Panta Rei

In photography and optics, a neutral density filter or ND filter is a filter that reduces and/or modifies intensity of all wavelengths or colors of light equally, giving no changes in hue of color rendition. It can be a colorless (clear) or grey filter. The purpose of a standard photographic neutral density filter is to allow the photographer greater flexibility to change the aperture, exposure time and/or motion blur of subject in different situations and atmospheric conditions.

The Irish Sea (Irish: Muir Éireann or Muir Meann, Scottish Gaelic: Muir Èireann or Muir Mhanainn, Manx: Mooir Vannin or Y Keayn Yernagh, Welsh: Môr Iwerddon, Scots: Erse Sea) separates the islands of Ireland and Great Britain. It is connected to the Celtic Sea in the south by St George's Channel, and to the Atlantic Ocean in the north by the North Channel. Anglesey is the largest island within the Irish Sea, followed by the Isle of Man. The sea is occasionally, but rarely, referred to as the Manx Sea.

The sea is of significant economic importance to regional trade, shipping and transport, fishing, and power generation in the form of wind power and nuclear plants. Annual traffic between Great Britain and Ireland amounts to over 12 million passengers and 17 million tonnes of traded goods.

Ireland (pronounced [ˈaɪrlənd] ( listen); Irish: Éire [ˈeːɾʲə] ( listen); Ulster Scots: Airlann or Airlan) is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth. To its east is the larger island of Great Britain, from which it is separated by the Irish Sea.

Politically, Ireland is divided between the Republic of Ireland, which covers just under five-sixths of the island, and Northern Ireland, a part of the United Kingdom, which covers the remainder and is located in the northeast of the island. The population of Ireland is approximately 6.4 million. Just under 4.6 million live in the Republic of Ireland and just under 1.8 million live in Northern Ireland.

Relatively low-lying mountains surrounding a central plain epitomise Ireland's geography with several navigable rivers extending inland. The island has lush vegetation, a product of its mild but changeable oceanic climate, which avoids extremes in temperature. Thick woodlands covered the island until the 17th century. Today, it is one of the most deforested areas in Europe. There are twenty-six extant mammal species native to Ireland.