Results 1 to 5 of 5
  1. #1
    dwultrabike's Avatar
    dwultrabike is offline Main Sequence
    Points: 6,367, Level: 55
    Level completed: 9%, Points required for next Level: 183
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!5 Threads Achievement!Gallery Achievement!50 Posts Achievement!
    Join Date
    Apr 2013
    Location
    Cuyahoga Falls, OH
    Posts
    56
    Points
    6,367
    Level
    55
    Thanks
    56
    Thanked 9x 8 Posts

    Default Filter thicknesses



    I have a set of Orion LRGB 1.25" filters. I would like to add an Ha to the collection and would prefer to pick one that was parfocal with the Orions. I see that the thickness for Astrodon filters are 3mm, 2mm for Baader, and 1mm for Astronomik, but have found nothing for Orion. I asked Orion and they stated that they do not publish that information.

    The Orions LRGB's "appear" to be 3mm thick, but I'm not 100% sure. Short of using a micrometer and scratching up the coatings, I don't have a good way of measuring to be sure. Orion recommended, to buy and try it and send it back if I'm not happy.

    Does anybody know the thickness of Orion filters, or do they vary?

    Thanks,

    Dave
    Website:
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    size="1">Scope: Celestron Edge HD 8", Orion 120mm f/5 ref, Canon EF 70-200 f/2.8L Mount: Orion Sirius EQ-G
    Software: PixInsight, AutoStakkert, Firecapture, Nebulosity, PHD2, EQASCOM, Stellariumscope, PolarisView
    Camera: 5DMarkII unmod, ATIK460EX mono, ASI178MM cooled, ASI178MC, ASI174MM, QHY5L-II

  2. #2
    seigell's Avatar
    seigell is offline HYPER GIANT
    Points: 27,090, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 0%
    Achievements:
    365 Days+ Registered Achievement!5 Threads Achievement!50 Posts Achievement!750 Days+ Registered Achievement!First 1000 Experience Points
    Join Date
    Jan 2011
    Location
    Gilbert AZ (Exiled to the Marshes of Central Florida)
    Posts
    5,692
    Points
    27,090
    Level
    100
    Thanks
    182
    Thanked 1,663x 1,479 Posts

    Default Re: Filter thicknesses

    Orion probably simply neither Knows nor Cares - they aren't really in the business of AP Imaging Filters.

    You could make the same Parfocal inquiries of Astrodon and Astronomik - they likely DO have Customers who they have worked with over these same concerns...
    ES AR152 / ES 80ED Apo / Orion 8in F/3.9 / C9.25-SCT / C6-SCT / C10-NGT / AT6RC / ST-80 / AstroView 90 / Meade 6000 APO 115mm
    CGEM (w HyperTune and ADM bling) / 2x CG5-AGT / Forest of Tripod legs / Star Adventurer / Orion EQ-G
    550D (Modded-G.Honis) / 60D / 400D / NexImage / NexGuide / Mini 50 SSAG / ST-8300C / ASI120MM-S / ASI1600MM-Cool
    Dark Skies in SW CO when I can get there, and badly light polluted backyard when I can't... (Currently Self-Exiled to Muggy Central Florida...)

  3. #3
    Hondo's Avatar
    Hondo is offline HYPER GIANT
    Points: 62,777, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 0%
    Achievements:
    5 Threads Achievement!365 Days+ Registered Achievement!50 Posts Achievement!2 Posts Achievement20 Posts Achievement!
    Join Date
    Sep 2011
    Location
    Earth
    Posts
    7,043
    Points
    62,777
    Level
    100
    Thanks
    7,365
    Thanked 3,621x 2,930 Posts

    Default Re: Filter thicknesses

    Generally speaking, the filters produced by the manufacturer for the same series are somewhat parfocal. I say somewhat because there are slight variations in the focus, how much variation depends on the QA of the manufacturer. Higher price = better quality. I have a complete set of Baader 36mm LRGB and NB filters, they were not cheap but there are very slight differences in the focus of each filter in a set that claims to be parfocal. I sent an e-mail to Baader ref this and here is an excerpt from the reply from Baader.

    "These filters are made with minimal tolerance in thickness, hence they are as parfocal as possible. But you have to realize that not all telescopes are fully color corrected, especially when drifting into blue or red the longitudinal focus difference results in a residual focus shift. This is true not only for refractors, even Apo, but also for mirror systems with some corrector lens elements.

    In addition our narrowbandfilters have (due to their complexity) unavoidable small focal differences which are stronger as with RGB filters. These are negligible with typical f7 instruments as our advertizement refers to, but f.e. f4 is much less forgiving. For extremely critical focus with fast telescopes focussing between different filters is always recommended.

    Even without filter differences frequent refocussing is a must with such instruments, especially when not perfectly temperature compensated
    ."

    Orion produces a 1.25 Ha filter that may work with your LRGB set. Good luck.

    1.25" Orion H-Alpha Extra-Narrowband Filter | Orion Telescopes
    This used to be a great place to hang out but now it is not safe here anymore.

  4. #4
    Johnny J.'s Avatar
    Johnny J. is offline SUPER GIANT
    Points: 17,579, Level: 91
    Level completed: 70%, Points required for next Level: 121
    Overall activity: 26.0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!5 Threads Achievement!50 Posts Achievement!First 1000 Experience Points
    Join Date
    May 2015
    Location
    South Dakota
    Posts
    979
    Points
    17,579
    Level
    91
    Thanks
    278
    Thanked 408x 334 Posts

    Default Re: Filter thicknesses

    Regardless of the thickness of the the substrates, the frequency of the wavelength that the filter is band-passing, will determine the focal point. Red will focus slightly different than Green and so for Blue and Ha. The thinner the substrate the better IMHO. The coatings are what is doing the work. The substrates are just there to support the coatings. Each channel will have it's own specific focal point. If you are trying to get by without re-focusing with each filter change....forget about it!

    JJ
    Telescopes: Assorted brands and designs from 60mm up to 203mm (9). Eyepieces: Two 6mm BO's (Brown Organics - Eye Balls). Mounts: Celestron, Meade, Orion, Vixen, Skywatcher. Cameras: Canons, Logitech, Orion, QHYs.

  5. #5
    dwultrabike's Avatar
    dwultrabike is offline Main Sequence
    Points: 6,367, Level: 55
    Level completed: 9%, Points required for next Level: 183
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!5 Threads Achievement!Gallery Achievement!50 Posts Achievement!
    Join Date
    Apr 2013
    Location
    Cuyahoga Falls, OH
    Posts
    56
    Points
    6,367
    Level
    55
    Thanks
    56
    Thanked 9x 8 Posts

    Default Re: Filter thicknesses

    I have been imaging planets with no refocusing issues between the Orion L, R, G, & B filters. I was hoping for the same for DSO's on my Edge HD 8. I realize if I use my refractor f/5 that it might be more of an issue even if everything is parfocal.
    Website:
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    size="1">Scope: Celestron Edge HD 8", Orion 120mm f/5 ref, Canon EF 70-200 f/2.8L Mount: Orion Sirius EQ-G
    Software: PixInsight, AutoStakkert, Firecapture, Nebulosity, PHD2, EQASCOM, Stellariumscope, PolarisView
    Camera: 5DMarkII unmod, ATIK460EX mono, ASI178MM cooled, ASI178MC, ASI174MM, QHY5L-II

 

 

Similar Threads

  1. Replies: 5
    Last Post: 10-07-2015, 12:01 AM
  2. Replies: 2
    Last Post: 10-06-2015, 10:13 PM
  3. Where do I attach this filter? Hutech IDAS LPS filter 48mm
    By erotavlas in forum Astro Imaging Forum
    Replies: 6
    Last Post: 07-24-2013, 02:12 AM
  4. Replies: 3
    Last Post: 04-27-2011, 08:30 PM
  5. Replies: 3
    Last Post: 01-16-2010, 03:59 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 10:42 AM.