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Thread: Focal Reducers

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    Default Focal Reducers



    I'm thinking of getting a Celestron 2" f/6.3 focal reducer for viewing DSOs with my f/10 SCT. Is that a good idea? My current EPs are in my signature. Pros and cons? Thanks for any advice.

    Marc
    TELESCOPE: Celestron CPC 925 (XLT)
    EPs: Tele Vue 12mm Nagler-T4 [196x TFOV=0.42°], 17mm Nagler-T4 [138x TFOV=0.59°], 31mm Nagler-T5 [76x TFOV=1.08°], 40mm Omni Plössl [59x TFOV=0.73°]
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    Default Re: Focal Reducers

    For DSOs it is definitely a good idea as you'll be able to get down to a reasonably low magnification (x48) with the 31mm as well as widening the view considerably. It should work very well with your eyepieces although the 40mm may be pushing it regarding the exit pupil size. I believe Antares also sell a very similar reducer.

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    Default Re: Focal Reducers

    The 31 Nagler will benefit big time with a Focal Reducer the 40 mm Plossl most likely will show a little vignetting ..with all the others I personally do not see any advantages at all with a focal reducer for visual at least..

    I use my Focal reducer (actually a 0.66 not a 0.63 which is built into my Denk S1 P/S diagonal the vast majority of the time when using my 26 31 and 35 mm 68 degree eyepieces my 40 (also a 68 degree eyepiece vignettes to the point I rarely use it with the reducer in play...BTW I seldom use the built in 2x Barlow in the diagonal

    Bottom line .... I would NOT like to be without the Focal Reducer...I make good use of it

    Bob G
    CPC1100 housed in a slotted domed observatory (Exploradome) 4 and 5 inch refractors for use from the lawn, a 8" Sct (NS 8i) for star parties...
    I Hate the winter so I use heated Motorcycle clothing to stay warm while observing in winter
    Retired, also have 2 other hobbies
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    Default Re: Focal Reducers

    Thank you Dave and Bob,

    I suspected that the focal reducer would only be useful with the 31mm Nagler.

    Marc
    TELESCOPE: Celestron CPC 925 (XLT)
    EPs: Tele Vue 12mm Nagler-T4 [196x TFOV=0.42°], 17mm Nagler-T4 [138x TFOV=0.59°], 31mm Nagler-T5 [76x TFOV=1.08°], 40mm Omni Plössl [59x TFOV=0.73°]
    CAMERA: Nikon D300

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    Default Re: Focal Reducers

    [QUOTE=Bob327;1058027532]...(actually a 0.66 not a 0.63)... Bob G

    Bob,
    just to confirm that I am looking at the right reducer, I have it as a Celestron f/6.3 Reducer-Corrector for Schmidt- Cassegrain, Model #94175. Are we referring to the same unit?
    TELESCOPE: Celestron CPC 925 (XLT)
    EPs: Tele Vue 12mm Nagler-T4 [196x TFOV=0.42°], 17mm Nagler-T4 [138x TFOV=0.59°], 31mm Nagler-T5 [76x TFOV=1.08°], 40mm Omni Plössl [59x TFOV=0.73°]
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    Default

    Just to be different I have no problems with the f6.3 reducer and an old 2" 40mm Meade SWA in my 11" SCT. The exit pupil may be getting a bit big at 6.3mm or so, but it works fine for me - so it's worth trying your 40mm as well.

    And the shorter eyepieces should be fine as well - they may not give you field sizes that you can't get to without the reducer, but they'll still work OK - so you don't need to be swapping the reducer in and out all the time.

    Interesting to see that you've ended up with a similar set of eyepieces to me - I also use the 12T4 and 17T4 Naglers, and a 2" 40mm. I also have a 28mm UWAN - couldn't stretch the budget to afford a terminagler .

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    Default Re: Focal Reducers

    Jerry,

    no coincidence there... see the old post below:

    With my N11GPS, I usually use an old Meade 2" 40mm SWA and 17T4 and 12T4 Naglers. If you're looking for a cheap ultrawide 30mm, there's a Chinese made 2" 30mm 80 degree model that goes for about 100€ - it has problems in fast scopes, but just has a bit of edge softness in an SCT. Not as good as a Nagler or WO UWAN, but not bad - and a fraction of the price.


    Many thanks Jerry! I took your advice and got a good spread of 2" Naglers... 31mm T5, 17mm T4 & 12mm T4. I sort of broke the bank but I couldn't pass up a great sale.
    Marc
    TELESCOPE: Celestron CPC 925 (XLT)
    EPs: Tele Vue 12mm Nagler-T4 [196x TFOV=0.42°], 17mm Nagler-T4 [138x TFOV=0.59°], 31mm Nagler-T5 [76x TFOV=1.08°], 40mm Omni Plössl [59x TFOV=0.73°]
    CAMERA: Nikon D300

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    Default

    Ha! I should have remembered that . I hope you enjoy using them as much as I do mine - I'd love to add one of the 31mm Naglers sometime, but there's lots of other stuff in the queue for cash .

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    Default Re: Focal Reducers

    The standard FR is 0.63 BUT MY Diagonal (Denkmeier S1 Power Switch has both a built in 0.66 FR as well as a built in 2x Barlow which I can push a lever in to place the FR or the barlow in the visual path ...(not at the same time naturally) ... so yes you are on the same page...

    Somewhere long ago I read in a Celestron publication that they do not recommend a focal reducer to be used with a higher power eyepiece 12 mm or less... (or was it 25 mm or less...??? I can not remember )... but I do know that there was a cut off point

    In any case like I said I use my FR 95 percent of the time when I have my 26 31 or 35 mm eyepiece in that diagonal...and I rarely ever use the barlow with any eyepiece

    Bob G
    CPC1100 housed in a slotted domed observatory (Exploradome) 4 and 5 inch refractors for use from the lawn, a 8" Sct (NS 8i) for star parties...
    I Hate the winter so I use heated Motorcycle clothing to stay warm while observing in winter
    Retired, also have 2 other hobbies
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    2. make a heck of a lot of sawdust in my wood shop.

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    Default Re: Focal Reducers

    interesting information. I only thought the FR was for AP and not for visual use. I would love to reduce the focal ratio of my Meade LX 90 8" (SCT)which is also F 10, especially after using my NP 101 which has a Focal ratio of 5.4. In my meade the largest field I can get is approx. 1.2 with my 31 nagler. would appreciate any recommendation for an FR and how to use it. clear and warm skies, allen g

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    : TeleVue NP-101, Meade LX 90 8" ACF, DiscMount (DM-4) with Sky Commander
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