Do filters have a right and wrong way round?

[blinky]

Just recieved my new camera ZWO1600MM Pro and I also bought the RGB and Narrowband 31mm filters and wheel.  When mounting the filters in the wheel is there a right and wrong way round for them and how do I tell which is which?  Im thinking it might not matter but wanted to check before I spend the time mounting them and then have to remove again to check which way round they are!

[Dr_Ju_ju]

I have the 1.25 wheel variant & mine just get screwed in from the same side that gets exposed when you remove the facia panel.... 

On mine if I did it the other side, they would clash with the casing...

[blinky]

I mean the actual filters - do they have a right and wrong way round?  Should there be a face of the filter which faces the stars and a face which faces the camera?

[drjolo]

Usually it should be recommended by manufacturer - for interference filters at least. For example for Baader mounted filters the side with thread should point to camera. For Baader unmounted filters there is a mark at the filter edge that should point to telescope. I asked Baader once about it, and my conclusions were:

1. proper orientation is more important for filters that pass less light, like narrowband, so the reflected light will be pointed towards telescope and sky, not camera
2. in some rare cases, when you see much reflections you can try to mount filter other way to check
3. another way to fight with reflections is to change distance between sensor and filter. Sometimes a few mm makes difference

I don't know however if that also applies to ZWO filters ( I suppose it does ).