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90mm ED Refractor

Discussion in 'Telescopes and Mounts' started by sojourneyer, Sep 4, 2023.

90mm ED Refractor

Started by sojourneyer on Sep 4, 2023 at 12:38 PM

3 Replies 656 Views 0 Likes

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  1. sojourneyer

    sojourneyer Well-Known Member

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    sojourneyer, Sep 4, 2023
    #1
    I have always felt that a 90mm was an optimal scope for lightweight grab and go purposes.

    A 102ED with rings weighs in the area of 12 lbs which is too much for many lighter weight mounts to handle.
    By lighter weight mounts I am alluding to the Versago, smaller Twilight, etc mounts. If you add a 102ED for example to a Twilight I you are talking about 30 lbs plus.

    A 90ED would be easily under 10 lbs and with some of the smaller mounts the total weight would be under 20 lbs which is great for a quick grab and go viewing at night.

    Do you think that there is a market for a reasonably priced 90mm ED in the low $500 range?

    If someone made a doublet paired up a FPL-51 glass with one Lanthanide glass the CA would somewhat negligible. Svbony has those two types of glass in their 102ED and users have raved about that scope. This is where a $500 price point seems realistic.

    I just checked and the only 90 mm EDs are triplets costing around $1500.
     
    Last edited: Sep 4, 2023
  2. PXR-5

    PXR-5 Well-Known Member

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    PXR-5, Sep 12, 2023
    #2
    I was actually just thinking about this over the weekend.

    I have the Orion 80ED f7.5, (but it's in a 102 tube) it rides nice on my Vixen Porta Mount II.

    Yet I once owned the Synta 102 achro f10, and the Porta did not like it.

    A 90mm apo doublet, about 7.5 would be the ticket. :)
     
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  3. Mak the Night

    Mak the Night Well-Known Member

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    Mak the Night, Sep 13, 2023
    #3
    I have the SW version:

    [​IMG]

    Mine now has a Long Perng rotatng focuser.
     
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  4. Gabby76

    Gabby76 Well-Known Member

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    Gabby76, Sep 15, 2023
    #4
    90mm can be a good size but compared to more available apertures it is left in the cold a bit.
    With so many 80mm and 100mm refractors available it makes the 90mm redundant in most situations.

    To see a visible increase in brightness and image scale you need at least 20mm of aperture increase hence 80mm > 100mm.
    It may make a difference used photographically but since I personally do not do that I do not know.
     

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