Catchlight Studios Photography

Flash Power Compared

Like many photographers, we use small (shoe-mounted) flash as well as larger, studio-type units depending on how much power we need. Although other things, such as portability and recycling time, factor into the choice of lights for a particular job, more often than not, power is a large component of the decision. We also use Quantum flashes as they tend to sit somewhere between the other two in the terms of power, but have faster recycling and less overheating issues than the small flash units.

Trying to directly compare the power output of these various units is an exercise in frustration as small flash power is typically expressed as a "guide number" while studio strobes use the "watt-second". The latter is variably calculated by different manufacturers, complicating any comparison still further.

To create my own comparison, I set up various lights exactly 10 feet away from a Sekonic 758DR flash meter and measured the light output after triggering the flashes manually. All lights were used in the manual mode and set to full power unless stated otherwise. The studio lights were fitted with their standard 7" reflector.

The contenders were two Quantum flashes (TD-5r and TRIO), two Nikon Speedlights (SB900 and SB800), and three studio strobes from Paul C. Buff (Einstein, Alien Bee 800 and Alien Bee 400). All light measurements were taken in duplicate at ISO 200 and to an accuracy of 0.1 EV. Duplicate light measurements never varied by more than 0.1 EV. The results are shown in the chart below.

A few observations can be made. First, the Quantum TD-5r is about 1.5 stops more powerful than the shoe-mounted TRIO (no surprise there) and adding the diffusor discs to both flashes robs about 1.5 stops of power from each of them. Using the Quantum bare bulb enhancer (which provides 180 degrees of flash coverage with the flash head pointed straight up) lost only about a half stop compared to the diffusor (in the indoor setting used for this test).

Second, while the undiffused larger Quantum out-gunned the Nikon SB900 when the latter was set to its minimum head zoom position (24 mm), the smaller flash performed more powerfully when zoomed to 200 mm. Adding the Nikon diffusor dome (which also limits the zoom) reduced effective power by about one stop. Similar results were obtained for the Nikon SB800, although its lesser zoom capabilities (maximum 105 mm) gave slightly less maximum power than its bigger brother. I imagine that the Quantum would regain the advantage when fitted with its telephoto reflector (which I did not have available for test).

It was no surprise that the Einstein at full power was the most powerful light source, which is why it is currently our first choice for overpowering the Florida sun for on-location work. The AB800 and AB400 lights were slightly less powerful than the Einstein turned down to 320 and 160 w/s, respectively, even though they should theoretically have been the same powers.

So there we have it - a comparison that at least I can use when choosing the best flash unit for the job at hand. The biggest news (to me at least) was just how potent the Nikon SB900 became at its fully zoomed position which opens up some real possibilities for location work where you want to really knock down the ambient light. Watch this space for some future real world applications of this.

 

 

Choosing a focal length for portrait photography

In portrait photography, the choice of lens - more specifically, the focal length of the lens - can make an enormous difference to both the quality and impact of the image.

The series of images below were taken at focal lengths of 14, 24, 50, 70, 135 and 200 mm on a full-frame digital camera (Nikon D3s). Each image was framed so that the subject about filled the frame (top to bottom).

Two things are evident from these images. First, the perspective distortion at the shorter focal lengths (14 and 24 mm) would be distinctly unflattering for a human subject. In contrast, the proportion of the features is much more natural at the longer focal lengths (135 and 200 mm). Second, as the focal length increases, the background appears progressively closer to the subject (and larger in comparison).

The use of wide angle lenses for portraits is better reserved for the 'environmental' style of portrait, when you want to show the subject in their surroundings, as for example, this image of local art critic Josh Garrick. Note, however, that we avoided getting too close to our subject and therefore minimized perspective distortion. Such wide lenses additionally exhibit edge distortion which is also unflattering to a human subject, but we can minimize this effect by keeping our subject in the center of the frame.

Longer focal lengths, in contrast, are useful for (1) providing a more flattering facial perspective, (2) isolating the subject, especially when combined with a large aperture, and (3) compressing the background perspective. The latter makes it easy to use something relatively distant as a complementary background for the portrait - as in this image of Robyn taken with a 200 mm lens at f/2.8.

In the end, our choice of lens is simple and depends entirely on the kind of image we want to create. In general, however, the photographer (and the subject) will be better served with a longer focal length. This is the reason that 80%+ of our portrait photography is done with one of three lenses; 85 mm f/1.4, 70-200 mm f/2.8, and 200 mm f/2.

Fast Glass

In portrait photography, the importance of having lenses with a wide (greater than f/2.8) maximum aperture cannot be over-estimated. In photography circles, such lenses are known collectively as "fast glass".

One of the most common problems encountered by beginning photographers is being able to minimize background distractions. Sometimes, it is possible to do this just by choosing the location carefully, or by changing your viewpoint. Sometimes, however, this is not possible and a busy or distracting background can easily ruin the image.

In these situations, a fast lens can solve the problem by rendering the background so far out of focus than nothing is recognizable. This immediately draws the viewer's eye to your subject since there are no longer any competing elements in the photograph.

Shooting at very wide apertures (f/2.0 and larger) can be challenging because the depth of field (the front-to-back distance that is visually sharp) can be extremely small (an inch or two) so it is critical that the most important part of the subject is in focus. In portraiture, this is the nearest eye to the camera.

This first image of Maria was shot with a Nikon 85 mm f/1.4 lens. Notice how the subject's eyes are sharp, but the sharpness falls off rapidly across her hair.

The next two images were made with the Nikon 200 mm f/2.0 lens. These photographs both had potentially busy backgrounds which were rendered completely out of focus with this amazing lens (by far my personal favorite).

In the next image, the Nikon 85 mm f/1.4 created a dreamy, high key feel to this portrait of our pet cat, Toulouse.

Wide apertures are also incredibly kind to skin, so your female portrait subjects will thank you. In this engagement portrait of Tracie, the Nikon 200 mm f/2.0 renders her (already lovely) skin very softly, and the slats of the chair she is sitting on become almost abstract.

Although I do favor longer focal lengths for portraits, the 50 mm f/1.4 lens is certainly capable of nice portrait images. In this shot of bride-to-be Jen, the Sigma f/1.4 - shot wide open of course - produced this delicate portrait.

Unfortunately, the ability to create such beautifully out of focus backgrounds comes at a price. Fast glass is always more expensive than, for example, the 'kit' lens that comes with the typical prosumer DSLR and which usually has a maximum aperture between f/4.5 and f/6.3. Nevertheless, if gorgeous location portraits are what you strive for, nothing will get you there quicker than an investment in a fast lens.

If you are a wedding photographer, a fast lens will not only assure you of lovely bridal portraits in almost any environment, but also allow you to photograph in dimly lit churches where flash may not be allowed. My workhorse 'fast' portrait lens is the 70-200 mm f/2.8, but I love to shoot with the 85 mm and 50 mm f/1.4 lens for razor-thin depth of field. As mentioned above, my favorite is the 200 mm f/2.0 which has a quality unmatched by any other lens I own. Both Nikon and Canon make great examples of all these lenses - Canon also has a superlative 85 mm f/1.2.

Shooting with fast lenses is not easy - but the results will make the effort worthwhile!

 

Wedding Workshop

We had a great time yesterday at our 2011 Wedding Workshop. The weather was kind to us, The Duncan House in Tavares, Florida provided a wonderful location and we had a great group of participants.

We also had six great models - Robyn, Rachel, Brooklyn, Dan, Reggie and Christiaan. Christiaan van Breman also provided us with outstanding hair styling for the event. Here are a few images - there are more on the Harmon's School of Photography Facebook Page. Please stop by and LIKE us!

The first one is possibly my favorite image of the day. The model is the lovely Brooklyn Wallace who came all the way from Miami to be with us for the workshop. The image was shot with a Nikon D3s and 24-70 mm lens (1/250 s, f/14, ISO 100) and lit with an Einstein strobe at full power (640 w/s) and a beauty dish.

Model Reggie Peters features in this image, also shot using the Einstein strobe at 1/250 s and f/22 to reduce the ambient light as much as possible.

Christiaan van Breman posed for this image under similar lighting conditions, but shot with the Nikon 70-200 mm f/2.8 lens.

I love this image of Rachel Panoff taken in front of the mirror. This shot used the Nikon 70-200 lens at f/4.5 and 1/25 second, and was lit with a single Nikon SB800 to the left of the model in a Lastolite Ezybox and fired with a PocketWizard Plus II transceiver.

Here is Brooklyn again, photographed with an identical lighting system as the image above.

Dan Reinecke and Robyn Germyn together in a pose inspired by great wedding photographer, Doug Gordon. Shot with the 70-200 mm lens and lit with the single SB800 in the Lastolite Ezybox.

Here's Robyn laying on one of the many beautiful beds in The Duncan House. I love the dreamy, high key feel of this image, again lit with the single SB800 flash.

Here is Dan standing on the second floor balcony. Just available light for this one - Nikon 70-200 mm lens, 1/160 s, f/2.8, ISO 1250.

In addition to the individual brides, groom, and couples shots, we set up a mock cake cutting, and plenty of detail shot opportunities for the participants. I took an opportunity to photograph Susan's wedding dress hanging on the end of this amazing 4-poster bed. This is a 3-shot HDR image.

And finally, what wedding would be complete without a wedding party jump shot! This image of all our models catching air was captured with the Nikon 14-24 mm lens at f/10 and 1/250 second, and lit with a single Einstein studio strobe and dish reflector at full power (640 w/s).

Thanks to all our models for their hard work, Christiaan for hair styling, Reg Garner for acting as co-instructor and Linda from The Duncan House for making this amazing property available to us. Finally, a big thank-you to all the workshop participants for coming and making it such a great day.