I’m going to stick with my unmodded 450D for now. I would like to continue to use it for normal photography as well. IR filters are installed by the camera manufacturer to prevent IR light from reaching the imaging sensor. This helps to produce photos that reproduce what our eyes see (we can’t detect IR energy with our eyes- it is outside the visible spectrum). But these filters also make the camera respond poorly to important hydrogen alpha light from emissions nebula like the Veil and the background nebula of the Horsehead. Thus, the photos of emissions nebula with an unmodified DSLR may appear a bit washed out. The unmodified DSLR should work just fine for other types of nebula as well as galaxies and star clusters though.

There’s two main ways of modifying DSLR’s. One is to remove the stock IR filter completely and another is to remove it and replace it with a filter that blocks IR but passes most of the hydrogen-alpha energy. I have never tried this so I can’t provide guidance on how it is actually done!

I hope this helps

Ray Shore

Robert