Neutral Density Filters
The big Lee 10 stopper ND filter works out an expensive piece of equipment, first you have the filter itself add a holder to put it in plus the adapter ring to suit your lens and you are talking over £150 before you can even get out and try it. So what are the alternatives if you want to shoot long exposures to blur those clouds and give water that silky sheen
Welding Glass as a ND Filter is not a new idea but it was a viable alternative to explore the world of ultra long exposures. Sourcing any kind of high end photo gear in Portugal is hard work and in the Algarve there are No specialist Camera Shops to be found anywhere. But there are a few welding shops here in Faro and a 15 minute walk brought me to his front door.
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You can imagine the conversation in the shop this mad englishman wants a 100 x 100mm shade #10 welding glass for photographic use. The bad news was he did not have any that size but after a 10 minute search in a store room came back with two pieces 100 x 75mm @ €1.00 each so the deal was done for the shade #10 piece for €1.00.
The next dilemma was something to attach it to and the ony filter I have with me was a polarising filter so that would have to do. The welding glass was attached to the filter with black electrical tape, firstly to hold it and secondly to ensure no stray light could get in round the side of the glass. 10 minutes later and I was ready for my first test.
First job was to calculate the exposure compensation and then the white balance adjustment because welders glass gives a green cast. A row of whitewashed buildings was my first shot with the camera set to RAW format without the filter ISO 50 F11 1/125 sec (see below left).
Next step was to correct the colour cast which proved to be much easier than I expected, The Canon software for the camera DPP (Digital Photo Professional) has an eye dropper white balance adjustment tool so all I needed to do was click on the white buildings and the cast was gone. I saved this adjutment for future use, a single click will use those settings again.ISO 50 F11 120 sec with Welders Glass
Next I processed the image using exactly the same settings as the first image
The Corrected Photo with the same processing as the one without the welders glass,notice how the clouds have become a blur.
My next step was to work out the exposure compensation using 1/125 Sec. to 120 Seconds = 14 stops. I then produced a table to reflect this for a number of different shutter speeds.
Shutter Sec. Min.
1/250 64 1' 04"
1/125 128 2' 08"
1/64 256 4' 16"
1/32 512 8' 32"
1/16 1024 17' 04"
1/8 2048 34' 08"
1/4 4096 1. 08' 16"
1/2 8192 2. 16' 32"
1.0 16384 4. 33' 04"
The ISO and aperture do not effect the exposure compensation. so set the aperture and ISO to get the shutter speed you require without the ND Welders Glass and read off the increased exposure with the ND Welders Glass.
Next was to go out and shoot a proper long exposure with both clouds and water however the weather and tide were all wrong, strong winds and shooting at 4:00pm with the sun straight in the camera lens made for difficult conditions, but I still got the shot at the top of the post. Without Welders Glass it metered 1/125 Sec, F14, ISO 100.
With Welders Glass the exposure was 128 seconds F14 ISO 100.
So for a total cost of €1.00 I now have a new addition to the photographers tool box which I can't wait to try out in the right conditions..
ManateeVoyager June 2013
A travelling photographer from the South of England who is on a journey of discovery around Europe in his sailboat Trelawney.