Browsing articles in "Scuba News"
Mar 23, 2014

Water quality around the South-West

As everyone is aware the vis has been really bad around the UK over the last few weeks since the storms, especially so in the South-West and some divers have reported 2-5m in some areas but the normal level has been 0.5m-1m and it can clearly be seen from the surface that it is extremely milky.

The amount of runoff from the river catchments has been high due to the excessive rainfall we have had since the start of December but this would be expected to clear within a week or 2 from the time the rainfall ended as the waterlogged ground drained. This hasn’t happened and the water has remained milky without falling out in an expected time frame, so this brings into question what the issue is and what is (are) the contaminant(s) that is creating the problem.

I have trawled through the various agency sites looking for answers but have found none, one possibility that occurred to me was the palm oil that is dumped as the high volume of cargo ships clean out their ballast tanks, I do not think this is the most likely cause though as the amount of palm oil would be in the many millions of  tons to cause it to last this long. Another possible cause is something in the sediment that has been released as the many billions of tons of sand around the South-West was disturbed back into the water column, the heavier sand and pollutants falling out quickly leaving this milky substance that is ruining our pleasure of the sea at present.

I am going to be getting onto the Environment agency and Devon and Cornwall councils in the next few days to see if they would be willing to run some water quality tests over the next month or so, outside of their normal testing dates, to find the cause and to find if it is harmful in any way. As of yet none of the DivingJunkies in the South-West have grown 2 heads or complained of anything when they have come out of very short and uneventful dives but without knowing what it is, and if there is any longer term exposure issues it is best to say that everyone needs to be careful when they are diving, to try not to consume large amounts of sea water and to make sure they shower as soon as possible after their dive.

Will keep you updated when I find out more.

Aug 16, 2013

Underwater Photography and looking for the right camera

Part 1.

As a diver the feeling you get sharing the experience of being underwater is something special but it is hard to fully portray what it is like to non-divers unless you have photographs, or video to show them. I have been lucky enough to reach the big 40 this year and I was bought an awesome present by my family; which if you haven’t guessed yet is an underwater housing and camera with macro and wide angle wet lenses so I could share my underwater photography with them and anyone else I could bore.

The camera I now have is the Olympus PEN mini E-PM1, called a micro four thirds system, and the Olympus PT-EP06L housing with the Epoque DCL-20 Wide angle and Epoque DML-2 Macro lenses and as I learn how to use it and get good and bad shots will write about that in my dive logs.

Olympus E-PM1 and PT-EP06L underwater photography kit.

I would like to go through the process that led me to choose this camera and housing within the budget I was given for my present and it was hard in the end as it came down to 3 cameras, the E-PM1 and the Canon Powershot S range (S95 and S100 ), and they all excelled for what they are; making the final decision even more difficult.

Friends and advice

I have to say I was lucky here with having a friend that works in the film industry, doing the special effects that make us excited as we watch them. He has worked on a quite a few films and T.V. shows over the years but will leave it at that. With what he does he has to take many factors into account and has spent time away from his work learning about cameras so he has been able to match the computer generated components better to the filmed components. He had a limitation with his knowledge though, underwater photography and videography, he hadn’t spent as much time learning about this as he had not been involved with any of those scenes.

Even though I had a 35mm film camera when I was younger, and took many photos, I wasn’t fully aware of the differences with digital cameras and how much they had improved. I knew that sensor size and pixel count was important but not to which degree, or what other factors could make one or both of those irrelevant. The main considerations he taught me were the size of the sensor and its compatibility with the lens/lenses as well as the the ability to control white balance. We had many beers as I pried this information out of him but it was worth every mouthful of the golden nectar.

I also then have to say social networking can come in handy, which is where I met a couple of other people who are extremely knowledgeable as they are kinda semi-pro photographers who have been published in magazines and won an award or 2 in the underwater photography world.

It was while chatting to them that I found a website called imaging-resource with a fair system for testing the abilities for each camera, and as there are plenty of review sites on the internet with many good and bad points I felt this one covered enough for my level of understanding. The E-PM1 and S100 are thoroughly covered along with many other makes.

The importance of sensor size

I am sure someone is going to pick me up on techno babble but the way I see it after it was explained to me is that as the technology improves the number of smaller pixel sensors will increase and less software driven enhancements will need to be made to a point, so a full frame sensor (which is 35mm) may have had 8 million pixels resolution a few years ago, now is about 20-24 million and in the future will probably see it up in the 40 million range, but just like the restrictions on processor size due to the size of an electron, there will come a time when this reaches a limit as well due to the size of a photon. Both CCD and CMOS have filters in front of the sensor that allow the Blue/Green/Red wavelengths to get to the sensor which then uses some software enhancements to mosaic the image, but ideally this is where you want the enhancements to stop as a sensor doesn’t see in colour.

So taking each wavelength into account, you have the wave height from peak to trough, or amplitude, and if the sensor is too crammed for pixels then you wouldn’t get the full amplitude of each colour; this is where the limit of pixels to sensor size comes in I spoke of above. In underwater photography this is even more important to allow the most amount of light to be recorded as the image and insuring each colours wavelength is adsorbed by the sensor is critical. This also goes the other way, too much space for the pixels and you would get a washed echo effect making the colours less sharp.

Having this limitation with a sensor is where the software driven enhancements then come into play, from what I was told more recently than I started writing this article, is that any camera that goes below ISO 160 (sensitivity of light) is enhanced anyway, so choosing a camera with an ISO of 160-200 would insure you would not have any interference from over processed software enhancements.

Ability to customise white balance

This is fairly self explanatory, has the camera you are choosing got an option to manually select the white balance, or more accurately hold a white slate (or old ice cream container) at the distance you normally shoot underwater so the camera can adjust the pictures and you get the correct colours across that depth. This is where knowing the depths the wavelengths are no longer visible is handy.

Underwater camera choice

I told you earlier about the 2/3 options that were left for me after doing as much research as I could on what kind of cameras was available and it was either the Canon S95 (would have been secondhand), S100 and E-PM1. It was actually a hard decision seeing that each camera had advantages in their own right, and that the Canon cameras are slightly better for underwater photography due to the sensor being a little more sensitive. I think what did it for me was one of the evenings on the nectar with one of my friends in which he said ‘the limitations of only having one lens (the Canons) might get on your nerves when you shoot things on land’ and we went online and searched for mounts to use different lenses for the E-PM1 and the Canons and it was seeing the flexibility of the E-PM1 in this area that clinched it. Currently I have 8 lenses and only use the stock 14-42mm when I go diving, I am extremely impressed that a professional level lens 20 years ago can be bought for less than £40 today.

Underwater photography

I do not have an underwater photography gallery like many do on their sites, instead I am placing pics from my dives in my diving log, that way they can be seen in context with where I was diving. So feel free to check out my dive logs so far, I do have photos from a few places that are not mentioned in any dive books, or by any other clubs or schools but like everyone, it is nice to have a couple of dive spots to yourself and one day I will get round to sharing them. It will also be clear as to the lessons I am learning along the way and the quality of pictures improving as well as the composition.

Vobster Quay 10th Birthday Party

Vobster Quay 10th Birthday Card

Congratulations to Vobster Quay for a successful 10 years this year and what a way for them to celebrate, other than the Vobster Quay 10th birthday party over the weekend of the 7th and 8th September. For only £10 all camping and diving is paid for, air fills, food and drink are not but they will have a fully licensed bar onsite and a BBQ. There will be a live band in the evening with fireworks; tickets are going to be sold out quickly as limited space for camping.

Don’t miss out, contact them now to book your place for the Vobster Quay 10th birthday party.