Tuesday, 12 February 2002 Meeting

Photography in the Dark

A Talk given by Ivor Thurgood

Ivor began by describing his three main hobbies, that of: Hill Walking, Mineral Collecting and Photography and how he has combined these. His first slide was of a map of the main mineral locations in the British Isles, he then went on to show us some pictures taken underground at Cornish Mines circa 1900. All these pictures had to be posed as any movement would have destroyed the effect because of the long exposure times..

Ivor mused over the problems these photographers faced in those days. Miners used to work by candle light and the photographers had great big plate cameras and a magnesium flare flash to gain extra light need for their exposures.

Today, the technique he uses to light the interior of even the largest of underground chambers, is to set a tripod mounted camera on an open shutter release. Effectively, with no light available underground the shutter would stay open indefinitely. Ivor just wanders around with a flash gun and repeatedly illuminates various parts of the chambers, attempting to give an overall compound illumination. Eventually the camera shutter closes automatically when enough light has been received.

To focus his camera in the dark, he uses a quartz halogen torch to illuminate the area, this gives him enough light to be able to make adjustments prior to taking the picture. The light from the flash gun is far too short a duration for the eye to respond, other than blink.

He has further refined the technique and made his own battery powered strobe flash as commercial flash guns are not suitable. Ivor said that the environment underground was quite hostile to cameras and that he fitted a 24mm lens (wide angle) and never changed it again whilst below ground. If he has to change the film underground he does it beneath a cloth and by a sense of touch to avoid contamination by all the dust/moisture.

We were then treated to an awesome slide show of pictures taken by Ivor whilst on his many trips down old mines. (DON'T EVEN THINK ABOUT IT!!!RC) When he first started there were very few restrictions on entering old mine workings and collecting minerals. Today it is different. Illegal is the word most often used!.

Ivor concentrated on the Weardale Area, especially Nenthead and the Smallcleugh Mine. (My favorite too!). He said that relics of the old mining industry were being preserved in this area and being opened up to public access with conducted tours into Smallcleugh.

Ivor showed us one or two slides of mineral specimens of Sphalerite, Baryte and Fluorite before reluctantly closing his talk. One tip Ivor passed on, was that we should all keep our old maps and not dispose of them as much of the detail about now defunct mine locations does not appear in the new series.

His shear enthusiasm for the subject had me enthralled as I only collect minerals from Weardale and Scottish Agates, so naturally I'm biased! RC

Smallcleugh: Be prepared, make yourself comfortable before trying this link. It takes time to download, only a few minutes but it's worth it. When page one is loaded you will have to navigate to page 2.

More Mines: From the same area, same problem it takes time to load but I like both these.

Whatever you think, the small pictures here give you an idea of what you may have missed projected on a big screen during Ivor's talk. There is still lots of extra info. Take my advice concentrate on downloading the pages, don't try to read them. You might forget your on line and run up the bill! Yes I did almost get carried away. Read them later and enjoy! RC

Member's Finds on Display at the Meeting

Pyrite Cluster from the Upper Chalk exposed at Climping Beach, West Sussex.

This was one of several found by Sandra Blackburn. The other half of this team, Bob, went home empty handed.

(Having collected similar clusters from the Chalk, I found that some specimens are prone to decay whilst others remain stable. Something to watch for!).

A rather large fossil sea urchin (Echinoid) found on Climping Beach by Ursula and John Deith. (I'm not sure who wants to claim this one? ).

This is a specimen said to be an Echinocorys (It's about the size of the palm of a hand and is a big as they come for this species). The fossil appears to have been formed by the replacement of the soft body inner of the Test (casing/shell) with flint. The outer casing having been eroded away later. The patterns on the flint reflect those found on the the inside of the Test.

Calcite Crystals from Croft Quarry, Leicestershire.

Les Lanham had on display many (they swamped a 6 foot table) of the Calcite crystals he collected from Croft quarry a few years ago. This is just a taste of things to come as the Society has a Field Trip planned for later in the year. You can see some of this collection on the Club stand and discuss with Les, all the other minerals found at this quarry, at the Show, this Saturday, 16 February.

RC 13/02/2002                                                                                               Archive Reports