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Upgrading my Diagonal

Discussion in 'Beginner's Corner' started by Pleiades, Sep 14, 2017.

Upgrading my Diagonal

Started by Pleiades on Sep 14, 2017 at 6:24 AM

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  1. Pleiades

    Pleiades Well-Known Member

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    So, what's the flip side on diagonals? I am seeing prisms that Correct, "top to bottom and left to right". That's self explanatory I guess, but is there a draw back? I'm seeing mirrors as well with Al-SiO2 coatings; which I've read enough to realize that this is like catnip to astronomers.

    So Prism, or Cat nip?
    This will be going on my old Tasco 60mm f13, so I don't want to put a fortune in a diagonal. I'm thinking of one of the GSO diagonals.

    Thanks in advance.
    http://agenaastro.com/gso-1-25-90-refractor-mirror-star-diagonal.html
    or
    http://agenaastro.com/gso-1-25-90-erect-image-prism-diagonal.html
     
  2. Dave In Vermont

    Dave In Vermont Well-Known Member

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    I very much like the GSO 1.25" Dielectric Mirror-Diagonal RACI. That's Right-Angle Correct-Image. In other words, you get the same orientation as with your eyes. Everything is right-side-up and correct left & right view.

    I have a fleet of William Optics 2" Dielectric RACI's, but If I needed another 2" - I'd get the GSO. Been hearing lots of good things about them, and they're less $$$. If a 1.25" - the GSO's are great!

    Last I looked, Agena was begging $69.95 for these. I got mine awhile back for $75.00 and no complaints. You can go for a less expensive GSO Prism Diagonal. But I suggest throwing a bit of extra $$ for the higher-quality mirror. The diagonal can easily be transfered for use in future scopes you may buy. Or can be sold if you need for some unforseen circumstance. Us astro-folks tend to take excellent care of our gear, and there's a thriving used-market. The usual re-sale is from 66% to 75% of original. This can be handy if you want to try lots of things before setting things in the proverbial stone. Ergo - you can buy x,y,z used and re-sell x,y,z and not lose much $$$ in the bargain.

    Enjoy!

    Dave
     
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  3. Mak the Night

    Mak the Night Well-Known Member

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  4. Mak the Night

    Mak the Night Well-Known Member

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    Are you sure a mirror diagonal doesn't have a mirror reversed image Dave?
     
  5. Pleiades

    Pleiades Well-Known Member

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    Awesome article. Seeing that my primitive star hoping techniques often require me to find a star, the go a little to the left or right with a lower power to find my intended target. A corrected diagonal sounds great.
     
  6. Mak the Night

    Mak the Night Well-Known Member

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    There's a lot of myths about Amici prisms, although the roof of the prism is sometimes more apparent on refractors than cat's, I tend to use them a lot. The upside down world of the Newtonian is normal to me, I even prefer viewing the Moon and the planets inverted. But I can't get my head around a mirror reversed universe for some reason lol. I think for a lot of DSO's I can live with it, but not for the Moon.

    4 diag.jpg
    gso2.jpg

    The GSO Amici is actually very good, I think it has a slight edge on the Orion Amici.

    Baader Amici 2.jpg

    I have a Baader 2" Amici, it wasn't cheap though.
     
  7. Dave In Vermont

    Dave In Vermont Well-Known Member

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    On my land-targets I use to align the finder and the main-scope, I get the same view as with my eyes on that church-steeple a mile or two off from me. Maybe because it's bouncing upwards as well? Beats me - but it works. At least the thing isn't upside-down! :p

    Oh goodie! It's raining again...

    <growl>

    Dave
     
  8. Mak the Night

    Mak the Night Well-Known Member

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    I'm pretty sure mirror diagonals give upright mirror image views. I thought for a bit some of them reversed the image! I suppose it doesn't matter on many DSO's but it really bugs me on the Moon. Yet inverted views I can live with, I must just be weird lol.

    We keep having sun, then rain, then sun, then rain, then sun, then rain ... :rolleyes:
     
  9. Pleiades

    Pleiades Well-Known Member

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  10. Mak the Night

    Mak the Night Well-Known Member

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    Looks good.
     
  11. Dave In Vermont

    Dave In Vermont Well-Known Member

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    That'll do what you need. And the price is good!

    Dave
     
  12. Gabby76

    Gabby76 Well-Known Member

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    For scatter control the Zeiss/ Baader prism is top notch but expensive closely followed by the AP Maxbright dielectric, though again expensive.
    Ï have compared the Stellarvue and TeleVue 2" diagonals and surprisingly found the SV to be just a bit better and at $100USD cheaper than the TV a bargain for a mid-priced "high end" dielectric.

    PS: I like the new pic Dave, very hip! :)
     
  13. Dave In Vermont

    Dave In Vermont Well-Known Member

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    Thanks, Gabby, it's an old picture though.

    If one of my fleet of William Optics 2" Dielectric diagonals should get lost, stolen, or commit suicide - I'm going to get a 2" GSO Dielectric model. I was, and remain, quite impressed with the optical qualities on my 1.25" GSO Dielectric. Which I've used with both the ST80, and the 150mm Maksutov F/12.

    I wish no ill feelings for my WO-fleet though! They are excellent quality glass.

    Here's a Pdf. of an older review on some diagonals in CloudyNights -



    Stars & Mars,

    Dave

    Diagonal Review on CloudyNights.pdf
     

    Attached Files:

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  14. Gabby76

    Gabby76 Well-Known Member

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    One other feature I do like about the 2" Stellarvue diagonal is that if it needs to be collimated all adjustments can be made from the top of the diagonal.
    You can see the adjustment screws in the pictures here: http://www.stellarvue.com/dielectric-star-diagonal-2-d1029ed/

    Not that I have ever had to use them but it is a nice "just in case" feature.
     
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  15. Dave In Vermont

    Dave In Vermont Well-Known Member

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    Very nice feature, Gabby. This goes on my short-list to look into <koff!> should the need arise again. I have too many 'toys' in my toy-box(es) now, so 'necessity' has become my mantra-du-jour. :p

    Thank you!

    Dave
     
  16. Gabby76

    Gabby76 Well-Known Member

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    I am trying to clear out some room in the "toy closet" at the moment lol
    At the moment that has led to questions of future purchases and contemplating "improvements" :eek:
     
  17. Dave In Vermont

    Dave In Vermont Well-Known Member

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    Sounds familiar.....:D
     
  18. Gabby76

    Gabby76 Well-Known Member

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    I am selling off my Synta mounts and looking at getting one more Vixen SXP or a Losmandy G-11 and then looking at the Berlebach Planet or Avalon T-Pod 130 to put it on.
    Of course to keep this on topic I will need to buy another diagonal also, any other suggestions? lol
     
  19. Dave In Vermont

    Dave In Vermont Well-Known Member

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    How about a stolen mirror off the wall of a gas-station Mens Room in New Jersey by EXIT 4, propped-up at the right angle by a couple lime-slices from some Gin & Tonics?

    :eek:
     
  20. Gabby76

    Gabby76 Well-Known Member

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    No I have already used Celestron diagonals before. :D
     

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