Do i need to add a filter after doing a full spectrum mod to my DLSR?

[bluesilver]

Hi,  I have recently just modified my Canon EOS 600D DLSR doing the Astronomik MC clear class modification.

It is just basically completely removing the low-pass fliter 1 completely,

And also removed the IR Fliter ( Low-pass filter 2) and replacing this with the IR cut filter completely and replacing this with the Astronomik MC clear class.

The result it that you get a very red tinge if trying to use it in daytime with a lens,  which it is not intended for.

At night taking photos of nebular and the like i get a lot of red, too much red in fact.

I attach the camera directly to the scope, a Dobsonian in this case,  so i am not using the camera lens.

What i would like to know is,  Should i or is there a filter that i should be using in the T-Ring to get better colour?  as at the moment the images are way too red.

Should i be using something like the Badder Neodymium & IR-Cut Filter,  Or Lumicon oiii filter,  or Lumicon UHC Filter screwed onto the the T-Ring?

Any advice or information would be appreciated.

Thanks.

Edited August 8, 2020 by bluesilver

[endless-sky]

The color cast can be corrected in post-processing.

You could also just put back into place one of the two low-pass filters (I don't remember which one, but one of the two will only filter UV and IR). This should make things a little better, but you'll still probably have some color cast that needs to be corrected in post-processing.

That said, the main reason for not going completely full spectrum is that, when using lenses, or refractors, not all light wavelengths focus on the same focal plane. This effect is more evident the further into the red (IR and past) and into the blue (UV and before) you go, resulting in bloated stars or purple/magenta halos around them. That's why you want to put back the UV/IR cut low-pass filter or another type of UV/IR cut filter.

This, however, shouldn't matter if you only have mirrors in your imaging train (but will as soon as you add a lens - coma corrector, for example, if you use one).

Edited August 8, 2020 by endlessky

[Merlin66]

An UV -IR somewhere in the optical in the optical trainwill work well.