This is intended to be the first in a series of articles
about flash photography, but, first things first.
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| Owen Loves Yogurt : Perfect! |
Ok, I may be getting carried away, but he is a great little
Kid. Since he was born, Sue and I have
been excited to spend as much time as possible with Owen, but over the last
LONG months we have been frustrated by our pandemic-induced isolation. We have been forced to make do with frequent
Facetime visits and Zoom family meetings.
We are grateful for the new technology, but it cannot replace the warmth
of real physical contact. All we wanted
to do was blow kisses into his neck, inducing the inevitable chortling
giggles.
Happily, after 2 weeks of
strict isolation in their home outside of Boston, the family came to join us
for an extended stay in New Hampshire.
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| Flat Mat Rickey |
Because of the scarcity of willing models during the pandemic, I have been forced to use more compliant subjects. Meet "Rickey the Head". Rickey was originally designed to demonstrate various CPAP masks for patients with Obstructive Sleep Apnea, but with a coat of mat paint to blunt his plastic sheen, he is a reasonable subject for my flash experiments. Owen would have been MUCH better!
Flash (Some Basics)
I don’t think I can get more obnoxious, so I guess I better
move on. One of the side benefits of
spending so much time photographing Owen is that I have become more comfortable
with the use of my flash.
Given my
concentration on landscape photography, I have seldom needed to use artificial
lighting. For portraits, I have depended
on natural illumination, even when that meant that I was forced to either use
high ISO or suffer from soft blurry images.
I have never been thrilled with the results from my flash
photography. It is not because of a lack
of gear. I have always felt that I
possess more speed lighting equipment than the knowledge to use it effectively.
Over the years, I have regretted this deficiency. I have felt uncomfortable that my
Introduction to Digital Photography Course contained no discussion of the use
of flash. My next offering of the course
is scheduled for next autumn and will be on-line. I had already planned to expand the course to
five sessions and include a preliminary discussion of flash photography. I have always found that the best way to
learn something is to be forced to teach it, but Owen’s 3-week residency
provided an even better opportunity to expand my understanding of flash and prepare for my class discussion.
I will venture into a discussion of the types and usage of
flash, but, this week, I will touch on a somewhat disconnected collection of information will include:
More details will be coming, although much of my time is still filled with Owen duty - both the activity and the brown residue.
- How electronic flashes work
- How the burst of light synchronizes with a camera's shutter
- What effects the exposure of flash images
- How the quality of the light can be modified
More details will be coming, although much of my time is still filled with Owen duty - both the activity and the brown residue.
Types of Flash
Sadly, I am old enough to remember when “flash” meant using flash bulbs for a quick crude blast of light. Over recent decades, single-use bulbs have been replaced by electronic strobes.
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| Tubes for Canon 580EX II Flash |
By comparison, Apple iPhones and most other smart phones use a short blast of LED light for their flash. The light is less intense and therefore must be of longer duration and less able to freeze action.
Synchronization
Cameras generally have a maximum shutter speed for
synchronization with the flash burst.
The great majority of DSLRs use a focal plane shutter. In these, a first leaf moves across to expose
the sensor and then the second follows to end the exposure.
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| Example of Flash Duration at Full and 1/2 Power At half power flash cuts of at 50% brightness |
At slow shutter speeds, usually less than or
equal to 1/200 - 1/250 the shutter is fully open for a short period of time
before the second leaf closes, and a properly timed flash can expose the entire
sensor evenly. At faster shutter speeds,
the second leaf must begin its trip across the sensor before the first leaf is
fully open.
The result of this moving
slit is that there is no moment when the flash can expose the entire
sensor. My Canon 5D Mark IV has a
maximum Synch speed of 1/200. Above this
I will see a dark curtain across a portion of the image where the flash failed
to expose the sensor.
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| Fast Shutter Dark Curtain (Wikipedia) |
Happily, when the
flash is engaged, my camera routinely does not allow shutter speeds faster than
the max synch. My 580EX II, and many
other flashes, have a setting for “High Speed Synch” which allows faster shutter
speeds by using a series of fast bursts to prolong the flash duration.
Flash Exposure
The important thing to remember is that the electronic flash is generally much faster than the synchronization speeds, and therefore, the exposure is independent of the shutter speed and is governed by:
The important thing to remember is that the electronic flash is generally much faster than the synchronization speeds, and therefore, the exposure is independent of the shutter speed and is governed by:
- Flash “power” (actually, the duration),
- Aperture size
- ISO
The shutter speed only affects the amount of
ambient light seen in the image. So:
Basic Rules of Flash Exposure:
- Exposure of the flash subject can be modified by changing the flash power, the aperture (f-stop), or the ISO
- Changes in the shutter speed only affects the brightness of the ambient light.
- Changes in the f-stop affects the flash brightness more than the ambient background light, but if you adjust f-stop to alter flash exposure, you still may need to compensate for the change in ambient light with an adjustment in the shutter speed.
- Changes
in the ISO affects the brightness of both the flash and ambient light.
Simple, more on this later
Flash Quality
All electronic flashes work in a similar way to illuminate a subject, but the
quality of the light can vary greatly. The quality of light depends on multiple factors including:
- The size of the tube. The larger the size of the flash, the softer the light.
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| 580EX II Flash vs Pop-up flash on the Canon SX50 HS |
- The ability to control the light intensity, most notably with manual controls or feedback systems such as TTL (Through the Lens) metering.
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| TTL Mode on Canon 580EX II |
- The ability to modify the light with diffusers, umbrellas, soft boxes. All to increase the apparent size of the flash, which softens the light and allows it to bend around the subject.
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| Globe Diffuser Handy when on the fly chasing a rug rat |
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| Owen Chews, Globe Diffuser |
- The flash location (on or off the camera) Please, if possible, get your flash off the camera.
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| 26 Inch Octa Soft Box, Off Camera with Radio Trigger |
- The ability to combine lighting with other flashes as a master or slave, using cables, or optical, infrared or radio triggers.
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| Godox Radio Trigger |
- The ability to modify the color temperature of the flash with gels
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| Honl Full CTO (Color Temperature Orange) Gell: Adjusts flash to match incandescent light or warm evening light |
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| Read the Books! |
A great choice for those shooting with Canon equipment. I
have the first edition, which although missing information about Canon’s latest
top-level flash (e.g. the 600EX-RT), still Covers my 580EX II and does a wonderful job making flash
comprehensible. The 2nd Edition is quite
pricey, but I may go for the new book if I get the 600EX. Of course, by then there will probably be a
700EX.
A short book which clearly sets out Scott’s simple approach
to flash in his folksy style. It is not as encyclopedic as Syl Arena’s guide, burt unlike Syl’s, it
is not directed toward a specific system.
Also it is a whole lot cheaper.
Although Scott’s basic approach to manual control of flash is mercifully
straight forward, he suggests a long list of additional, wonderful, but
expensive equipment. That cheap book has already cost me a lot more money!
Read the
Damn Manual:
Your camera and flash manuals are full of great information
which is specific to your gear. They are
free and, unless, like me, you can’t find the manual for you’re 580XE II, you already have them, Never fear, copies of
all the manuals are available on-line.
The manuals are a great start, but they necessarily tend to be focused
on the specific gear. Books such as the
ones above excel in discussing how flash can be modified and crafted to fulfill
your artistic vision.
You have your camera and flash, now you need to get out and
shoot. Read the manual, try different
settings, and learn from your mistakes with the instant feedback which digital photography
provides.
Modern flashes are wonders of
smart technology, but I recommend starting with manual. As you become more comfortable with how
electronic flash works, you will be able to identify the situations in which
manual or smart setting, such as TTL, are best used and be able to tell why things go wrong.
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| Globe providing fill flash to balance with the background ambient light |
My grandson Owen is back for another stay, prolonged I hope,
and I anticipate getting more experience in the use of artificial light. The
learning never stops.
Jeff Newcomer
www.partridgebrookreflections.com
www.partridgebrookreflections.com
