Eddy's Scuba Blog

On the second day at Beneath the Sea, I took another underwater photo half-day seminar. This one was on "Mastering Strobe Techniques" with Cathy Church. I have gone to another underwater photography seminar by Cathy before. It was at the Boston Scuba Show in Boston in 2005. I find her to be one of the best instructors in underwater photography because of her teaching style and presentation. She encourages audience participation and she is very knowledgeable and enthusiastic. She is so good in my opinion that one day I will go to the Cayman Islands for a one-on-one course. Her website is www.cathychurch.com.

The seminar was very well structured and with lots of practical examples. People were encouraged to bring their strobes and we would measure their power with a light meter. I found her content to have a good mix of "classical" underwater photography and digital underwater photography. I find that most of the underwater photography experts have been doing film underwater photography for a long time and have switched to digital recently.

Here are some notes from the seminar:

Understanding Exposure Systems

• Digital ideal -2/3 EV because of red/blue sensors
• Most metering systems want to yield grey
• Never use "program" mode or "underwater" mode
• Point and shoot cameras adjust for ambient light, try -2 EV
• F/stops control amount of light in exposure
• Shutter speed controls duration of exposure
• Background sun contributes to the "blue" in pictures, you want to minimize that, you want your light to come from the strobe
• Shutter speed synch is important, SLRs are slower in this regard, digitals are faster
• TTL will only help with over-exposure, not under-exposure
• A strobe diffuser usually costs one f/stop

• Controlling strobe light vs. sun light:

  
  

  1. Balanced flash fill

     • Set for ambient sun light
     • Adjust strobe/shutter speed to provide equal ambient and strobe
  
  
  

  2. To increase strobe against sun light

     • Use faster shutter speed, wider aperture
     • Move strobe closer
     • Use more strobes
     • Use highest strobe power, remove diffuser
     • Shoot at lower camera angle
  
  
  

  3. In dim sun light

     • Use slower shutter speed, smaller aperture
     • Move strobe away
     • Use lower strobe power, add diffuser
     • Shoot at higher camera angle
  
  
  

  4. To change strobe intensity only

     • Change strobe power setting
     • Change distance to subject
     • Change number of strobes
     • Change diffuser
  
  
  

  5. To change background (sun light) exposure

     • Change shutter speed
     • Change camera angle toward or away from sun
     • Change time of day, depth, season or weather. Noon is the worst time to shoot pictures.
     • Use diffuser in dark day, don't use diffuser in bright day (kinda opposite)
  
  

Lighting Techniques

• Avoid backscatter

  • Get away from short arms
  • Aim at real image, because of water difraction images appear closer
  • Avoid front light, never use embedded flash in point and shoots
• Side light for texture
• Rim light for separation and emphasis
• Backlighting for translucent subjects and hairs
• Use multipe strobes for better coverage
• Use multiple strobes for nicer shadows
• When using two strobes try this for drama and emphasis, one on the left, and the other above and a bit behind the subject

In March I attended Beneath the Sea in NJ, the biggest scuba conference in the North East. In addition to exhibits by equipment vendors, travel agents, dive destinations and dive operators, there were scuba related seminars. I attended the seminar "Underwater Digital Techniques" by Jack and Sue Drafahl.

I have attended one of their seminar before at the Boston Sea Rovers and have purchased their book "Digital Imaging for the Underwater Photographer." I consider Jack and Sue Drafahl, the foremost experts in digital underwater photography. They already had many Photoshop plugins to fix underwater photos, even before underwater digital photography was popular (around 2002). The book talks about those techniques. The Drafahl's website is www.jackandsuedrafahl.com.

This particular seminar was more on digital tips and techiques. Here are some tips that I wrote down:

• Look for a digital with a custom (adjustable) white balance, this feature allows you define "what is white". When under water, carry a white piece of plastic to adjust the white balance. The white balance matters most when shooting wide angle and with no strobe (when using sun light).
• Jack recommends carrying a CD writer when traveling. He recommended the Apacer Steno. The Apacer Steno is a flash card reader that writes the contents to a CD or DVD.
• ISO 400 is the best for digital in Jack's opinion.

• Tools for recovering lost pictures in your camera:

  • PhotoOne Recovery
  • Image Recall
• If using an SLR, shoot in RAW mode.
• The "blooming" phenomena when shooting the sun underwater (discontinuos white blob) is caused by a flaw in the red sensor of digital cameras. A way to fix it is to reduce the exposure.
• Digital f16 is equivalent to film f32
• When shooting sillouetes, don't use flash
• Use a Pelikan carry-on for digital equipment when traveling. Take your camera as carry-on.
• Ultralight sells a battery for meter to check the life of you rechargable batteries. It costs about $30. They are also the preferred vendor for strobe arms for Jack and Sue. I've heard this from other uw photo experts as well.