Astronomy & Electronics Centre

PROFESSIONAL STANDARD TAKAHASHI EYEPIECES

QUICK LINKS: LE & Hi-LE, TOE, TAK-UW, Abbe Ortho

TAKAHASHI LE & Hi-LE Series

There are several types of eyepieces in the market. Some look very good; some have long eye-relief; some are sharp; some are cheap; some are expensive! However, when it comes to the highest contrast, maximum sharpness, high light transmission, good eye-relief and the best colour rendition, the Takahashi "LE" and "HI-LE" eyepieces have no rivals!

Below are a few comments from an expert amateur astronomer, who wrote a three-page test report on the Takahashi "LE" oculars.

Under test the LE Series oculars provided:

* Increased light transmission through the eyepiece. In other words all the LE oculars provide a brighter image;
* Increase in contrast in every case;
* Sharper images in every case;
* Increase resolution in every case.

The LE series improved every object throughout all the focal length ranges, and in comparison to both standard Plossl field of view and wide-field oculars. This is in brightness, contrast, image resolution and detail of bright and faint objects!

"...I cannot forget when, about two years ago, I had trouble splitting the double star Antares with my Takahashi FS-102 FL refractor, using five different well-known 7.5mm oculars. I started thinking that the said refractor wasn't as good as I thought. Eventually, it dawned upon me that may be I wasn't using the best oculars for the job. However, all my worries disappeared as soon as looked through an LE 7.5mm ED ocular, which fortunately I had still in stock. Antares' green companion, 7th-magnitude star, was there in all its glory!"
(Claude Voarino AEC, 2013)

LE & Hi-LE Technical Specifications and Price

Part Number	Model	Apparent Field	Eye-Relief	Weight	Barrel Diam.
TKA00520	LE-5mm ED	52°	10mm	130g	31.7mm
TKA00521	LE-7.5mm D	52°	10mm	115g	31.7mm
TKA00528	LE-10mm	52°	-	-	31.7mm
TKA00522	LE-12.5mm	52°	9mm	100g	31.7mm
TKA00523	LE-18mm	52°	13mm	125g	31.7mm
TKA00524	LE-24mm	52°	17mm	150g	31.7mm
TKA00525	LE-30mm	52°	20mm	170g	31.7mm
TKA00526	HI LE-2.8mm	42°	5.8mm	130g	31.7mm
TKA00527	HI LE-3.6mm	40°	7.5mm	130g	31.7mm
TKA00531	LE-50mm	52°	40mm	570g	50.8mm

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TAKAHASHI TAK-UW Series

Takahashi LE and Hi-LE Eyepieces are well known to be the best eyepieces on the market for sharpness, colour correction, contrast and resolution; now Takahashi has expanded their range of professional-standard eyepieces with the new TAK-UW Extra-Wide-Field (90°) Series

Takahashi TAK-UW Technical Specifications

Part Number	Model	Focal Length	Apparent FoV	Eye Relief	Weight
TKA00600	TAK-3.3UW (10 Elements in 6 groups)	3.3mm	90 degrees	12mm	470g
TKA00601	TAK-5.7UW (10 Elements in 6 groups)	5.7mm	90 degrees	12mm	450g
TKA00602	TAK-7UW (8 Elements in 5 groups)	7mm	90 degrees	12mm	430g
TKA00603	TAK-10UW (8 Elements in 5 groups)	10mm	90 degrees	12mm	420g

TAK-5.7UW mounted on TOA-130

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TAKAHASHI Abbe-Ortho Series

Takahashi Abbe-Orthoscopic Technical Specifications

Part Number	Model	Apparent FoV	Eye Refief	Weight
TKA00700	Abbe 6mm	44°	4.8mm	N/A
TKA00701	Abbe 9mm	44°	7.5mm	80g
TKA00702	Abbe 12.5mm	44°	10mm	N/A
TKA00703	Abbe 18mm	44°	15mm	110g
TKA00704	Abbe 25mm	44°	22mm	N/A
TKA00705	Abbe 32mm	44°	28mm	155g

TAKAHASHI TOE Series

Ultimate visual observation is observation with an excellent eyepiece for an excellent telescope close to the diffraction limit. With this combination, you can deliver the resolution of the telescope optical system to the entire field of view. TOE eyepiece developed based on this concept.
If the astronomical telescope equipped with a high performance objective lens is used not only for our products but also for other companies' products using the TOE eyepiece, we can demonstrate the performance of the objective lens without regret and high resolution that you can fully convince over the entire field of vision we can provide.

The TOA, FOA, FSQ, TSA, Mewlon-CRS etc. which corrected aberration to the limit is not only used as a photographic telescope, but also it is a system that you can fully convince eye visual users by using TOE eyepiece .

The TOE eyepiece was designed with priority on easy-to-view magnification, easy to use when observing the moon / planet with high magnification. When TOE - 2.5 mm, TOE - 3.3 mm, TOE - 4.0 mm are attached to TOA - 130, it becomes 400 times, 300 times, 250 times respectively. This is a magnification that across the 320 times excessive magnification for double stars, it is just a good focal length lineup to change the magnification according to the sky conditions. In order to obtain high magnification with FSQ of f / 5, it is better to obtain a higher magnification after attaching a dedicated extender to f / 8.

The apparent field of view is same as other LE series at 52 ° wider than 40 ° of Hi - LE, and the eye relief also secures 10 mm which is the same as LE - 5 mm and LE 7.5 mm, the same as other eyepieces of Takahashi at parfocal, it is easy to use enough as an ultra high magnification eyepiece. Even if you use it for planet only for wide field of view, it will be easy to use as it is easier to catch into the field.

Evaluation of aberrations by Strehl ratio, spot diagram
When the eyepiece is combined with the objective lens, it becomes an afocal optical system which does not form an image, and the evaluation of aberration was difficult. In Takahashi, the design of the eyepiece is optically designed as an afocal system in combination with TOA - 130. In addition, as a wave optical evaluation, we use the spot diagram as the Strehl ratio which is the ratio with the diffraction limit optical system, geometrical optics evaluation. If you look at the figure below, you can see that the Strehl ratio falls to over 98% in the entire visual range of wavelengths from 486 nm to 656 nm and in the whole visual field.

There is not much to disclose the spot diagram of the eyepiece so it is not familiar, but the round frame becomes 10 micro radians of the angle. The resolving power of an aplanatic lens with a 130 mm aperture can be determined from the dose limit equation as 0.9 s squares = 4.5 microradians, so all the TOE series are far below the diffraction limit in all fields of view. In addition, it can be seen that magnification chromatic aberration (color misregistration in the surroundings) which is difficult to completely eliminate with the eyepiece is also very small.

Takahashi's unique lens composition
Optical design of the TOE series of 4 groups / 6 elements is Takahashi's original lens composition which optimizes totalization of the front group 's smice lens and the rear group' s master lens, and includes spherical aberration, chromatic aberration, field curvature, astigmatism , Distortion aberration, chromatic aberration of magnification and other various aberrations are designed to be minimized.
Also, by selecting the lens curvature that reduces ghosts and flares, by designing hardware, you can observe the moon and the planet with a good contrast image. Broadband multi-coat is applied to each boundary surface of the lens, and on the surface where necessary, a flat multi-coat with less fluctuation in transmittance due to wavelength is applied to correct the color balance and we are striving to improve the contrast.
Also, sanitizing is done on the edge surface of the lens, and we are trying to prevent stray light by carrying out a matte treatment also on metal parts.

Takahashi TOE Series Technical Specifications

Part Number	Model	Apparent FoV	Elements/Groups	Eye Refief	Barrel Size	Tube Diam.	Tube Length	Weight
TKA00613	TOE-2.5mm	52 º	6/4	10mm	31.7mm	39mm	76mm	150g
TKA00614	TOE-3.3mm	52 º	6/4	10mm	31.7mm	39mm	72mm	140g
TKA00615	TOE-4mm	52 º	6/4	10mm	31.7mm	39mm	68mm	130g

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