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3.7mm Ethos SX Eyepiece - It's Arrived


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Televue 3.7mm Ethos SX Eyepiece - It's Arrived

Well a surprisingly large box arrived this morning. It looked big enough to hold a set of eyepieces, but no it was just the 3.7 Ethos SX in it's fitted box. This is

one seriously big eyepiece. ;) Indeed it's actually 1mm taller than a 21mm Ethos. Although it is a big eyepiece fortunately it's not that heavy though and is the

same weight as a 10mm Ethos and just a couple of ounces lighter than a 13mm Ethos. It's quite a bit taller than a 13mm Ethos but not quite as "fat". Little bit bigger than the 9mm TMB Planetary eyepiece in the middle isn't it. :p

I really like the fact that the 2" barrel is a removeable part. While the Ethos eyepieces up to 13mm are a 1.25"/2" dual barrel arrangement they don't feel very

secure in a 1.25" eyepiece adaptor or diagonal and are better used in a 2" fitting. But in the case of the 3.7mm Ethos SX it is a proper 1.25" eyepiece that

feels very secure in a 1.25" fitting. I see the 2" barrel as being just a convenience if you're using other 2" eyepieces and don't want to bother with a 1.25

adaptor just for this eyepiece. One other small improvement is that the safety undercut on the 1.25" barrel is bevelled so it doesn't hang up on the compression

ring in the eyepiece adaptor.

I have an A&E supreme APO triplet 1.5x barlow element (made in Japan) that screws onto the eyepiece and makes it into a 2.47mm Ethos SX. That should be interesting if seeing conditions allow! The upper lens is very concave and the photo taken with a flash throws up some interesting reflections. The blue circular pattern is the ring flash on the camera.

The local forecast shows skies clearing about midnight so there may be chance for a first light report tonight or is that asking too much. :)

Size: 6.1 in. x 2.2 in

Weight: 17.6oz

Fields stop diameter: 7.0mm

Eye relief: 15mm

FOV: 110 deg.

Barrel: 1.25" with a screw on 2" adapter

Quote from Televue

"Since the SX design does not lend itself to longer focal lengths without compromises, and shorter focal length applications have limited appeal, we now

consider the Ethos line complete with this seventh model introduction."

Televue's blurb

" The 3.7mm Ethos-SX is designed and crafted to combine its exceedingly wide field of view with all the contrast, color-rendition, distortion correction and

center-to-edge sharpness needed to achieve that natural view. Beyond the desire to simply achieve 110-degrees, the extended field of view gave Tele Vue the

ability to produce a superb planetary eyepiece with a deep sky true field of view that logically fits within the rest of the Ethos eyepiece line. With 110-

degrees, the Ethos-SX has 21-percent more AFOV area than the 100-degree Ethos design. This permits a nice 62-percent power increase from a 6mm Ethos,

while retaining 68-percent of its TFOV. The 3.7mm actually has more TFOV than our 8mm Plossl, 6mm Radian, and 5mm Nagler Type-6! The 3.7mm is a

1.25-inch format and is parfocal with the wide range of 1.25-inch Tele Vue Plossls, Panoptics, Radians, Naglers, Nagler Zooms, and 6mm and 8mm Ethos

eyepieces. The screw-on 2-inch adapter (included) is designed to make it parfocal with 13mm and 10mm Ethos when they are used in their 2-inch modes –

Hey, it also doubles as a functional display stand! We don't think we can aptly describe Al's original experience of "flying over the moon," but for the first

time, YOU can experience what the astronauts saw four decades ago."

John

Edited by johninderby
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Great photos John - very exciting !.

I agree that the eyepiece looks better with the 2" adaptor removed - slightly reminiscant of the original Speers-WALER's

Looking forward to your 1st light report of course :)

Congratulations !.

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John that looks a very impressive EP. I will be interested to read your review especially if you are observing doubles.

I note from the following photo that the 2" adaptor has a smaller hole - is this for screwing 1.25" filters?

Mark

The black plate in the bottom of the 2" barrel has a male 1.25" filter thread on the inside of it and this screws into the filter thread of the 1.25" barrel. The hole in the plate is actually 20mm and is unthreaded. There is also a step ring inside that fits over the ring on the top of the 1.25" barrel so that the 2" barrel doesn't actually contact the body of the eyepiece and scratch it. Quite a clever and well engineered design.

John

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Wow. That looks awesome. I saw a 13mm Ethos sell on eBay last week for £330, but your 3.7mm model appears to be much nicer (aesthetically).

Unless you now confess your telescope is a Tasco refractor, I'm going to be very jealous :)

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**** Oooops - duplicate post - don't know what happened there ! ****

....Unless you now confess your telescope is a Tasco refractor, I'm going to be very jealous :)

Yep - John has a Tasco with a Feathertouch focuser ....... ;)

Edited by John
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First light with the 3.7mm Ethos SX

Seeing conditions are absolutely rubbish tonight and I wouldn't have bothered except I really, really wanted to try out the new eyepiece. Vega reminded me of one of those old type blue lights on a police car as it was flashing so much. Anyway I got the FLT98 out with my grab'n'go Alt-Az mount.

Jupiter looked absolutely stunning, and even though it was boiling really badly an impressive amount of detail could be seen with great contrast as well. With the 110 degree FOV Jupiter stayed within the FOV without moving the scope for long enough that I had the time to concentrate on observing. If Jupiter looks this good with rubbish seeing what's it going to be like using this eyepiece with good seeing.

The moon fitted within the FOV of the eyepiece. Very odd using a such a high mag eyepiece and being able to see the whole moon. Actually the view was so wide that I couldn't take it all in with my central vision and had to move my eyeball from side to side to see all the detail near the limb. I found it was more comfortable to back off a bit so I didn't see quite as much. Despite it being a full moon there was still plenty to look at around the limb. This is where the eyepiece really came into it's own. While looking at a crater on the limb I could concentrate on it for a while (amazing contrast and sharpness BTW) and then just move my gaze around the entire limb or anywhere else until I found something I wanted to look at without having to move the scope. This is the ultimate lunar eyepiece.

It's a very comfortable eyepiece to use with no blackout problems at all. The eyepiece is sharp from edge to edge of the FOV and I just didn't detect any distortions at all. It does take a little getting used to as the 110 degree FOV changes the way in which you will observe. I found it best not to even try to take in all the FOV available but instead concentrate on specific areas and then glance over to something else. It's this ability to just glance to one side and see something else without having to move the scope that changes things. Early days yet but I couldn't help thinking that this is my favourite Ethos.

Now just bring on some decent seeing conditions so I can give this eyepiece a proper workout.

John

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Nice write-up John. I must admit that these days I'm becoming more concerned with FOV and the 'framing' of objects, and the Ethos giving you the ability to view the whole of the moon at 160+ magnification is phenomenal. In my scope with a Baader Hyperion I can just about manage seeing all of a full moon at just over half that magnification, and that's considered a wide-field eyepiece!

One question: Is the actual view you get with an Ethos totally without a visible edge? I've heard that a Nagler is like looking out of a porthole, so is an Ethos like you're standing on the outside?

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One question: Is the actual view you get with an Ethos totally without a visible edge? I've heard that a Nagler is like looking out of a porthole, so is an Ethos like you're standing on the outside?

When observing the full moon and I had my eye right into the eyecup I could detect the edge a bit. However while I was observing Jupiter the eyepiece just seemed to disappear and it was like naked eye observing as I just didn't notice the edge at all.

A 3.5mm Nagler's FOV would make it feel like an Ortho in comparison. Even the FOV of a regular 100 degree Ethos now feels a bit restrictive.

John

Edited by johninderby
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Sounds a nice EP (he said, aiming for the understatement of the year award;)). Is the eye relief not a little tight for those wearing glasses? I find I want to replace my 14mm UWA for a 12 or 17mm T4 Nagler. I gather the Ethos line has just 15mm eye relief, just like my UWA, so this is holding me back a bit.

So when will we get a 120 or 140 deg FOV? :)

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Not wearing glasses to observe with the eye relief is not a problem for me so it's not something I can really comment on for glasses wearers. However it does seem to be a genuine 15mm. Apparently some manufacturers measure from the top of the lens and some measure from the deepest point which can mean that the actual eye relief can vary between different brands by a few mm from the stated eye relief.

John

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Not wearing glasses to observe with the eye relief is not a problem for me so it's not something I can really comment on for glasses wearers. However it does seem to be a genuine 15mm. Apparently some manufacturers measure from the top of the lens and some measure from the deepest point which can mean that the actual eye relief can vary between different brands by a few mm from the stated eye relief.

John

I will have to check them out then, though the 3.7 is out of the question with my scope (until I get that 12"F/5 newt).

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I will have to check them out then, though the 3.7 is out of the question with my scope (until I get that 12"F/5 newt).

hi Michael

I wear specs but not to observe. I'll make a point of trying my 13mm with specs and report back.

Edited by Moonshane
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Nice write up John and congrats on your new EP - it certainly sounds like a "keeper". Where did you get it from (apologies if posted elsewhere ?)

I got it from Stayfocused. I believe that they've got a few more in now. Apparently Televue won't be shipping any more until December so once the initial shipment is sold out it'll be a couple of months wait.

I'm waiting until I've had a chance to use it in the 14" f4.6 dob before doing a proper first light report.

John

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  • 2 months later...

Hi John, thanks for the review.

I'm considering buying the SX. Can you let me know what your feelings are on this eyepiece now you have had it for a while.

I was going to get an 8mm ethos and use my powermate to get a 4mm ethos (which I would use more of the time than at 8mm) but I am now thinking that this is maybe the better option because of the extra FoV and no messing with the powermate.

Edited by Kef9
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No proper review yet as the weather hasn't exactly been co-operating lately! It seems to have been either cloudy or clear with poor seeing. :D

However from the limited use it's had the first impressions stand up. I think it's definitely the ultimate lunar eyepiece. I'm still getting used to being able to look at the entire lunar disc while using such high mag. It is as good on Jupiter etc. of course, but it's the lunar observing that sticks in my mind the most. It really is incredibly sharp and contrasty and gives a nice bright image. I used to have a TMB 4mm Supermono and going from memory I think the 3.7 SX would if anything have a small advantage in sharpness. It's that close.

It's also the only Ethos that sits comfortably in a 1.25" diagonal or eyepiece adaptor. I know all the other Ethos eyepieces with dual barrels can be used in the 1.25" format but they always seem a bit precarious to me. The 3.7 SX may be the most specialised of the Ethos lineup, but it does what it was designed to do so brilliantly I just wouldn't give it up. My favourite Ethos. :)

John

Edited by johninderby
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