stacking filters

[Daniel-K]

Just a couple of questions.

do I need to use my Lfilter with my LP or HA filter when taking subs?

is it okay to screw filters into each other to stack them?

until I get my filter wheel and 2" IDAS I'm a little unsure how one goes about using filters with my atik414ex and just using the nose piece.

For the time being I've decided to just use it as mono and HA to keep it simple until I get get to grips with the setup.

[MattJenko]

Narrowband filters will not need to be stacked with other filters because they restrict so much of the spectrum anyway, the additional frequency blocking LP filters are not required as the light is already blocked by the narrowband filter. For broadband filters and Lum filters, it is less clear cut (pardon the pun). If the wider band of frequencies allowed by the broadband filter covers specific bandwidths that an LP filter restricts, then there may be some benefit in having both filters. the certainly applies to Lum, which will allow the widest range through. Hope that makes sense.

[MattJenko]

I do know that some people screw the 2" LP filter into the end of a 2" nosepiece and nosepiece is then T threaded onto the filterwheel/camera and then the whole thing slotted into the focuser. This can be left in place for any filter chosen in the filterwheel.

[Droogie 2001]

14 minutes ago, MattJenko said:

Narrowband filters will not need to be stacked with other filters because they restrict so much of the spectrum anyway, the additional frequency blocking LP filters are not required as the light is already blocked by the narrowband filter. For broadband filters and Lum filters, it is less clear cut (pardon the pun). If the wider band of frequencies allowed by the broadband filter covers specific bandwidths that an LP filter restricts, then there may be some benefit in having both filters. the certainly applies to Lum, which will allow the widest range through. Hope that makes sense.

If like me you have a LP filter screwed into the imaging train already is there going to be an issue when capturing Narrowband light? As you mention Narrowband filters a lot of the unwanted light anyway but just wondered if by having an LP there is it going to reduce what the Narrowband will receive? Its not a show stopper but it would nice to be able to leave the LP in permanently rather than having to remove it when I want to image Narrowband targets

 

[MattJenko]

LP filters attempt to block light at particular frequencies that are emitted by standard human generated lights, like sodium streetlamps etc and they transmit the rest. These blocked bands do not correspond to the very narrow bandwidths that the narrowband filters allow, like the Ha band, Oiii band etc, so in effect the LP filter will block out light that the narrowband filter will also block, so there is no theoretical problem in stacking them. In reality there will be a tiny amount of loss as I don't imagine any filter has 100% perfect transmission, as it is a piece of glass at the end of the day, but the loss/degradation will be insignificant with a decent LP filter.

[Droogie 2001]

Thanks for the explanation that's good to know..