Page 1 of 2 12 LastLast
Results 1 to 10 of 13
Like Tree8Likes

Thread: Question in on minimum magnification

  1. #1
    Leopard11's Avatar
    Leopard11 is offline White Dwarf
    Points: 58, Level: 1
    Level completed: 16%, Points required for next Level: 42
    Overall activity: 0%
    Achievements:
    2 Posts Achievement
    Join Date
    Sep 2017
    Location
    Maryland USA
    Posts
    7
    Points
    58
    Level
    1
    Thanks
    0
    Thanked 0x 0 Posts

    Default Question in on minimum magnification



    Ok, so I am pretty much a newbie to astronomy. I was looking to get my 1st real scope but didnt want to go in on something new. So i was lucky to find a barely used celestron 127eq which some lady got for her son and said it was too complicated. I paid $40, everthing works perfect, few missing pieces lat screw which i found an easy replacement that works the 4mm eyepiece also but ive been told it junk anyways, came with a 15mm and 20mm and the sub par 3x barlow. So im looking to add a few ep and a better barlow of 2x or 3x. From what i have read it seems that i will get more use of lowe mag ep. Im thinking 40mm. After checking the min mag which ive read is the focal ratio 7.87 in my case multiplied by 7 which comes out to be something around 54. But what i dont understand is how that could be or be useful if the focuser is 1.25" thats like twice the size of the inside bore or whatever. Please explain how that works how i could use an ep as much as 50mm in this thing. My gut tells me that something around 30mm is going to be my best option just curious..

  2. #2
    KathyNS's Avatar
    KathyNS is online now Super Moderator
    Points: 172,512, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 79.0%
    Achievements:
    200+ Posts Achievement!Ghost Achievement! Averaging 5+ posts a day!First 1000 Experience Points400+ Posts AchievementGot three Friends
    Awards:
    Reply Award
    Join Date
    Nov 2010
    Location
    Nova Scotia
    Posts
    25,150
    Points
    172,512
    Level
    100
    Thanks
    6,658
    Thanked 14,977x 9,536 Posts
    Blog Entries
    3

    Default Re: Question in on minimum magnification

    You are correct that the minimum magnification is with an eyepiece of 7x your focal ratio. You are also correct that the 1.25" focuser will limit your eyepieces. It does not limit the focal length - a 54mm eyepiece will work just fine in theory - but it does limit the field of view. A 54mm eyepiece would have a maximum AFOV of 30 degrees.

    If you are going for the low magnification to maximuze surface brightness, that may be acceptable. But if you want the low magnification for a wide field of view (for searching for DSOs, for example), the limited field of view will not be useful.

    This is why many long focal length eyepieces are designed in the 2" format. However, you may have to do surgery on the scope to install a 2" focuser. Here is a spreadsheet that will help you with telescope / eyepiece combinations: http://www.dulcemelos.ca/en/articles/scopes.xls

    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.


    DSO AP:
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,LRGB filters; KWIQ/QHY5 guide scope; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome;
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    (pier);
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    .

    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.

  3. The Following User Says Thank You to KathyNS For This Useful Post:

    helicon64 (09-21-2017)

  4. #3
    12richardk's Avatar
    12richardk is offline HYPER GIANT
    Points: 15,994, Level: 87
    Level completed: 27%, Points required for next Level: 256
    Overall activity: 12.0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!5 Threads Achievement!50 Posts Achievement!Gallery Achievement!
    Join Date
    Dec 2015
    Location
    Johannesburg/Prague
    Posts
    4,111
    Points
    15,994
    Level
    87
    Thanks
    105
    Thanked 727x 710 Posts

    Default Re: Question in on minimum magnification

    As Kathy mentioned you will have to change the focuser however I think your scope is the 127 power seeker which is a sort of Bird Jones scope with a built in Barlow in the focus tube so unfortunately changing it is almost impossible, just use as is with a 32mm that's about the lowest you will get
    Ozman13 likes this.
    Richard
    Reflector GSO 200
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    F6
    Refractors Tasco 10 TE-5 F 15 ,
    MCT Bosma 150 F12 on a EQ5
    SCT C5 Celestron SLT Alt/AZ Go To mount,

  5. #4
    Ozman13's Avatar
    Ozman13 is offline HYPER GIANT
    Points: 28,958, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 60.0%
    Achievements:
    2 Posts Achievement5 Threads Achievement!20 Posts Achievement!365 Days+ Registered Achievement!50 Posts Achievement!
    Join Date
    Jun 2013
    Location
    Hopkinsville Kentucky
    Posts
    8,375
    Points
    28,958
    Level
    100
    Thanks
    170
    Thanked 2,223x 1,996 Posts

    Default Re: Question in on minimum magnification

    Richard is correct, because of the design of your scope, you are stuck with either a 32mm plossl or a 24mm ES 68 which are as wide as you can possibly go. Changing focusers is practically impossible because of the modified Barlow in there and I would not spend the cash on that scope to work out a fix. Use it for what it is and save up for another MOUNT, yes you will need a different STURDY mount and then get another scope. Unless you can afford to get both at the same time, but don't skimp on the mount.
    helicon64 likes this.

    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    ACF 8"SCT,
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.

    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    ,
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    120, ES 102CF Apo triplet, ES AR102, ST100, ST90, Apex 90mm Mak, ST80, ETX60,
    Oberwerk BT-82XL-ED, 25x100s, 15x70s, 8x56s, Kasai 2.3x40s, Celestron AVX, CG4, SLT, LCM, Obie HD Parallel Bino mount
    Explore Scientific 82 degree and 68 degree EPs, Baader 9mm Ortho, Meade 5000 SWA EP set, many more various EPs, Baader
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    &SkyGlow, FringeKiller, SemiApo filters, Celestron UHC, Meade 4000 Nebular Filter, Kson OIII, DGM NPB and lots of astro stuff.

  6. #5
    Leopard11's Avatar
    Leopard11 is offline White Dwarf
    Points: 58, Level: 1
    Level completed: 16%, Points required for next Level: 42
    Overall activity: 0%
    Achievements:
    2 Posts Achievement
    Join Date
    Sep 2017
    Location
    Maryland USA
    Posts
    7
    Points
    58
    Level
    1
    Thanks
    0
    Thanked 0x 0 Posts

    Default Re: Question in on minimum magnification

    Great info thank you, i think i will get a nice 32mm and just use that.

  7. #6
    Leopard11's Avatar
    Leopard11 is offline White Dwarf
    Points: 58, Level: 1
    Level completed: 16%, Points required for next Level: 42
    Overall activity: 0%
    Achievements:
    2 Posts Achievement
    Join Date
    Sep 2017
    Location
    Maryland USA
    Posts
    7
    Points
    58
    Level
    1
    Thanks
    0
    Thanked 0x 0 Posts

    Default Re: Question in on minimum magnification

    Would a nice barlow be useful at all or just a waste with this scope?

  8. #7
    12richardk's Avatar
    12richardk is offline HYPER GIANT
    Points: 15,994, Level: 87
    Level completed: 27%, Points required for next Level: 256
    Overall activity: 12.0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!5 Threads Achievement!50 Posts Achievement!Gallery Achievement!
    Join Date
    Dec 2015
    Location
    Johannesburg/Prague
    Posts
    4,111
    Points
    15,994
    Level
    87
    Thanks
    105
    Thanked 727x 710 Posts

    Default Re: Question in on minimum magnification

    Don't spend too much a 32 plossl will do fine ,I personally would not use a Barlow in that scope for Max magnification rather get a 8 mm eyepiece
    Richard
    Reflector GSO 200
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    F6
    Refractors Tasco 10 TE-5 F 15 ,
    MCT Bosma 150 F12 on a EQ5
    SCT C5 Celestron SLT Alt/AZ Go To mount,

  9. #8
    Leopard11's Avatar
    Leopard11 is offline White Dwarf
    Points: 58, Level: 1
    Level completed: 16%, Points required for next Level: 42
    Overall activity: 0%
    Achievements:
    2 Posts Achievement
    Join Date
    Sep 2017
    Location
    Maryland USA
    Posts
    7
    Points
    58
    Level
    1
    Thanks
    0
    Thanked 0x 0 Posts

    Default Re: Question in on minimum magnification

    Thnx, at $40 I cant really complain being my 1st scope contimplating for 2 years and got lucky with a barely used one.

  10. #9
    Ozman13's Avatar
    Ozman13 is offline HYPER GIANT
    Points: 28,958, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 60.0%
    Achievements:
    2 Posts Achievement5 Threads Achievement!20 Posts Achievement!365 Days+ Registered Achievement!50 Posts Achievement!
    Join Date
    Jun 2013
    Location
    Hopkinsville Kentucky
    Posts
    8,375
    Points
    28,958
    Level
    100
    Thanks
    170
    Thanked 2,223x 1,996 Posts

    Default Re: Question in on minimum magnification

    Quote Originally Posted by Leopard11 View Post
    Would a nice barlow be useful at all or just a waste with this scope?
    I would not get a Barlow, I would just use a shorter EP for higher power. Inside the focuser is already a Barlow and mating another one to the scope doesn't work very well. You will need to remove that Barlow in the focuser when you collimate the scope and then re-install.
    12richardk likes this.

    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    ACF 8"SCT,
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.

    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    ,
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    120, ES 102CF Apo triplet, ES AR102, ST100, ST90, Apex 90mm Mak, ST80, ETX60,
    Oberwerk BT-82XL-ED, 25x100s, 15x70s, 8x56s, Kasai 2.3x40s, Celestron AVX, CG4, SLT, LCM, Obie HD Parallel Bino mount
    Explore Scientific 82 degree and 68 degree EPs, Baader 9mm Ortho, Meade 5000 SWA EP set, many more various EPs, Baader
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    &SkyGlow, FringeKiller, SemiApo filters, Celestron UHC, Meade 4000 Nebular Filter, Kson OIII, DGM NPB and lots of astro stuff.

  11. #10
    Leopard11's Avatar
    Leopard11 is offline White Dwarf
    Points: 58, Level: 1
    Level completed: 16%, Points required for next Level: 42
    Overall activity: 0%
    Achievements:
    2 Posts Achievement
    Join Date
    Sep 2017
    Location
    Maryland USA
    Posts
    7
    Points
    58
    Level
    1
    Thanks
    0
    Thanked 0x 0 Posts

    Default Re: Question in on minimum magnification

    Excellent thnx, maybe a 9mm for high mag and 32mm low.
    helicon64 likes this.

 

 
Page 1 of 2 12 LastLast

Similar Threads

  1. Going below the minimum magnification
    By pederv in forum Astronomy Digital Cameras Forum
    Replies: 5
    Last Post: 08-08-2015, 12:09 AM
  2. Star Gazing - Minimum magnification?
    By Ronvent in forum Astronomy Beginners Forum
    Replies: 13
    Last Post: 05-08-2013, 02:32 PM
  3. Minimum Magnification?
    By Simon01351 in forum Telescope Eyepieces Forum
    Replies: 8
    Last Post: 05-22-2009, 06:45 PM
  4. Question about magnification
    By Nodgiles in forum Astronomy Beginners Forum
    Replies: 9
    Last Post: 03-17-2009, 11:40 PM
  5. minimum magnification for Saturn's rings?
    By Paul Murphy in forum Amateur Astronomy Forum
    Replies: 15
    Last Post: 03-30-2005, 09:27 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Powered by vBulletin® Version 4.2.0
Powered by vBulletin®
All times are GMT. The time now is 10:58 PM.