Telescope Basics 3 (of 6): Understanding common eyepieces for telescopes

Hosted by David Fuller of “Eyes on the Sky,” this video goes over the various sizes and types of basic eyepieces for many amateur telescopes. The three most common eyepiece barrel diameters are discussed, as well as the types of lens configurations which determine how well the eyepiece forms an image for the user – including the concept of eye relief which can matter a lot to those who wear eyeglasses. Discussed are Huygens, Ramsden, Kellner, RKE, Modified Achromat, Plossl and some advanced designs, plus some information about anti-reflection coatings. An excellent primer for anyone wanting to understand more about telescope eyepieces.



Photon 666 says:

Hell, I’ve tried putting a eyepiece on my new telescope but it did not fit in properly. I am not sure what did I do wrong. The eyepiece was 20mm. Thank you.

radio boys says:

got more questions, you might want to see Cloudy Nights web site

Basil Alzubaydi says:

The wig look is good 🙂 Informative video, good stuff.

Bor1ng B1tch says:

I got a Explore One Theseus Telescope. I am new to the telescope owners club and I have no idea about anything to do with them. But I have always like outer space and always wanted to be able to see outer space up close. So I got this telescope for Christmas today but it did not come with any instructions of any kind. It just came with a list of all it’s parts. I can NOT find this telescope anywhere (as in I can NOT find videos or tutorials or manuals about this telescope anywhere). It is a basic simple telescope. It has the main telescope which is 700mm with 60mm diameter and it came with 3 interchanglable zoom lenses. One SR4mm, H12.5mm, and a H20mm lens. And it also came with a tiny little mini lens called a moon filter that  can attach to whichever one I am using. And it came with a 1.5x erecting eyepiece. Okay so the question is, I have know idea about these different eye pieces or exactly how to use each one. What is the difference between them? What does SR mean? What does H mean? What is and erecting eyepiece (I did find something that said that is so you can look at things on earth, something like the telescope flips earth things upside down, and the erecting eyepiece is apparently supposed to be attached to the telescope so that it flips earth things upright so you can look at things on earth) but I have no idea??? Do you know anything about this Explore One Theseus Telescope????? Also it did not come with any switches or dials or things that I have to align or anything. It is just a basic tube with different zoomy eyepieces and a tripod and I can move it up or down. It doesn’t swivel or twist or anything fancy.

Dave Carsley says:

The Trump stuff is even funnier now considering current events

Mike Stap says:

what gives telescope aperture? is it the primary mirror or secondary mirror.
Ive seen sites selling good secondary mirror can they increase telescope brightness or eperture?
my current scope aperture 130mm.

JohnnyScience says:

This is a great series as a beginner. Bravo to you sir.

Eyes on the Sky says:

I think the Celestron Accessory Kit provides a better, more useful range of eyepieces, though I am torn because Orion does offer excellent customer service.

John Russell says:

Make Astronomy Great Again

Sotiris Krol says:

Would a X-CEL lx 5mm eyepiece be good with a 700mm focal length refractor,the magnification it would produce is x140,which is within my resolution

Eyes on the Sky says:

You’re welcome Diane – glad it helped!

Jesse Burgess says:

I have a Celestron 114LCM. What eyepiece do I need to get a good up close view of the planets Jupiter and Saturn? The telescope has a 1000mm focal length, f/9, 4.5″ aperture

Eyes on the Sky says:

Unfortunately I have never used with of those eyepieces, so I cannot provide any guidance on their performance.

rusko123 says:

jus got 1 for xmas..not a clue..untill now are my saviour..good stuff m8

Pulkit Pun says:

I am a beginner and am going to buy celestron astromaster 130eq with out motor drive.(with the accessory kit)
Any comments on that?

Matt Smith says:

I have a crescent telescope which is a astonomical scope D-80mm by F-1200mm. My 12.5, 9, and 6mm have a HM on the top of the eye piece what does that mean? Any body know.

Natan Luis says:

poe um video em portugues

jonathan archer says:

Another Hit by David Fuller, just starting my journey to become an amateur astronomer wannabe fledgling, I’ve found the Eyes in the Sky forum (Web site and Youtube) to be a great companion providing me valuable guidance to make my experience more effective. This entire series is a must, and I only wished I had review these before I rushed out to buy my eyepieces (clearly without knowing what I was doing).

Mistery Smithers says:

So, a 2800mm Matsukof-Cassgrain has too little aperture to use anything less than 8mm eyepiece? (gives it 350 magnitude on a 7.1 inch aperture)
Same with a 1800mm Matsukof-Cassgrain using less than 6mm eyepiece? (gives it 300 magnitude on a 6 inch aperture)

Gabriel Y. Soto Rivera says:

hi david, a few months ago, i bought the celestron powerseeker accesory kit at an affordable price, anyway, in the instructions manual says that they are fully coated kellner eyepieces, and the reflection is blue, instead of green or purple… any ideas?

sdp123321 says:

David, 1st, I love and appreciate the videos. Thank you. 2nd, could you (or anyone knowledgeable) help me figure out gaps to maximize this experience? I have an Orion Skyview 8″ EQ w/25 & 17mm lenses. What lenses/Barlow should I buy for this rig.? There are a couple Orion lense/filter kits, but the math you were doing threw me off a bit.

Gabriel Y. Soto Rivera says:

ok thanks anyway…

Eyes on the Sky says:

It still may be considered a Plossl, as in order to achieve the very short focal length some changes to the optics may be required, but I don’t know enough about that to be sure. 4mm Plossls have VERY short eye relief though; I imagine that is hard to see through…..

Kevin Mccarthy says:

Helo , I just bought a stellervue, 50mm refractor and want to maximize the power. I have a 25mm plosii and the barlow lense of twice the power but seams like more, The little rascal is only 4.1 focal lenth. I was wondering if I sould invest in a better barlow or eye pieces.

Joe Ocegueda says:

I have a Orion SkyQuest XT8 Classic Dobsonian Telescope and want to get the best of it. Which do you think is a best buy?

Orion 1.25 Inch Premium Telescope Accessory Kit
Orion High-Power 1.25″ 3x 4-Element Barlow Lens
Orion High-Power 1.25″ 5x 4-Element Barlow Lens

Eyes on the Sky says:

The classifieds section of Cloudy Nights is a good place to look for used astro-products. I am not presently selling any astro-gear.

Mike Stap says:

need to know Something about Secondary mirror.
1.Secondary supplied Minor Axis 30 mm
2.Secondary supplied Minor Axis 50 mm
What is the difference between the 2 and how does it work for a telescope with eaither 1 or 2.

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