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  1. #1
    Mirfak's Avatar
    Mirfak Guest

    Default Which Go-To Cassegrain?




    For ten years, I've been using an excellent 7" Dob (Starmaster Oak Classic)
    under dark skies. Now, I'm looking to purchase a Go-To Cassegrain in
    the 9-10" range. The equipment has changed so much over the past ten years,
    I hardly know where to begin to look. Superior optics are my main priority.
    Would appreciate recommendations. TIA.

  2. #2
    Roger Hamlett's Avatar
    Roger Hamlett Guest

    Default Which Go-To Cassegrain?

    On Wed, 17 Oct 2007 05:37:30 +0000 (UTC), Mirfak <null@none.invalid>
    wrote:

    By Cassegrain, do you want a 'traditional' Cassegrain,
    Maksutov-Cassegrain, or a Schmidt-Cassegrain?.
    There are a lot of very acceptable optics available now, at prices
    that only a few years would have been 'amazing'. The problem
    generally, is that _mechanics_ have not advanced in quite the same
    way, and the mounts, while often fitted with 'lovely gadgets' (GoTo
    etc.), which could not have been built at any reasonable price a few
    years ago, are often not really 'up to' the scopes... :-(
    Now, The first thing I'd say, is take your time. If there is a
    local(ish) astronomy club, then pay them a visit or two, and get a
    feel of what is around. It is also worth asking how you intend to use
    this (fixed, or having to set up each night? would you be wanting to
    image if the chance existed?). These scopes just begin to approach the
    point, where as you get older, they might become hard to deal with for
    nightly setting up, so it is worth being sure that you are totally
    'comfortable' with the configurations before progressing. Alt/Az
    systems, are generally quicker to setup, but have the disadvantage,
    that because the mount, and OTA, are permanently attached to one
    another, the individual assembly is heavy. I'd feel much 'happier'
    (for example), setting up a 11" Celestron scope, on a GEM mount, than
    setting up a 10" Meade, on it's Alt/Az mount.
    Now, there is then the huge question of price?. You could (for
    example), buy a mount like the AP900, and fit something like a
    Takahashi Mewlon250 (Dall-Kirkham Cassegrain), or the Vixen VMC260,
    and have something quite nice, or go really 'upmarket', and fit a 10"
    RC OTA. However you will still have the 'caveat', that will apply to
    most scopes this size/type, that they are relatively 'narrow field'
    instruments. If you want to look at DSO's, and cover a reasonably
    large FOV, then it is worth considering whether this really is the
    best choice for you.
    Personally, I'd actually say to pay as much attention to the mount, as
    to the scope, and get something that would hold a choice of OTA's, so
    if you decided latter that you would like to look at wider FOV's, you
    can instead attach something like a small APO. In terms of mounts, for
    this size of scope something like the Losmandy G-11, is a good 'value'
    mount, while something like the AP900, is getting towards 'prime'
    territory, while both are still useable for nightly setups if needed.
    For OTA's, the Meade 10" LX200R, or the Celestron C9.25, are both good
    performers, without inducing bankruptcy. Though it'll cost more, buy
    from a local shop, with the support that they will fix the units if
    there is a problem. The Meade's in particular at times can suffer from
    some 'odd' mechanical failings (more on the RCX models, than the plain
    'R'). If you are prepared to go a fraction larger, the Celestron C11,
    and is a similar weight.
    There are a huge range of choices, and I personally believe, there is
    'no such thing as a perfect scope'. The different designs all have
    their weaknesses...

    Best Wishes

  3. #3
    AM's Avatar
    AM Guest

    Default Which Go-To Cassegrain?

    Mirfak wrote:




    CPC 9.25


    --

    AM

  4. #4
    Rick Frazier's Avatar
    Rick Frazier Guest

    Default Which Go-To Cassegrain?

    Mirfak wrote:

    Celestron cge 11" -- can be had on ebay from reputable dealers for
    around $2200 plus shipping if you're willing to wait for the right
    auction/buy it now...

    great scope, large apeture, and still transportable on a cg-5 mount...
    Just make sure you take off the tube and counterweights if you want to
    avoid a hernia in transport anywhere more than a few yards from the car.
    --Rick

 

 

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