Quote:
Originally Posted by Millsy
Ok so I bought an L-Extreme duo band filter secondhand.
To be honest I expected more. It was ok but I dont see much difference than I did with my Zwo Duo Band.
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Hi M,
Looking at the transmission curves , roughly lined up below, you can see that the transmission in both Ha & OIII is similar for both filters at around 90%, with the ZWO having a much broader OIII bandwidth and a slightly wider Ha bandwidth. Depending on your local sky conditions (light pollution) and the spectrum of emissions from the target you might not notice that much difference.
Where there is sometimes some differences seen between filters is in halo effects, especially noticeable around bright stars/objects which are related to coatings and optical precision of surfaces.
You could only really know if there are differences with a true back to back comparison of the filters on the same night, same object using the same gear. Of course, as Bojan suggested (Hi Bojan), you could always try to test the transmission spectrum for the filter using spectral analysis gear.
Best
JA