which filter will help with a dslr to catch nebulosity

[beamer3.6m]

I want to advance in the world of dso imaging and I feel a filter is required to make such a move.

However I am a little confused.

I want to bring out the nebulosity of the plaides for example with my canon 400d attached to my explorer 200p at prime focus.

Any ideas on the best filter and the corecy size.

I am hopeful to spend around the 50.00 mark but this could be short.

Any help appreciated.

Cheers guys.

[Merlin66]

If your Canon is not modded, the response to red H alpha light is pretty poor and very long exposures are required to pick up the detail in DSO's. This then adds to problem of sky glow and light pollution.

Blue reflection nebula should be OK.

The favourite solution for a DSLR seems to be the CLS clip in filter, which also acts as a dust shield.