Results 1 to 6 of 6
Like Tree7Likes
  • 3 Post By Ozman13
  • 2 Post By harryhh
  • 2 Post By Gabby76

Thread: Can I change a 8 to 24mm zoom into a longer focal length zoom?

  1. #1
    harryhh's Avatar
    harryhh is offline Main Sequence
    Points: 1,380, Level: 21
    Level completed: 80%, Points required for next Level: 20
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!5 Threads Achievement!50 Posts Achievement!Ghost Achievement! Averaging 5+ posts a day!
    Join Date
    Jun 2017
    Location
    Northcentral Illinois
    Posts
    168
    Points
    1,380
    Level
    21
    Thanks
    0
    Thanked 12x 4 Posts

    Default Can I change a 8 to 24mm zoom into a longer focal length zoom?



    Hi All,

    I would like to have a zoom eyepiece with a range of something like 20 to 40mm, or 15 to 45mm. Something like that anyway. But, they don't seem to make anything like that.

    I was wondering if a 0.5 focal reducer and a 8 to 24mm zoom could be used?

    Is there some other kind of device that could be used to get the zoom range I'm looking for?

    Harry
    Orion Apex 102mm Mak, Celestron 6x30 finder, Orion 90* prism diagonal, 45* erecting prism diagonal, Celestron straight through porro prism, Tele Vue 1.8x Barlow, 25mm 52* Super Plossl eyepiece, SVBONY 23mm 62* Aspheric eyepiece, 8.5mm Konig eyepiece

  2. #2
    Ozman13's Avatar
    Ozman13 is online now HYPER GIANT
    Points: 28,945, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 89.0%
    Achievements:
    2 Posts Achievement5 Threads Achievement!20 Posts Achievement!365 Days+ Registered Achievement!50 Posts Achievement!
    Join Date
    Jun 2013
    Location
    Hopkinsville Kentucky
    Posts
    8,371
    Points
    28,945
    Level
    100
    Thanks
    170
    Thanked 2,223x 1,996 Posts

    Default Re: Can I change a 8 to 24mm zoom into a longer focal length zoom?

    You could use it but it would not be very useful. The shorter lengths would just duplicate the longer lengths and the reducer introduces serious field curvature which gets worse as the EP gets longer. So the longer lengths would not even come to good focus. About the only use would be at 16mm to 32mm but the already narrow view (scope and zoom EP) would end up like looking through a straw. It would be much better to just get a 32mm GSO plossl or an ES 24mm 68 and stay with the zoom as is.
    Gabby76, dagadget and Macrob1 like 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.

  3. #3
    harryhh's Avatar
    harryhh is offline Main Sequence
    Points: 1,380, Level: 21
    Level completed: 80%, Points required for next Level: 20
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!5 Threads Achievement!50 Posts Achievement!Ghost Achievement! Averaging 5+ posts a day!
    Join Date
    Jun 2017
    Location
    Northcentral Illinois
    Posts
    168
    Points
    1,380
    Level
    21
    Thanks
    0
    Thanked 12x 4 Posts

    Default Re: Can I change a 8 to 24mm zoom into a longer focal length zoom?

    Thanks Ozman,

    From an answer Gabby gave me along this same subject, I agreed there must be various problems with long field length zooms. So, if they can't manufacture them to be useful, anything I rigged would be even worse.
    Ozman13 and Macrob1 like this.
    Orion Apex 102mm Mak, Celestron 6x30 finder, Orion 90* prism diagonal, 45* erecting prism diagonal, Celestron straight through porro prism, Tele Vue 1.8x Barlow, 25mm 52* Super Plossl eyepiece, SVBONY 23mm 62* Aspheric eyepiece, 8.5mm Konig eyepiece

  4. #4
    harryhh's Avatar
    harryhh is offline Main Sequence
    Points: 1,380, Level: 21
    Level completed: 80%, Points required for next Level: 20
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!5 Threads Achievement!50 Posts Achievement!Ghost Achievement! Averaging 5+ posts a day!
    Join Date
    Jun 2017
    Location
    Northcentral Illinois
    Posts
    168
    Points
    1,380
    Level
    21
    Thanks
    0
    Thanked 12x 4 Posts

    Default Re: Can I change a 8 to 24mm zoom into a longer focal length zoom?

    Well Ozman, I'm taking your advice on buying the GSO eyepiece. At first I was wanting to get a zoom eyepiece, but now I find that the 8 to 24mm is perhaps a bit too powerful for my waterfowl viewing. The couple of places around here that I have to go for waterfowl aren't as large as the slough I used to go to. The ducks aren't as distant and I don't need as much magnification.

    Amazon and Agena were out of the GSO 32mm so I purchased a GSO 40mm form Agena. I will purchase the 32mm when in stock.

    I have purchased one of those really inexpensive SVBONY Aspheric 23mm 62* eyepieces. $12.50. It seems to give me a good enough image for my waterfowl, but I don't have any high quality eyepieces to compare it to, and I haven't yet used it much. It doesn't have a long enough eye relief for my glasses though.

    I have on order the SVBONY 10mm. If it works out, I might order the 4mm also. That's supposed to be too much magnification for my scope, but at less than $13, if I get only a little use out it that would be good.
    Orion Apex 102mm Mak, Celestron 6x30 finder, Orion 90* prism diagonal, 45* erecting prism diagonal, Celestron straight through porro prism, Tele Vue 1.8x Barlow, 25mm 52* Super Plossl eyepiece, SVBONY 23mm 62* Aspheric eyepiece, 8.5mm Konig eyepiece

  5. #5
    Gabby76's Avatar
    Gabby76 is offline Super Moderator
    Points: 82,830, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 99.8%
    Achievements:
    2 Posts Achievement20 Posts Achievement!Gallery Achievement!Album Achievement!50 Posts Achievement!
    Awards:
    Activity & Post & Thread Master
    Join Date
    Jan 2016
    Location
    Slovakia
    Posts
    19,210
    Points
    82,830
    Level
    100
    Thanks
    3,684
    Thanked 5,990x 5,032 Posts
    Blog Entries
    4

    Default Re: Can I change a 8 to 24mm zoom into a longer focal length zoom?

    The thing to remember with Plossl eyepieces is that the eye relief is approximately 80% of the focal length so if you need to wear glasses it is something to be aware of.
    Macrob1 and harryhh like this.
    Refractors: Antares 105 f/15, Celestron 150 f/8, Stellarvue NHNG 80 f/6.9, TAL 100RS f/10, TS 102 f/11, UR 70 f/10, Vixen SD115s f/7.7
    Mounts: Celestron SLT w/ pier mod & EQ-3 tripod, Celestron hypertuned CG-5 w/ tracking motor & Argo Navis, Manfrotto 028B w/ Stellarvue M2C, Manfrotto 055PRO w/ 128RC, TAL-1 HD EQ, Vixen SXP w/ HAL-130 SXG & half pier
    Diagonals: 2" Astro-Physics MaxBright, 2" Zeiss/ Baader prism, 2" Baader Herschel Wedge (Photo Version), 2"
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    Amici prism, 2" Stellarvue Dielectric, 2" TeleVue Everbrite
    Eyepieces: A-Z

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

    The weakest link in the optical chain is the large nut located directly behind the eyepiece/ camera. - Gabrielle
    Ya gotta keep this Apo/
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    thing in some balance of perspective. Apos are awesome, but long focus Achros aren't that far behind them - Siriusandthepup (CN)

    Refractors kick arse precisely because they don't hide behind excuses. That is, they have no obstructions to hide behind. - Jon Isaacs (CN)

  6. #6
    harryhh's Avatar
    harryhh is offline Main Sequence
    Points: 1,380, Level: 21
    Level completed: 80%, Points required for next Level: 20
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!5 Threads Achievement!50 Posts Achievement!Ghost Achievement! Averaging 5+ posts a day!
    Join Date
    Jun 2017
    Location
    Northcentral Illinois
    Posts
    168
    Points
    1,380
    Level
    21
    Thanks
    0
    Thanked 12x 4 Posts

    Default Re: Can I change a 8 to 24mm zoom into a longer focal length zoom?

    Well that's a handy bit of information.
    Orion Apex 102mm Mak, Celestron 6x30 finder, Orion 90* prism diagonal, 45* erecting prism diagonal, Celestron straight through porro prism, Tele Vue 1.8x Barlow, 25mm 52* Super Plossl eyepiece, SVBONY 23mm 62* Aspheric eyepiece, 8.5mm Konig eyepiece

 

 

Similar Threads

  1. Focal Reducer same as just using a longer focal length eyepiece?
    By Gaff in forum Astronomy Beginners Forum
    Replies: 3
    Last Post: 07-24-2017, 12:13 AM
  2. Zoom eyepiece versus single focal length, and to Barlow or not?
    By stargazer55 in forum Telescope Eyepieces Forum
    Replies: 16
    Last Post: 04-25-2013, 12:32 PM
  3. Vixen Zoom LV 8-24mm
    By aod in forum Telescope Eyepieces Forum
    Replies: 10
    Last Post: 10-28-2011, 07:24 PM
  4. Celestron Zoom 8-24mm
    By jaredgiese in forum Telescope Eyepieces Forum
    Replies: 18
    Last Post: 09-27-2010, 10:47 PM

Tags for this Thread

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 02:24 AM.