Titan Type II ED 30mm 2" 68° wide field eyepiece

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The Astro-Tech Titan Type II ED 2” 30mm eyepiece has a wide 68° field of view, so large that the tack-sharp image more than fills your eye. While it provides superb wide field views with any telescope type, it is particularly well suited for low power viewing with a fast focal ratio Dobsonian reflector. Its 30mm focal length gives you a 6.67mm exit pupil with an f/4.5 reflector, just about the largest exit pupil that a normal fully-dilated eye can accept, for the brightest wide field views possible.

The 30mm Titan Type II ED’s six-lens wide field ED optical design is superb for viewing large-scale deep space objects like nebulas, open star clusters, and the star clouds in Sagittarius. Its high contrast and bright images make faint nebular wisps pop out against a very dark sky background, as well as showing myriad subtle levels of contrast in bright nebulas. Pinpoint stars across the entire field make open clusters look like a handful of diamonds scattered across a black velvet cloth.

This stunning views you will see in this 3-7/8” long 11 ounce 30mm Astro-Tech Titan Type II ED eyepiece will take your fast focal ratio wide field observing to an entirely new level, at a price/performance ratio no other top-quality eyepiece can touch.

Field of view:
The field of view (FOV) is the amount of observable world one can see at any given moment.
Eye Relief:
Eye relief is the distance from the last surface of the eye lens of an eyepiece to the plane behind the eyepiece where all the light rays of the exit pupil come to a focus and the circular image is formed, sometimes called the “Ramsden Disk.” This is where your eye should be positioned to see the full field of view of the eyepiece. If you must wear glasses because of astigmatism, you’ll usually need at least 15mm of eye relief or longer if you want to see the full field of view with your glasses on.

A note on our eye relief figures: Quite often, our eye relief figures will differ from those of the manufacturer. This is because we measure the “usable” eye relief, while the manufacturers specify their usually-longer (but technically correct) “designed” eye relief.

The eye lens of the eyepiece is normally recessed below the rubber eyeguard or rubber rim of the eyepiece to keep the lens from being scratched during use. An eyepiece might have a “designed” eye relief of 15mm (and the eye relief will truly measure 15mm from the eye lens to where the image forms). However, if the eye lens is recessed 3mm below the eye guard, the Ramsden Disk forms only 12mm above the eyepiece body (the 15mm “designed” eye relief, less the 3mm of eye relief made unusable by having the eye lens recessed into the body of the eyepiece). This “usable” eye relief of 12mm (measured from the rolled-down eyeguard – the closest point you can get your eye to the eye lens – to where the image forms) is the eye relief figure we would measure and list in this website.

Why is it important to list the “usable” eye relief? For those people who don’t wear eyeglasses while observing, a few mm difference between the eye relief they expect from the manufacturer’s literature and the shorter eye relief they actually get in real life doesn’t mean a lot. They can simply move a little closer to the eyepiece to see the full field, and never realize that the eye relief is a little shorter than they expected. However, some people must wear eyeglasses while observing, because of severe astigmatism. These observers can’t move closer to the eyepiece if the eye relief is shorter than expected because their glasses get in the way. For these people, the real life “usable” eye relief is more important than the technically correct but sometimes not fully usable “designed” eye relief. We measure and list the actual usable eye relief so that people in the real world can pick the eyepieces that will work best for them.

Focal Length:
This is the length of the effective optical path of a telescopeor eyepiece (the distance from the main mirror or lens where the lightis gathered to the point where the prime focus image is formed). Focallength is typically expressed in millimeters.

The longer the focallength, the higher the magnification and the narrower the field of viewwith any given eyepiece. The shorter the focal length, the lower themagnification and the wider the field of view with the same eyepiece.

Number of optical elements:
Barrel Size:
The industry standard diameter, as of 2011, is 1.25" and is the most common.  Other sizes available are .965" and 2".
The weight of this product.
11 oz.
2 years
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1. Jay on 4/16/2013, said: AstronomicsAstronomicsAstronomicsAstronomicsAstronomics
Please note - the 30mm would get 4.5 stars for use with an f/10 SCT, but 3 stars with an f/6 short tube refractor.

With a longer focus scope, the only potential drawback of the 30mm compared to the 40mm, is that the 40mm seems to give a little 'roomier' feel to eye placement, even though eye relief specs are the same.

One good use of the 30mm on 8-inch SCT is for a whole-disk view of sun through white light objective filter.

But in an f/6 achromat, the 30mm edges don't fare as well as the great view through the 40mm. For that I would give only 3 stars as a 'finder' eyepiece.

The virtues of good build quality, functional eyecup, light weight for an eyepiece of these specifications, and moderate price are the same for the 30mm as the 40mm.

There must be a cutoff somewhere between f/6 and less than f/10 for the 30mm where edge sharpness gets as good as the great views through the 40mm AT Titan II ED.

This seems like a good, compact and light weight wide field option for longer focus use, but try out for your scope if it's much below f/10.
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65mm x 80mm eyepiece container
by Astronomics
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Helpful Formulas
Telescope Eyepiece Formula
To calculate the magnification and approximate actual field of view of this eyepiece on your telescope, enter the focal length of your telescope below and press the "Calculate" button.

Enter your telescope's focal length: mm   

Astro-Tech - Titan Type II ED 30mm 2" 68° wide field eyepiece

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Astro-Tech - Titan Type II ED 30mm 2" 68° wide field eyepieceImage showing a typical Titan Type II ED eyepiece with the twist-up eyecup both retracted for eyeglass use and extended for use without glasses.
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Clear skies,

This low power wide field 2” Astro-Tech Titan Type II ED eyepiece is superb for viewing large-scale deep space objects – open clusters, nebulas, star clouds, and more – particularly with a fast focal ratio Dobsonian reflector . . .

. . . our 36th year