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100° eyepieces so why have so many?


spaceboy

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Isn't our retina and its FOV limited to 120 degree per eye ? Going higher than this wouldn't make too much sense.

since we were talking about iPhones higher up in that thread, Steve Jobs said something like :"it's perfect when there is nothing left to remove", meaning that reaching the minimum latches, buttons, plugs to still be functional was his goal... In a way I am trying hard to do the same with eyepieces, but failing dramatically: I love buying, comparing, testing and getting rid of eyepieces I don't use. For my Dob, 3 eyepieces and a Barlow is enough, but for my refractor, I have a set of 6 ortho's, a very wide field (long focal) and a barlow... I think it's still way too much... But I need way better weather on many nights to refine that selection, and it's been going on for years... :)

Material selection is as much fun as observing to me, really...

 

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On 21/07/2016 at 22:58, estwing said:

....I don't think you've upset anyone!?:thumbright:...for different targets you need different tools!...planets and lunar may need a close jump between ep's but DSO hunters get away with a couple of cheap ep's and a big mirror!!!!?!!!:rolleyes2:

 

Hello. As obviously my knowledge of "Big" scopes for DSO is limited(I thought my OO14 was big until some of the cannons appeared on SGL, Faulksy build ?) . I can see for DSO the " Big" mirror requirement. But the couple of cheap eyepieces? From what I can gather a lot of these big cannons of the Dob mob are at very fast focal lengths F4 or below. My understanding is the fast scopes are very testing on eyepieces, therefore better eyepieces are therefore required in fast scopes. So can you really get away with cheap eyepieces ?or do you need a quality eyepiece such as the ethos to use in these scopes (I understand Televue test to around F4mark).   

I hope I don't upset the Dob mob by raising this point as I am still a bit mentally battered by the other night session on this topic? , thanks

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40 minutes ago, Timebandit said:

 

Hello. As obviously my knowledge of "Big" scopes for DSO is limited(I thought my OO14 was big until some of the cannons appeared on SGL, Faulksy build ?) . I can see for DSO the " Big" mirror requirement. But the couple of cheap eyepieces? From what I can gather a lot of these big cannons of the Dob mob are at very fast focal lengths F4 or below. My understanding is the fast scopes are very testing on eyepieces, therefore better eyepieces are therefore required in fast scopes. So can you really get away with cheap eyepieces ?or do you need a quality eyepiece such as the ethos to use in these scopes (I understand Televue test to around F4mark).   

I hope I don't upset the Dob mob by raising this point as I am still a bit mentally battered by the other night session on this topic? , thanks

No need to feel "battered" buddy it's all friendly banter on here and I can assure you no one is upset. ;) I hope you aren't either :) 

One can use cheap eyepieces in a fast scope but as you correctly said there will be some noticeable aberrations. Specially if using cheap wides. Whether it bothers you is down to the individual.

I guess it's a bit like coma. I use a SIPS CC on my Dob as it bothers me at f/4 whereas I know Olly for instance does not on his twenty incher. Neither is right or wrong. It's just how we each roll. :) 

Have fun out there :) 

 

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On 7/21/2016 at 12:20, spaceboy said:

Is a night still spent swapping out one focal length for another when you have so many to choose from?

That's my type of night, and i prefer it that way !

I have one full set of BST starguiders, and can't fault them, except for a  missing 6mm?

From the start,  I wanted to collect a Plössl set [Meade] (over the standard supplied eyepieces)  but some  eyepieces in 'that' series  were not available to me at the time, so my first upgrade became the 8mm Starguider, the rest just had to follow!

I now have several Plössl eyepieces from Meade, Revelation, TeleVue and a few non-Plössl premium eyepieces, with FOV's from 50° to 52° ( half the field of those in the subject heading) allowing  me more selection and choice,  affording variable eye-relief and FOV, assuming I'm using the same focal length. These are all in  an ongoing  test phase, and its been over 8 Months now since I've had any suitable conditions!

We have mathematical equations for magnification, but what appeals more to me is the finished article, and how its framed? not how I got there, so  no matter what the eyepiece in use, If it looks sharp, detailed and framed,  then as far as I know, that is the  correct eyepiece for the occasion, although the next target may require a different eyepiece , but it  still remains for me to find the best available from my collection. I do like to frame my subjects, it gives them a sense of scale/meaning, but when it came to my 70° Panaview, I stopped to think, would I need more EPs with the same FOV?  I find 60° is ideal for my needs, and  the Moon looks very small with a 70° FOV! so I favour the 32mm 70° Panaview  for the Likes of M31.


My collection is predominantly  60° FOV, others may prefer wider, and my 72° collection seems to be building slowly, but at the end of the Day, its just down to personal choice, you either like/need them or not?

I'm  impressed with my results so far, the only thing to better what I have now, are  permanent darker conditions at my home observatory, favorable weather conditions  Oh!  and a larger aperture  maybe .

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Interesting thread as the opinions are quite polarised.

I have several ethos EPs and the views are great. Yes I hunt faint fuzzies and a lot of the time the 13mm seems to settle in the scope and remain there most of the night.

For me it wasn't about collecting them, it was about all the effort I'd put in to grinding the mirror and building the scope. The only EPs that did it the justice it deserved and make the best use of it would be 100°.

Having several focal lengths gives options and the minimum glass in the optical train as possible. Yes they are expensive things to gather dust but I don't see them as investments, just a way to get the best views that the sky conditions and scope can support.

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2 hours ago, Dude_with_the_tube said:

not entirely getting the point of this topic.Is this a sales pitch for Ethos or ? 

On another note, i have seen quite a few topics started by Spaceboy regards to eye pieces,may i know your current set up please? (telescope (s) eye pieces etc)

thanks

Plenty are happy with other options such as the ES 100° range. 

My 16", comparative pea shooter of a Dob, needs 80°+ eyepieces otherwise the view gets very claustrophobic. Unfortunately. To fund the Dob purchase, I sold my Ethos 21mm and some ES 82°s ??. Now sluming it with Delosses until funds recover.

Paul

 

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2 hours ago, Dude_with_the_tube said:

not entirely getting the point of this topic.Is this a sales pitch for Ethos or ? 

On another note, i have seen quite a few topics started by Spaceboy regards to eye pieces,may i know your current set up please? (telescope (s) eye pieces etc)

thanks

 

HTH

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5 hours ago, disciplus55 said:

Isn't our retina and its FOV limited to 120 degree per eye ? Going higher than this wouldn't make too much sense.

since we were talking about iPhones higher up in that thread, Steve Jobs said something like :"it's perfect when there is nothing left to remove", meaning that reaching the minimum latches, buttons, plugs to still be functional was his goal... In a way I am trying hard to do the same with eyepieces, but failing dramatically: I love buying, comparing, testing and getting rid of eyepieces I don't use. For my Dob, 3 eyepieces and a Barlow is enough, but for my refractor, I have a set of 6 ortho's, a very wide field (long focal) and a barlow... I think it's still way too much... But I need way better weather on many nights to refine that selection, and it's been going on for years... :)

Material selection is as much fun as observing to me, really...

 

I thought it was 60-70° when your looking through an eyepiece ? Maybe this is why eye lenses seem to be getting bigger and bigger ? Or is it 60-70° and the other 50-60° is peripheral vision ??? I don't know but what ever the case I have to look for the edge in both my 82 & 100° ep's so 120° would be a waste of time for me. I don't know how members get on with their 110° eyepieces but I bet globulars would look mind blowing even if you can't take it in all at once.

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.......it will be if the FOV for that eyepiece is set to produce 60°-70° FOV.
Due to the shape of your eye, one eye alone has anywhere between 60° to over 100° FOV depending on the direction measured from your fixation  point.
Having two eyes,  can guess the answer? well its a lot more! the combined FOV is estimated to be about 132° in the vertical plane and 200° in the horizontal plane,  so I can see  and understand why there are <100° FOV eyepieces out there.

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The money invested  and effort spent on hauling a bunch of heavy ethoses around has been offset by making my expensive gym membership  redundant....

RL

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I think if anything the way forward is not so much 120° eyepieces but making the 100° eyepiece lighter and if physically possible more compact. Admittedly most on the market when in a scope with a good focuser are useable but you really do have to watch your back lifting a case full them :D 

From a business point of view this would also make more sense as you have a chance to sell the lighter ep's to current fans of 100° eyepiece in much the same way people went out and bought the same movies on VHS, DVD then Blu-ray. Same movies just somehow more desireable. Then when you have exhausted all other options, wow the market with the release of a 120° eyepiece. At least lessons learned by making the 100° eyepiece more compact may contribute to making a useable 120° eyepiece rather than risking hanging an eyepiece the size of a breeze block out of your focuser.

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I agree with spaceboy's last point - bringing down the weight and size of 100 degree eps will be the next step forward. While even wider (100+ degrees) fovs will be bought by a select market, a slimmed down 100 degree EP range, perhaps with more generous eye relief, would have broader appeal.  So maybe that's what Mr Nagler and his team are working on now - and there's a perfect name for them - "Elite". (Thinks - should I copyright that name myself?).....

However, I can't imagine they would be cheap. The technological challenge of producing a smaller Ethos while maintaining the same exemplary views across the fov would no doubt be reflected by the price. 

 

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Could depend on the scope(s) you are using. I like the chunkiness of the ethos and 2" T5's. Used with my 14" dob they facilitate balance as this scope is bottom heavy. I can understand the weight thing, I used to have some of the T6's and the T516mm, which I enjoyed very much and for a time would employ the use of the TV Equalizer to aid balance when switching to or from say a delos or 26mm T5.  Become quite accustomed to the heavier breed though. 

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52 minutes ago, disciplus55 said:

What is the real gem in the Ethos line, the 21 mm ?

I would say the 13mm is the most versatile. It gives fantastic views in almost any scope and I am convinced that if I ever had to sell my set it would be the last one to go.

But the 8mm is fantastic, the 17mm is stunning, the 4.7mm is amazing, the 21mm is superb... :lol:

 

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100° eyepieces have an inherent positive attribute in that higher magnifications can be used without making the true fields too narrow.

And, a smaller set of eyepieces can be used in order to have a reasonable progression of true field sizes.

To wit:

If I use a criterion of a 50% decrease in width of true field from one eyepiece to another, i could use a 100° eyepiece in 

21mm, 10mm, 4.7mm and cover my needs.

If, on the other hand, I use a more reasonable 75% of true field for each step up, then my progression would go:

21mm, 17mm, 13mm, 10mm, 8mm, 6mm, 4.7mm and now you see why that is the progression of focal lengths in one series of 100° eyepieces.

But if you progress by a more normal progression using magnifications, 

then a set of 21mm, 13mm, 8mm, 4.7mm could suffice.

I have long argued the progression of focal lengths, at least in the TeleVue Ethos eyepieces, represents 2 possible sets for the observer:

the 21--13--8  set and the 17--10--6 set, with 4.7mm and 3.7mm chosen as a high power depending on seeing conditions and scope used.

When I observed at a site with mediocre seeing, the 21--13--8 set worked just fine.

Now that I observe at a site with generally better seeing, the 17--10--6 set gets used more.

One doesn't need, for most DSO viewing, a tightly-bunched set of focal lengths.

 

Now, planetary observing is a different thing.  And, as has already been stated, closer together focal lengths may make sense when one is fighting seeing.

For example, if one has a 10" f/5 scope (1270mm focal length) and one wants a 50X progression of magnifications from 250x to 500x, the focal lengths get really close together:

5.1mm, 4.2mm, 3.6mm, 3.2mm, 2.8mm, 2.5mm

 

 

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On 7/23/2016 at 08:12, spaceboy said:

I thought it was 60-70° when your looking through an eyepiece ? Maybe this is why eye lenses seem to be getting bigger and bigger ? Or is it 60-70° and the other 50-60° is peripheral vision ??? I don't know but what ever the case I have to look for the edge in both my 82 & 100° ep's so 120° would be a waste of time for me. I don't know how members get on with their 110° eyepieces but I bet globulars would look mind blowing even if you can't take it in all at once.

We have about a 5° center of field sharp vision in the eye, and a 30° "general" field of view.  Anything outside that is "peripheral vision" and though it varies, it's usually 140°+ in most individuals for a single eye.

I've used a 120° eyepieces in the field and my peripheral vision has no trouble at all picking up the field stop when I am staring at the center of the field.

Now, to look directly at the edge with that foveal vision requires looking through the eyepiece at quite an angle.  It's not that hard to do--it's similar to how one would look left or right through a porthole:

you move to the right to look left and vice versa.  Only in the case of an eyepiece, the pupil has to stay where it is and the head has to be rolled to the side to look at the edge directly.

In practice, though you CAN look at the edge, one doesn't do so very often--the hyperwide eyepieces are more about having a wider field of view to look at at higher powers.

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