Creating a basic set of eyepieces for your new telescope
- Lady Fraktor
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Re: Creating a basic set of eyepieces for your new telescope
The easiest way if you are going to be doing this quite often is to find focus with both eyepieces and mark how far out the focuser is. (if using a refractor)
Place the refractor with eyepiece on table top with focuser adjusted to focus and find the balance point.
Do the same with the other eyepiece.
Mark the tube for both balance points so that you can shift the tube up or down in the tube clamps to re-balance quickly.
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- notFritzArgelander
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Re: Creating a basic set of eyepieces for your new telescope
I only run into weight issues on my Z12Refractordude wrote: ↑Wed Oct 30, 2019 6:07 pmGreat info, but what about switching from a 12 ounce 2" eyepiece to a 20 ounce 2" eyepiece?notFritzArgelander wrote: ↑Wed Oct 30, 2019 6:00 pmThe Equalizer....Refractordude wrote: ↑Wed Oct 30, 2019 5:56 pm
Great idea, can you show me a link to such an adapter.
http://www.televue.com/engine/TV3b_page ... Tab=_equil
https://www.amazon.com/Ant-Mag-Carabine ... 2192&psc=1
https://www.amazon.com/Yes4All-Ankle-Wr ... s9dHJ1ZQ==
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Re: Creating a basic set of eyepieces for your new telescope
I was thinking about angle weights, the magnet hooks are a even better idea. ThanksnotFritzArgelander wrote: ↑Wed Oct 30, 2019 6:27 pmI only run into weight issues on my Z12Refractordude wrote: ↑Wed Oct 30, 2019 6:07 pmGreat info, but what about switching from a 12 ounce 2" eyepiece to a 20 ounce 2" eyepiece?notFritzArgelander wrote: ↑Wed Oct 30, 2019 6:00 pm
The Equalizer....
http://www.televue.com/engine/TV3b_page ... Tab=_equilDob where I use neodymium magnets with a carabiner and a weight.
https://www.amazon.com/Ant-Mag-Carabine ... 2192&psc=1
https://www.amazon.com/Yes4All-Ankle-Wr ... s9dHJ1ZQ==
- notFritzArgelander
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Re: Creating a basic set of eyepieces for your new telescope
Hooking the ankle weight to the magnets (two so no dangling) allows adjustment on the fly. They used to make elegant counterweight systems for OTAs. https://fullerscopes.blogspot.com/2015/09/Refractordude wrote: ↑Thu Oct 31, 2019 3:47 amI was thinking about angle weights, the magnet hooks are a even better idea. ThanksnotFritzArgelander wrote: ↑Wed Oct 30, 2019 6:27 pmI only run into weight issues on my Z12Refractordude wrote: ↑Wed Oct 30, 2019 6:07 pm
Great info, but what about switching from a 12 ounce 2" eyepiece to a 20 ounce 2" eyepiece?Dob where I use neodymium magnets with a carabiner and a weight.
https://www.amazon.com/Ant-Mag-Carabine ... 2192&psc=1
https://www.amazon.com/Yes4All-Ankle-Wr ... s9dHJ1ZQ==
- Mick
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Re: Creating a basic set of eyepieces for your new telescope
Regards
Mick
Plus growing bits and bobs.
- PalomarJack
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Re: Creating a basic set of eyepieces for your new telescope
Another good rule is that any eyepiece used on say my 8"
8" f/6 Newtonian on a German equatorial mount, all DIY.
DIY 90mm f/10 refractor on old medium duty Edmund Scientific German equatorial mount.
- Lady Fraktor
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Re: Creating a basic set of eyepieces for your new telescope
A spread from 1mm to 7mm will give you much more leeway for viewing.
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- notFritzArgelander
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Re: Creating a basic set of eyepieces for your new telescope
Agreed. With a mere 65 years of observing experience I choose evenly spaced exit pupils from 6mm down to the 2mm where maximum resolution is obtained and then evenly spaced focal lengths for high magnification.Lady Fraktor wrote: ↑Sun Nov 24, 2019 7:26 am Focal ratio is independent of aperture but a 40mm eyepiece in a 200mm f/6 is only slightly more than 5mm exit pupil and over 2mm in a f/12 which would be very restrictive on eyepiece selection.
A spread from 1mm to 7mm will give you much more leeway for viewing.
So using my
TV Panoptic 41mm gives ~6mm exit pupil
TV Panoptic 35mm gives ~5mm exit pupil (and does double duty as tough nebula detector, Magic Horsehead eyepiece)
TV Panoptic 27mm gives ~4mm exit pupil
TV Panoptic 19mm gives ~3mm exit pupil
TV Delos 14mm gives ~2mm exit pupil
Kokusai Kohki Fujiyamas in 9, 7, 6, 5, 4mm focal lengths for 1.3, 1.0, 0.85, 0.7, and 0.6 mm exit pupils, roughly.
That's a set that's fully capable of lower power, middle and high power work. It's what I'd pack for a vacation with that scope and be confident I could handle anything the weather permits and any object.
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Re: Creating a basic set of eyepieces for your new telescope
I am aware of that, however, the performance expectation will track evenly betweenLady Fraktor wrote: ↑Sun Nov 24, 2019 7:26 am Focal ratio is independent of aperture but a 40mm eyepiece in a 200mm f/6 is only slightly more than 5mm exit pupil and over 2mm in a f/12 which would be very restrictive on eyepiece selection.
A spread from 1mm to 7mm will give you much more leeway for viewing.
Yes, I do have a 90mm
8" f/6 Newtonian on a German equatorial mount, all DIY.
DIY 90mm f/10 refractor on old medium duty Edmund Scientific German equatorial mount.
- notFritzArgelander
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Re: Creating a basic set of eyepieces for your new telescope
It is not true that performance tracks well between different f ratios. An eyepiece that is designed to work well with an f10 cone of rays from the objective can turn to mush in an f6 scope. Also comparisons of performance should be done at constant exit pupil since that reduces the dependency on the eye's individual physiology.PalomarJack wrote: ↑Tue Nov 26, 2019 9:03 pmI am aware of that, however, the performance expectation will track evenly betweenLady Fraktor wrote: ↑Sun Nov 24, 2019 7:26 am Focal ratio is independent of aperture but a 40mm eyepiece in a 200mm f/6 is only slightly more than 5mm exit pupil and over 2mm in a f/12 which would be very restrictive on eyepiece selection.
A spread from 1mm to 7mm will give you much more leeway for viewing.f/ 6 andf/ 12 or between two different apertures of the same focal ratio for given eyepieces. I'm just pointing out the relationship between eyepiece selection and focal ratio. It can be a useful criteria when planning a build or purchase.
Yes, I do have a 90mmf/ 10 verses my 8"f/ 6, but the optics were at a price I just could not refuse.
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Re: Creating a basic set of eyepieces for your new telescope
I was only speaking of the relationship of eyepiece focal length andnotFritzArgelander wrote: ↑Tue Nov 26, 2019 9:27 pmIt is not true that performance tracks well between different f ratios. An eyepiece that is designed to work well with an f10 cone of rays from the objective can turn to mush in an f6 scope. Also comparisons of performance should be done at constant exit pupil since that reduces the dependency on the eye's individual physiology.PalomarJack wrote: ↑Tue Nov 26, 2019 9:03 pmI am aware of that, however, the performance expectation will track evenly betweenLady Fraktor wrote: ↑Sun Nov 24, 2019 7:26 am Focal ratio is independent of aperture but a 40mm eyepiece in a 200mm f/6 is only slightly more than 5mm exit pupil and over 2mm in a f/12 which would be very restrictive on eyepiece selection.
A spread from 1mm to 7mm will give you much more leeway for viewing.f/ 6 andf/ 12 or between two different apertures of the same focal ratio for given eyepieces. I'm just pointing out the relationship between eyepiece selection and focal ratio. It can be a useful criteria when planning a build or purchase.
Yes, I do have a 90mmf/ 10 verses my 8"f/ 6, but the optics were at a price I just could not refuse.
As far as sizing for exit pupil, it works very well and is the most accurate. Again, I was only introducing a criteria that could be included when selecting eyepieces used on multiple telescopes. In the end, eyepiece selection is not written in stone, anyway, except using ancient designs meant for enormously long refractors on an
8" f/6 Newtonian on a German equatorial mount, all DIY.
DIY 90mm f/10 refractor on old medium duty Edmund Scientific German equatorial mount.
- notFritzArgelander
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Re: Creating a basic set of eyepieces for your new telescope
The only room for differences of opinion are in matters of taste. For instance I regularly enjoyed meeting an old friend from school who continued to make a career in astrophysics retiring recently. We’ve been fighting a religious war over eyepiece designs for decades! My friend consistently upholds Plossl design orthoscopics which I disparage in preference to the Abbe design which is what folks usually refer to when using a capital O.
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Re: Creating a basic set of eyepieces for your new telescope
The majority of my favorite eyepieces are in the 25°-50°
Ramsden and Huyghenian eyepiece designs work well in longer refractors for double and carbon star viewing and the occasional view of the lunar surface.
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Re: Creating a basic set of eyepieces for your new telescope
Mostly I complain about the short eye relief on the Plossls compared to the Abbe's.Lady Fraktor wrote: ↑Wed Nov 27, 2019 7:01 am I am firmly in the middle as I use both Abbe and Plossl and short eye relief is not an issue for me as some find it.
The majority of my favorite eyepieces are in the 25°-50° AFOV and I still occasionally use .925", .965".
Ramsden and Huyghenian eyepiece designs work well in longer refractors for double and carbon star viewing and the occasional view of the lunar surface.
I haven't used Huyghenians and Ramsdens much since my student days.
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Re: Creating a basic set of eyepieces for your new telescope
With my
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Re: Creating a basic set of eyepieces for your new telescope
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Re: Creating a basic set of eyepieces for your new telescope
- Lady Fraktor
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Re: Creating a basic set of eyepieces for your new telescope
For planetary I use from 1.6mm to 28mm but only use barlows occasionally.
All personal preference.
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- FerrariMX5
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Re: Creating a basic set of eyepieces for your new telescope
I love this article because it covers a lot of material and the Google Translator makes for some amusing word associations, which adds a different perspective.Kos wrote: ↑Sun May 26, 2019 2:20 pm Всем привет! Очень полезная статья по окулярам и их выбору: http://astro-talks.ru/forum/viewtopic.php?f=31&t=622 , рекомендую! Не забудьте включить google переводчик!
Я люблю эту статью, потому что она охватывает много материала и Google Переводчик делает для некоторых забавных слов ассоциаций, которые добавляет различные точки зрения.
Tony
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Re: Creating a basic set of eyepieces for your new telescope
For now, I will stick to two.
a wide field of view 32mm which is equal to about 60 times magnification
and a 12.5mm which is equal to about 160 times magnification.
Many have told me that a 5mm (400 Mag) and a 7.5mm (270 Mag) would not be usable on an 8'
Still, if I come across a Celestron Kit of lenses and filters in a local yard sale, I will be tempted to give them a try.
Hobbies, what would we do without them?
Would love to participate in a local star party, then I could see what I am missing..
Since star parties are still canceled, What's your opinion of this kit? Celestron – 1.25” Eyepiece and Filter Accessory Kit
It comes with 32mm, 17mm, 13mm, 8mm, and 6mm. a 2X barlow and filters (In a case).
Tony
The speed of light: 299,792,458 Meters per Second
The speed of time: One Second per Second.
The speed of gravity: 299,792,458 Meters per Second
Warp 10: Touching all points in the universe at the same time.
Welcome to the Universe (Its bigger than you think).
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