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  1. #31
    8HHaggis's Avatar
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    Quote Originally Posted by 8HHaggis View Post
    I've gotta say that though the founder of Lumicon, Dr. Jack Marling, is a person I've worked with and consider a friend, this list is PRETTY simplistic. I wonder if it is a "new" one that the current owners of Lumicon have compiled, or if it's originally one that Jack Marling himself posted...?
    Steve W/8HHaggis
    Further examination of the list convinces me that it is a MODIFIED version of David Knisely's study of "Common Nebulae" (a title that bothers me a bit since to many observers well up into the middle range of deep sky trollers might never have heard of a lot of the objects. What's "common"?) The Lumicon 'version' leaves out some objects but does have a remarkable commonality with David's list--including some items that one wouldn't even immediately think of putting in! Indeed, many of the nebulae are nearly invisible unless you have a true dark-sky site (approaching 7th mag--or better!--naked eye stellar limit at zenith.) Not just a few of them have surface brightness levels of 15th magnitude--that's faint compared to the showpiece Messier objects or things that beginners want to study.

    But, the inclusion of many of the VERY obscure nebulae toward the end convince me that it's really, for the most part, David's very comprehensive list of emission nebulae--even Sh 2-292 is identified in BOTH of them *exactly* the same way: "vdB93 (Gum-1) " and "near IC 2177", suggesting cut-and-paste. Is David Knisely credited in any way for his original work? No! (Incidentally, Sidney van den Bergh's reflection nebulae are also referred to in professional catalogues as "VDB" or "VdB" but in both articles they are called "vdB" which is further suggestive.)

    Just below Lumicon's table the page says "Copyright © 2006, Lumicon International - A Division of Parks Optical"; I searched all over the article to find any credit to David, and none could be located! I personally don't think--IF they did use his paper for a basis--that this is collegial, fair, and proper. (I'd hope that perhaps Parks/Lumicon sent him a free filter, and their thanks! David is an extraordinarily well informed amateur, an excellent observer, and a thorough reviewer. His articles and papers and posts always make for a great read. If he did 'inspire' or provide background for this Lumicon chart, I think he deserves the credit!)

    There are so many similarities in "suggestion" for particular objects that, really, I think you would be better off reading Knisely's *original* article, as he has much more information and says WHY he prefers a certain filter, and what the others seem, in his opinion, to do as opposed to his preferential CHOICE.

    I believe the best version of his paper is almost always the one on his own astronomy club:The Prairie Astronomer

    The latest edition of this paper pleases me very much more than the earliest ones of the mid-2000s. David does answer some of my criticisms about omissions of crucial information; now he gives the scope used for the observation and more info on the development of the project; when it started; and that he wanted to try to inform observers of some specific things that he felt were not well understood in general. All very laudable!

    I *do* however have many differences of opinion on various objects but in general I am certain that with David's scope and magnification, I'd probably be so close to agreement -- if I were there, peering around the corner -- that we wouldn't differ very much. The areas where I sometimes have an opposite opinion, or choose another filter, are primarily related to my specific goals with a *particular* nebula, and the exact scope I was using.

    For instance: I found that in comparing our views of NGC 281, David using a 10 inch f/5.6, 52x, and me using an 80 mm f/5 refractor at a variety of magnifications from 12.5x to 53x, that I did NOT experience only the 'small differences of opinion' he anticipated from most other observers, as predicted in one version of his paper.

    In fact, some of my filter preferences were the *reverse* of what he posits, with respect to the individual filters he discusses in his tests of this nebula! So, assuming that I am "not actually objectively wrong and have not blundered badly", then, who is RIGHT? Is it necessary to say one person is "right" and the other is "wrong"? Cannot both persons have their own individual preferences??!! THAT is what I believe!

    For: some of the narrower band filters can emphasize ONE aspect of the nebula while diminishing others. One might feel -- I do -- that the 'dark lanes' of Sharpless 2-101 are better seen with the O-III filter (at least to my eyes they are, in both my 10 and 11 inch scopes) than with the UHC type filter. In David's "official" paper, he concludes merely that the OIII is "very dim" and recommends the UHC (and alternatively the H-Beta.)

    But, beyond merely the dark zones, I felt strongly that in my two scopes, on several nights of testing the object (abetted with views in a 4" class scope and others) that the OIII filter also helped me to discriminate and judge the luminosity of the two distinct lobes of the nebula. On the other hand: David preferred the UHC for that very task!

    So...

    How many folks have observed Sh 2-101 multiple times? Not hundreds; not thousands, for sure. And of two long time, dedicated observers (I believe that Knisely has stated he's been at the game for 40+ years while I started deep sky observing 37 years ago, though I began solar system observing with my first scope some 55 years ago - sheesh!) well, guess what: we disagree. And, here, we happen to disagree using a scope of identical aperture and pretty similar focal ratio.

    Am I 'entitled' to disagree? Sure! So is anybody else and David would be the first to concur.

    So, the Lumicon chart is not nearly as useful as his actual paper--it just throws away all the qualifiers and background info that makes his choices seem sensible! And, of course, other choices can also be 'sensible' or 'stupid' depending on the observer, situation, goals...

    The final opinion I'd like to offer is that what is much more important, overall, to any single observer is TO DO THE EXPERIMENT HERSELF OR HIMSELF using the common deep sky visual nebula filters. You might radically disagree with me or with David or anybody else; if there's some sense in your method and you haven't made "a bad blunder" then I don't see WHY you can't prefer something else altogether!

    Steve W/8HHaggis
    Last edited by 8HHaggis; 03-25-2012 at 04:07 AM.

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  3. #32
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    Default Re: Filter's

    I'm from the Kings Mountain in North Carolina and just recieved the zhumell Olll and UHC filters and can I tell ya the galaxies are poppin right out of the night sky.Last night was my second night of searching DSO's and I even tacked a satelite not to get off subject .I have a very simple game plan each night. My backyard is my world within reach,that's what it says on my light cannon 10".Can you say dark site,as long as Lany keeps the lights off,It took some time but I got my neighbors to cut the outside lights off when I go to my world.Pretty cool ,I've got some pretty cool neighbors. NOT EVERYONE CAN SAY THAT! Gameplan look at only bright or only dim,works for me and I get my views in not once ,not twice ,but several times over without have to let my peeps adjust.Try it sometime you won't be disappointed
    Last edited by stepping beyond; 08-09-2012 at 06:21 PM.
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  4. #33
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    Default Re: Filter's

    Perhpas someone could add advice to this (somewhat disputed) list to include Light Pollution options.

    Since it is a sticky, I would add such ammendments to the first post, so it appears on the first page.

    Clears,
    Joe
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  5. #34
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    Default Re: Filter's

    I got 5 planet filters & a free moon filter & i dont use any of them.

  6. #35
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    Default Re: Filter's

    Quote Originally Posted by 8HHaggis View Post
    I've gotta say that though the founder of Lumicon, Dr. Jack Marling, is a person I've worked with and consider a friend, this list is PRETTY simplistic.

    I was groovin' along with the list, very impressed with the part about the planets...but when I got to the deep sky objects, I stopped dead...because one by one, I either disagreed, or felt that the "best one" is not a really meaningful and possible choice for all viewers, all scopes, and for ALL aspects of these remarkably varied objects.

    In fact, though I've seen other compiled lists of recommended filters, including what is perhaps the most celebrated one, for emission nebulae (by David Knisely), I feel that it's important that one not just STOP at any single filter recommendation, but check the object with all the filters used for deep sky enhancement; at the very least, the LPR, UHC, and OIII types.

    The reason is that when you change magnification (& therefore exit pupil) you vary about everything you can see with any of the filters. Sometimes the LPR type (which might barely seem to do much of anything visually, at low power) will have an AMAZING improvement--at high power! And the opposite is true of the OIII--at high power, pfft. Most things except tiny planetaries are hard to see at super high power; at low to medium-low (in almost any scope!) that filter SINGS.

    And for every one of the filters *and nebula types* there are exceptions to what I've suggested, above.

    If you can handle an expenditure, BUY THOSE THREE TYPES. Then you are set and you can have a ton of fun experimenting--your results might be unique to your situation, and differ from the "advice of authority figures".

    (Uh...by the same token I advise you to be skeptical of MY advice and not just take it for granted!)

    Yours,
    Steve W/8HHaggis
    Hello Steve, hello all,

    I second to your experience, as summarized above.

    In fact, a set of the nebular filters, like OIII, H-Beta and UHC, is needed to extract as much as possible details from the emission and planetary (they are also emission) nebulas. There is a mass of examples on it, like observations o M42, or the '3D effect' on the Rosette,

    The Rosette Nebula through the Binoculars and Filters: 3D Viewing?

    I would include also my preferable set on observing details in the galaxies:
    UHC filter for the bright galaxies, like M33,
    SkyGlow multiband (Neodymium) filter to increase the contrast between the core and the outer halo
    blue(RGB) CCD interferometric (not color glass!) filter to increase the contrast of the outer spiral arms populated with the blue giants, like M31, M33

    Best

    JG
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  8. #36
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    Default Re: Filter's

    An oldie but a goodie, for information only...
    6 inch F/5 GEM mounted reflector

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