Celestron’s Luminous range of eyepieces is their ultra wide field, 82° apparent field of view range. The range consists of six different focal length eyepieces and a 2.5x Barlow lens.
Large field viewing is fantastic for bigger night sky objects, such as galaxies and star clusters. Looking through these eyepieces is like looking through a window in space because you don’t notice the field stop. Read on for our detailed review.
Celestron Luminos 1.25″ Eyepieces
Celestron Luminos 2.0″ Eyepieces
The Celestron Luminos Eyepiece Range
There are six sizes of eyepiece in the luminous range. The smaller three have 1.25″ barrels and the larger three have 2″ barrels.
The 1.25″ focal lengths are 7mm, 10mm, and 15mm; the 2″ barrel sizes are 19mm, 23mm, and 31mm. There is also a 2.5x Barlow lens within the range.
The whole point to this range is delivering a wide field of view and each of the eyepieces has an apparent field of view of 82°.
Luminos Eyepiece Construction
Each of the eyepieces in the luminous range consists of either six or seven lenses working together to provide a flat field, 82° apparent field of view.
The reason there are so many lenses within a technical eyepiece like this is they work together to reduce imaging issues. So with the luminous range you will find very little ghosting (reflection between lenses), astigmatism or field curvature (spherical aberration).
All Luminos eyepieces are multi-coated to improve light transmission through the multiple lenses meaning a better image at your eye and lens edges are blackened to improve contrast.
This works because the blackened edge stops light leaking out into the barrel of the eyepiece and bouncing around freely, keeping the image sharp at the pupil.
Parfocal Eyepiece Range
Each Luminos eyepiece is parfocal. Parfocal means that when swapping between different eyepiece sizes within the range, you won’t need to change the focus on your telescope (except maybe minimally).
This brings obvious advantages when changing eyepieces to get better or more magnified views of the object you are looking at. Swap out the 15mm for the 7mm and you won’t have to do mess around refocusing your telescope.
Notes on Fields of View
Field of View describes how much of the sky you can see through your telescope. It is a circle with a diameter measured in degrees. The looming side pieces all have an 82° apparent field of view and you can use this number with the magnification numbers given below (see Notes on Magnification, below) to work out the true field of view.
The formula is a simple one:
True Field of View = Apparent Field of View / Magnification
With the Luminos range, our apparent field of view is always 82°. All we need to do to understand our true field of view is plug-in a magnification.
For example, if we have a magnification of 100x the true field of view we get with this formula is 82/100 = 0.82°, i.e. you can see a circle of sky 0.82° across with 100x magnification.
As you’d expect, smaller magnification gives a larger field of view, 50x put through the same formula gives a viewing circle with a diameter of 1.64°.
Features of the Luminos Eyepiece
Each eyepiece in the range shares the same build standards. Each has a rubber cup shield to keep out stray light, or use retracted if you wear glasses. Funkily, the rubber cups on this range are revealed through a twist mechanism which raises and lowers the shield.
The barrels are made from anodised aluminium which gives good durability and offers scratch resistance. There is a groove machined around the barrel to prevent the EP accidentally slipping out of your telescope if a thumbscrew becomes loose.
All of the eyepieces in the Luminos range have a rubber gripper which makes handling them easier in cold or damp conditions.
The eyepieces are threaded to receive telescope filters. The 7mm, 10mm and 15mm eyepieces accept standard 1.25″ filters, while the larger 19mm, 23mm and 31mm models are threaded to receive 2″ filters.
This difference in size is one area where the Luminos range is not as great as it could be. Needing two different sizes of the same filter to swap between 19mm and 15mm eyepieces is obviously a pain but, given the strong quality-to-price ratio, is far from a dealbreaker.
Overall, Luminos eyepieces have a great appearance and feel like a well-built, sturdy and professional range. Which is all great, but what’s more important is their specification and how they perform, which we turn to next.
Luminos Eyepiece Specification
The table below shows the eye relief and weight of each model in the range:
|Luminos Eyepiece||Field Stop||Eye Relief||Weight|
Eye relief ranges from a fairly short 12mm on the seven and 10mm models up to 27 mm on the 31 mm focal length model.
Field stop diameters vary from 1.5 cm on the smallest eyepiece to a colossal 4.7 cm in the largest Luminous. That 31mm focal length eyepiece is the biggest in more ways than one, it weighs in at a colossal 2lbs 11oz, almost 3 times the weight of the 23mm eyepiece.
The lenses are noted to deliver pin sharp stars with good light transmission. There’s also a noted joy at seeing a wider field than you can get with most other eyepieces.
Notes On Magnification
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