For this week's Tuesday Tech tip we wanted to focus on the power of multi-band imaging filters, such as the Optolong and Triad options that seem to have carved out space as the most popular two. Unlike traditional narrowband filters, these ingenious accessories allow multiple bands of light (rather than individual bandwidths), and they are specifically geared towards color cameras which have not typically been associated with high quality narrowband images. The first of these we can recall seeing was the Optolong L-eNhance, which was a combination of Hydrogen alpha and Oxygen-iii. This allowed for a traditional "bi-color" pallet to be achieved without any of the hassle of having to combine images from multiple filters. This concept was further expanded upon by the OPT Triad (and then the Triad Ultra) filter, which added other bandwidths including Sulphur-ii and Hydrogen Beta. The added effect of these bandwidths was to so much to increase the color pallet or dynamic range, but rather to allow other details to show up that might have been hidden if they were only present in the Sii or H-beta gasses.
Attached here is an image by our very own Isaac Garfinkle (@irg.astronomy - Instagram), in which we can see 15hr of "multi-band" data on NGC 7822. This was taken with the #OPT Triad Ultra filter and a little 70mm #SV70T. Even in the individual sub-frames you can clearly see the traditional two-tone blend of a bicolor image, but the effect is drawn out with more exposure time and the results look almost identical to images taken with traditional mono imaging. The white(ish) areas are where the nebula is heaviest with O-iii light, and the red(ish) areas are where you'll find the most h-alpha. Stacking and processing was done in Pixinsight, with a process very similar to typical broadband images. Most notably, this image was taken with a nearly full moon (>80% all three nights) and was almost entirely unaffected.
If you have any questions you'd like us to address for our Tuesday Tech Tip please do not hesitate to reach out by phone, email, or live chat on our website.
