I have performed filter modifications on a number of DSLR cameras for me and my colleagues. It involves the removal of the stock UV-IR filter, making the camera more sensitive to H-alpha wavelengths. This modification is helpful only when shooting targets with H-alpha emissions, as Canon’s standard (stock) filter blocks this part of the spectrum.
Here are sample images taken with the modified cameras. Take note of the shift in white balance (reddish hue), which is to be expected in this type of modification.
Night Sky in Focus | Astronomy and Amateur Radio © Anthony Urbano | Manila, Philippines