Polarized light.... no more reflections!
Posted: 21 Dec 2010, 21:47
I have a plan to 100% eliminate reflections on the glass...
Best Option:
Use a sheet of linear polarizer positioned vertically in front of the lights illuminating the book, then a sheet of linear polarizer positioned horizontally in-front of the camera lens. What this will do is polarize all the light illuminating the book, and by putting the polarizer positioned the opposite way in-front of the camera all the light that is directly reflected by the glass will be eliminated, but all the light hitting the paper will be refracted and won't be polarized anymore and will pass through the filter in-front of the camera. One downside is each filter acts as a neutral-density filter reducing the amount of light that ends going to the camera, so brighter lights will be necessary.
See the picture how all light is blocked by positioning the films opposite:
Second Option:
Only use a polarizer filter in-front of the camera, and then angle the lights to minimize the glare, I think 45 degrees from the camera. This I don't think is the best option, but should eliminate far more glare than no polarizer filters.
Notes:
Also you need to make sure there isn't anything else that can refract the light and reflect on the glass.. so black fabric all over the place, behind the lights, behind the camera, etc... Paint everything flat black. Also bright lights are hot and any plastic polarizing film near it will melt, so be careful there too...
Source to get polarizing film, might not the be the cheapest, but was the first I found that has good options:
http://www.polarization.com/polarshop/
How does it work?
Heres a little graphic to illustrate how polarizers work
Best Option:
Use a sheet of linear polarizer positioned vertically in front of the lights illuminating the book, then a sheet of linear polarizer positioned horizontally in-front of the camera lens. What this will do is polarize all the light illuminating the book, and by putting the polarizer positioned the opposite way in-front of the camera all the light that is directly reflected by the glass will be eliminated, but all the light hitting the paper will be refracted and won't be polarized anymore and will pass through the filter in-front of the camera. One downside is each filter acts as a neutral-density filter reducing the amount of light that ends going to the camera, so brighter lights will be necessary.
See the picture how all light is blocked by positioning the films opposite:
Second Option:
Only use a polarizer filter in-front of the camera, and then angle the lights to minimize the glare, I think 45 degrees from the camera. This I don't think is the best option, but should eliminate far more glare than no polarizer filters.
Notes:
Also you need to make sure there isn't anything else that can refract the light and reflect on the glass.. so black fabric all over the place, behind the lights, behind the camera, etc... Paint everything flat black. Also bright lights are hot and any plastic polarizing film near it will melt, so be careful there too...
Source to get polarizing film, might not the be the cheapest, but was the first I found that has good options:
http://www.polarization.com/polarshop/
How does it work?
Heres a little graphic to illustrate how polarizers work