Calibrating a camera for colour underwater
The deeper you go when diving, not only does it get darker, the visible colour also changes. This is because water absorbs Red Light as you go deeper and therefore everything gains a blue hue. Digital cameras can be set to automatically compensate for this.
This picture is taken on the surface with the camera on its normal settings
and this picture is taken with the underwater colour compensation setting active. On my camera, you take a piece of white plastic down with you to around 25m depth and then take a picture of the plastic with the “calibrate” function active – the camera then says to itself “this picture is supposed to be white, how much red do I need to add to make it white” and the result is magic (at least they would be if the photographer was any good) and applied to all future photographs. One of our group (Ray Holliman) who really knows about photography (and took some amazing pictures with his camera equipment which weighed in at 15lb) also said that you should reduce the ISO rating of the picture settings to 200. His pictures were brilliant and a few of those which he shared with us have been used later in this blog.
As we leave Port Ghalib, the effects of the recession and politics upon tourism in Egypt are apparent. There are
some 30+ boats moored around the harbour, about one third of then are day boats and the rest are long range liveaboards such as the boat I am on. When we came back, 10 were moored during the middle of the day and none of the day boats which returned around 4 pm were anything like full.
Last night as I walked around the development, it was noticeable how many shops and cafes which were open the last time I was here are now closed and also that only three of the big boats had divers on them. There were few tourists around and shop keepers pounced on anyone who showed any signs of lingering.
It is also obvious that over the past two years, no further development has taken place. The Marina Lodge hotel is
still isolated on one edge of the development and is still surround by sand, and the yacht wreck which
was on the foreshore the first time I was here in 2008, is still there. They say this yacht was owned by an American whose engine failed as he was leaving the harbour in bad weather and his yacht was washed onto the rocks. The first time I was here, it was still on the rocks and its sails were in place – now it is a beached hulk.
Dive 1 Check Dive
The first dive of any trip is known as the Check Dive and its purpose is to enable us check our equipment is working ok before we get too far from a dive shop, to enable us to get our weights correct, to calibrate our cameras and also to let us practice a few of the essential diving skills such as putting up a surface marker buoy. It is probably also an opportunity for the dive guides to observe our diving skills – the number of dives held by people on the boat varies from 21 to 2000+.
Abu Dahab is about 2 hours south of Marsa and consists of a large coral reef, a wreck and numerous swim throughs, some of which are quite tight. We enter the water off the back of the GSS at a position between the two shoals and slightly north of the wreck.
The wreck is that of a liveaboard which caught fire whilst its guests were doing their check dive. Apparently the owner had had the kitchen converted from propane to electricity but had used the wrong size of cable. Whilst the check dive was taking place, the crew started to prepare lunch, the cable over heated and caught fire and the boat sank!
The boat’s engines are still visible and evidence of its life
as a liveaboard is given by this large metal serving dish
Underneath the stern in a large Crocodile Fish – we give it a wide berth although they are not poisonous and rarely grumpy unless closely disturbed.
We also encounter a Picasso Trigger Fish
a Blue Spotted Ray
Cauliflower Coral
a clam (which closes if you waive your hand over its mouth)
and a dead clam
a really beautiful Red Anemone lived in by a Clown Fish
Lots of nice coral trees
and Fire Coral which gives you a nasty sting if you touch it (the cure is to apply vinegar)
There are numerous twisting swim throughs with sunlight streaming through the coral roof.
If you are last in the group however, sand gets churned up from the sea floor and visibility can get considerably reduced as in the above photograph.
There were a number of the above on the sea floor around the reef. It is uncertain as to what they were. One dive guide said it was a shell, the other said it was Sea Cucumber Poo – I tend to go with the second guess because it does look like worm castes one sees in fields. The pile is about 15cm across and 10 cms high and could be the result of a sea cucumber ingesting and excreting sand.
The check dive goes without incident and I also demonstrate that I can put up a Surface Marker Buoy (SMB) without shooting to the surface at the same time. The water is very warm at 32C and therefore the 5mm suit gets confined to the suitcase for the rest of the week.
We then head further south for the next dive.
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