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Eyepiece Discontinuations

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#26 Sarkikos

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Posted 13 February 2018 - 08:01 AM

Tele Vue Eyepieces for Tele Vue Refractors at http://www.televue.c...n=Advice&id=220 still shows the 2.5mm Type 6 Nagler as a recommended eyepiece for the TV-76, NP-101 and TV-60 (below).

 

It is really nice in the TV-60 giving 144x and an optimal minimum exit pupil for me personally although I usually use the 4-2mm Nagler Zoom (discontinued).  I wonder if anything will replace the 2.5mm Type 6 Nagler.  Maybe a 2.7mm Ethos SX or maybe the T6 are all to be replaced with a 2-13mm 82 deg. Nagler Zoom.  Either one would be a nice eyepiece!

I'd like to see a 2.7mm Ethos 110 degree SX!

 

Mike



#27 turtle86

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Posted 13 February 2018 - 08:06 AM

Don't really see a need for T7 Naglers for now.  I suspect that any advancements that Televue has made in coatings in recent years have already been quietly incorporated into the Naglers. Despite the popularity of the Delites, Delos and Ethos, I still see a niche for the Naglers, especially the T6 Naglers. They really do pack a lot of punch for their compact size and are a great choice for those who want the 82 degrees AFOV but have smallish scopes or scopes with balancing issues.


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#28 BillP

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Posted 13 February 2018 - 10:10 AM

Once discontinued, the 11mm Nagler 6 will suddenly become a mythical, much sought after and highly desired eyepiece.

 

It is a well established fact, like that Bigfoot prefer deer as the staple of their diet then scream and bang on trees to communicate, that only so many eyepieces with "mythical" qualities can be manufactured because there is only so much magic available for any given item.  As a result, the mythical eyepieces discontinue first.  I would suggest, now knowing that the 11T6 and 2.5T6 production lines have run out of magic for those eyepieces, that everyone run out now and purchase remaining stock.  If you do not, then you will miss the opportunity to have these mythical magic eyepieces.  And once discontinued, no one would dare part with one so not likely to find any on the used market.  And given the value of possessing a "full" set of any eyepiece line, if you are missing these from your T6 line up then better hurry lest you forever regret.


Edited by BillP, 13 February 2018 - 10:42 AM.

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#29 Starman1

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Posted 13 February 2018 - 10:12 AM

It is hard to imagine what a T7, T8 (I dub the "Tate") etc. Nagler would look like since TV have done the Delos and Ethos. 

  • The T6's and most of the predecessor Naglers were in the ~12mm eye relief range except for some scaled varieties and one-offs (each T4).   
  • Al Nagler has turned over most of the design to Dellechiaie with two lines bearing his name in one way or the other. 
  • The Delos are somewhat narrower field than Naglers, but with 20mm eye relief for eyeglass wearers and allowing room for Dioptrx 
  • The Ethos define a whole different class with 15mm eye relief, and Dioptrx compatible. 

I guess the T6's could be replaced by a slightly longer eye relief (~15mm) Nagler field line with full Dioptrx compatibility, but as Allan notes it would poach the other two categories.  And it would likely be more expensive than the Delos.  The size might be intermediate with the shorter eye relief and wider field than the Delos, so that might have some appeal. 

 

Comfortable eye relief 20 years ago was 12mm.  Coming from short focal length Plossl's, Orthos, etc. with miniscule eye relief, 12mm was generous.  But now folks expect to be able to take in wide fields with their glasses on.  This is a problem for those of us not using glasses because the eye relief becomes too long, with extra reflections and difficulties with best eye placement.  On the other hand, it looks like Dioptrx takes a bit more than 12mm to avoid glasses altogether. 

 

So here we are.  I am glad I got my set together before the eyeglass contingent won.

So long as the eyepiece has some method of holding your eye at the right distance, I find I don't mind the long eye relief eyepieces.  They have larger eye lenses and the raised eyecups yield better contrast by removing any possible peripheral light scatter off the tops of the eyepieces.  Of course, not that I minded the smaller eye relief--I own a 16mm T5 with only 10mm of eye relief.


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#30 BGazing

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Posted 13 February 2018 - 11:58 AM

Truth be told, I did notice that my 11mm T6 gave views that have that extra 'something', but could not put it in words...now I know...it was 'mythical' and 'magical'.



#31 CrazyPanda

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Posted 13 February 2018 - 01:36 PM

It is a well established fact, like that Bigfoot prefer deer as the staple of their diet then scream and bang on trees to communicate, that only so many eyepieces with "mythical" qualities can be manufactured because there is only so much magic available for any given item.  As a result, the mythical eyepieces discontinue first.  I would suggest, now knowing that the 11T6 and 2.5T6 production lines have run out of magic for those eyepieces, that everyone run out now and purchase remaining stock.  If you do not, then you will miss the opportunity to have these mythical magic eyepieces.  And once discontinued, no one would dare part with one so not likely to find any on the used market.  And given the value of possessing a "full" set of any eyepiece line, if you are missing these from your T6 line up then better hurry lest you forever regret.


*Panics and buys two of every eyepiece on the market to be safe*

#32 Sarkikos

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Posted 13 February 2018 - 01:52 PM

 

*Panics and buys two of every eyepiece on the market to be safe*

 

Must have a binoviewer ...

 

Mike


Edited by Sarkikos, 13 February 2018 - 01:53 PM.


#33 BillP

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Posted 13 February 2018 - 03:00 PM

 

 

*Panics and buys two of every eyepiece on the market to be safe*

 

Must have a binoviewer ...

 

 

I like this!  All mythical magical eyepieces must be used in binoviewers to preserve one's peace of mind that they might damage one then be left with none.  Make perfect sense.


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#34 Peter Besenbruch

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Posted 13 February 2018 - 03:43 PM

 

Does TV have a T7 Nagler series up their sleeve with long eye relief?

Or do they think 31..22..17/16..13..9..7..5..3.5 might be enough Naglers to make a set?

I'd bet on the latter.

I am hoping its a T7 Nagler series!!!! A eyepiece series 17-20 mm in eye relief, physically bigger than a Delos but a bit smaller than the Ethos, with the same coatings and eyepiece design technology used in the Delos/Ethos.

I'm still holding out for the type 3.


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#35 Alan French

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Posted 13 February 2018 - 04:06 PM

Type 3 is exclusively used in Area 51.

 

Clear skies, Alan


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#36 Jon Isaacs

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Posted 13 February 2018 - 04:46 PM

The prototypes of the Type 3 Naglers were fantastic eyepieces but were never produced because at that time,  there was a shortage of magic. 

 

The production of new designs were not possible until Harry Potter first defeated Voldemort in the Sorcerer's Stone . 

 

Jon


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#37 MitchAlsup

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Posted 13 February 2018 - 06:11 PM

The only Nagler I still have is a 7mm T1 and it is only used for fine collimation.



#38 Phil Cowell

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Posted 13 February 2018 - 09:11 PM

Type 3 is exclusively used in Area 51.

 

Clear skies, Alan

They recently moved them to Area 52 to make room for the T6’s.



#39 BarrySimon615

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Posted 13 February 2018 - 11:43 PM

Looking at eyepiece "series" what is in a series often makes little sense in respect to magnification increases.  Now recommendations for magnification step increases are across the board with everything from small step increases (perfect for someone who would like to get virtually every number in the metric alphabet from 1 mm to 80 mm expressed by an eyepiece in their collection).  At the other end of the spectrum some seem to be happy with 100% magnification increases per eyepiece, maybe a set yielding 25x, 50x, 100x, 200x and 400x.  Others like variable increases between a low power and high power eyepieces typically with larger percentage jumps at the low magnification end such as 25x to 50x, a 100 percent increase, and smaller percentage jumps at high magnification as in  300x to 350x, which is only a little over a 16% magnification increase.

 

Looking at various "sets" of eyepieces the magnification steps vary across a wide range.  Using what has been a very typical series or orthoscopic eyepieces we have 25 mm, 18 mm, 12.5 mm, 9 mm, 7 mm , 6 mm, 5 mm and 4 mm (University Optics "volcano" tops) we have percent increases in magnification of about 39% (25 mm to 18 mm), 49.5% (18 mm to 12.5 mm), 39% (12.5 mm to 9 mm), 28.6% (9 mm to 7 mm), 16.6% (7 mm to 6 mm), 20% (6 mm to 5 mm), and 25% (5 mm to 4 mm).  Note that the percent magnification increase does not change irrespective of the focal length of the telescope but what does change is the magnification numbers.  In a 500 mm focal length telescope a 7 mm eyepiece gives you 71.4x and a 6 mm eyepiece gives you 83.3x so here you have a 16.6% increase which is only about a 12x increase.  With a 3000 mm focal length telescope the same 7 mm eyepiece gives you 428.6x and the 6 mm eyepiece gives you 500x, so that 16.6% increase jumps the magnification by about 71x.  Having both a 6 mm and a 7 mm eyepiece your case much less in the same series makes more sense with a longer focal length scope.  (At least to me, your mileage may vary!)

 

So why even consider this in respect to this thread discussion?  I think, basically the way many of us think (note - I said many, not most, as opinions run the spectrum) is that we would like to see sets of eyepieces that have logical steps for us, and for not only one telescope but for several and sometimes many.  Personally l would think a set would be perfect for me if each step up in magnification represented a magnification increase of about 40% as the ideal and anything between about 30% and 55% being acceptable.  An eyepiece that due to it's placement in a series represents an illogical step may be the first to be discontinued due to poor sales. As a lot of the discussion here has focused on the TeleVue Nagler Type 6 eyepieces, let's take a look at them -

 

18% increase in magnification going from the 13 mm to the 11 mm, 22% going from 11 mm to 9 mm, 28.6% going from 9 mm to 7 mm, 40% going from 7 mm to 5 mm, almost 43% going from 5 mm to 3.5 mm and 40% going from 3.5 mm to 2.5 mm.  The high magnification steps seem very logical to me, steps of about 40%, but this breaks down somewhat in the magnification increase between the 9 mm and the 7 mm eyepiece which is 28.6%.  A 10 mm eyepiece instead of a 9 mm would have made more sense, 10 mm to 7 mm would be a 43% increase in magnification, throwing out the 9 mm, if we had a 10 mm, the next in the series should have been a 14 mm, which would have given a 40% magnification increase in going from a 14 mm to a 10 mm.  Working with what is in the series, I personally chose the 11 mm over both the 9 mm and the 13 mm (even though the 13 mm to 9 mm magnification increase is a very nice 44%).  11 mm to 7 mm gives a percent step increase of 57%, a bit much based on my criteria, but better to have the one 11 mm eyepiece than having steps that are too close by adding both the 13 mm and the 9 mm.  Additionally to complement the 11 mm going to a lower magnification I have the 15 mm Panoptic and the magnification increase in switching from the 15 mm Panoptic to the 11 mm Nagler represents a 36% increase,  (I also have a 16 mm Nagler Type 5 and the magnification step increase between the 16 mm and the 11 mm is a bit over 45%.)  So bottom line the 11 mm works for me and both the 13 mm and the 9 mm do not, no matter how much I try to logically justify them.  It would cost me over $600 to complete a set and I just cannot justify that.

 

Bottom line, as others have said regarding discontinuations in sets is how the individual units in a set sell and how they sell may be dependent upon how well they fit in with others in the set in respect to magnification jumps and if they don't fit in well, they don't sell well, they are discontinued.

 

Barry Simon 


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#40 astro744

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Posted 14 February 2018 - 01:31 AM

Note when comparing eyepieces with different apparent fields you should also look at the field stop diameters to see how true fields compare.  You could be seeing the same amount of sky but at a different magnification as was precisely the case with the 20mm Plossl, 15mm Panoptic and 12mm Type 4 Nagler (17.1mm FSD) and almost the case with either of these and the 13mm Type 6 Nagler (17.6mm FSD).

 

Having a nice range of magnification is more important for high power planetary viewing but for low power deep sky viewing, especially the larger objects, it is more important to frame the object and for this field stop diameter increments should be considered.  See second last para at http://www.televue.c...rn=Advice&id=79. (I find the information under the 'Advice' section on the Tele Vue site very helpful).

 

 



#41 tony_spina

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Posted 14 February 2018 - 01:36 AM

I think there will still be an active used market in T-6's. My guess is that they are seeing pressure from the Delos eyepieces with their more comfortable eye relief.  I had been pondering putting together the entire set of T-6's, I need the 2.5, the 11 and the 13, along with the 16mm T-5 I have, that would be a nice set of 1.25 inch eyepieces. 

 

Jon 

Jon,

i like my 2.5mm Nagler in the NP101. I use the brass 2” to 1.25” adapter to help minimize the weight difference with my heavier eyepieces 

 

the views are realy nice with the 2.5mm. Love it on the moon, planets, and double stars



#42 Jon Isaacs

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Posted 14 February 2018 - 02:05 AM

 

I think there will still be an active used market in T-6's. My guess is that they are seeing pressure from the Delos eyepieces with their more comfortable eye relief.  I had been pondering putting together the entire set of T-6's, I need the 2.5, the 11 and the 13, along with the 16mm T-5 I have, that would be a nice set of 1.25 inch eyepieces. 

 

Jon 

Jon,

i like my 2.5mm Nagler in the NP101. I use the brass 2” to 1.25” adapter to help minimize the weight difference with my heavier eyepieces 

 

the views are realy nice with the 2.5mm. Love it on the moon, planets, and double stars

 

 

I find the 5mm with a 2x Barlow does a nice job and for close double stars I will use the 3.5mm with the 2x Barlow, I'll have the Barlow out so it just don't see the need for the 2.5mm.  With my 10 inch I also use the 3.5 mm with the 2x Barlow for close doubles.  

 

18% increase in magnification going from the 13 mm to the 11 mm, 22% going from 11 mm to 9 mm, 28.6% going from 9 mm to 7 mm, 40% going from 7 mm to 5 mm, almost 43% going from 5 mm to 3.5 mm and 40% going from 3.5 mm to 2.5 mm.  The high magnification steps seem very logical to me, steps of about 40%, but this breaks down somewhat in the magnification increase between the 9 mm and the 7 mm eyepiece which is 28.6%.

 

 

Barry:  I have the 3.5mm, 5mm, 7mm and the 9mm type 6's.  The step sizes are not perfect but very usable.  Ideally, the 29% jump would be at the between the two shortest focal lengths but this works.  As far as the 11mm and the 13mm, I think these are pick your poison, one or the other.  For a number of years, the 12mm Type 2 was the next eyepiece in my case which was a 33% increase and then the 16mm, which was another 33%.  

 

These relatively close steps at these mid range focal lengths were actually very useful because they spanned the range I would normally use for the planets in the 25 inch F/5, the 16mm providing 230x, the12mm 304x and the 9mm 406x.  The 7mm provided 520x.  Those worked well together. 

 

So I don't think one has to own every eyepiece in a series, particularly at lower magnifications. 

 

Jon 



#43 jjack's

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Posted 14 February 2018 - 04:02 AM

Barry Simons youre right.. the root square of power double the area seen in the same afov.

So 40% to 50% i s a good approximation.

Ideally a perfect set of eyepiece must be like diaphragm step on an objective camera so : 2.8/ 4 /5.6/8/11/16 /22/32.

Or : 2.5/3.5/5/7/10/14/20/28/40/56.

As you can see, the perfect set of naglers is difficult to reach.



#44 turtle86

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Posted 14 February 2018 - 07:31 AM

 

 

 

*Panics and buys two of every eyepiece on the market to be safe*

 

Must have a binoviewer ...

 

 

I like this!  All mythical magical eyepieces must be used in binoviewers to preserve one's peace of mind that they might damage one then be left with none.  Make perfect sense.

 

Televue likes this too! :lol:



#45 slack

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Posted 14 February 2018 - 07:31 AM

I think there will still be an active used market in T-6's. My guess is that they are seeing pressure from the Delos eyepieces with their more comfortable eye relief. 

I've had every T6 (in pairs, and many times over...), I've had all the Pentax XW and the Nikon SW of comparable focal lengths, plus the Docter 12.5 and Leica zoom and several Delos, and I can't fathom how the T6 line compares to the Delos, even remotely; they are very compact by comparison, a different AFoV, non-mechanical in operation, and shorter ER, and more... They aren't at all similar. If they were, I wouldn't have both types of EPs.


Edited by slack, 14 February 2018 - 07:18 PM.


#46 BarrySimon615

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Posted 14 February 2018 - 10:11 AM

Barry Simon you're right.. the root square of power double the area seen in the same afov.

So 40% to 50% i s a good approximation.

Ideally a perfect set of eyepiece must be like diaphragm step on an objective camera so : 2.8/ 4 /5.6/8/11/16 /22/32.

Or : 2.5/3.5/5/7/10/14/20/28/40/56.

As you can see, the perfect set of naglers is difficult to reach.

Agreed, I especially like the thought of a series of eyepieces be it type 6 Naglers, orthoscopics or Delos that would follow the 2.5, 3.5, 5, 7, 10, 14, 20, 28, 40 and 56 pathway.  Both the Nagler Type 6 and the Delos lines follow this path for part of both series of eyepieces but then diverge from it.  The Nagler Type 6 line does it with the 2.5, 3.5, 5, and 7 but then move away from it.  I bet if TeleVue would drop the 9, 11 and 13 and instead replace that with 2 new ones, a 10 mm and 14 mm sales of the new ones would outstrip sales of the three discontinued  (looks like the 11 is being discontinued anyway).  In my case I would absolutely purchase a 10 mm and the 14 mm, and likely sell my 11 mm.  Others would have to have a complete set and they would buy the new ones in spite of the fact that their expanded set would now include a 9 mm, 10 mm and 11 mm.

 

With the Delos line the numbers for what I would consider a perfect set would be a little different with 33% magnification increases between eyepieces, doing that you would retain the 4.5, the 6, the 8, and the 14.  A 3.4 and a 10.5 would be ideal, but the current 3.5 and the 10 mm are probably close enough for government work.  At the low magnification end, if the optical gurus at Televue could manage to scale the Delos line to include a 18.6 mm instead of the current 17.3 mm that would preserve a 33% magnification increase in going from 18.6 mm to the 14 mm and would make more sense than the current magnification increase of just 23.5%  in going from the 17.3 Delos to the 14 mm Delos.  So, in the current line up the 17.3 and the 12 would be discontinued and possibly 10 mm if a 10.5 mm could be substituted.

 

Of course all of this is idle speculation and wishful thinking, but something I would like to see.  Note - the 19 mm Panoptic coupled with the 24 mm Panoptic can be utilized for a 1.25" eyepiece set that cuts off the Delos line at 14 mm for the lowest magnification Delos but continues to lower magnifications with the 19 mm and the 24 mm Panoptics.  Going to lower magnifications the 32 mm Televue plossl has that 33% difference between it and the 24 Panoptic, and then for really low magnifications the 40 mm TV plossl can complete the set consisting of eyepieces from 3 lines.

 

Us retired people have a lot of time on our hands to even think about this stuff much less to write about it!shocked.gif 

 

Barry Simon 



#47 Redbetter

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Posted 14 February 2018 - 10:41 AM

Barry Simons youre right.. the root square of power double the area seen in the same afov.

So 40% to 50% i s a good approximation.

Ideally a perfect set of eyepiece must be like diaphragm step on an objective camera so : 2.8/ 4 /5.6/8/11/16 /22/32.

Or : 2.5/3.5/5/7/10/14/20/28/40/56.

As you can see, the perfect set of naglers is difficult to reach.

That only works for the low and mid-power end.  In my experience  40 to 50% steps are far too wide on the high power end, a very poor way to match the capability of a scope with the available seeing and the exit pupil that a given person's eye will find most useful.  The jump from 7 to 5 is too wide for example in longer focal length scopes, while 7 to 9 works well.   Ironically, 2x Barlowing the 11mm would help fill the wide gap between 7 and 5, as does the 6mm setting on the 3-6 zoom.

 

For refractors at f/6, f/7, and f/7.5 I find a substantial difference in only 0.5mm increments at the very end of the range for planetary, and 1mm increments work well from 6mm to 4mm.  That is why the 3-6 planetary zoom is so useful.  I tend to favor 4mm for the f/7 and f/7.5 most nights on planets, 5mm on a poor night, and on better nights can push a little past...but 3.5mm has proven marginal.  At f/6 3mm is an improvement over 3.5, and 2.5 is marginal.    

 

Never have found that I have too many steps available, but I have repeatedly found in the past that I had too few available.  I used 5/7/9 progression for the 20" on planets in a former locale, and have found more need of 11/13 and even 16 here for planets...with the 9 and 7 only coming out for planets on better nights, and the 5 not being usable for planetary detail a single night in 2 years. 


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#48 Starman1

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Posted 14 February 2018 - 10:41 AM

One fly in the ointment, so to speak, of a linear progression of magnifications:

Many "planetary" observers like their high magnifications to be much closer together because they are always pushing the limits of seeing

and smaller jumps at the high end allow them to maximize magnification while pushing against the ceiling allowed by seeing conditions.

So, though a 40-50% jump may be appropriate for low powers, much smaller jumps may be appropriate at high power, like 15-20%.

I've seen sets of 6mm, 5mm, 4mm, 3.5mm, 3mm, 2.5mm, 2mm, as an example.

 

Additionally, I find that close jumps at low power usually aren't necessary.  If I start out with a really good low power that frames objects well,

if I feel I need a higher power to improve resolution or view smaller details, anywhere from a 60% to 100% jump is just fine for the next step up.

Having a bunch of low powers usually results in my just using one eyepiece to the exclusion of all the others.

 

Then there is the rational philosophy of having magnifications be closer together near the "sweet spot" of magnification for the type of object viewed.

So if I like a 10mm eyepiece for most of my observing of, say, galaxies, then I might want a 25% increase or decrease from that for other sizes

of object or details, while as I move farther from the sweet spot I can tolerate larger jumps like 40% or 50% or even 60%.

 

Among the eyepieces I own, I tend to use them in subsets, dependent on seeing conditions or objects viewed.

I either use a set where the increases from low power are: 61%, 63%, 70%  or 71%, 66%, 62%.  I always have the in-between eyepieces there if I need them, but I tend to use a subset of 4 most of the time: 21..13..8..4.7mm  or 17..10..6..3.7mm

 

But we all will use a much larger skip for particular objects.  I'll use a low power to find a planetary nebula, but then immediately jump to a much higher power to view it.

I have often used a 87x to 304x jump because long experience shows me I'll use the 304X to view the object anyway.  Why waste my time with in-between magnifications I won't stay with?

 

So there are magnification protocols that may require a completely different set of eyepieces than Barry's progression.  Even in an SCT, I'd find the 20mm to 40mm jump just fine, and I'd

see no reason for the 28 or 56mm eyepieces.


Edited by Starman1, 14 February 2018 - 10:42 AM.

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#49 Jon Isaacs

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Posted 14 February 2018 - 11:56 AM

 

I think there will still be an active used market in T-6's. My guess is that they are seeing pressure from the Delos eyepieces with their more comfortable eye relief. 

I've had every single T6 (in pairs, and many times over...), I've had every Pentax XW, and the Nikon SW of comparable focal length, plus the Docter 12.5 and Leica zoom and several Delos, and I can't fathom how the T6 line compares, even remotely; they are compact, of a mostly different AFoV, non-mechanical in operation, very compact by comparison, shorter ER an mostly AFoV, and more... They aren't at all similar. If they were, I wouldn't have them—the T6s are very different from those.

 

 

As I said, there was a time when the T-6 Naglers were all TeleVue offered (other than the Radians), you didn't have a choice of long eye relief with a 70 degree AFoV, you didn't have a choice of 100 degree eyepieces.  

 

Things are different now, you have a choice.   You can choose the Delos, you can choose the Ethos.  And you can choose the T-6 Naglers.  

 

It seems most are choosing either the Delos or the Ethos rather than the T-6 Naglers but in any event there are now three and even four with the Delite to choose from. 

 

Jon



#50 Alan French

Alan French

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Posted 14 February 2018 - 11:57 AM

At the higher powers I tend to base it on exit pupil, aiming for ~1.5, 1.0, and 0.8. Smaller than that doesn't generally provide an advantage and my floaters get really annoying, although I sometimes go to a 0.5mm exit pupil. This is with scopes up to 10-inch aperture. Seeing rarely allows such small exit pupils (high powers) on large apertures.

 

My best view of Jupiter, on a night of perfect seeing, was at 567x (~0.6mm exit pupil) on a 12.5-inch, so it's nice to have suitable eyepieces for the smaller exit pupils on hand, even with larger apertures.

 

Clear skies, Alan


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