To Felix Sim - Re: Dental Macro Photography
Felix Sim wrote:
Hi Marco,
thanks for your detailed reply. I came across this thread when researching the canon m50 with the ef m 28mm lends like what you use.
I’m an maxillofacial surgeon and take photos of both intraoral and extra oral photos. I’m realising that this combo of camera and lens is not suited for an external ring flash.
Is the built in light on the lens sufficient for intra oral photos? I assume that the lens would have to be close to the object.
If using regular Macro, you can focus from infinity to VERY CLOSE. But with a slight additional twist of the lens, you can access "Super Macro" which requires the lens to be around an inch from the subject. In Super Macro mode the camera lens can be close enough to bump the subject but the additional magnification is there if needed. Most of the time, regular macro is just fine and offers a little more flexibility.
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The lens body is a polymer construction which means it's unlikely to damage or chip teeth if it comes in contact with them. I sometimes use a small flashlight like the one below if examining my teeth. It has different levels of brightness and a removable USB-rechargeable battery,
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Manker E04 Mini 550 lumen LED flashlight
EF-M 28mm f/3.5 IS Macro STM lens - Extracted Tooth .
For extra oral photos such as photos of a fibula harvest, I worry that without a ring flash, natural light alone won’t be bright enough with f18-22 aperture setting.
I’d greatly appreciate your thoughts.
Thanks,
Felix
My dentist said he received an EOS M50 from his wife and was interested in the EF-M 28mm f/3.5 Macro IS STM lens I was using on my M6 when I happened to stop by for a checkup. I had the camera clipped to my belt and he saw it when I removed it. I was experiencing something unusual that nobody was able to explain at the time (nor since). I'd cut the inside of my gumline in my mouth (inside with jaw below a molar) with the sharp edge of a freshly sliced apple.... There was a small flap of skin that felt like it was triggering a nerve every time I touched it so I gently removed it with a surgical scalpel and assumed it would heal. But the wound refused to heal for a week when suddenly the area began to shed shards of bone. They just kept sticking out and when removed, they would reappear. This went on for at least a couple of months before it stopped. My dentist seemed convinced it couldn't be bone and must be a foreign object that had entered the wound... yet he pulled some fragments out himself and was amazed. He gave me a referral to see a maxillofacial specialist... however, the strange wound eventually just closed up and I've not had any issues since, But I did take the opportunity to take a few pictures with the EF-M 28mm Macro lens.
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EOS M6 + EF-M 28mm Macro lens - a fragment of bone sticking out of the gumline. I think I may have used a tiny external LED flashlight for this image.
EOS M6 + EF-M 28mm Macro lens - One of the bone fragments (about 3mm long)
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It was easy enough to fit some of the lens into my mouth although fogging the lens was something I needed to be wary of. The end of the lens is tapered as an intentional part of the design so it's not too wide at the end. You'd probably need to handle one with the lens unlocked and extended to see if this is small enough. I'm sure there's other devices available on the market but I haven't looked. My own dentist has a tiny camera with a light on it that's on a flexible cable but the images tend to be low resolution. I recently tried to photograph a tooth in my mouth with the rather excellent iPhone 13 Pro macro lens but that didn't work out at all since I couldn't get the darned thing into my mouth - plus I couldn't see what I was doing or focusing on.
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EOS M6 + EF-M 28mm f/3.5 IS Macro STM lens (with lens extended for use)
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I found the Canon lens LED lights were fine for interior illumination since the light can reflect off the interior surface of the mouth. An extra light can be introduced into the mouth if needed (see above). Personally I found it a little tricky to do myself since I was holding a camera in my mouth with both a dental mirror and sometimes an additional source of illumination for some other images (not shown here). I then needed to position a mirror so I could see the LCD on the rear of the camera... and of course everything reflected is in reverse. You could see any defects on the tooth surfaces, including surface putting and microfractures... and I used the camera/lens combo to identify a cracked filling plus a damaged tooth from a foreign object that was in my food that was cause for a repair later. The ring-light built into the EF-M 28mm lens is (as you know) not a 'flash' but an LED illuminator - which does help with focus but is designed to be able to illuminate the surfaces of a subject when up close. But it does not have the power of a traditional flash, such as the Ring-Flash below...
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EOS M + EF 100mm f/2.8L IS Macro USM lens + Ring-Flash
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The larger EF 100mm f/2.8L IS USM lens requires a much longer shooting distance between the lens and subject. It's a much larger system and it requires the use of the ring-flash for proper illumination. I believe that this is a much harder system to be used handheld although some dentists do use this combo. The EF 100mm Macro lens accepts a 67mm filter thread yet the EF-M 28mm Macro lens takes a 43mm filter thread, demonstrating the difference in optics width.
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Frankly, I think that Canon never considered the EF-M 28mm Macro lens as a dentistry accessory but it may have a use as one. You can rest the camera lens against the other teeth for added stability if needed and there's no risk of damage due to the high-impact polymer used. Not sure about hygiene though you could apply a latex dental-dam to the barrel before use for additional cushioning and to avoid contamination.
