Narrowband Filter Choice - AstroGab2024-03-28T12:33:56Zhttps://astrogab.ning.com/forum/topics/narrowband-filter-choice?feed=yes&xn_auth=noIan, thanks for the feedback,…tag:astrogab.ning.com,2013-02-02:6354305:Comment:1225732013-02-02T05:41:34.977ZGreg Marshallhttps://astrogab.ning.com/profile/GregMarshall
<p>Ian, thanks for the feedback, even if it is late!</p>
<p>I didn't have any trouble with the H-alpha filter (I was using a 6nm filter for H-a). I'm sure it's true that you can't use a very narrow filter with a super fast scope because of the angle, but f/2 is pretty extreme. You must be using a hyperstar system, right? My primary scope is f/5.6 and other s I sometimes use are slower.</p>
<p>Some very knowledgeable people on another forum suggested I get a 5 or 6 nm filter for H-a and 3nm for…</p>
<p>Ian, thanks for the feedback, even if it is late!</p>
<p>I didn't have any trouble with the H-alpha filter (I was using a 6nm filter for H-a). I'm sure it's true that you can't use a very narrow filter with a super fast scope because of the angle, but f/2 is pretty extreme. You must be using a hyperstar system, right? My primary scope is f/5.6 and other s I sometimes use are slower.</p>
<p>Some very knowledgeable people on another forum suggested I get a 5 or 6 nm filter for H-a and 3nm for OIII and SII. However, I ran across a good deal on a set of 3nm filters - all three wavelengths plus a filter wheel. If it turns out that the H-a is too narrow I'm sure I can find someone who will trade a 5 or 6, since those are much less expensive.</p> I don't say that I'm an exper…tag:astrogab.ning.com,2013-02-02:6354305:Comment:1224872013-02-02T03:58:01.604ZIan Ghttps://astrogab.ning.com/profile/IanG
<p>I don't say that I'm an expert in this. But... when I was facing this question myself, and asked around, I found out that a major consideration in it is the f-ratio of your system. I even consulted with Dean at Starizona, since I image mostly with Hyperstar. He told me that I should be using not 7-10nm filters but much broader one. At f/2 the light cone is very steep and it actually shifts the band that is being filtered out. I ended up using Baader's 35nm H-Alpha. It is inexpensive,…</p>
<p>I don't say that I'm an expert in this. But... when I was facing this question myself, and asked around, I found out that a major consideration in it is the f-ratio of your system. I even consulted with Dean at Starizona, since I image mostly with Hyperstar. He told me that I should be using not 7-10nm filters but much broader one. At f/2 the light cone is very steep and it actually shifts the band that is being filtered out. I ended up using Baader's 35nm H-Alpha. It is inexpensive, high-quality and easier on the exposure times. Just my 2c.<br/> Ian</p>