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Canon Macro Ring Light and Twin Light

by Philip Greenspun, February 2008


Canon makes two similar macro flash systems, the MR-14EX Ring Lite and MT-24EX Twin Flash. Both are intended to surround the front of a standard Canon macro lens, e.g., the Canon EF 100mm f/2.8 Macro USM, (compare prices) (review), which is the lens used for all of the example images here.

The MR-14EX Ring Lite has two tubes forming a ring around the front of the macro lens. This will be a reasonably diffuse light source if the object to be photographed is small, e.g., less than four inches in width. Ring lights are among the most uniform light sources, producing shadowless images with little variation from photographer to photographer. As such, they are the standard for much medical photography.

The MT-24EX Twin Lite is basically the same hardware, but the two strobes are packaged into mini shoe-mount boxes. These can be packed on either side of the lens, in which case the light is similar to that from a ring light. They can be angled. One or both strobes can be held off-camera. The MT-24EX offers much more creative control of light at some risk of operator error.

Compatibility

Both of these units are designed to work with any Canon EOS macro lens, including the big Canon EF 180mm f3.5L Macro USM, (compare prices) (review), which requires the Macro Lite Adapter 72C. These units also work with the Canon MP-E 65mm f/2.8 1-5X Macro, (compare prices) (review).

Typical Ring Flash Photos

Here are a couple of typical ring flash photos, both taken with the Canon EF 100mm f/2.8 Macro USM, (compare prices) (review). These are the kinds of pictures you might expect a doctor's assistant to create. Notice the reflection of the ring flash itself in the subject's eye.

Selling Stuff on eBay

Suppose that you discover that your $5000 Rolex is less accurate than a $10 Timex. You decide to sell it before it needs another $500 cleaning. Let's try a couple of images first with the MR-14ex ring flash. Note that the first image required exposure compensation of +2/3 f-stop and the second, due to the glare from the crystal, required reverting to manual flash at 1/32nd power. Both are with the 100mm lens at f/11. Adjusting relative power between the ring light tubes did not reduce the glare, only shifted it around.

Here is the same subject with the MT-24ex twin light. Automatic exposure, compensated +2/3, worked fine for this and glare from the crystal was not a problem. For the first image, the two strobes remained mounted to the ring. For the second image, also including the entire watch, one strobe was handheld above the subject pointing straight down. This brightened the background a bit.

Selling Stuff on photo.net

Suppose that you had been saving a treasured Canonet QL17 compact 35mm film camera as a 16th birthday gift for your beloved first-born child. Upon reaching that age of wisdom, he scorns the gift saying "What's wrong with you, gramps? Where do you think I could ever buy film for that thing? Do you really want to destroy the environment with chemicals anyway? All the cool kids use cell phone cameras." Time to sell the camera in the photo.net classifieds. Below are a couple of images with the MR-14EX Ring Lite. Note the uneven illumination.

Switching to the MT-24EX Twin Lite and keeping both strobes on the lens ring, we get very similar images:

Holding one strobe of the MT-24EX Twin Lite off camera results in substantially more even light:

Adjusting the Output Ratio

Both macro strobes provide for an adjustable output ratio between the two tubes. The effect of a 4:1 ratio is much more dramatic with the Twin Lite than with the Ring Lite. Here is a series of Twin Light images, at 1:1, 1:4, and 0:1 (only the right tube firing). All were taken with the 100/2.8 USM lens at f/16 and a magnification of 1:1.

With the 65mm 1-5X Lens

Here are some images with the Canon MP-E 65mm f/2.8 1-5X Macro, (compare prices) (review), a truly bizarre lens.

with the ring light...

with the twin light...

The Power Pack

The basis of both of these macro strobes is a big power pack that mounts into any Canon EOS body's hot shoe. The power pack design appears to have been lifted from the standard EOS system speedlites. The switches and display are more or less the same. The features are the same, including ones that wouldn't seem to be useful in a macro strobe, such as second curtain sync, high-speed sync, and exposure bracketing. The battery compartment holds four AA cells and there is a jack for an external power pack.

The main physical difference between the power pack for these stobes and a standard EOS strobe is that there is no actual strobe lamp. One or two cables come out from the power pack to attach to the strobe tubes at the front of the lens.

Power Output

These are powerful flashes. Unfortunately, in macro work that is not necessary a good thing. Despite that nobody taking macro photos is going to think in terms of guide number, Canon specifies the flash power as if these were conventional on-camera strobes. The Twin Light has a guide number of 85 in feet at ISO 100. This means that, at a distance of 20', a properly exposed photo could be taken at ISO 100 and f/4 (divide guide number by distance to get aperture).

Unless the aperture is set to a fuzzy-from-diffraction f/32, which becomes f/64 when a macro lens is racked out to 1:1, such an abundance of power is typically unnecessary for macro work. A more interesting question is how little power the flash can be set to put out. At optimum sharpness apertures around f/8 and a subject that is only a few inches from the lens, a huge blast of light is not required, especially at ISO settings or film higher than 100. The owner's manual (disappointingly not available online) includes a table of workable magnifications and apertures. At ISO 400 with a 100mm lens, for example, the MR-14EX ring light is overpowered at f/2.8 through f/8. At ISO 100, the flash should work for all magnifications between 0.33 and 1 and all apertures between f/2.8 and f/32. In manual mode, the minimum flash output is 1/64th of full power, i.e., six f-stops less than full power.

Wireless

Both macro strobes can control an off-camera EX-series EOS speedlight wirelessly. The command sequence to do this is complex enough that you will need to bring the owner's manual with you, but it should work well once configured. The off-camera strobe will be useful for background illumination.

Alternatives

Digital photo titled jelly-flash-plus-reflector

The cheapest and simplest alternative to this system is a standard flash, an off-camera cord, and a white reflecting card. The image at right was taken with a Canon MP-E 65mm f/2.8 1-5X Macro, (compare prices) (review) and just such a setup.

For taking pictures of small objects, a superior light source is often a softbox (see our studio photography primer) or a full light tent (see www.ezcube.com). These are the standard ways to get uniform shadowless illumination. Below are a couple of images taken with a small softbox on a portable strobe, held off-camera with Canon Off Camera Shoe Cord, (compare prices) (review).


Conclusion

The MR-14EX Ring Lite is the best choice if you need a consistent series of shadowless photos of small objects, especially if the photographers are going to be inexperienced. The MT-24EX is a better choice for creative projects.

Where to Buy

You can get these strobes overnight from amazon.com:

More

Examples

Amethyst very close to 1:1. The image at left is with the ring flash; the image at right with the twin flash.

Image at left: MR-14EX Ring Light. Notice how the light reaches into the interior of the flower.

Image at right: MT-24EX Twin Light. The subject, the flower interior, comes out darker than the surrounding pedals. This is one where the ring light works decisively better.


Text and pictures copyright 2008 Philip Greenspun. Unless otherwise noted, all images on this page were taken with a full-frame Canon EOS 1Ds Mark III, (compare prices) (review) and Canon EF 100mm f/2.8 Macro USM, (compare prices) (review).

Article created February 2008

Readers' Comments


Add a comment



Joseph Wisniewski , March 04, 2008; 11:04 A.M.

"The features are the same, including ones that wouldn't seem to be useful in a macro strobe, such as second curtain sync, high-speed sync, and exposure bracketing."

That, and your comments about "alternatives" and "superior light sources" suggests you may be thinking about macro from within the framework of your particular choice of subjects, which appear to be technical and product. There's nothing wrong with this, most of my own macro work is highly technical.

That's one reason I don't own a ring light or multiple head light. The biggest consumers of ring lights, twin lights, macro brackets, and even monsters like the Nikon R1C1 (up to 8 heads on the ring) are the "bug hunters". Not being a frequent bug chaser, I make do with a "butterfly bracket" holding two general purpose flashes (and a ringlight bracket that holds 4 regular flashes).

But I disagree totally with your comments about "useful" features.

I've used rear curtain sync quite successfull on butterflies, dragonflies, and even once on a mouse in a maze. Tiny creatures have every bit as much right to motion streaks behind them as dancers, acrobats, running children, and all the other "classic" rear curtain sync subjects.

The high speed sync addresses one of your very first complaints: "too much power". It lets you knock that down a few stops.

Bracketing addresses another of your complaints: the need for exposure compensation. Exposure errors in macro are not the fault of your equipment: the subjects simply exceed the capabilities of any known metering system. My own decades of macro experience have taught me that bracketing is a Godsend.

Lester Wareham , March 04, 2008; 01:36 P.M.

One important distinction between the two models you have missed is the operation of the incandescent focusing lights.

There is a flash control panel button for these, they activate for 20 seconds or until the flash is fired.

The difference is the twin flash includes C.Fn-9 which permits the focusing lamp to be turned off and on with a double tap on the shutter button.

The focusing lamps are invaluable in poor light or with the MP-E 65mm lens at high magnification.

As the MP-E 65mm is the lens of choice for photographing small insects in the field, this feature is of enormous value and under these conditions and so an important differentiator between the two flashes.

For completeness there is another twin flash only F.Fn-8 which switches between 1/2 and full stop ratio control increments.

Alan Myers , March 04, 2008; 03:39 P.M.

I've been using the MT-24EX Twin Lite since it was first introduced a few years ago. It works well and gives me more modeled lighting than a ring light would, which is what I prefer personally.

I can add a few minor things to your very useful review...

Anyone who wishes to fit the Twin Lite to the EF 180/3.5L will also need the Macrolite Adapter 72C (currently $40), if they plan to use Canon's on-lens flash head mounting system.

Personally, shortly after I got it, I stopped using Canon's on-lens mount entirely. Instead I use a Lepp/Stroboframe Deluxe II dual flash bracket. It's bulkier, but far more flexible in terms of positioning the flash heads.

However please note I use the Twin Lite with 100/2.8 and 180/3.5 macro lenses. If I were using the MP-E 65mm lens with it's much higher magnification and shorter working distances, I'd very likely use the on-lens mounting system with this flash, or for that matter might opt for the MR-14EX Ring Lite instead.

If you wish to use lens hood with the Twin Lite, you may have to get a more compact, generic, screw-in one. Neither the matched hood for the EF 100 nor the one for the EF 180 can be used when Twin Lite is mounted to the front of the lens.

Finally, for all practical purposes I haven't found the Twin Lite to be over powered. This because I'm most often using quite small apertures anyway, trying to find some depth of field at macro magnifications.

However, anyone who runs into problems where the Twin Lite is overpowered might try the Lepp/Stroboframe bracket which will allow them to move the flash heads a lot farther away from the subject. Alternatively, get some white gauze bandage/cloth at a local pharmacy. Cut a few smaller pieces from it and use rubber bands to hold a layer or two (or more) of the gauze over the flash head, reducing the output as needed.

There appears to be a slot to clip accessories such as filters or diffusers over the tubes of the Twin Lite flash heads, but to the best of my knowledge Canon has never offered any sort of accessories to fit this.

Cheers!

Anthony Akins , April 04, 2008; 09:12 A.M.

I own the MT-24EX and I purchased Sto-Fen's to soften the light. I was surprised to find out that Sto-Fen makes them for the MT-24EX. I purchased them at Samy's Camera, two in a pack, and about $20.00.

Anthony

Thanakorn Balankura , December 05, 2010; 04:08 P.M.

Thank you very much for these great articles. I'm holding a notebook on my side summarizing the points made along the way. A lot of technical terms not familiar with my amateur level but you made them so easy to understand. As I understand more my excitements to try keeps me from sleeping ... can't wait till it's time to grab my camera .... Many thanks again.

Non, BKK Thailand

 


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