bomberbaz Posted April 12, 2023 Share Posted April 12, 2023 Hello all. I currently use this ZWO dual band Filter when imaging nebula and the details can be found at the link. This has a fairly high bandwidth of 15nm in HA and stated transmission of "over" 80%. I don't like this because this could vary from 80.01 to 89.99, a considerable difference but that's another story. I was wondering if adding more data to an hydrogen rich image using a tighter bandwidth filter is worthwhile consideration with the OSC camera (It's the ZWO 183 MC Pro ) ZWO 1.25" Ha 7nm Narrowband Filter | First Light Optics Has anyone tried this and had any success ? cheers steve 1 Link to comment Share on other sites More sharing options...
Lee_P Posted April 12, 2023 Share Posted April 12, 2023 Tighter bandwidths do make a difference. See my review of some dualband filters here for examples. The Optolong L-Ultimate is possibly the best available right now (Ha / OIII dualband, 3nm) but it's 2" only and expensive! 1 Link to comment Share on other sites More sharing options...
vlaiv Posted April 12, 2023 Share Posted April 12, 2023 48 minutes ago, bomberbaz said: . I don't like this because this could vary from 80.01 to 89.99, a considerable difference but that's another story. Depending on conditions of the night that you don't control difference of 9.99% in light transmission is small. You can get up to 40-50% loss of light depending on how and when you choose to image a target - and most people don't ever consider this. 49 minutes ago, bomberbaz said: I was wondering if adding more data to an hydrogen rich image using a tighter bandwidth filter is worthwhile consideration with the OSC camera (It's the ZWO 183 MC Pro ) ZWO 1.25" Ha 7nm Narrowband Filter | First Light Optics Same principle applies to OSC as does to Mono when comparing two filters with different bandwidth. Both will let same signal pass (with differences to a few percent in transmission). Where they differ is amount of other light that they will pass. This is value of NB filter - in cutting off unwanted light. Tighter the bandwidth - less unwanted light is passed. This is especially important in light polluted scenarios, or when you want to separate close lines - like Ha and SII (656nm and 672 - so gap between is about 16nm and filters like Ha with 30nm bandwidth might not separate the two - depending on CWL). 1 Link to comment Share on other sites More sharing options...
bomberbaz Posted April 12, 2023 Author Share Posted April 12, 2023 6 hours ago, Lee_P said: Tighter bandwidths do make a difference. See my review of some dualband filters here for examples. The Optolong L-Ultimate is possibly the best available right now (Ha / OIII dualband, 3nm) but it's 2" only and expensive! Great review Lee. If I had a bottomless wallet it would be the L-ultimate, shame they don't do a 1.25"! However the Askar dual band is a compelling buy at that price and performance. Thanks for bringing it to my attention. Steve 1 Link to comment Share on other sites More sharing options...
Elp Posted April 12, 2023 Share Posted April 12, 2023 What's wrong with the L-Extreme? 1 Link to comment Share on other sites More sharing options...
Lee_P Posted April 12, 2023 Share Posted April 12, 2023 1 hour ago, Elp said: What's wrong with the L-Extreme? L-eXtreme is a solid choice, and the OP should be able to find a second-hand one for a good price. The catch is that it does feel a bit "last generation" compared to new models like the L-Ultimate (which, to be fair, it is!) Specifically, the L-eXtreme gives halos around bright stars, and is 7nm. Excellent results are still possible of course. I used an L-eXtreme extensively before the L-Ultimate came out. Link to comment Share on other sites More sharing options...
licho52 Posted April 16, 2023 Share Posted April 16, 2023 I think it's worth doing and I have done with some star fields in the galaxy disk like Cas. It's a very clean Ha signal without the O-window, especially with light pollution and/or moon. First I'd look in classifieds where 1.25 Ha filters may pop up for a much friendlier price. 1 Link to comment Share on other sites More sharing options...
900SL Posted April 24, 2023 Share Posted April 24, 2023 Antlia ALP-T is working for me, and it seems to be an accurate bandpass. Link to comment Share on other sites More sharing options...
iantaylor2uk Posted April 24, 2023 Share Posted April 24, 2023 I like the L-Enhance filter for my OSC - it doesn't have as much of a halo problem around bright stars that the L-Ultimate has. Link to comment Share on other sites More sharing options...
bomberbaz Posted May 5, 2023 Author Share Posted May 5, 2023 For anyone interested I eventually went for the askar, the price and shootout results made it a compelling buy. If they ever bring out a 1.25 ultimate, I would be tempted. 1 Link to comment Share on other sites More sharing options...
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