[jase (Jason)]

Jason,

Welcome. No need to lurk around here.

You’ll find that regardless of the filter manufacturer, light pollution will always compound the performance of a given RGB filter set. If light pollution is a real issue, consider narrowband imaging or escaping to a dark sky site to collect the RGB data – depends on how keen or serious you are.

I’ve had the pleasure of using both Astrodon and Custom Scientific filter sets. The three manufacturers you mention all produce excellent filters for the amateur. It would appear Astrodon is becoming the de-facto standard. The “tru-colour” design is achieved through colour cross over techniques between the individual R,G,B wavelengths. This technically allows an RGB balance of 1:1:1. In reality, the balance is never 1:1:1, but is close. I’d still recommend performing a G2V star calibration. The Custom Scientific filter set also produces nice results – I currently use these.

The nice attribute of the Astrodon filters is that the colour cross over allows for OIII teal to be successfully acquired. I found this is only really prevalent for certain targets, namely the Dumbbell nebulae. You can of course still obtain similar results with other filters by blending specific data in to the G and B channels. Many believe the Astrodon filters make imaging easier. I certainly haven’t found using them any easier than other filters. There is still the opportunity for colour gradients to occur on each channel, balance issues, reflections etc. Just about all manufacture par-focal filters so refocusing between filters isn’t an issue. Though I typically refocus anyway. Keep in mind that an LRGB set may not be par-focal with narrowband filter set. The Astrodon’s are, but the narrowband Custom Scientific narrowband filters aren’t. Again, this isn’t a big issue if you refocus between filter changes, or even better configure a filter focus offset so that when the filter is made active, the motorized focus compensates for this. Plenty of ways to solve the par-focal problem.

I’d recommend getting some unmounted filters for the SBIG carousel to minimize vignetting (very minor anyway). Something that I don’t like with the Astrodon’s is that there is and I and E series of filters based on the chip you are using. From my perspective, this is too limiting. What if I wanted to change from the STL11k to an STL6303? You guessed it, I need to purchase a different set of Astrodon filters to match the transmission/chip sensitivity to maintain balance. I do however know of a few people that use the I series with an ST10XME with no ill effect, but you’ve got to wonder…

StrongmanMike (check deep sky section) has punched out some magnificent images with an Astronomik filter set riding the ProLine. Its difficult to go wrong with either of these three (CS, Astronomik or Astrodon) filter set manufacturers for LRGB sets. In comparison, narrowband filters require additional consideration. Only a few manufacturers offer small bandpass window such as 4.5nm Ha filter. You need to shop around and calculate your optimal imaging train configuration. A larger bandpass window will let more continuum energy through (more stars etc), thus will reduce the required exposure time, but may upset the Ha purist who want the cleanest possible transmission or looking to use a companion Ha continuum filter to remove the remaining impurities (typically faint stars). A wider bandpass can also result in star bloat problems if not careful (usually manageable through image processing). If you're doing self-guiding and the guide chip is also behind the Ha filter, you may find guide star selection will become difficult - you may need to bin the guide chip boost the sensitivity (compensate for the lack of light the filter is permitting through). Plenty of other things to consider. The narrowband filter selection is probably another discussion.

The above is probably not a great help, but will try to answer further questions you may have.