Recently two of my patients, both of whom are professional wedding photographers, came in complaining of lower back pain following weekend photo shoots. Each were treated and their pain resolved with a single treatment. Sacral dysfunction was the area of greatest restriction. When it happened a second time for each of them after their next photo shoot, I began to question what it was about their actual jobs that might have been contributing to their back pain. It appeared that if they were not shooting, they were not in pain. After each session, they were in my office complaining of back pain. I set out to see if I could come up with a reason for their symptoms. The following is a description of an experiment and the findings that might explain the reoccurrence.
With the advent of DSLR (digital single lens reflex) cameras, the ability to utilize professional grade photography equipment became available to the masses. Most DSLR cameras utilize a TTL (through the lens) focus mechanism which allows the photographer to look though a view finder and “see” what the camera will photograph. Most DSLR’s have interchangeable lenses. Many have variable focal lengths. These lenses allow you to change the focal length of the lens to be able to make the object fill more or less of the picture. The lenses are measured in millimeters of focal length (mm). These cameras also have a viewfinder, through which you look to take the picture. Most viewfinders, much like a pair of binoculars, have an adjustment to bring the image into sharp focus as you view it.
The standard for lens focal length measurement is based on the 35mm film cameras. The following table gives the optical comparisons between camera lenses, object appearance, and eyeglass lenses (this is what the camera “sees” on its sensor):
|
Focal Length |
Magnification |
Object Appearance |
Spherical Diopters |
|
18mm |
-3x |
One Third Size |
-8.0 |
|
25mm |
-2x |
Half Size |
-4.0 |
|
50mm |
0 |
Actual Size |
Plano |
|
100mm |
2x |
Double Size |
+4.0 |
|
200mm |
4x |
Quadruple Size |
+12.0 |
In a 18-200 variable focal length camera lens, this can be the equivalent of roughly -8 to +12 diopters sphere. This is what the camera is using, in the way of optics, to make the image either larger or smaller and then to bring it into focus on the CCD (the part on a digital camera that actually takes the picture – the sensor).
When looking through the view finder of the camera, the TTL image viewed will have an effect on the eye. This effect is dependent on the distance from the view finder, the view finders focal adjustment, and the focus of the actual image through the lens.
This effect is best explained as if we were doing an eyeglass exam placing lenses in front of the eye. We will look at three examples: 25mm, 50mm, and 200mm. Both will be viewed from the effect on the cranium and the sacrum.
50mm: This lens is the equivalent of a plano lens. When looking through the camera the TTL image is focused on the retina (assuming the object is in focus and the viewfinder eyepiece is correctly adjusted). This means there is no optical magnification, and thus, no influence on flexion or extension in the cranium, and similarly, no influence on the sacrum.
200mm: This lens creates magnification of the image. Optically it is a +12 spherical lens held in front of the eye. It is placed in front of one eye only if using the TTL feature of the camera. That means that one eye has “correction” (with the camera) and one eye does not. Plus spheres are typically used to treat hyperopia, or far sightedness. In hyperopia the image forms behind the retina. This places the image out of focus. To correct it a lens which brings the light rays into focus earlier is used to correct this problem (a convergent lens). Twelve diopters a is a very large correction in optometry. In a “normal” eye (or one that is corrected to 20/20 vision) this could make the images coming through the camera focus far in front of the retina of that eye if the viewfinder adjustment is not correct. Cranial extension will be the bodies response as it attempts to focus on the image coming from the camera. This extension response will be a large one, and it will be unilateral. The body will try to move the retina forward to meet the image. Because it is a unilateral response (the camera is only in front of one eye) one side of the sphenoid will be in strong extension while the other side will be in mild extension or flexion (normal motion). This will create a torsion strain pattern in the cranium, as well as a hemi vertical strain. Optical aberrations can place more strains over the top of these yielding a very complex strain pattern.
18mm: Optically this is a -8 spherical lens held in front of the eye. It is placed in front of one eye only if using the TTL feature of the camera. That means that one eye has “correction” (with the camera) and one eye does not. Minus spheres are typically used to treat myopia, or near sightedness. In myopia the image forms in front of the retina. This places the image out of focus. To correct it a lens which brings the light rays into focus later is used to correct this problem (a divergent lens). Eight diopters a is a large large correction in optometry. In a “normal” eye (or one that is corrected to 20/20 vision) this could make the image coming through the camera focus far behind of the retina of that eye if the viewfinder adjustment is not correct. Cranial flexion will be the bodies response at it attempts to focus on the image coming from the camera. This flexion response will be a large one, and it will be unilateral. The body will try to move the retina forward to meet the image. Because it is a unilateral response, (the camera is only in front of one eye) one side of the sphenoid will be in strong flexion while the other side will be in mild extension or flexion (normal motion). This will create a torsion strain pattern in the cranium, as well as a hemi vertical strain. Optical aberrations can place more strains over the top of these yielding a very complex strain pattern.
The camera lenses noted above are used to give the reader an idea of what happens with the mechanics of the lens and what strain pattens it can cause if it were an eyeglass lens. If the image in the lens (and thus the viewfinder of the camera) is out of focus, which can occur for multiple reasons, the image that the lens picks up is blurry and that is passed to the camera viewfinder. Thus, the output of the image to the eye via the viewfinder is only as good as the image coming into the lens.
These strain patterns will transfer to the sacrum via the attachments of the dura at the second sacral segment. In a effort to understand what was happening with my patients, the following experiment was performed: A Nikon D7000 DSLR with a 18-200 lens focused at 200 mm was placed in front of one eye and the other eye was closed. The open eye looked through the viewfinder (TTL). The camera operators sacrum was palpated both before, during and after the viewing through the lens. The following results were noted:
|
Eye Open |
Eye Closed |
L5 |
Sacral Pattern |
|
Left |
Right |
Rotated Right |
R/L Torsion |
|
Right |
Left |
Rotated Left |
L/R Torsion |
|
Left/Right |
None |
Rotated Right |
L/R Torsion |
|
Right/Left |
None |
Rotated Left |
L/R Torsion |
In the experiment the camera was first tested with one eye open and the other closed. The same test was carried out with both eyes open and the camera in front of the first named eye. No noticeable change was recorded between the non-camera eye being open or closed.
Of special note is that the pattern of L5 and the sacrum rotating in the same direction when looking through the lens. This is not the compensated motion they normally follow. This motion, and that of the sacral torsions were maintained during the gait cycle (walking with the lens in front of the eye). Again, this is not the normal motion of the pelvis during the gait cycle (L/L and R/R is expected). The camera appears to have a large impact on the sacrum and gait mechanics.
The experiment was repeated with the lens focused at 18 mm and the opposite sacral findings were recorded. (left eye camera gave L/R torsion, etc.)
It is surmised that these cranial patterns will transfer to the sacrum via the dural tube, and, if the patient moves forward or backward while shooting, could lock the sacrum in this pattern or one similar to it.
Conclusions
The camera lens is a powerful tool. Not only can it capture special moments in time, it can also apply significant forces into the head and body through the eyes and cranium. These forces seem to move the body in a way that predisposes it to injury or, at least, strain. By opposing the common patterns seen during the gait cycle and influencing the cranium to enter non-physiologic patterns, the camera operator is more likely to get “stuck” in one of these patterns. Adding in the weight of the camera equipment and the long times spent in one position, somatic dysfunction can result. This seems to be the likely cause of my patients pain following their weekend photo shoots. Both came in with backward sacral patterns.
Follow-Up
My patient bought a new camera body. After many discussions with over what we could do to change the camera to work better for each of us, we tried a second experiment: The (new) camera with lens attached was focused on a fixed object. The operators sacrum was palpated and this time we only adjusted the focus of the viewfinder eyepiece. The camera, and the object being focused on, remained constant.
Much like the fine focus ring on a pair of binoculars, the focus of the viewfinder eyepiece is measured in “+” and “-“ from a “0” detent. You can move the ring to bring the object into sharper focus. We experimented with three camera operators, each moving the focus of the viewfinder one detent at a time until palpation of the sacrum yielded little to no change. The adjustment of the focus ring was different for each operator. The “clicks” up or down from “0” were recorded for each. This is the setting that the operator uses to shoot pictures now.
This fine tuning of the camera viewfinder eyepiece made a major difference in the impact of the camera on the operator. With the camera adjusted in this way, there was minimal impact on the sacrum – unless the object being focused on was intentionally out of focus (which we noticed when the focus ring of the main lens got moved).
Discussion
This experiment seems to have bring out two parts of the picture shooting experience that can effect the operator and introduce somatic dysfunction. The first is the optics of the camera and how they focus. Better lenses yield better (sharper) pictures, all other things being equal. The way your particular camera focuses, and the speed in which is does it can impact the TTL view and thus the sacrum. We noted that an out of focus image (camera lens out of focus or the auto focus on the camera not calibrated properly) added to prominence of the sacral findings. The second part is the viewfinder eyepiece. This seems to be the biggest factor (and easiest to correct) portion of the experiment. When properly adjusted, it minimizes the impact of the camera lens on the operators body.
Modern cameras have a “live view” or way to show the photo on the cameras screen prior to shooting. This is similar to smaller point and shoot cameras or cell phone cameras. Unfortunately the view through the lens is much better than that of the screen. As a photographer myself, I certainly wish there was a way around this apparent dilemma, one that could avoid the apparent predisposition to fatigue and pain during and after shooting. However, I will continue to use the TTL view and can now just explain the intricacies of why I am dysfunctional after a day of taking photos if anyone asks…
After calibrating the viewfinder to each of my patients’ cameras, I rarely see them for back pain anymore. They still may come in occasionally after weekend long back to back weddings, but we all feel like we have optimized the gear for the individual. It was a fun application of the principles of optics and osteopathy.