Page 2 of 2 FirstFirst 12
Results 11 to 16 of 16
Like Tree12Likes

Thread: Fast Newtonian eyepiece query

  1. #11
    MistrBadgr's Avatar
    MistrBadgr is offline Bronze Supporter
    Points: 9,185, Level: 66
    Level completed: 45%, Points required for next Level: 165
    Overall activity: 3.0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!50 Posts Achievement!5 Threads Achievement!200+ Posts Achievement!
    Join Date
    Aug 2016
    Location
    Broken Arrow, Oklahoma
    Posts
    1,865
    Points
    9,185
    Level
    66
    Thanks
    236
    Thanked 520x 450 Posts

    Default Re: Fast Newtonian eyepiece query



    Frosty,

    I have a Meade LX 70 eight inch f/5 reflector (1000mm focal length like yours). The smaller diameter of my scope matches up similarly to my eye pupil as your scope probably does for you. I happen to be a Meade guy and my 82 degree eyepieces are the Meade 5000 series. I have the whole series, but what works well for me in my scope is the 24, 14, 8.8, and 5.5 mm eyepieces. I find that I rarely use the 30mm and the 20mm. I also have an Explore Scientific 18mm that goes unused as well.

    When people get into the realm of eyepieces that you are talking about, most will end up using a string of eyepieces that will start with one that will give them close to the maximum field they can comfortably get into their eye, to help with finding things in the eyepiece. They will then moved down, as needed for the object, in steps of 50 to 65% of the field diameter of the sky they are seeing, (true field of view or TFOV) With eyepieces of the same apparent field of view (the field width as it looks in the eyepiece, such as 82 degrees), just using the focal length for comparison is appropriate.

    Other limits for you include some limit for the size of your scope as a general rule of thumb. At the elevation where I live, 700 ft, two times the diameter of the scope in mm, seems to work for smaller scopes. However, that tends to give out as the scope gets to the size of my eight inch as it will for your scope. The f-ratio also comes into play as well, with the upper magnification limit decreasing some for the more radical focal ratio. I have also been told that it takes really pristine skies to go higher than 400X, unless at high elevations, like several thousand feet. If you live at sea level, the magnification limit for your scope may be as low as 300X under good conditions.

    A long time astronomer, who has completed most of the Astronomy League programs, all that she sees that has any relevance to her, told me that she rarely ever has a need to go above 300X, even though her 13.5 inch, premium reflector is quite capable of higher magnifications. Personally, unless I am viewing something specific on the Moon or attempting to split really difficult/tight double stars, I generally do not go above 200X. Your scope, with something like my 5.5 mm eyepiece will give a magnification of about 180X. With a good 2X Barlow, that makes 360X, which would most likely be as much or more magnification than needed.

    Hope this helps.
    Bill Steen
    Sky Hunters' Haven Observatory, Broken Arrow, Oklahoma
    Meade LX 70 8R & 6M, Infinity 60, 80 & 102, Polaris 112, 127, & 130, DS 2102 OTA, DS 90 OTA, 60 mm f/15, Lightbridge 12, Lightbridge Mini 82, Eclipseview 76 & 114, Sky Shed 3 Bay POD, LPI-G Color

  2. #12
    MistrBadgr's Avatar
    MistrBadgr is offline Bronze Supporter
    Points: 9,185, Level: 66
    Level completed: 45%, Points required for next Level: 165
    Overall activity: 3.0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!50 Posts Achievement!5 Threads Achievement!200+ Posts Achievement!
    Join Date
    Aug 2016
    Location
    Broken Arrow, Oklahoma
    Posts
    1,865
    Points
    9,185
    Level
    66
    Thanks
    236
    Thanked 520x 450 Posts

    Default Re: Fast Newtonian eyepiece query

    The wording around the 50 to 65% is not worded quite right. What I was meaning is that the next eyepiece down in focal length will normally give you a field that is about half to two-thirds the diameter of the previous one. It just depends on how big of a step you care to take. For most of my time with astronomy, I have stayed around the 60 to 65% range simply from a fear of taking too big of a step and loosing the object. If I get into something at a really high magnification, I will drop to as small of a step as I can, simply because it is easier to loose an object at that high of a magnification.
    Bill Steen
    Sky Hunters' Haven Observatory, Broken Arrow, Oklahoma
    Meade LX 70 8R & 6M, Infinity 60, 80 & 102, Polaris 112, 127, & 130, DS 2102 OTA, DS 90 OTA, 60 mm f/15, Lightbridge 12, Lightbridge Mini 82, Eclipseview 76 & 114, Sky Shed 3 Bay POD, LPI-G Color

  3. #13
    Robrj's Avatar
    Robrj is offline Gold Supporter
    Points: 27,628, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!50 Posts Achievement!5 Threads Achievement!200+ Posts Achievement!
    Join Date
    Dec 2014
    Location
    Escondido, CA
    Posts
    2,493
    Points
    27,628
    Level
    100
    Thanks
    154
    Thanked 855x 633 Posts

    Default Re: Fast Newtonian eyepiece query

    You're not letting the team down by staying within your budget. Plus, going with 1.25" is actually a good choice. Bigger isn't necessarily better. Other than a wide field, there's no real benefit to a 2" optic. 1.25" optics aren't inferior in quality just because they're 1.25". Often a 1.25" is easier to make well, lighter, and costs less. The only real reason to go to a 2" eyepiece is because you want a wider view than you can get with a 1.25". You could make a convenience case for a having them all be 2" eyepieces if you're willing to pay that much to not have to swap in an adapter. I have all 2" eyepieces: 5.5mm 100°, 9mm 100°, 18mm 82° and 24mm 82°. I like the wide view. But a 1.25" 4.7mm Explore Scientific 82° is a really good eyepiece as well and costs about 1/3 the cost of the ES 5.5mm 100° and is still a huge view. Same with the 1.25" 8.8mm ES 82° vs the 9mm 100°. So, why do I have them? I found an open box NEAP deal on the 9mm 100° that was a demo unit and it tempted me ($150 off). If I ever wanted to get my money back, it would easily sell for what I paid, maybe more. My wife bought me the 5.5mm 100° for Christmas. Otherwise, I would be equally happy with 1.25" ES 82° eyepieces (it's still pretty wide). Also, I'd rather have a quality 1.25" eyepiece than a cheap 2" wide field eyepiece. You'll find that's true especially at f/4.

    Also, try not to sweat the cost of the eyepieces. It'll take you a little longer to build up a good set but they will probably be with you for life. Plus, they hold their value pretty well if you take care of them.
    Last edited by Robrj; 12-01-2016 at 10:56 PM.
    TheFatKitty and MistrBadgr like this.
    Rob

    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.
    : Celestron 130SLT,
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    Skyview Pro 8",
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    12"
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    Dob. Orion ED80T CF
    Mount: AVX
    Cameras: Starlight Xpress Lodestar X2M, ZWO ASI294MC, ASI224MC
    My Images: http://www.astrobin.com/users/Robrj/

  4. #14
    Frosty-vegi's Avatar
    Frosty-vegi is offline White Dwarf
    Points: 1,622, Level: 24
    Level completed: 22%, Points required for next Level: 78
    Overall activity: 0%
    Achievements:
    First 1000 Experience Points365 Days+ Registered Achievement!750 Days+ Registered Achievement!1000 Days+ Registered Achievement!3 Years + Achievement
    Join Date
    Oct 2014
    Location
    Brisbane, QLD
    Posts
    7
    Points
    1,622
    Level
    24
    Thanks
    0
    Thanked 2x 2 Posts

    Default Re: Fast Newtonian eyepiece query

    Now I know why everyone looks at me funny when I say I have a HEQ5.. it's a NEQ6.. just shows you how long it's been since I've used my scope and mount frequently... wish I knew how to edit posts.. or travel back in time..

  5. #15
    not_Fritz_Argelander's Avatar
    not_Fritz_Argelander is offline HYPER GIANT
    Points: 183,440, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 29.0%
    Achievements:
    365 Days+ Registered Achievement!2 Posts Achievement20 Posts Achievement!750 Days+ Registered Achievement!First 1000 Experience Points
    Join Date
    Jul 2011
    Location
    US
    Posts
    22,039
    Points
    183,440
    Level
    100
    Thanks
    7,254
    Thanked 46,396x 14,953 Posts
    Blog Entries
    59

    Default Re: Fast Newtonian eyepiece query

    When I use my 8" f4 a good coma corrector is essential. My 12" f5 can do without. I find I use the TV Paracorr most conveniently. Advice to try a bunch of alternatives with different AFOVs should help a lot. It turns out I really don't like the 82 AFOV format. The AFOV isn't wide enough to make up for the pincushion distortion but I enjoy 100 degree AFOVs just fine. I wish I had sorted that out before buying my Naglers and selling them off.

    Anyway my main set for the f4 is Paracorr, Panoptics and Delos. The Delos is crisper to my eye than Delite. When I want to go crazy with wide field wonderment I use the ES 100 series.
    j.gardavsky likes this.

  6. The Following User Says Thank You to not_Fritz_Argelander For This Useful Post:

    j.gardavsky (12-02-2016)

  7. #16
    Robrj's Avatar
    Robrj is offline Gold Supporter
    Points: 27,628, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 0%
    Achievements:
    2 Posts Achievement20 Posts Achievement!50 Posts Achievement!5 Threads Achievement!200+ Posts Achievement!
    Join Date
    Dec 2014
    Location
    Escondido, CA
    Posts
    2,493
    Points
    27,628
    Level
    100
    Thanks
    154
    Thanked 855x 633 Posts

    Default Re: Fast Newtonian eyepiece query

    Quote Originally Posted by Frosty-vegi View Post
    Now I know why everyone looks at me funny when I say I have a HEQ5.. it's a NEQ6.. just shows you how long it's been since I've used my scope and mount frequently... wish I knew how to edit posts.. or travel back in time..
    Editing on the forum times out at about 15 minutes. After that time, a post can't be edited by us mere mortals.

    Another option is to buy used. Since people like to upgrade, you can get many of the higher quality eyepieces for much cheaper than buying new (abotu 60% to 70% of the new price) and they're usually well taken care of. Plus, with a used eyepiece, you can usually sell it for close to what you paid if you later upgrade. CloudyNights.com has a big classified section. Astromart is a good place as well but it costs to join ($15/year). There are classifieds on here as well but the selection is more limited and they tend to go fast. The downside is it takes patience and repeatedly checking to see what's new. Plus, it helps to know what you want ahead of time.
    Rob

    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.
    : Celestron 130SLT,
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    Skyview Pro 8",
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    12"
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    Dob. Orion ED80T CF
    Mount: AVX
    Cameras: Starlight Xpress Lodestar X2M, ZWO ASI294MC, ASI224MC
    My Images: http://www.astrobin.com/users/Robrj/

 

 
Page 2 of 2 FirstFirst 12

Similar Threads

  1. GSO 2" Coma Corrector for fast Newtonian Telescope
    By WConde in forum Astronomy Forum
    Replies: 1
    Last Post: 10-26-2015, 07:45 PM
  2. Eyepiece locating query on 6SE and focussing accuracy
    By Mystery57 in forum Astronomy Beginners Forum
    Replies: 6
    Last Post: 01-23-2014, 07:27 AM
  3. Fast Focus Short Tube Newtonian Telescopes
    By philip d in forum Reflector Telescope Forum
    Replies: 14
    Last Post: 04-27-2012, 06:24 PM
  4. Planetary imaging with fast Newtonian
    By Max in forum Amateur Astronomy Forum
    Replies: 20
    Last Post: 10-20-2005, 02:37 AM
  5. Which eyepieces for a fast newtonian?
    By Chris Jewell in forum Amateur Astronomy Forum
    Replies: 9
    Last Post: 02-19-2004, 12:51 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 02:41 AM.