Two inch eyepieces exist simply because you cannot squeeze a combination of long focal lengths (low magnification) and wide fields of view in a narrow 1.25" barrel. It's a matter of lens size needed, not optical quality.

Why do we use two lenses in an eyepiece?

2 Eyepieces. An eyepiece is essentially a combination of lenses used as a magnifier, the latter being a positive lens of short focal length that forms a magnified virtual image of the object placed at a distance from the lens less than its focal length.

What is the difference between the 1.25 and the 2 eyepiece?

A 2" eyepiece will have a larger field stop than a 1.25" giving you a wider field of view. Typically this would be for eyepieces 30 - 40mm focal length. Usually you only need one eyepiece in this range for your lowest power views.

Do eyepieces make a difference?

As far as how much difference a high end eyepiece makes.. Some but the differences are subtle.. today's eyepieces are quite good, even the simple, affordable eyepieces. Big improvements in sharpness and contrast come from better seeing, a larger or better quality telescopes.

Why do we need eyepieces?

It is so named because it is usually the lens that is closest to the eye when someone looks through the device. The objective lens or mirror collects light and brings it to focus creating an image. The eyepiece is placed near the focal point of the objective to magnify this image.

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

25 related questions found

What is an H12 5mm lens?

Well, now I know: H12. 5mm is a Huygen lens with a 12.5mm focal length and the SR4mm is a Symmetric Ramsden which offers more magnification than my 2-lens Huygen. ... These typically include the Huygens (marked with an “H”) and Symmetric Ramsden (typically marked “SR”).

How many eyepieces do you need?

In other words, three eyepieces as a minimum. Another possibility is two eyepieces and a barlow lens. A barlow lens attaches to an eyepiece and doubles or triples the magnification of the eyepiece, depending on the magnification of the barlow. Just be sure the barlow doesn't give you too much magnification.

Why are eyepieces so expensive?

(1) Newer, more complicated designs (the Nagler and its derivatives and competitors) with much wider fields. (2) Rising expectations of both field of view and sharpness over the whole field. Even conventional designs are expected to be better designed and made these days.

What is a Nagler eyepiece?

In the early 1980's, Al Nagler created a small sensation when these eyepieces were introduced. ... His goal was to create a "spacewalk" feeling when looking through these eyepieces. This is accomplished by sticking a barlow-like lens group inside the barrel of a long focal length eyepiece.

Why are telescope eyepieces so expensive?

It is recognized as a long tube that increases in length until it gets to the lens. This lens requires special crafting, which is why they are so expensive. ... These types of telescopes use mirrors where the objective lens would be in refractor telescopes but are also more common than the latter.

Are 2 inch eyepieces worth it?

The reason to design an eyepiece with a 2 inch barrel is because the design requires a field stop that is larger that a 1.25 inch barrel will allow. Larger field stops provide wider fields of view. By the way, the field stop is the ring you see as the edge of the field of view.

Which telescope eyepiece is best?

Best telescope eyepieces

1. SVBONY Telescope Lens 62° Aspheric Eyepiece for 1.25 inch (4 mm; 10mm; 23 mm) ...
2. Gosky Plossl 40 mm Telescope Eyepiece - 1.25inch. ...
3. Meade Instruments 10 mm, 100 Degree MWA 1.25-Inch. ...
4. Explore Scientific 40 mm - 68° Field of View Eyepiece.

Do all eyepieces fit all telescopes?

Unlike microscopes, eyepieces for telescopes are interchangeable. However, not all eyepieces will work equally well for all telescopes, the shorter focal ratio telescopes are very hard on simpler and less well corrected eyepieces.

What is the advantage of using more than one lens in combination?

COMPOUND LENSES

The use of multiple elements allows for the correction of more optical aberrations, such as the chromatic aberration caused by the wavelength-dependent index of refraction in glass, than is possible using a single lens.

Why Ramsden eyepiece is used in spectrometer?

What is the main reason for which Ramsden's eyepiece is used with a spectrometer? Ans. In this eyepiece, the cross wire is outside the eyepiece and hence mechanical adjustment and measurements are possible.

When using multiple lenses in a telescope How must they be spaced apart?

How far apart should the two lenses be to make a telescope? Find q_o and p_e (in the notation of the thin lens equation) where the subscripts o and e refer to the objective and the eyepiece respectively. The distance between the lenses is just their sum q_o+p_e.

What is flat field eyepiece?

Flat field eyepieces are designed to assist telescopes, primarily fast telescopes with focal ratios around f/4 or f/5, correct the curvature of the image that would be seen. In essence they make the visuals flatter and more pleasing for the user.

How do you buy telescope eyepieces?

The largest-focal-length eyepiece you can use with your telescope is easy to calculate: multiply the focal ratio (the focal length of your scope divided by its aperture) by 7. For example, your Newtonian scope is f/5: the largest-focal-length eyepiece you should use is 35 mm.

Are Plossl eyepieces good?

Plössl eyepieces are good all-around performers, producing sharp images at the center of the field, but they have only four lens elements. Better edge correction with a short-focus telescope is one of the things you pay extra money for, and sophisticated eyepiece designs have as many as eight elements.

Are telescopes expensive?

While you can find some worthwhile telescopes under $200, most good telescopes cost anywhere from $300 right up to $20,000 USD! The price you pay for a telescope is dependent on many factors including the type of telescope, quality of mirror and glass coatings, aperture size, technology and included accessories.

Which eyepiece is best for viewing the Moon?

For a medium power eyepiece (approximately 150X) a 13mm or 14mm eyepiece would do. For a low power eyepiece (about 75X), which are great for finding and centering or observing very large and close objects like the Moon or Sun, an eyepiece between 25mm and 30mm would work well.

What type of telescope is a Dobsonian?

A Dobsonian is a reflecting telescope (uses a mirror, not a lens) in the same design as a Newtonian telescope (concave collecting mirror is at the rear of the telescope tube, eyepiece is on the side of tube, up near the front).

What is the telescope's focuser?

The focuser moves the eyepiece holder up and down slightly, adjusting the focus of the eyepiece for each individual observer. There are friction focusers or rack-and-pinion focusers. Regardless of the type on your telescope, your focuser should move smoothly without causing your telescope to shake.

What is a H20mm lens?

H20mm Telescope Eyepiece Multi-coated 0.965"/24.5mm. Application：Support all types of telescopes, reflector, refractor, to observe the star clusters, moon, sky, planets and other celestial bodies. 35 Degree Field of View：Wide viewing field with extra sharpness and long eye relief.