The Lum filter is a temporary reflection testing filter we fitted in in preparation for another filter I have on order, Pete need not have bothered sending you the flats for this sorry Richard, so please ignore them :(
This leads me into the other new filter we are fitting on the next trip, Its a luminance filter with enhanced HA response whilst still maintaining colour balance, I was hoping it would be useful for H2 regions in galaxies plus other things. I was trying to keep this one under my hat LOL
The IDAS HEUIB-II (H-α Enhanced UV IR Blocking) filter is designed for enhanced spectrum DSLR's and one-shot colour CCD astronomical cameras.
Besides removing the IR and UV ends of the spectrum which are often out of focus in refractive optics, it isolates the common H-alpha line relative to the surrounding extreme red end of the spectrum, making it easy to bring out the faint H-alpha emission nebulosity of astronomical photos, yet retain the background colour balance of broadband photos.
Available in 52mm and 48mm sizes mounted in standard camera filter rings, 37mm size mounted for the Canon MFA, and unmounted in 36mm and 49mm sizes. The filter is also available as a Nikon front filter.
Some comparison shots taken with the enhanced Canon 6DH (standard Canon UV/IR blocking filter vs. HEUIB-II filter) show a clear difference both in background sky color balance and contrast of H-alpha nebulosity in the extremely faint object IC1396. Note the good background colour balance as shown in the histograms of the individual color channels of the HEUIB-II filtered image. Click on images to view enlargements.
The HEUIB-II filter also returns normal daylight colour balance to spectrum-enhanced cameras as can be seen in this photo at right taken with normal DSLR auto-white-balance (AWB) enabled.