Best eyepieces

[Harryjones]

What 3 eyepieces should I get for a 10” dobsonian?
Thanks

[Rainmaker]

Pentax XW30, XW10 & XW7

[Pierre_C]

I think it depends on so many variables including telescope focal length, telescope quality, existing eye pieces, local observing conditions, preferred targets, age, experience, eye health, budget etc.

As a starting point, I would suggest building around a quality 10 mm eyepiece. For higher magnification, I think ~7mm would be reasonable. For medium to lower magnification, I think ~15-30mm (or somewhere in between around 20mm, or even both) would be reasonable. This advice would vary depending on the factors above.

[Startrek]

Probably the first thing to consider is your budget $$$$

Eye Pieces can range from entry level Plössl type at $50 each to high end premium Televue at +$1000 each

Here’s some basic technical eye piece info below I put together years ago that might be of interest…….,

Telescope Eye Pieces

Various Eye Piece Formulae

Magnification or Power is the amount that a telescope enlarges an object when viewed through an Eye Piece.
A telescopes useful magnification is generally twice its aperture in millimeters ( mm) but this can vary due to many factors like atmospheric turbulence , high cloud , humidity , light pollution and so on …….

Magnification of Telescope = telescope focal length in mm / eye piece focal length in mm

True Field of View of an Eye piece
This is the amount of Sky you can see through an eye piece without being attached to the focuser of a telescope
True Field of View is expressed in degrees
TFV = Apparent field of view / Magnification

Apparent Field of View of an Eye Piece
This is the amount of sky you can see through the Eye Piece when attached to the Telescope.
Apparent Field of View is expressed in degrees
Apparent field of view of an Eye piece = TFV / Eye piece magnification

Telescope focal ratio is a measure of the speed and angle of the light cone from a telescope.
Fast telescopes usually have a focal ratio of f4 to f5 and provide a wider field of view
Slow telescopes usually have a focal ratio of f6 to f10 and provide a narrower field of view

Telescope focal ratio = telescope focal length / telescope aperture


Eye piece exit pupil is the small beam or disc of light ( image ) that leaves the eye piece in order for your eyes to focus on. A young persons pupil dilates to around 7mm but an older person only dilates to around 5mm.
The pupil is like the shutter on a camera. The older you are more difficult it is to maximise the exit pupil out of the eye piece

Eye Piece Exit pupil = eye piece focal length / telescope focal ratio


Eye Piece Field Stop is the edge of the view or black ring you see when viewing through an eye piece which differs from eye piece to eye piece and is measured in millimeters.


Eye Piece Barrel
The Eye piece barrel is the chrome cylindrical section that is inserted into the telescopes focuser to hold it in place.
Eye piece barrels generally come in 1 1/4 “ or 2” barrels. Most telescope focusers are 2” and can accommodate both 1 1/4” ( with a 2” adapter) eye pieces and 2” eye pieces.


Eye Piece Focal Lengths
Eye piece focal lengths ( mm ) usually range from 3mm up to 50mm

3mm to 10mm range are high powered eye pieces for viewing Planets , the Moon and Stars.

10mm to 20mm are medium to high powered eye pieces for viewing Stars , Star clusters , Galaxies and Small nebula and the Moon

20mm to 32mm are medium powered eye pieces for viewing Stars , Star clusters , large galaxies, large nebula and the Moon

32mm to 50mm are low powered eye pieces for viewing Large Star clusters , large Nebula and the Moon.

Filters
Eye piece filters are generally required for Lunar observing and Planetary observing to reduce reflections, glare and enhance colour and detail.
Filters for Light Pollution and Contrast can be used for deep sky objects like planetary nebula and emission nebula to enhance detail.

Clear Skies
Martin

[Harryjones]

I want to get them second hand for around 200 each when second hand. Thanks

[Startrek]

Your budget of $200 each should allow you to pick up some good eye pieces on this forum’s classifieds
Plössl’s eye pieces at 50deg AFV are usually the lowest cost due to being a base line eye piece ( less glass ) with the exception of Televue.
Obviously as your AFV increases , costs increase ( more glass ) and the same with focal length ( more lens / glass and coatings )
AFV usually start at 50 degrees ( Plössl’s) and go all the way up to 110 degrees which are the high end Televue 3.5mm and 4.5mm.

Entry level brands
Skywatcher , Saxon , Bintel ( GSO )

Mid range
Celestron , Baader , Pentax , Takahashi

High end
Televue , Pentax , Explore Scientific

There are many more brands but these are just a few commonly used by amateur observers.

At this stage I’d buy the following 3 eye pieces -
7mm to 10mm
15mm to 20mm
25mm to 32mm

Obviously try to buy at least 1 eye piece with a minimum of 60 to 70 degree AFV but again your budget will decide on this option.

Also if you wear glasses to observe try to buy eye pieces with an eye relief of at least 18mm to 20mm.

A moon filter would be an advantage when doing lunar observing. Also planetary filters are a must especially when observing Saturn and Jupiter.

Hope all the above is helpful

NB: I started observing full time in 2016 and ventured into Astrophotography in 2018 so I’ve only been a part time observer over the last 5 or 6 years , most of my time these days is spent on Deep Space Long Exposure Astrophotography. However I do still enjoy observing at my dark site with the SW 12” Goto Dob and my array of Televue eye pieces and accessories.
I’d say I’m only a part time observer.

Good luck with your astronomy journey !!

Martin

[JoeBlow]

Another thing to point out is eyepiece preference is a highly individual thing. Everyone's eyes and eye sockets are different. You may have one observer tell you eyepiece 'A' is fantastic and yet another observer tell you they just couldn't get along with the same eyepiece. I would recommend going to some public viewing sessions if you can and try out some different eyepieces to get a feel for them.

[refractordude]

Hello There

The underrated budget Olivon 22mm with 70 degrees field of view. It is now under a variety of names made by the same manufacturer. Some like it better than the Nagler 22mm. I have the Astromania version of the 22mm Olivon.

https://www.google.com/search?q=olivon+22mm&client=firefox-b-1-d&sca_esv=6cae8d09a1050544&tbas=0&source=lnt&sa=X&ved=2ahUKEwjQ7da5_LSMAxVyFFkFHbyGBJ sQpwV6BAgFEAY&biw=1280&bih=637&dpr=1.5



Clear Skies

[Spacedad]

Hi Harry,
1. buy a 10mm eyepiece first. It makes calculating magnification easy. From there you can decide if you want more or less magnification.
2. Buy second hand. People tend to look after their eyepieces. Some are very well priced. Keep your eyes open.
3. Buy the best Quality. It makes a difference
Mark

[JoeBlow]

If you can stretch your budget a little, it's worth checking out some second hand Pentax XW's like Matt suggested. It's hard to go wrong with them, particularly the focal lengths Matt recommended. I would avoid the 20mm & 14mm due to some 'field curvature' in fast telescopes like yours, but the rest of the series is fine. The XW's can last you a life time without the need to replace them. But what I said earlier still stands, try some different eyepieces out first if you can.