Hopefully this may be helpful for anyone wanting a play with long exposures without spending much (each filter was £3.00) its not perfect and the stronger the filter the greener the image you can colour correct but easier to go mono.
I didnt have a lot of time so nipped down to Hardwick hall late Sunday to take some test images using the 3 pieces of welding glass that I have which are.
1. No5 glass about 6.5 stops
2. No9 glass about 10.5 stops
3 No13 glass about 16 stops
My ready reckoner/memory aid was a piece of paper with a list of shutter speeds from 1,000 of a second to 128 minutes in one stop steps.
1,000, 500, 250, 125, 60, 30, 15, 8, 4, 2, 1second, 2, 4, 8, 15, 30, 1minute, 2, 4, 8, 16, 32, 64, 128
All images where taken on a Canon 40D with a tamron 11-18 lens manually focused and locked in position with some electrical tape.
The images below all connect to a larger image just click on an image to load a large version.
The light was changing from overcast to sunny evident in the last image of the big house by the stronger shadows and reflections on the windows this made it a little tricky keeping equal exposures,you can see the difference mainly in the sky and clicking through to the large size images there is plenty detail showing including all the lattice work in the windows, the very long shots the first of the stable yard 7 minutes had kids chasing all around me but you cannot see them and on the big house one there was someone who leisurely walked all around the garden in shot including standing in front of the camera and you cannot see her at all.
Please note the old lady in the wheelchair was alive although she doesn’t appear to move as much as the branches in the wind.
Anyway here is what I got all shot at f8 and ISO100
Taken with UV filter only 1/200 second
Taken with No5 welding glass 1/2 second
Taken with No9 welding glass 8 seconds
Taken with No13 welding glass 7 minutes
Taken with UV filter only 1/125 second
Taken with No5 welding glass 1 second
Taken with No9 welding glass 12 seconds