New Astro-Tech PF Eyepieces have been announced by Astronomics. The new line of eyepieces are offered in five different focal lengths and offer 60° or 65° apparent field of views. This series of eyepiece is designed to have an inherently flat field, so it will excel at wide field observation.
Astro-Tech 5.5mm 1.25″ PF Eyepiece
The Astro-Tech 5.5mm PF eyepiece offers a 60° apparent field of view and is designed for medium to medium high magnification viewing with short to medium focal length refractors and reflectors. It is also usable with long focal length refractors and catadioptric scopes under good or better seeing conditions.
Average seeing conditions will limit its usefulness with long focal length scopes due to the inherent high magnification of its 5mm focal length. Using it with a 2000mm 8″ f/10 catadioptric, for example, will result in 363x (45x per inch of aperture) and a 0.5mm exit pupil (about 1/50th of an inch across). Both of these are just under rule of thumb limits for maximum magnification per inch of aperture and minimum exit pupil size for usable observing under good to very good seeing conditions for a reasonably experienced observer.
The six lens/four group design of the 5.5mm Astro-Tech PF provides high contrast, a sharp and flat field from edge to edge, excellent color fidelity, and low astigmatism and barrel distortion. It has a usable eye relief of 16mm, excellent for such a short focal length eyepiece. The eyepiece some with a traditional rubber fold down eye cup to assist that glasses wearers of the world find a comfortable eye position.
Astro-Tech 10.5mm 1.25″ PF Eyepiece
This Astro-Tech 10.5mm PF eyepiece offers a 60° apparent field of view and works well for medium magnification viewing with short to medium focal length refractors and reflectors. It is also extremely usable with long focal length refractors and catadioptric scopes under virtually any seeing conditions. This focal length tends to hit the sweet spot in most long focal length telescopes.
With a short focal length refractor it is a low power eyepiece. With the 430mm focal length Astro-Tech AT72EDII, its five lens/four group multicoated glass optics provide 40x and a field over three times as wide as the full Moon. This is well suited for observing globular clusters such as M13 and M22. Both fit nicely into its 1.67° field with the AT72EDII, with a framework of black sky around the clusters to set them off. Its sharpness and lack of astigmatism across the field make globular clusters sharp, vivid, and nearly three-dimensional. This series of eyepiece is designed to have an inherently flat field, so it will excel at wide field observation.
It functions so well for medium high magnification observing with long focal length refractors, reflectors, or catadioptric scopes. On an 8″ f/10 catadioptric, for example, it yields 190x. This is an excellent magnification for planetary and close-up lunar observing.
The five lens/four group design of the 10.5mm Astro-Tech PF provides high contrast, a sharp and flat field from edge to edge, excellent color fidelity, and exceptionally low astigmatism and barrel distortion. It has a usable eye relief of 16mm, excellent for such a short focal length eyepiece. The eyepiece comes with a traditional rubber fold down eye cup.
Astro-Tech 15.5mm 1.25″ PF Eyepiece
The Astro-Tech 15.5mm PF eyepiece offers a five lens/three group design and is an excellent medium power eyepiece for all types of observing in all types of seeing conditions. A focal length like the 15.5 fits a natural step left behind by most telescopes standard 25mm or so eyepiece.
With a short focal length refractor it is a low power eyepiece. With the 430mm focal length Astro-Tech AT72EDII, its five lens/three group multicoated glass optics provide 27.8x and a field over four times as wide as the full Moon.
It functions well for medium high magnification observing with long focal length refractors, reflectors, or catadioptric scopes. On an 8″ f/10 catadioptric it yields 129x. Its overall performance makes it a good choice as a second eyepiece than merely doubling the power of most scopes’ standard 25-26mm eyepiece with a Barlow.
The Astro-Tech 15.5mm PF has a usable eye relief of 16mm. The eyepiece offers a traditional rubber fold down eye cup and has a nice 65° apparent field of view.
Astro-Tech 19mm 1.25″ PF Eyepiece
The Astro-Tech 19mm PF eyepiece is an excellent medium to medium low power eyepiece for all types of observing in all types of seeing conditions. A focal length like the 19 fits a natural spot left behind by many standard 25mm or so eyepieces. The 19mm PF eyepiece physical size and flat field would also make them excellent choices for a binoviewer.
With a short focal length refractor it is a low power eyepiece. With the 430mm focal length Astro-Tech AT72EDII, its five lens/three group multicoated glass optics provide 22x and a field over five times as wide as the full Moon. This is well suited for lunar observing, encompassing globular clusters, getting lost in the faint details of emission and reflection nebulas among other things. This series of eyepiece is designed to have an inherently flat field, so it will excel at wide field observation.
It functions well for medium high magnification observing with long focal length refractors, reflectors, or catadioptric scopes. On an 8″ f/10 catadioptric, for example, it yields 105x. It has a 65° apparent field of view and a usable eye relief of 20mm.
Astro-Tech 25mm 1.25″ PF Eyepiece
This Astro-Tech 25mm PF eyepiece is an excellent medium to low power eyepiece and the 25mm should be a noticeable step up from the 25/26mm eyepiece that comes with most scopes as standard equipment.
With a short focal length refractor it is a low power eyepiece. With the 430mm focal length Astro-Tech AT72EDII, its four lens/three group multicoated glass optics provide 17x and a field that is nearly seven times as wide as the full Moon. This is well suited for scanning the crowded star clouds of Sagittarius, encompassing globular clusters, getting lost in the faint details of emission and reflection nebulas among other things.
It functions so well for medium magnification observing with long focal length refractors, reflectors, or catadioptric scopes. On an 8″ f/10 catadioptric, for example, it yields 80x.
The four lens/three group design of the 25mm Astro-Tech PF has a usable eye relief of 23mm, which is just excellent for all observers. The eyepiece some with a traditional rubber fold down eye cup to assist that glasses wearers of the world find a comfortable eye position. The eyepiece has a nice 65° apparent field of view.
You can learn more about the new Astro-Tech PF Eyepieces here.
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