Televue Ethos 21mm

[Mark at Beaufort]

Just when I thought I had decided on a new EP for my 10" Flextube I found that a new Ethos had arrived!!

Focal Length: 21mm

Apparent Field: 100°

Eye Relief: 15mm

Effective Field Stop Dia.: 36.2mm

Barrel Size: 2"

Weight: 2.25 lb.

Maximize your "spacewalk" experience with the 21mm Ethos. Transform your passage through the Milky Way with the 21mm’s nexus of contrast, power and field. Larger deep sky objects and rich star fields are its natural playground. Looking on-axis your field-of-vision is filled with 100º of stars, however wherever you chose to concentrate your attention you’ll see sharpness and richer contrast.

The optical performance of the 21mm is the work of Ethos lead designer Paul Dellachaiae, who achieved a level of optical aberration correction right in line with his other Ethos designs. Contrast and transmission have been maximized using the same advanced coating techniques and further aided by the internal mechanical design techniques used in all Tele Vue eyepieces.

Extending the Ethos focal length range to 21mm while maintaining the original performance goals of the rest of the series brings the eyepiece up against the mechanical limits of the 2” barrel and focus constraints. The 21mm provides the maximum true field of view, has no significant vignetting at the edge of the field, and is parfocal with the 31mm Nagler Type 5.

The 21mm focal length completes the logical set of 21mm/13mm/8mm and nicely juxtaposes the 17mm/10mm/6mm combination. Each step within these two sets approaches a 3X field area gain. The 21mm’s effective field stop diameter is 36.2mm, bringing its true field close to the 35mm Panoptic (38.7mm Field Stop diameter). Its true field is also larger than the 26mm Nagler with its 35mm effective field stop diameter. In an f/4 Dobsonian, the exit pupil is just 5.25mm using the 21mm Ethos instead of 8.75mm with a 35mm Panoptic, or 6.5mm with a 26mm Nagler.

Like all Tele Vue eyepieces, every 21mm Ethos goes through our optical and cosmetic quality control procedure in Chester, NY and should your eyepiece ever need service we can do everything from replacing a dented barrel to replacing a scratched eyelens.

Since all Ethos models accept Dioptrx, you now also have the “final frontier” – the ability to compensate for your own eyesight astigmatism with a superb multi-coated lens providing your exact correction, rotation orientation and centration over the eyepiece. This is the culmination of our quest to not only bring you observing experiences “…even better than you imagined,” but a 30-year recognition of being “tops in the field.”

Has anyone seen this EP yet?

Mark

[John]

I don't think they are actually on the market yet Mark, even in the USA. The folks over at Cloudynights are still awaiting a price - $800 seems to be a popular guess.

Even at that price I guess the Ethos 21 will still be popular.

John

[davinchi]

ETA is december if I´m not wrong , E.Scientific will release the 20mm sooner , I own the 14mm one and it´s amazing ... the only drawback is it´s pretty heavy

[Ben Ritchie]

Even at that price I guess the Ethos 21 will still be popular.

I preordered today, and i'm not in the first dozen on the dealer's list...

[Lee]

Thats going to be some eyepiece. The FOV should be just smaller than a 31mm Nager...

...and just in time for Christmas.

[GazOC]

I might treat myself to this one....

[Ben Ritchie]

True field of view is 26T5-like, the 31T5 Nagler still shows more sky (15% greater diameter, I think), but the 21mm Ethos has an exit pupil better suited to a fast Dob under less than perfect sky. Been looking forward to this one for a while - the wait until Christmas will give me a chance to pay for it

The verdict of someone on CN who has tried it out at Stellafane

The folks on Breezy Hill were treated to "First Dark Light" of the new member of the Ethos family, and let me just say one word, WOW. Everything you've seen or heard about the Ethos line has reached eyepiece maxima. The views through the new TeleVue baby are magnificent.

P.S. the dealer's in the US, in case anyone is wondering...

[johninderby]

Prototype 21mm Ethos Eyepiece Auction

In case anyone is interested a 21mm Ethos will be put up for auction on eBay (US) starting on Tuesday, 1st September and ending on Saturday 5th September.

Wonder what it will end up going for?

John

[PeterW]

Too much!

PEterW

[Marmite]

Count me out.

I've observed with a couple of these EPs and I still believe it's way too much money for some extra field.

TV have improved the colour over the regular Nags, but the Ethos still has a bit of that blumming horrible sepia-tone thing going. Just IMO naturally, but I'm not the only one to notice the lack of colour neutrality.

Call me odd if you like, but I'll happily settle for a slightly smaller FoV if it doesn't appear to be viewed through a cup of coffee, especially if it costs me half as much or even less!

The Ethos pricing is too much extra for too little extra, although obviously many disagree, and so I say good luck and happy observing to those who purchase the Ethos!

[Ben Ritchie]

I agree about the colour, I certainly prefer the Pentax XW in that respect, although i've never found the TeleVue tint bothersome.

To be fair though, you're not just getting extra FOV with the Ethos, you're also getting top notch optical performance too - i'd say the Ethos is a step up from the majority of the Nagler series in that respect, probably all, and especially for on-axis performance. The Ethos does impressively well as a planetary eyepiece, and gives up very little against the Pentax which i'd regard as the benchmark for on-axis sharpness in a "complex" eyepiece (i.e. not simple orthoscopic etc.).

Yeah, they're a lot of money, and it's down to individual budgets and priorities as to whether it's worth it - for me, the 13mm Ethos almost lives in my focuser, with both the refractor and the dob it's such a useful focal length that it probably gets used more than the rest of my collection put together. So I feel like i'm getting value for money..

[johninderby]

The advantage of the Ethos is not it's 100 degree FOV. It's the sharpness and contrast that really impress once you've used them for a little while and aren't thinking about the FOV. The Ethos simply don't have the warmer tone that the Naglers have. Some observers seem to be super sensitive about "a warm tone" but many simply aren't bothered or even prefer it.

The 6mm Ethos is an amazing lunar/planetary eyepiece. The only other eyepiece that I've used that equals it is a TMB Supermono ( with it's huge 30 degree FOV ). While obeserving the crater Plato recently I could make out a number of craterlets while using a Nagler, but when I put the Ethos in the craterlets became sharply defined craters with detail. That's when I realised how special the Ethos was.

Another factor is the scope you are using. In a slow SCT then probably the FOV is the main thing you would notice, but in a faster and thus more demanding scope that's where the Ethos really comes into it's own.

Obsevers nowdays are really being spoiled with great eyepieces like the Ethos and Pentax XWs to choose from.

John