Musings on the Use of Aspect Ratio and Guide Lines
in Photographic Composition- by Ed Overstreet (May 2012)
Some digital cameras, notably all Panasonic Lumix models I’ve owned, provide two settings that are extremely useful for in-camera composition: aspect ratio; and guide lines.
My current Lumix cameras (the GH-2, GH-1, and GF-1) all provide four aspect ratios (1:1, 4:3, 3:2, and 16:9) for still images (video is constrained to 16:9 for HD and 4:3 for non-HD) and four guide line choices (no guide line, moveable cross-hair, rule-of-thirds, and quarter-lines-pluscorner- to-corner-diagonal-lines; with the latter two you also get a centre point – with the singlearea AF bracket default on the rule-of-thirds display, and with the intersection of the diagonals on the last display).
In some compositions it may be important for you to have two or more key elements in a
specific compositional relationship. For example, you may want all of them arrayed on the
image diagonals. Or you may want them all located at rule-of-thirds intersection points, perhaps also with one element in the exact centre of the frame.
Guide lines are necessary to ensure such a relationship in-camera before firing the shutter. But it is also important to ensure that you are using the same aspect ratio as you intend for the final image display, and that you do the composition in-camera and NOT do cropping of any kind in post-processing. Any cropping of the original frame, whether or not it preserves the aspect ratio, will inevitably change the geometric relationship of key elements within the rectangle, if there is more than one such element.
For example, two elements arranged in-camera on rule of thirds points cannot possibly both remain on rule-of-thirds points in the final image, if that image is cropped in any noticeable way on one or more sides of the rectangle in post-processing. For precise composition, it is important to “get it right the first time” in-camera – both on the guide lines, and also within a fixed and uncropped aspect ratio.
The correct camera workflow in a precise-composition case is a) select the aspect ratio, b) select the guide-line pattern to be used, c) organize the composition in-camera by adjusting the camera position and/or lens focal length to ensure the key elements are appropriately positioned within the viewfinder or LCD frame, d) take the photo, and e) do NOT crop the photograph in postprocessing. What is the “best” aspect ratio to use? That will depend on the particular subject matter and intended composition, but also may be influenced by the output format intended to display the photograph. The “optimal” use of the display format is to have an image whose aspect ratio most closely matches that of the display, to fill the surface area of that display (whether paper or screen) as much as possible. If there is one strongly-preferred print or display medium intended
for the photograph, the aspect ratio of the intended final output is probably the best in-camera choice to use in composing the photograph.
For display of digital images, there is no particular output-specific advantage to
using the 1:1 aspect ratio in-camera, unless the photographer intends to blend the
images with uncropped scans of legacy 1:1 film photographs in an audio-visual
presentation. The only advantages to the 3:2 in-camera aspect ratio would be for blending
images with uncropped scans of 35mm slides or negatives in an AV show, or for
making full use of the area of 4×6 or perhaps 8×12 printing paper.
For printing on all other commonly-used sizes of photographic paper (5×7, 8×10,
11×14 and 16×20) the optimal use of the paper surface would indicate using a 4:3
in-camera aspect ratio, in preference to the other three options. Projection on
most digital projectors and display on standard-format television or computer
screens also will have maximum impact in 4:3 aspect ratio.
Display on high-definition screens, and AV blending with high-definition
videography, would optimally be done using the 16:9 in-camera aspect ratio.
When uncertain about the output medium to be used for displaying the edited image, my
preference is to use the 16:9 in-camera aspect ratio. On my Lumix GH-2, that ratio gives the most pixels in the long dimension (though the third-most overall pixel count when you take the short dimension into account) and also ensures the best blending with highest-definition video clips in AV presentations. The 16:9 ratio generally offers the most flexibility for a highresolution cropping into a different aspect ratio in post-processing, though (as noted above) at the risk of destroying the geometric relationship between multiple centres of interest within the composition that existed at the time the photograph was taken. Owners of the Lumix GH-2 should note that the camera comes with three customizable “function” buttons which can be programmed to pop up certain feature menus. Among those choices are aspect ratio and guide lines. See page 17 of the camera’s operating instructions manual for how to program these buttons. Other Lumix models may have function buttons with these choices. Depending on how often you think you might want to change the aspect-ratio or guide-line display, it could be more efficient to access those menus via the function buttons than always to have to search for them in the more complex Record and Custom screen menus.
Neither the aspect-ratio nor guide-line menu can be accessed via the camera’s Quick Menu
button, which is another reason to program two of the function buttons for this purpose, if you think you’ll be using those menus often. Owners of other makes of digital cameras might wish to review their camera manuals to see whether comparable choices are provided for those models.
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