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
We cover off lots of useful astronomy formally in our resources section. However, in an article about telescope eyepieces is useful to have a recap on how to work out magnification in your telescope.
The formula is simple:
Magnification = Telescope Focal Length / Eyepiece Focal Length.
For example, if your telescope has a focal length of 500mm and you insert a 10mm eyepiece, you get a 50x magnification, i.e. 500mm/10mm=50.
The table below can be used as a ‘ready reckoner’ for the magnifications you could achieve using the Luminos range of eyepieces in a telescope with 750mm, 1000mm and 1250mm focal lengths.
If you add the Luminos 2.5x Barlow Lens, you get the magnification number in brackets, which is derived by multiplying the initial magnification by 2.5.
|Eyepiece||750mm FL Scope||1000mm FL Scope||1250mm FL Scope|
|7mm||107x (268x)||143x (357x)||179x (446x)|
|10mm||75x (188x)||100x (250x)||125x (313x)|
|15mm||58x (144x)||67x (167x)||63x (208x)|
|19mm||39x (99x)||53x (132x)||66x (164x)|
|23mm||33x (82x)||43x (108x)||54x (136x)|
|31mm||24x (60x)||32x (81x)||40x (101x)|
Luminos 2.5x Barlow Lens Review
- The Celestron 2.5x Luminos Barlow increases the magnification of any 2” or 1.25” eyepiece by two and a half times
- High-quality 4-element optics produce a flat field for sharp images that are free of extraneous color
- Hard-anodized aluminum barrel is threaded to accept 2” filters
- A brass compression ring holds eyepieces firmly in place, and large thumbscrews are easy to turn, even with gloves on
- A 2” to 1.25” adapter is included. Allows the use of both 2” and 1.25” eyepieces.
As mentioned at the start of this article, Celestron’s Luminos range also includes a 2.5x Barlow lens.
It will receive the 2″ eyepieces directly and takes the 1.25″ models with the use of an included adapter. The eyepieces fit snugly into the Barlow and are held in place with compression rings which hold them tightly without any point pressure damage.
The Barlow is the same style and quality of design as the eyepieces and includes oversized thumbscrews to aid their use in cold weather or when wearing gloves.
The Barlow itself is threaded to accept 2 inch filters and is apochromatic (i.e. colors don’t split out) thanks to its four lens elements which work together to produce a flat field.
Fully multi coated to dramatically improves light transmission through the lenses, this Barlow lets more light through than cheaper models.
The video below gives a decent review of the Luminos Barlow lens.
Cons of the Luminos Range
There are lots of Positive things to say about this eyepiece range, from build quality and finish to specification and price point.
However, nothing in this world is perfect and the luminous eyepieces are no exception. Thankfully though, there are only a couple of minor issues we’ve discovered.
Edge of Field Brightening
This is where objects in the field of view appear to be brighter at the edge of the field than in the center.
This can be frustrating but is far from being a significant problem. Indeed, many astronomers report it being hardly noticeable in this thread from Cloudy Nights astronomy forum.
It’s also noted in the thread that this is a minor issue given the price of this range when compared to a Nagler eyepiece.
Some users report seeing coma in some telescopes. Coma is where stars develop tales most commonly at the edge of a field of view. Although we can’t say for certain, it is more likely that coma is seen where Luminos eyepieces are used in faster telescopes, i.e., those below f/5.
There is speculation in this Stargazers Lounge thread that the range is optimised for f/10 – f/5 scopes, which makes sense given what Celestron have to say about them (see next section).
We’ve not found other incidents of coma being reported so expect it is a problem related to the telescope being used rather than the eyepieces themselves.
Which Telescopes Do Luminos Eyepieces Work With?
This range of eyepieces works well for most kinds of observing from low-power through high. They’re compatible with all kinds of telescopes but certainly work better with those which deliver a flat field.
As noted in section above, they also seem to be optimised for telescopes in the f/10 to f/5 range. In faster telescopes, they produce less sharp images and perhaps needing a field flattener for best results.
Celestron themselves recommend them for use with Cat’s and high end refractors. Take a look at our best telescopes if you’re in the market for a new one.
Celestron’s Luminos Wide Field of View eyepiece range is ideal for both new and experienced astronomers looking to step up the quality of their eyepieces, or invest in ultra wide field of view for the first time, without spending a fortune.
The comprehensive range is well built and delivers fantastic performance at an incredibly reasonable price point. You will be hard pushed to find higher quality wide field of view eyepieces in this bracket.
Use the tables below to see current pricing on Amazon and click to find out more button for more information and detailed reviews.
Celestron Luminos 1.25″ Eyepieces
Celestron Luminos 2.0″ Eyepieces
Last update on 2020-01-17 / Affiliate links / Images from Amazon Product Advertising API