Tele Vue Ethos-SX 3.7mm Eyepiece (1.25"/2.0") AFOV: 110

[bhighlander]

Hello,

Any thoughts on the Tele Vue Ethos-SX 3.7mm Eyepiece (1.25"/2.0") AFOV: 110? 

I'm considering investing$$$ in this (with a 2" diagonal).  Will be used with a 6" refractor.  The 3.7 will take me to my max magnification of 324X (1200 / 3.7).

Would the ultra wide view allow deep-sky observing at this high magnification?  I'm assuming very good lunar observing...

I'm new to Stargazers Lounge.  Have only been seriously into astronomy for a couple of years.  Look forward to meeting ya'll.

Thank you,

bhighlander         

[Stu]

Hi,

It would help us help you more if you let us know more detail about your scope. Is it an achro, ED doublet, triplet?

My first thoughts are that it is likely to be too much power to be regularly useable on anything other than the moon. The exit pupil will be 0.46mm so the image will be quite dim and you may see floaters in your eyes.

That aside, it would probably be useable on bright globulars and planetary nebulae or for splitting tight doubles, but the field of view would only be around a 1/3 of a degree so you would struggle on anything larger.

If your scope is an achro then the objective may show abberations at such high powers which make the view less than satisfactory.

Which other eyepieces do you have? Can you Barlow to the same power to see what it looks like?

[glowjet]

I have a gut feeling that to use such an expensive eyepiece to push a basic Achro, to its extreme, if that is what you have, may not bring about the results you desire. I have no idea what your night sky is like in Oregon, but you would need extremely dark skies and the seeing to be at its best, to give yourself any chance of using the eyepiece, to bring out its full potential. Your 2" diagonal would also need to be of excellent reflective quality. You may, however, find that the objective could possibly be a weak link in the optical chain.

Perhaps a search of your own countries major forum "Cloudy Nights" may come up with some useful observations on this EP and its use with various telescopes. A visit to one of your Astro group meetings could help, as it is possible someone may be using such an optic. Enjoy your Astronomy and the forum

[John]

Hello and welcome to the forum !

While Ethos eyepieces are superb provided that you have the funds, don't wear glasses when observing and are comfortable with the hyper-wide field (some are not), I'm not sure that the 3.7mm would be great for deep sky observing other than teasing out tiny planetary nebulae and very small galaxies. If your scope has quality optics the eyepiece will produce some stunning views of the Moon, Saturn and Mars under excellent seeing conditions and will be good for splitting tight binary stars.

It's an excellent but expensive eyepiece that might not see a lot of use if your seeing conditions are anything like ours in the UK, much of the time !

[busdriver]

hi and welcome to sgl

[bhighlander]

Thanks for all the good advice.  Don't think the Ethos is quite worth the investment.  Thought the ultra-wide AFOV would be of more benefit. 

My refractor is a Celestron AVX 6.  I am partial to refractors, and am very happy with my "lawn canon."

The viewing in Oregon can be spectacular, but we do get a lot of clouded-out nights.  We just had our Oregon State Star Party in Central Oregon.  The viewing was exceptional.  We even were treated to an Aurora Borealis.  

The OSP site is in the high-desert on a mile-high plateau...

bhighlander     

[estwing]

welcome along...

[Stu]

Thanks for all the good advice. Don't think the Ethos is quite worth the investment. Thought the ultra-wide AFOV would be of more benefit.

My refractor is a Celestron AVX 6. I am partial to refractors, and am very happy with my "lawn canon."

The viewing in Oregon can be spectacular, but we do get a lot of clouded-out nights. We just had our Oregon State Star Party in Central Oregon. The viewing was exceptional. We even were treated to an Aurora Borealis.

green aurora.jpgaurora.jpg

The OSP site is in the high-desert on a mile-high plateau...

bhighlander

I'm assuming that's the f8 6" Achro? If so it will give you great results on low to medium magnification targets, lovely contrast but will show some CA at higher powers. That's one reason why I don't think it worth investing so much in one eyepiece which likely won't show the scope at its best.

Don't confuse apparent field of view with field of view. The 3.7 Ethos will give 0.34 degrees at x324 with a 0.46mm exit pupil.

The general guideline for best contrast on DSO's is somewhere around 2mm exit pupil. This would put you in the realm of a 17mm T4 Nagler or an Ethos. The 17 Ethos would give a 1.42 degree field of view at x70.6 with a 2.1mm exit pupil.

This would give you excellent performance on many DSO's in your scope. If you try to go much higher on galaxies then the smaller exit pupil will just make them too dim.

Brighter objects like globular clusters and some planetary nebulae perhaps can take more magnification so perhaps something like a 10mm or an 8mm would work well for these.

Here are some examples of the fields of view of the 3.7mm vs a 17mm, the 17 being the larger circle of course. Whilst it may look in certain cases that the 3.7 gives you a closer view, the reality would be disappointing.

I've used a 3.7mm Ethos for a while, but on smaller scopes with a shorter focal length. This kept the magnification down to sensible levels whilst maintaining a useable exit pupil.

I hope that's of some help.

[Mark at Beaufort]

Welcome to SGL. I have a son in Livermore, California and I am hoping to visit Oregan for the Total Eclipse in 2017.

With regard to your scope it appears to be a f8 Achromtic and therefore I totally agree with comments that Stu (BigSumoriam) made. Depending on what eyepieces you have I would consider the Baader Hyperion Zoom with the matching barlow. This will give you a huge range of magnification and if you want a wider field of view you could buy an EP in the 30+mm range. All this would cost less than the Ethos.

I attach a website showing the EP which I appreciate is UK site but you can buy this setup in the United States.

http://www.firstlightoptics.com/baader-planetarium/baader-hyperion-zoom-eyepiece.html

http://www.firstlightoptics.com/baader-planetarium/baader-hyperion-zoom-barlow.html

I am sure others will give more advice with many recommending individual eyepieces. There are so many quality EPs available at the moment the most recent being Baader Morpheus - http://www.firstlightoptics.com/baader-planetarium/baader-morpheus-76-degree-wide-field-eyepieces.html

[Stu]

Totally right Mark, at f8 top end Ethos aren't really necessary to get good results so that opens up a very wide range of lower cost options

[bhighlander]

Mark,

You may want to consider the Oregon Star Party for the solar eclipse in 2017.  The dates for the 2017 event have been changed to coincide with the eclipse.  The site is very close to totality and the seeing should be great.

bhighlander  

[Dave In Vermont]

Some of us with achromatic refractors and rather short focal-points, such as my F/9.3 5" Meade LXD55, aren't bothered by the CA. Most of what was written back when they came out around 2003 didn't even mention CA. The 6" F/8 was the most written about of the two. And the problems most expressed was the rather poor focuser that came with. This was also problematic on the 5" I chose to buy - always bucking trends. I fixed my focus problem with a motorized-focuser from JMI. Still works great, by the way.

So if the CA doesn't bother you, feel free to accessorize as the spirit moves you. You can see some wondrous sights with a large achromatic refractor. I love mine.

That's my 2¢ worth,

Dave

[Charon]

Welcome aboard.

[michigander]

Welcome to SGL, Bhighlander!

Mariners fan?

Dana

[Pete Presland]

Hi welcome to SGL from Pete in Bedfordshire  your skies look very nice.

[Bizibilder]

Hello Bhighlander and welcome to SGL!!

[glowjet]

Hi Bhighlander and welcome to SGL. A little belated, as I did not mention this in my first post, being carried away with thinking of that 3.7mm Ethos, enjoy the forum

[triton1]

Hi there and welcome to SGL

[DRT]

Hi Bhighlander,

Welcome to SGL

If you really want to spend $$$$ on an Ethos I would recommend starting with the 13mm. I have all of them from 6mm to 21mm and the 13mm gets more use than the other five combined, including in my 6" f8 refractor.

But as others have said, the f8 doesn't really need a $600 eyepiece so lots of other options are available.

Best of luck.

Derek