zoom lens
Recently Published Documents


TOTAL DOCUMENTS

444
(FIVE YEARS 55)

H-INDEX

22
(FIVE YEARS 3)

2021 ◽  
pp. 127881
Author(s):  
Kun Zhang ◽  
Xing Zhong ◽  
Zheng Qu ◽  
Yao Meng ◽  
Zhiqiang Su

2021 ◽  
Author(s):  
Kenta Uchida ◽  
Albert A. Burkle ◽  
Daniel T. Blumstein

Ecotourism promotes conservation efforts while also allowing for low impact observation of wildlife. Many ecotourists photograph wildlife and photography plays an important role in focusing the public’s attention on nature. Although photography is commonly believed to be a low impact activity, how the visual stimulus of a camera influences wildlife remains unknown. Since animals are known to fear eyes pointed towards them, we predicted that a camera with a large zoom lens would increase animal’s vigilance levels. Using yellow-bellied marmots (Marmota flaviventer) as a mammalian model, and adopting a behavioural approach to identify how marmots responded to cameras, we experimentally quantified vigilance and flight initiation distance towards humans when marmots were approached with and without a camera. While a camera was pointed at an individual, marmots allocated less time to searching predators and increased time to looking at the observer than they did without a camera. However, whether a camera was pointed at a marmot or not had no effect on the distance the marmot flushed. Our results indicated that cameras distracted marmots but did not influence subsequent risk assessment (i.e., flight initiation distance); marmots may be curious about cameras but were not threatened by them. Capturing animals’ attentions reduces searching for predators and may increase the vulnerability to predation. Therefore, regulating photography in locations where predation risk is high or vulnerable species ranges’ overlap with humans may be required to reduce photography’s impact on wildlife.


2021 ◽  
Vol 11 (21) ◽  
pp. 10200
Author(s):  
Chun-Feng Chou ◽  
Cheng-Mu Tsai ◽  
Chao-Hsien Chen ◽  
Yung-Hao Wong ◽  
Yi-Chin Fang ◽  
...  

In fields such as biology, archeology, and industry, underwater photogrammetry can be achieved using consumer-grade equipment. However, camera operations underwater differ considerably from those on land because underwater photogrammetry involves different optical phenomena. On the basis of the requirements and specifications of the marine vessel Polaris, we developed a novel underwater camera with prime and zoom lenses and a high resolving power. The camera can be used in the spectrum in shallow water and the blue–green spectrum in deep water. In the past, ordinary cameras would be placed in waterproof airtight boxes for underwater photography. These cameras were not optimized to the underwater spectrum and environment, resulting in no breakthroughs in resolving power. Furthermore, the use of the blue spectrum greatly increases during underwater and particularly deep-water surveying. Chromatic aberration and focus-point displacement generated by the shift from the shallow-water spectrum to the blue–green spectrum in deep water makes universal underwater photography even more difficult. Our proposed optical design aimed to overcome such challenges for the development of a high-resolution underwater surveying camera. We designed a prime lens and a zoom lens. We adopted a waterproof dome window on the outer surface as the basic structure and optimized it in accordance with the conditions of different water depths and spectra to obtain distortion within ±2% and high-resolution underwater imaging quality. For the zoom lens design, we employed a genetic algorithm in Zemax to attenuate chromatic aberration as a kind of extended optimization. This novel optical design that can be used in all waters is expected to greatly reduce the volume and weight of conventional underwater cameras by more than 50% and 60%, respectively, and increase their resolving power by 30–40%.


2021 ◽  
Vol 6 ◽  
pp. 100-108
Author(s):  
Dmitry A. Izhbuldin ◽  
Tatiana N. Khatsevich

Trends in the development of IR lens systems, possible problems and solutions arising in the development of LWIR variofocal lens systems interfaced with uncooled matrix receivers, company products and the characteristics of the lens systems they produce are considered. The analysis of the considered products has been carried out, as a result of which the most optimal characteristics for development have been identified. The aim of the study is to obtain in the paraxial approximation a mathematical model of a variofocal LWIR objective coupled with an uncooled matrix receiver, and to identify the relations in such a model. The research results will be used for further theoretical and practical research in the master thesis.


Sign in / Sign up

Export Citation Format

Share Document