Happy Holidays, everyone! I want to share my initial experiences with the SVBony SV220 dual-band 7nm SII-OIII filter for narrowband imaging with colour cameras. If you are currently only using the SV220 7nm/3nm Ha-OIII filter or any other HO dual-band filters at similar/smaller bandwidths for narrowband OSC imaging, the SV220 SO filter will be an excellent and cost-effective addition to your inventory, enabling you to compose beautiful tri-colour images with S, H and O signals.
The SV220 SO filter I have is the 2-inch version for larger sensors, as my primary OSC is the ToupTek ATR2600C with the APS-C-sized IMX571 sensor. The filter is also available in 1.25-inch for smaller sensors such as the IMX533 and IMX585.
Each one of the SV220 filters comes in a well-padded case. The transmission chart attached shows both signal peaks at SII and OIII reaching 90% transmission. The filter itself is protected by films on top and bottom, ensuring that the surface stays as clean as possible during transportation.
The filter’s sides have a similar reflective appearance, and the orientation is distinguished by a silver ring on the upper edge and the threads at the bottom.
I have the filter screwed into a filter wheel that also holds a UV/IR-Cut filter and a 6nm Ha-OIII filter from another brand. The SV220 SO filter is standard-sized, such that it’s compatible with all mainstream filter wheels/drawers on the market.
Because of the harsh winter weather, I had limited opportunities to try it out. Nevertheless, I was recently able to collect around 4.5 hours of data on each of my HO and SO filters under clear skies with good transparency. Below are some snapshots of SV220 SO frames through the newly released ToupTek HOPE D60 astrograph, each being a 300s exposure on the California Nebula (NGC 1499).
In my tests, the filter exhibited very good halo control, with no visible halos on moderately bright stars such as Menkib here. There could be faint halos and/or reflections from the brightest stars (such as Altinak) if used on certain systems/imaging train configurations, though I hardly saw any in my D60 at its 280 mm FL and f/4.66. It was a very pleasant experience to collect data through the SV220 SO filter, and it easily reveals SII signals in a reddish hue and OIII signals in a teal hue.
For OSC tri-colour composites, the DBXtract script in PixInsight can be employed to extract the individual S, H and O signals from the HO (left) and SO (right) dual-band stacks. The signals can then be combined in your favourite palette to produce the composite image :)
A traditional SHO palette is used here, which assigns the SII to R, Ha to G, and OIII to B.
The final processed image from the dataset above. The SV220 SO filter played an important part here in supplementing the OIII signals from my HO filter, as well as providing the SII signals that give the characteristic orange-golden highlight on top of Ha in green.
If you are interested in the filter and would like to give it a try, you may click on the link below to quickly access the SVBony online shop. Search “Narrowband Filter 7nm SII & OIII SV220” for this filter, or browse around and check out other items at good deals. Thanks for reading my review, and to all the users, I hope you will enjoy it as well!🙂
