on the R100 and used it to good effect here (Canon EOS R100, Canon RF 100mm f/2.8 Macro lens, Ikelite housing, dual Retra Flash Pro Max strobes, f/10, 1/200s, ISO 100)


5. Final Thoughts

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With nice glass conducive to underwater shooting, the Canon EOS R100 in Ikelite’s housing is a great value system capable of producing beautiful images in a wide variety of situations

With nice glass conducive to underwater shooting, the Canon EOS R100 in Ikelite’s housing is a great value system capable of producing beautiful images in a wide variety of situations. If you want the ultimate in compact size and value, the R100 is hard to beat, and if its limitations are understood, it can serve an underwater photographer well.

Canon has crammed a lot of features and functionality into the R100’s tiny body for an insanely low price, while the Ikelite ecosystem—housing, strobes, sync cords, TTL converters, trays and handles—allows you to get shooting underwater with the minimum of fuss and damage to your wallet.

Of course, some compromises have been made, but this rig certainly has the potential to give you excellent pictures—that’s especially true if the money saved on the camera and housing is put to good use buying great lenses! To those coming from compacts or earlier generation Micro Four Thirds cameras, the R100 deserves some very serious consideration.

Close-focus wide-angle images are possible with the R100 in combination with the RF 15–30mm, as it focuses quite closely. There is no barrel distortion such as you’d find on a fisheye lens to overly emphasize the subject (Canon EOS R100, Canon RF 100mm f/2.8 Macro lens, Ikelite housing, dual Retra Flash Pro Max strobes, f/13, 1/200s, ISO 100)


About the Reviewer: Matthew Sullivan is a Florida-based wildlife photographer who has been diving since he was 10 years old. He has traveled extensively, visiting well-known dive destinations such as Guadalupe Island, Indonesia and the Philippines, but he also likes to dive closer to home in the Pacific Northwest. When not taking pictures underwater, he can be found trekking mountains, or exploring national parks and rainforests in search of new adventures and wildlife encounters.


When purchasing underwater photography equipment like the products mentioned in this article, please support DPG by supporting our retail partner—Backscatter.com
Canon EOS R100 Camera
Ikelite housing for Canon EOS R100 with Dome Port
Ikelite DL5 DS Link Canon
TTL Converter and Hot Shoe
Canon RF-S 18–45mm Lens
Canon RF 15–30mm Lens
Canon RF 100mm Macro Lens
Ikelite TTL Fiber Optic Transmitter
Ikelite DS51 II Strobe
Ikelite RC2 TTL Receiver



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