Televue evolution

[madtuna]

We've seen Televues EP's evolve over the years from type I through to types V & VI, now we have the 13mm and 8mm Ethos.

Will the Ethos 100 deg AFOV become availiable in thier entire EP range?
Will we soon have the ability to by a 31mm Ethos etc?

I've searched the Televue website and cant find any mention... any rumours out there?

[Kevnool]

If the consumer shows interest and the CEO of televue has a vision then yes it will happen,who knows what there developing behind closed doors ,time will tell.

[wavelandscott]

In summary, I don't know...

I thought I read a comment somewhere, maybe Cloudy Nights, that made mention of speculation or TV comment (I don't recall) that the Ethos were not a scaled design...not sure what that means with respect to future sizes though nor can I add any verification or validity to the above comment as I don't know...

In my own opinion I am not sure of the overall utility in having a whole range of Ethoi (insert correct plural)...

No doubt they are incredible achievements and will drive our hobby forward and one day I have little doubt I will own them but I wonder at what point the specification will cut in to their overall usability and future sales.

Maybe they will allow us to get to that magic spot where only a high power, medium power and low power is needed...all ultra mega wide. What will I do with my eyepiece cases?!?!

Other than price, which may or may not be justified by some, assuming the other eyepiece characteristics are comparable (eye relief, sharpness, transmission et. al) why wouldn't they displace all other eypieces including TV's own ranges? I'm not sure if it makes good business sense to bring out a whole range...

I have no problem with owning premium glass (and paying the big dollars for it), I just have not felt the need to go that way and displace most of my eyepieces...but if I was just starting to put my eyepiece collection together I'd likely include them (13 and 8) in my set of tools...they could displace/replace several in my current tool kit.

I'm rambling now and straying from your original post (which I do not know the answer to) so I will wish you all clear skies...

[skies2clear]

one thing is for sure, you won't see a 31mm Ethos in 2" barrell, or 1.25" barrell for that matter. The 2" barrell and 100 deg apparant field of view limits the maximum focal length. Expect that the biggest Ethos could only be around 20 something mm (26mm)

Clear skies

[erick]

26mm, 100 degree AFOV - that would be worth looking through!

[ColHut]

Well funny this should come up. I have a 10" f5 dob and I cannot find the optimum UWA eyepiece. You see My eyes are not young and a maximum exit pupil of 6mm would be best (less better still), But in a 2" barrel, The best field stop I might get is only 48mm which woulds allow 2.2 degrees of TFOV. My maths says a 30mm lens would be 1250/30=41.67 magnification. As AFOV=MagXTFOV then AFOV = 41.67X2.2 = 92 degrees. This does not really come close to the 31mm Nagler, and both it and the Moonfish have restrictive field stops - The Nagler according to reviews noticeably so. Really an exit pupil of 5mm would be better so lens is 25mm, mag is 1250/25 = X50, and AFOV = 50X2.2=110 degrees. I would settle for a 28mm with a 98 degree AFOV which will give me the same 2.2 TFOV and a 5.6mm exit pupil. I am sure this would be possible!. Surely Televue should make this a priority. Just keep an eye on the field stop thanks. Those with 12" dobs would have to shift for themselves....

cheers!

[StarLane]

Hi mate,

Your best bet at this point in time is a Nagler 26mm T5 with 82 degrees AFOV. Exit pupil= 5.2mm and will pull in 1.71 degrees of sky. I know it's not 2.2 like you have mentioned, but exit pupil is very important regarding useability, especially in town.
A William Optics 28mm UWAN with 82 degrees AFOV may be an option, although I'm not sure about the edge correction for a semi fast reflector.
I have a Pentax 30mm XW 70 degrees AFOV and love it. Gives me an exit pupil of 6mm and 1.68 degrees of sky and the edge correction is pretty good. Still get the space walk feel. To me the difference between the 82 and a 70 degree EP is not much when looking through it, well a Pentax compared with a Nagler anyway IMO.
I have the same scope as yours 1250mm 10 inch F5 and I researched alot of EP's before I settled on the 30XW. I looked through plenty and was never really satisfied till I had a go with a Nagler 26T5 and the Pentax 30XW. You also need to consider eye relief. Around 15 to 20mm is good, 20 being better for the long haul. A combination of ER and AFOV and exit pupil is what you need to work out, whats best for your eyes. My eyes are not real old, but I love the comfortable viewing through the Pentax.

PS. If you want to get the real space walk feel, get an ED80 with a 26-31mm 70 or 82 degree EP, wow, gives you about 3.5 to 4.5 degrees (depending on focal length), second thoughts, just get some binoculars.

[ColHut]

Thanks for that. I use the GSO 30mm Superview which I really like, but I am sure that the pentax would be sharper. I was light-heardely considering what I would get if I could... I Am sure Televue will take this to heart :) and was diappointed by the (relatively) narrow field stop reported for the Nagler. If they improved their 31mm Nagler Field stop to 48mm that would allow 2 degrees in my scope which would be fine! Thanks for your serious comments though - I am thinking about where to from here.

cheers

[Starkler]

I had one of those and sold it because the eye relief was too short to take in the entire field at once. If i cant see 82 degrees im not paying for 82 degrees!

[erick]

Just read the following in a review by Ed Moreno in Astromart from 2006:-

"But you know what? Of the THOUSANDS of objects visible in the night sky, only a TINY fraction of one percent of them WON’T fit in a 1.38 degree field."

So what is an acceptable/useful actual FoV? (Let's presume the entire field is sharp, bright and usuable - hence quality eyepiece.)

[StarLane]

Yep, that's why I went with the 30XW, 20mm ER and adjustable eye cup, extremely comfortable to use, easily see the full field, well corrected for my scope.