SCUBA diver-operated low-light-level video system for use in underwater research and survey

1987 ◽  
Vol 67 (2) ◽  
pp. 299-306 ◽  
Author(s):  
G. W. Potts ◽  
J. W. Wood ◽  
J. M. Edwards
Keyword(s):  
High Resolution ◽  
Power Supply ◽  
Light Level ◽  
Natural Light ◽  
Scuba Diver ◽  
Ambient Light ◽  
Low Light ◽  
Marine Research ◽  
Light Levels ◽  
External Power

Television cameras and video equipment are well established as tools in many areas of marine research and have been reviewed by Barnes (1963), Myrberg (1973), Harris (1980), and Holme (1984, 1985). The TV camera is usually mounted on a remote sledge (Machan & Fedra, 1975; Holme & Barrett, 1977) or submersible, often with arrays of lights, and lacks the manoeuvrability that is necessary for many types of detailed survey and behavioural recording. Commercial and industrial uses also demand high-resolution equipment that is often contained in bulky underwater cases capable of operating at great depths and well below that possible by the conventional SCUBA diver. It is not unusual for the equipment to be used in conjunction with external lighting units where natural light levels are too low for the use of ambient light, and is dependent on an external power supply normally situated in the surface support vessel or within a submersible (Sisman, 1982).

scholarly journals Interactive effects of temperature and light on reattachment success in the brown alga Fucus radicans

2019 ◽  
Vol 62 (1) ◽  
pp. 43-50
Author(s):  
Ellen Schagerström ◽  
Tiina Salo
Keyword(s):  
High Temperature ◽  
Water Temperature ◽  
Asexual Reproduction ◽  
Net Primary Production ◽  
Light Level ◽  
Interactive Effects ◽  
Low Light ◽  
Dispersal Capacity ◽  
Light Levels ◽  
The Baltic

Abstract Fucus radicans is an endemic habitat-forming brown macroalga in the Baltic Sea that commonly complements its sexual reproduction with asexual reproduction. Asexual reproduction in F. radicans takes place through formation of adventitious branches (hereafter fragments), but the exact mechanisms behind it remain unknown. We assessed experimentally the importance of two environmental factors determining the re-attachment success of F. radicans fragments. By combining different light conditions (daylength and irradiance; high or low light) and water temperature (+14°C and +4°C), we mimicked ambient light and temperature conditions of winter, spring/autumn and summer for F. radicans. Fragments were able to re-attach in all tested conditions. Temperature and light had an interactive impact on re-attachment: the combination of high temperature and high light level resulted in the highest re-attachment success, while light level had no effects on re-attachment success in cooler water temperature and the re-attachment success in high temperature under low light levels was very low. The results suggest that rhizoid formation, and thus re-attachment success, may depend on the net primary production (metabolic balance) of the fragment. However, whether the re-attachment and asexual reproduction success simply depends on photosynthetic capacity warrants further mechanistic studies. Understanding the mechanisms of asexual reproduction in F. radicans is important in order to assess the dispersal capacity of this foundation species.

scholarly journals Adjustable light source for low light level with nearly constant correlated color temperature

2022 ◽  
Vol 2149 (1) ◽  
pp. 012016
Author(s):  
Z F Wu ◽  
L Li ◽  
C H Dai ◽  
Y F Wang ◽  
Q T Cheng ◽  
...  
Keyword(s):  
Light Source ◽  
Spectral Distribution ◽  
Light Level ◽  
Color Temperature ◽  
Spectral Radiance ◽  
Integrating Sphere ◽  
Spectral Difference ◽  
Low Light ◽  
Light Levels ◽  
Variable Aperture

Abstract Low light level (LLL) calibration becomes more and more important since the rapid growth of remote sensing. The spectral radiance at normal higher light levels can be calibrated with good accuracy, while LLL spectral radiance cannot. If an adjustable light source can be designed at nearly constant correlated color temperature (CCT) covering several orders of magnitude, low light level spectral radiance can be obtained with the help of a photodetector. Whether or not the spectral distribution of an integrating sphere based light source is nearly constant is investigated. By adjusting the diameter of the variable aperture between the integrating sphere and tungsten lamp, the spectral radiance can be varied over 6 orders of magnitude. However, the relative spectrum in the red region increases notably when the spectral radiance is decreased to 1/100000. If the spectral radiance is decreased further, the spectral difference can be more than 300% and CCT decreases more than 250 K. By using baffles and another integrating sphere, low light level radiation source at nearly constant spectral distribution is obtained. The variation of CCT is less than 50 K over 6 orders of magnitude.

Matched filtering in the visual system of the fly : large monopolar cells of the lamina are optimized to detect moving edges and blobs

1990 ◽  
Vol 240 (1298) ◽  
pp. 279-293 ◽  
Keyword(s):  
Receptive Field ◽  
Receptive Fields ◽  
High Light ◽  
Vertical Stripe ◽  
Ambient Light ◽  
Low Light ◽  
Temporal Properties ◽  
Light Levels ◽  
Spatio Temporal ◽  
Temporal Inhibition

At high levels of ambient light, large monopolar cells (LMCS) display spatially antagonistic receptive fields and a biphasic response to a brief flash of light from an axially positioned point source. In low ambient light the response becomes monophasic everywhere within the receptive field. Using the theory of matched filters, we infer that the LMCS are optimal for the detection of moving edges at high light levels, and for ‘blobs’ in low ambient light. The spatio-temporal properties predicted by the theory are in agreement with experimental observation. At high light levels, the strong temporal inhibition, the weak, diffuse lateral inhibition, and the non-separability of the receptive field in space and time are all properties that promote the sensitivity to a moving edge. At low light levels, the lack of spatial or temporal antagonism enhances the sensitivity to a blob. Our hypothesis is reinforced by the observation that flies tend to walk toward the edges of a broad, dark vertical stripe at high light levels, but uniformly toward all regions within the stripe in low ambient light.

An Evaluative Study of Three Photographic Focusing Screens under Two Levels of Illumination

1980 ◽  
Vol 9 (1) ◽  
pp. 37-44
Author(s):  
John B. Bunch
Keyword(s):  
Light Level ◽  
Illumination Level ◽  
Low Light ◽  
Evaluative Study ◽  
Light Levels ◽  
High Illumination ◽  
Significant Difference ◽  
Low Illumination ◽  
Post Hoc

The purpose of this experiment was to evaluate the ability of photography students to focus a camera accurately under two levels of illumination (high/low) with three types of focusing screens (plain groundglass, split-image and microprism). The participants were required to focus each screen three times under each light level; scores were focus errors in feet. A 2 × 3 MANOVA design was used, and post hoc comparisons were made for plain vs. split-image, plain vs. microprism, and plain vs. microprism and split-image combined. There was significantly less focus error (p < .05) under the low illumination level, but no significant difference between screen types across both light levels. The screen type X light level interaction was much higher than the p .05 required in this study. Plain groundglass produced the least overall error; microprism yielded the least error under low illumination and the highest error under high illumination; and split-image was the most accurate under high illumination and the least accurate for the low light level condition.

scholarly journals Plastic responses in the coral Pocillopora acuta to extreme low-light conditions with and without food provision

2021 ◽  
Vol 168 (7) ◽  
Author(s):  
Jenny Fong ◽  
Rosa Celia Poquita-Du ◽  
Peter A. Todd
Keyword(s):  
Species Differences ◽  
Light Level ◽  
Ambient Light ◽  
Light Conditions ◽  
Feeding Rates ◽  
Low Light ◽  
Reef Environment ◽  
Ambient Light Level ◽  
Related Stress ◽  
Plastic Responses

AbstractThis study examines phenotypically plastic responses in Pocillopora acuta collected from a highly urbanized reef environment to extreme low-light conditions. While among-species differences in how corals cope with low light are well documented, much less is known about within-species responses. It also remains unclear how extreme low light and provision of food may interact and influence coral physiology. Clonal fragments from six colonies (genotypes) of P. acuta were subjected to two light treatments with mean midday irradiances of 4 and 40 μmol photons m−2 s−1 photosynthetically active radiation (PAR), representing just 0.5 and 5% ambient light level, and were either fed with zooplankton or not fed for nine days. Corals maintained in 4 PAR had lower endosymbiont density but higher cellular chlorophyll a concentration than those in 40 PAR. Feeding rates were similar in both light treatments and had no significant effects on endosymbiont density and chlorophyll a concentrations. While genotypes varied in the level of phenotypic plasticity expressed for both photoacclimation and heterotrophy, most displayed similar directions in their responses, indicating photoacclimation in P. acuta is broadly predictable. Our study demonstrates that P. acuta from Singapore is able to acclimate to very low-light conditions by adjusting their photophysiology, providing additional evidence that this species is resilient to urbanization-related stress.

scholarly journals Visual Comfort of Tablet Devices under a Wide Range of Ambient Light Levels

2021 ◽  
Vol 11 (18) ◽  
pp. 8679
Author(s):  
Hsin-Pou Huang ◽  
Minchen Wei ◽  
Hung-Chung Li ◽  
Li-Chen Ou
Keyword(s):  
Evaluation Model ◽  
Light Level ◽  
White Background ◽  
Psychophysical Experiment ◽  
Visual Comfort ◽  
Ambient Light ◽  
Viewing Condition ◽  
Light Levels ◽  
Ambient Light Level ◽  
Wide Range

E-reading devices are becoming more and more common in our daily life, and they are used under a wide range of ambient light levels, from completely dark to extremely bright conditions. In this study, a psychophysical experiment is carried out to investigate how ambient light level affects the visual comfort of an e-reading device. Human observers compare the visual comfort of pairs of different text-background lightness combinations on a tablet device under three ambient light levels (i.e., 150, 1500, and 15,000 lx). With our previous work, the experimental results show that the trend of visual comfort interval scales below 1500 lx (i.e., Dark, 150, 300, and 1500 lx) are similar to each other but not for those under illuminance above the 1500 lx (i.e., 3000 and 15,000 lx). For the same lightness difference between text and background, the observers tend to read the text with a white background compared to a black background, especially for 3000 and 15,000 lx. Moreover, a black text on a light-gray background is the most comfortable combination under these two illuminance levels. An evaluation model is proposed based on ambient illuminance, screen parameters, and visual estimation to design an optimal viewing condition when reading on the tablet display.

Ambient light alters temporal-updating behaviour during mate choice in a Neotropical frog

2010 ◽  
Vol 88 (5) ◽  
pp. 448-453 ◽  
Author(s):  
Alexander T. Baugh ◽  
Michael J. Ryan
Keyword(s):  
Decision Making ◽  
Mate Choice ◽  
Light Level ◽  
Ambient Light ◽  
Light Conditions ◽  
Predator Detection ◽  
Physalaemus Pustulosus ◽  
Light Levels ◽  
Risk Of Predation ◽  
Assessment Time

It is well known that animal decision-making can be influenced by environmental variables, such as the risk of predation. During the breeding season, nocturnal amphibians encounter a range of environmental conditions at breeding aggregations, including variable ambient light conditions. For nocturnal frogs, illumination is expected to minimize conspicuous movement that might increase predator detection. Previous work has shown that female Physalaemus pustulosus (Cope, 1864) (= Engystomops pustulosus (Cope, 1864)) are sensitive to variation in light levels during mate choice. Here we use an acoustic playback design in which stimuli are adjusted for intensity and complexity during female phonotaxis to show that choosiness is influenced by light level. Frogs were more likely to commit to an initial mate choice despite a dynamic reduction in mate attractiveness under dim light conditions compared with darkness. These results suggest that females are trading off the attractiveness of potential mates with the perceived costs of executing mate choice by committing to an initial decision and thereby reducing assessment time and movement. The dynamic playback design used here provides an approach that could be applied in other systems in which context-dependent decision-making is thought to be important.

Auto-gated power supply for low-light level image intensifier

2013 ◽  
Author(s):  
Ye Yang ◽  
Qiang Zhi ◽  
Bo Yan ◽  
Ze Yao ◽  
Jun-guo Li ◽  
...  
Keyword(s):  
Power Supply ◽  
Image Intensifier ◽  
Light Level ◽  
Low Light
Sign in / Sign up

Export Citation Format

Share Document