Astronomics is now carrying a 60 to 65-degree line of Astro-Tech PF Eyepieces (PF is short for Premium Flat Field). These 1.25” eyepieces provide high contrast, a sharp and flat field from edge to edge, excellent color fidelity, and low astigmatism and barrel distortion.
This series of eyepiece is designed to have an inherently flat field, so it will excel at wide field observation. Each eyepiece offers excellent build quality with a traditional rubber fold down eye cup to assist that glasses wearers of the world find a comfortable eye position. The eyepieces come in the following configurations.
Astro-Tech PF Eyepiece – 5.5mm
The Astro-Tech 5.5mm PF eyepiece is excellent for medium-to-medium high magnification viewing with short to medium focal length refractors and reflectors. The 1.25″ eyepiece 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 has a usable eye relief of 16mm, excellent for such a short focal length eyepiece. The eyepiece offers 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 60° apparent field of view.
The Astro-Tech 5.5mm PF eyepiece specifications include:
– Barrel Size: 1.25″
– Eye Relief: 16mm”
– Field of view: 60
– Field Stop: 6.4mm
– Focal Length: 5.5mm
– Number of optical elements: 6
– Weight: 7.2 oz.
Astro-Tech PF Eyepiece – 19mm
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. The 1.25” eyepiece has a focal that fits a natural step left behind by many standard 25mm or so eyepieces. The physical size and flat field 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, for example, 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. 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.
The five lens/three group design of the 19mm Astro-Tech PF has a usable eye relief of 20mm, which is excellent for most observers. The eyepiece has a 65° apparent field of view, which is a tad wider than the 5.5 and 10.5 Astro-Tech PF eyepieces.
The Astro-Tech 19mm PF eyepiece specifications include:
– Barrel Size: 1.25″
– Eye Relief: 20mm
– Field of view: 65
– Field Stop: 20.3mm
– Focal Length: 19mm
– Number of optical elements: 5
– Weight: 5.2 oz.
Astro-Tech PF Eyepiece – 10.5mm
This Astro-Tech 10.5mm PF eyepiece is excellent 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 the 430mm focal length Astro-Tech AT72EDII, for example, 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. It offers sharpness and lack of astigmatism across the field.
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 190x. This is an excellent magnification for planetary and close-up lunar observing. Its overall performance makes it a nice choice as a second eyepiece as opposed to doubling the power of a 25-26mm eyepiece with a Barlow.
The five lens/four group design has a usable eye relief of 16mm and a 60° apparent field of view.
The Astro-Tech 10.5mm PF eyepiece specifications include:
– Barrel Size: 1.25″
– Eye Relief: 16mm
– Field of view: 60
– Field Stop: 11.7mm
– Focal Length: 10.5mm
– Number of optical elements: 5
– Weight: 5.2 oz.
Astro-Tech PF Eyepiece – 25mm
The Astro-Tech 25mm PF eyepiece is an excellent medium to low power eyepiece for all types of observing in all types of seeing conditions. This 25mm should be a noticeable step up from the 25/26mm eyepiece that comes with most scopes as standard equipment. The eyepiece’s physical size and flat field would also make them excellent choices for a binoviewer.
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 well for medium magnification observing with long focal length refractors, reflectors, or catadioptric scopes. On an 8″ f/10 catadioptric it yields 80x. You can get lost inside clusters or just gazing at the moon for hours on end.
The 25mm Astro-Tech PF has a usable eye relief of 23mm, which is excellent for virtually all observers. As with the Astro-Tech 19mm PF eyepiece, the 25mm has a 65° apparent field of view, which is a just a little wider than the 5.5 and 10.5 Astro-Tech PF eyepieces.
The Astro-Tech 25mm PF eyepiece specifications include:
– Barrel Size: 1.25″
– Eye Relief: 23mm
– Field of view: 65
– Field Stop: 25.9mm
– Focal Length: 25mm
– Number of optical elements: 4
– Weight: 5.2 oz.
Astro-Tech PF Eyepiece – 15mm
The Astro-Tech 15.5mm PF eyepiece is an excellent medium power eyepiece for all types of observing in all types of seeing conditions.
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. 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.
It works well with medium high magnification observing with long focal length refractors, reflectors, or catadioptric scopes. On an 8″ f/10 catadioptric it yields 129x. This is an excellent magnification for planetary and close-up lunar observing.
The five lens/three group design of the 15.5mm Astro-Tech PF has a usable eye relief of 16mm and a 65° apparent field of view.
The Astro-Tech 25mm PF eyepiece specifications include:
– Barrel Size: 1.25″
– Eye Relief: 16mm
– Field of view: 65
– Field Stop: 17.4mm
– Focal Length: 15.5mm
– Number of optical elements: 5
– Weight: 5.2 oz.
You can learn more about the Astro-Tech PF Eyepieces here.
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