Flash Photography: How to Use a Flash for Better Photos in Any Situation

Curious about this, I began to look into photography bans and found that while the guard's idea was bizarre, it was no crazier than some of the other "reasons" for photography bans, and apparently wasn't even a one-off aberration: In the work by Evans (linked below), he reports "A friend of mine was once admonished by a museum attendant, who said that the light was so bright that it could freeze an object, and this sudden cold shock would be damaging to a delicate wooden exhibit!" Apparently, the idea of a flash "freezing" motion has translated into a meme among museum staff of flash "freezing" objects.

Flash Photography

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I myself rarely use flash, especially the little ones built into my cameras. I prefer to use existing light as I did in the pictures with this post. Nonetheless, we have all seen the signs prohibiting photography and especially flash photography.

One reason, told to photographer Paul Harcourt Davies by a museum guard, was that photography was banned to keep crowds moving. At a popular exhibit, people wait on line for hours and any photography slows down the line. Fewer people can get in to see the exhibit and revenue is lost. There is another very real reason to ban photography: gift shop sales. Most museums make a substantial amount of their revenue from the sale of postcards, posters and other bric-a-brac. The fear is that people taking their own photos, no matter how badly, are going to spend less at a gift shop.

From Martin Evans' perspective, the good news is that flash photography does not hurt artwork. What remains is the bad news that despite the science, galleries and museums believe what they believe and continue the bans.

Millions of people take animal pictures during wildlife interactions, yet the impacts of photographer behaviour and photographic flashes on animals are poorly understood. We investigated the pathomorphological and behavioural impacts of photographer behaviour and photographic flashes on 14 benthic fish species that are important for scuba diving tourism and aquarium displays. We ran a field study to test effects of photography on fish behaviour, and two laboratory studies that tested effects of photographic flashes on seahorse behaviour, and ocular and retinal anatomy. Our study showed that effects of photographic flashes are negligible and do not have stronger impacts than those caused solely by human presence. Photographic flashes did not cause changes in gross ocular and retinal anatomy of seahorses and did not alter feeding success. Physical manipulation of animals by photographing scuba divers, however, elicited strong stress responses. This study provides important new information to help develop efficient management strategies that reduce environmental impacts of wildlife tourism.

Despite the lack of scientific evidence, a multitude of regulations exist related to photographing marine wildlife based on the unsubstantiated concern of causing (temporary) blindness in animals, either while scuba diving or visiting aquaria. Public aquaria around the globe prohibit the use of flash while taking photographs, without any scientific evidence to support the ban. Scuba dive resorts in Southeast Asia often restrict the use of flash while photographing pygmy seahorses29 and in the U.K. a ban on using flash while taking pictures of seahorses is in place, despite open acknowledgment of a lack of evidence to support the ban10.

Charismatic and cryptic species such as seahorses (two families within the sub order Syngnathoidei) and frogfishes (family Antennariidae) are highly popular with underwater photographers and are often displayed in public aquaria26,30. Cryptic species such as these depend on camouflage to avoid predation. Many are slow swimmers not capable of fleeing from scuba diving photographers. Flash photography does not affect site persistence of seahorses, but touching them elicits, at the very least, short-term stress behaviours23. Species like seahorses are visual predators that rely on accurate resolving power to catch prey. Any reduction in visual acuity or sensitivity is likely to reduce survivorship31. The high intensity light of photographic strobe lights could theoretically result in phototoxic retinal damage. This damage could be either short term or permanent retinopathy due to photothermal, photomechanical and/or photochemical effects of high retinal irradiance. Retinopathy has been previously observed in mammals, including humans (e.g.32,33), and also in the photoreceptors of teleosts (e.g.34,35). However, a link between flash photography and damage to the eye structure of animals has yet to be shown. In addition, questions remain about the effects on fishes of scuba diver behaviour associated with flash photography, in particular the potential effects on feeding efficiency due to temporary reductions in visual acuity and other stress responses.

To answer these questions, we conducted an in situ behavioural experiment on 13 species of teleosts from three families (Syngnathidae, Solenostomidae and Antennariidae) commonly found at dive sites throughout Southeast Asia (Fig. 1). We then ran two controlled aquaria experiments to assess the behavioural and pathomorphological effects of flash photography on a species of seahorse. Specifically we set out to: (1) Quantify the effects of diver behaviour associated with flash photography on slow-moving, cryptic fishes; (2) Assess the effects of photographic flashes on the Western Australian seahorse (Hippocampus subelongatus) and (3) Examine the pathomorphological impacts of photographic flashes on the ocular and retinal anatomy of H. subelongatus.

Wildlife tourism is important for supporting livelihoods worldwide, but potential impacts caused by photography or photographer behaviour need to be minimised to ensure sustainability and for best practice in animal welfare. This study showed that repeated photographic flashes delivered over a period of 34 days and involving 4600 exposures to full power flash gun discharges per animal did not cause overt changes in ocular morphology or retinal gross anatomy, such as the thickness of retinal layers or photoreceptor size, in Hippocampus subelongatus. More importantly, these flashes had no observable impact on foraging behaviour or feeding success rates in a species that is known to rely on vision to capture small moving prey and has relatively high spatial resolving power31. Manipulation of animals by photographing divers in the wild, however, elicited very strong flight and stress responses. These results provide important new information for the development of best-practice photography guidelines for wildlife tourism.

Tourism management bodies including those in government organisations and public aquarium facilities, as well as tourism operators, have developed rules and regulations restricting the use of flash guns or strobes, while photographing a range of animals10,29. These well-intended preventive measures have not been based on scientific evidence. This experiment demonstrates that repeated photographic flashes do not appear to cause gross retinal damage in the seahorse Hippocampus subelongatus, at least over the duration of this experiment and under these conditions. In this study, we used a strobe at a higher intensity (double to triple) than is usually applied when photographing seahorses in situ underwater, and at a much higher intensity than could be reached by compact or phone cameras in an aquarium. In addition, phototoxicity is more frequently associated with extended exposure to intense light sources, in contrast to the very short exposures typical of photographic flashes32,33 which suggests that flash exposures may be less likely to cause retinal damage.

Our field experiment demonstrated that cryptic fishes are most strongly affected by diver manipulation. The highly significant increase in movement for frogfishes, species which rarely move if undisturbed, implies a considerable energy expenditure which could lead to decreased fitness39. Movement reactions differed between Solenostomus spp. and Hippocampus spp., reflecting different defence mechanisms used by each family. Seahorses are less mobile than ghostpipefishes (Solenostomus spp.) and rely more on camouflage than on flight response. When divers manipulated animals there was no difference whether or not the diver also used flash. In most cases, flash photography had no more effect than diver presence.

We demonstrated that the argument that flash photography might negatively affect feeding behaviour due to temporary blindness caused by flash photography does not hold up for the species tested in this study. Neither the field nor tank experiment yielded a decrease in the time spent hunting or in feeding efficiency in H. subelongatus. Even in the treatments that caused movement reactions, feeding rates were unchanged, indicating that despite potential distress, visual acuity was not impacted. Similar results have been observed when testing the effects of temperature stress on H. guttulatus where food intake in seahorses was not decreased despite increased ventilation rates40.

High flash treatment caused similar increases in ventilation rates, indicating seahorses might have experienced stress. It remains unclear if this increased ventilation was caused by the observed increase in movement, or how strong this stress reaction was and if the animals were indeed stressed. While ventilation rate can be used as a proxy for stress, it does not always reflect the strength of the stimulus41. However, increased gill ventilation rates in animals experiencing high flash exposure, regardless if caused by stress or through increased movement, suggests increased metabolic rates, which, if sustained, would have consequences for food requirements. In the case of photographic flash, the direct effects seem to be relatively small and were likely exacerbated by seahorses being kept in captivity without the possibility of escaping the stressor. While scuba diving, the reactions seen in the tank study would likely translate to the animal fleeing. 2ff7e9595c