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by Andy McInroy
Photograph Of The Month - October 2008

Cathedral Cave, White Rocks, Portrush, County Antrim
5P27, Cathedral Cave, Whiterocks, Portrush, County Antrim

A Fisheye Perspective

My photographic study of Antrim's sea caves has continued at a good pace this year. I originally imagined that the project might take six months to complete. However, I am now twelve months in and it looks like the adventure will continue well into 2009. The more research I do to uncover these secret caverns, the more I find. Unfortunately, the Atlantic swells are starting to pick up again as we head towards the winter. Many of the larger basalt caves will be off limits to my small dinghy until next year.

I recently purchased a specialist lens called a "Fisheye" which I hope will give a new perspective on some of these huge caverns. The fisheye lens is a super-wideangle lens which takes in a hemispherical view. The lens, a Pentax 10-17mm fisheye, offers views up to 180 degrees and allows larger sections of these caves to be captured on camera. Fisheye images typically display a distorted, convex appearance but I had a feeling that the enclosed surrounding structure of the caves would disguise the distortion.

I decided try out the lens in the cave which inspired this whole project, Cathedral Cave at the White Rocks. I was accompanied on this visit by some friends who were able to assist me by standing in shot, thereby providing some scale. The same, tried and tested techniques were used to expose the photographs. The camera was sat on a tripod and five photographs were taken spanning the exposure range from the bright opening to the darkest shadows. The sequence of five photographs took 60 seconds to fire off and during that time my subjects were under strict instruction to stand as still as statues.

Back at the computer I used specialist computer software to merge the 5 exposures together using HDR (High Dynamic Range) techniques. The interesting feature of the fisheye lens is how it maps a large, hemispherical space onto a flat, two-dimensional image. The walls of this cave actually angle back from the cave entrance yet in the photograph they appear flat with the opening. This optical illusion gives the cave an exaggerated sense of space and takes the photograph to the limits of what is believable.

It remains to be seen if I can apply this lens to general landscape photography. It is a difficult lens to work with when the horizon starts to bend and the sky becomes immense in the frame. However, I'll certainly have some fun with it in these dark caverns of Antrim. Just as long as remember to keep my own feet out of frame !

Technical Details (5P27 above)
Date/Time: 12.15pm 14th September 2008
Aperture: F8
Exposure time: 1/250th, 1/60th, 1/15th, 1/4, 1 second
Exposure blending: HDR using Photomatix
Focal Length: 10mm uncorrected fisheye (APS Sensor)
Lens: Pentax 10-17 DA Fisheye
Camera: Pentax K10D
Support: Tripod with cable release
Filtration: None

Technical Details (5P29 below)
Date/Time: 12.03pm 14th September 2008
Aperture: F8
Exposure time: 1/250th, 1/60th, 1/15th, 1/4, 1 second
Exposure blending: HDR using Photomatix
Focal Length: 10mm uncorrected fisheye (APS Sensor)
Lens: Pentax 10-17 DA Fisheye
Camera: Pentax K10D
Support: Tripod with cable release
Filtration: None

Cathedral Cave, White Rocks, Portrush, County Antrim
5P29
Cathedral Cave
White Rocks,
Portrush, County Antrim


Text and photos © Andy McInroy