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Dental Photography in Practice Part 21 - Choosing the Light Source

Posted on 24 January 2012

To read Mike Sharland's other articles on dental photography, access his expert column by clicking here

 

Following on from the last article, I have done a comparison between the flashes and will highlight some of the differences in this and the next article.

As stated in the last article....”The light source is a very important part of your system, and there are a number of options available. I will only cover flash light sources, as in my opinion this is your only practical choice for easy consistently lit images.”

Flash types fall into 3 broad categories:

  • Ringflash (wired or wireless) (manual or automatic)
  • Twin flash (wired or wireless)
  • Ring and Point flash

Ringflash

Wired……Sigma, Canon and Marumi

Wireless…Metz.

 

As you will see from the examples all the flashes performed well, the amount of specular reflection (reflection of the flash on ‘wet’ areas) though different, is very similar from each flash.

All would produce correctly exposed images at 1:3 magnification @ f22.

Slight difference between shadowing at the back of the mouth, pure ringflashes such as the Dine and Marumi produced little or no shadowing, whereas the others which are basically twin flashes produced a little shadowing with the Nikon twin flash producing the most noticeable shadows. Is this a problem …I don’t think so.

Weight wise the Dine and Marumi come in the lightest with the Metz a close second and the Nikon Twin flash the heaviest.

As far as size is concerned, the Dine flash wins hands down, with again the Marumi next and the Nikon Twin flash the biggest.

You will see from the examples that all these flashes produce standard views well, so why the price difference? I have stated in previous articles that the flash should be controllable manually, all of these flashes except the Marumi will work in manual mode…hence the price difference.

Why do you need manual flash? Most of the shots you take will work well on something called ETTL (Electronic Through The Lens), however this does mean that the flash is assessing every shot you take, and making flash output changes accordingly. Which means that often if you are using a ‘Contraster’ (black paddle for isolating quadrants) the flash will automatically try to get some detail in the ‘Contraster’ and consequently the teeth may be too light. This can also affect ‘before and after’ shots where there are marked differences in the subject, in particular, tooth whitening, amalgam..white fillings, rubber dam etc. etc.

In the next article I will try shots using a contraster with each flash, and test the adaptability of these flashes in terms of getting the view you want, to communicate to the patient what you can see, but perhaps the camera isn’t, this will largely be down to the light source and its positioning. Flashes such as the Dine, Nikon, Canon Sigma and Metz all have options for using left and right flashes independently by manually switching flashes off, the Dine flash has a single switch to do this and a separate flash which rotates around the lens, a main reason for it being my flash of choice and supplied on all my kits. If you cant wait to buy a flash then my recommendation would be the Dine Ring and Point flash, investing wisely in your photography will save time and is a great diagnostic/marketing tool.

if you can’t wait contact me for more details mike@thedigitaldentist.co.uk.

2 Comments
27/01/2012

Thx for your goos information... please tell me if you know about Opteka ring flash for Canon..It is a cheaper that Metz but I don't know if it is OK for dental macro fotography.
Best regards,
Dr Lupu Sebastian

27/01/2012

Thx for your good information... please tell me if you know about Opteka ring flash for Canon..It is a cheaper that Metz but I don't know if it is OK for dental macro photography.
Best regards,
Dr Lupu Sebastian

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