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  1. #1
    Mark Smith's Avatar
    Mark Smith Guest

    Default How Do I - Getting Started with Filters and Evaluating the need for Eyepieces



    2 questions but first, my feel good story from last weekend.

    I was set up to a couple of monster telescopes (you know it is going
    to be impressive when the first thing out of the guys van is a 10 foot
    stepladder!) and what I was told was a nice 4" Refractor (a
    Takasomthingorother Flourite). I was having fun and the people with
    the refractor were very generous showing their photos. In any case, I
    was on M51 and they were viewing some dense cluster (omega something,
    very low on the southern horizon from 32 degrees N). We traded
    telescopes for a few minutes and both of them said they were impressed
    by the view through mine (I complimented them as well, it was a very
    nice view of the cluster). Later on, several people stole looks of M3
    and M13 and I got several compliments, a couple saying that the view
    through my telescope was the best they'd see that night (well, I had
    the 35mm Pan in so...). I know it doesn't mean much, but it certainly
    made me feel good.

    Oh, yes. There was a real point to this post.

    I've had my telesope for almost 4 months now and have had it out a
    number of times both in my back yard and at dark sky sites. I have
    been looking at the eyepieces I use alot and thinking about what I may
    want to upgrade. I know that evaluating the "need" for a new eyepiece
    is more like "I want it, I want it, I want it" (you feel like a 5 year
    old in a candy shop), but what do you look at when you are deciding
    which one to buy next? So many of these eyepieces are very close to
    each other that the choices can be a bit bewildering.

    My more immediate question, however, involves filters.

    I got the Celestron "package" when I bought my telescope that includes
    a Lunar Filter and a bunch of the standard colored filters (all 1
    1/4"). I've use the lunar filter a bit and know (or at least I THINK
    I know) that the colored filters are primarily used for trying to
    tease details out of planets. I can just start to experiment and see
    where that takes me.

    My real question is where to start on trying to tease details out of
    DSO's. I'm guessing that a filter won't do much for a cluster, but
    I've read that various filters help bring detail out of galaxies and
    nebulas. What are the essential filters to get (the top 2 or 3 )? I
    notice that my William Optics Dielectric has a threaded insert. Can I
    screw the filter into that so I don't have to keep changing the filter
    to each eyepiece? Is there any disadvantage to doing that? Is there
    any other advice you have?

    Thank you for your continued help.

  2. #2
    Jim's Avatar
    Jim Guest

    Default How Do I - Getting Started with Filters and Evaluating the need for Eyepieces

    Mark Smith <emarksmi@san.rr.com> wrote:


    No filter will enhance galaxies (with the possible exception of a light
    polution filter) as galaxies are broad spectrum emitters.

    The top 4 filters, as I understand it, are:

    UHC (Ultra High Contrast): enhances detail in most emission nebulae.
    Stars dim by between 0.5 and 1.0 magnitude.

    OIII (Oxygen 3): passes less light than a UHC but dramatically icreases
    contrast. The filter of choice for most planetary
    nebulae and the Veil complex. Stars dim by between 1.0
    and 2.0 magnitudes

    Hb (Hydrogen Beta): Used for very few objects, most notably the
    Horsehead.

    Light Pollution: Blocks wavelengths associated with common light
    sources.

    The rule of thumb that I heard ages ago is 'if you can only afford one
    filter, get a UHC'. I had chance to try mine out for the first time last
    w/e and I can confirm that it brings out detail in objects like M27 and
    M57 that you previously couldn't see.

    Jim
    --
    jim@magrathea.plus.com AIM/iSight:JCAndrew2 - Log in and say 'hi'
    "We deal in the moral equivalent of black holes, where the normal
    laws of right and wrong break down; beyond those metaphysical
    event horizons there exist ... special circumstances" - Use Of Weapons

  3. #3
    Tom Hole's Avatar
    Tom Hole Guest

    Default How Do I - Getting Started with Filters and Evaluating the need for Eyepieces

    Best filter gouge I've seen for deep space:

    http://pages.sbcglobal.net/raycash/filters.htm

    As for selecting ep's, you could do what I do and rent them from Astromart.
    Minimal to no depreciation if you take care of them. Here's what I've
    collected and sold over the past year or so:

    http://www.tomhole.com/Oculars%20Filters%20Etc.htm

    BTW, you never revealed what scope you had.

    TOm

    "Mark Smith" <emarksmi@san.rr.com> wrote in message
    news:3b5ja09k0gmadhmirqumepka175rpa2gvs@4ax.com...



  4. #4
    Mark Smith's Avatar
    Mark Smith Guest

    Default How Do I - Getting Started with Filters and Evaluating the need for Eyepieces

    >


    Sorry. I usually do give the telescope information. It is a
    Celestron C 9 1/4 SCT.

 

 

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