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Equipment Discussions >> Eyepieces

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Jon Isaacs
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: Starman1]
      #5651494 - 01/30/13 12:58 AM

Quote:

There are 1.25" eyepieces with 29mm field stops, a diameter larger than the inside diameter of the bottom barrel. How? Accept lower illumination of the edge that would be the case in a 1.25" eyepiece with a 27-27.5mm field stop.
As was said earlier--it's all about compromises and where one draws the line.




TeleVue seems to draw the line at about 27mm for a 1.25 inch barrel non-negative positive eyepieces. The 20mm Type 2 Nagler has a 27mm effective field stop diameter but the clear aperture of the field lens is 36mm...

Jon


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Sgt
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: Starman1]
      #5651729 - 01/30/13 07:46 AM

Quote:


I could see some company, and it probably would be TeleVue, coming out with a line of long eye relief 82 degree eyepieces. That would heavily expand the market for 82 degree eyepieces, whether they had field stops of the I.D. of the barrels or not.




Thats what I was hoping for when I first caught wind of TV coming out with something after Ethos. Ultimately I was disappointed by the Delos because as far as I see, they just produced something that did the same as an eyepiece line around for years (the XW's). I continue to wait and hope.


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Tom TAdministrator

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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: Starman1]
      #5651736 - 01/30/13 07:53 AM

Quote:

There are 1.25" eyepieces with 29mm field stops, a diameter larger than the inside diameter of the bottom barrel. How? Accept lower illumination of the edge that would be the case in a 1.25" eyepiece with a 27-27.5mm field stop.
As was said earlier--it's all about compromises and where one draws the line.




Ubetcha.


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BillP
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: Tom T]
      #5651893 - 01/30/13 09:37 AM

Quote:

Back to the eyepiece. Question: Have you made one? If so, I'd love to see it. If not, then show me it can be done and (here's the kicker) for a reasonable cost with good quality and performance. Otherwise, with respect sir - you ain't got nuttin.

TV (or really *any* other company out there) aren't idiots. If they could make one that would turn them a profit (and not dilute their brand) - they would.




Ahhh...now the argument is changing. First it's "it can't be done" and now it's "to turn a profit"...fundamentally different reasons for not making one. Sorry..can't have cake and eat it too...so ain't got nuttin also

By your reasoning then, using the substantially appeal to authority fallacy you offered...

Back to the eyepiece... Question: Have you made one and failed Tom? If so, I'd love to see that failed attempt. If not, then show me how it can't be done and (here's the kicker) that it must be for an unreasonable cost and sacrificed quality and performance. Otherwise, with respect Tom - you ain't got nuttin.

The point it...forsaken long focal lengths. Yes, let's look at the facts (note - full range of focal lengths defined as from max TFOV 2" to at least 4mm)...

50-degree class - TV Plossls - available in FULL range of focal lengths - still alive and well

60-degree class - Radians - NOT available in full range of focal lengths - not doing so well, slowing dying.

68- degree class - TV Panoptics - NOT available in a full range of focal lengths - not doing so well, units are phasing out

72 degree class - Delos - NOT available in a full range of focal lengths - too new to determine longevity

82 degree class - Nagler - available in a full range of focal lengths - still alive and well

100 degree class - NOT avilable in a full range of focal lengths (missing a sole max TFOV 2" version) - too new to determine longevity.

So from the perspective of creating a line that can service all focal lengths to take advantage for TFOV capabiltity of the barrel to short plantary focal length...the lew lines from TV in the recent years fall short. As far as can a 25mm 100 degree EP be made well? If you say it can't then you obviousley should not be in that business as you won't be successful not being able to innovate to the needs of the consumer. As one looks over past successful lines that have stood the test of time, a full range of focal lengths seems to be a key factor. In the end, the consumer's will prevails as they speak with their pocketbook...and there sure is history showing its speak!


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MRNUTTY
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: BillP]
      #5652172 - 01/30/13 12:03 PM

Bill, not to waltz on in a lively discussion, as a consumer I don't require all focal lengths to be available in a single line from a single vendor to be a target for purchase. I am happy with 2 or more lines from that vendor, as long as the lines adequately serve their purpose; such as as Delos + Panoptic make an adequate solution for me.

Note: my superlatives may vary over time :-)

Edited by MRNUTTY (01/30/13 12:04 PM)


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Paul G
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: BillP]
      #5652189 - 01/30/13 12:13 PM

Quote:

Quote:

Back to the eyepiece. Question: Have you made one? If so, I'd love to see it. If not, then show me it can be done and (here's the kicker) for a reasonable cost with good quality and performance. Otherwise, with respect sir - you ain't got nuttin.

TV (or really *any* other company out there) aren't idiots. If they could make one that would turn them a profit (and not dilute their brand) - they would.




Ahhh...now the argument is changing. First it's "it can't be done" and now it's "to turn a profit"...fundamentally different reasons for not making one. Sorry..can't have cake and eat it too...so ain't got nuttin also

By your reasoning then, using the substantially appeal to authority fallacy you offered...

Back to the eyepiece... Question: Have you made one and failed Tom? If so, I'd love to see that failed attempt. If not, then show me how it can't be done and (here's the kicker) that it must be for an unreasonable cost and sacrificed quality and performance. Otherwise, with respect Tom - you ain't got nuttin.

The point it...forsaken long focal lengths. Yes, let's look at the facts (note - full range of focal lengths defined as from max TFOV 2" to at least 4mm)...

50-degree class - TV Plossls - available in FULL range of focal lengths - still alive and well

60-degree class - Radians - NOT available in full range of focal lengths - not doing so well, slowing dying.

68- degree class - TV Panoptics - NOT available in a full range of focal lengths - not doing so well, units are phasing out

72 degree class - Delos - NOT available in a full range of focal lengths - too new to determine longevity

82 degree class - Nagler - available in a full range of focal lengths - still alive and well

100 degree class - NOT avilable in a full range of focal lengths (missing a sole max TFOV 2" version) - too new to determine longevity.

So from the perspective of creating a line that can service all focal lengths to take advantage for TFOV capabiltity of the barrel to short plantary focal length...the lew lines from TV in the recent years fall short. As far as can a 25mm 100 degree EP be made well? If you say it can't then you obviousley should not be in that business as you won't be successful not being able to innovate to the needs of the consumer. As one looks over past successful lines that have stood the test of time, a full range of focal lengths seems to be a key factor. In the end, the consumer's will prevails as they speak with their pocketbook...and there sure is history showing its speak!




Lumping the Naglers together isn't appropriate. The type 4, 5, and 6 Naglers are three completely different designs, and none of them cover the full focal length range. The only design that does so is the Plossl. On various forums in the past Al Nagler and others from TeleVue have posted reasons why each of those designs maxes out at a certain focal length, usually due to size or performance constraints.

Tom brings up a good point as well, the eyepieces need to appeal to a large enough number of buyers to make a profit. With companies like ES knocking off designs it cuts some of the profit out of bringing out a new eyepiece, not as much incentive to push the envelope.


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Paul G
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: MRNUTTY]
      #5652196 - 01/30/13 12:15 PM

Quote:

Bill, not to waltz on in a lively discussion, as a consumer I don't require all focal lengths to be available in a single line from a single vendor to be a target for purchase. I am happy with 2 or more lines from that vendor, as long as the lines adequately serve their purpose; such as as Delos + Panoptic make an adequate solution for me.




This. The existing lines complement each other nicely. With TV I have 2 mm through 41 mm covered.


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Jeff Morgan
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: BillP]
      #5652284 - 01/30/13 01:05 PM

Quote:



50-degree class - TV Plossls - available in FULL range of focal lengths - still alive and well

60-degree class - Radians - NOT available in full range of focal lengths - not doing so well, slowing dying.

68- degree class - TV Panoptics - NOT available in a full range of focal lengths - not doing so well, units are phasing out

72 degree class - Delos - NOT available in a full range of focal lengths - too new to determine longevity

82 degree class - Nagler - available in a full range of focal lengths - still alive and well

100 degree class - NOT avilable in a full range of focal lengths (missing a sole max TFOV 2" version) - too new to determine longevity.






Perhaps TeleVue is hamstringing themselves by marketing the product name too tightly with the performance parameters (i.e., Delos is always 72 AFOV and 20mm eye relief). Relaxing these may be a way around the field stop limitations.

If a 23mm Delos "only" had 68 AFOV and 18mm eye relief I would still buy the thing, provided the field flatness and sharpness down to f/4 was there. That's where they really need to hold the line, a slight variation on AFOV and eye relief are only material to the most obsessive/compulsive among us.

And given the proven history of Tele Vue updating existing focal length designs (Naglers 9, 11, 12, 13, 16, and 20 come immediately to mind) and the timeline I laid out it would appear that the 22+ designs are long overdue for update.


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Tom TAdministrator

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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: BillP]
      #5652429 - 01/30/13 02:11 PM

Quote:


Ahhh...now the argument is changing. First it's "it can't be done" and now it's "to turn a profit"...fundamentally different reasons for not making one. Sorry..can't have cake and eat it too...so ain't got nuttin also






Oh bull Bill and you know it. Nothing's changed (either in my argument, or in the years since I was last an active poster here) Bottom line is that it simply does not matter if it can or can't be done (yet) or if it's not profitable. My point is that there could be many different reasons, and it's not necessarily the sole one that you're putting forward.



Quote:


Back to the eyepiece... Question: Have you made one and failed Tom? If so, I'd love to see that failed attempt. If not, then show me how it can't be done and (here's the kicker) that it must be for an unreasonable cost and sacrificed quality and performance.





And as per failure? Seriously Bill? Are you implying that I can't show you a failure? Geeze, I wish I was as talented as you seem to think I am. I fail at things all to often. How can you "prove" a negative Bill? Even if I showed you my attempt, why would that imply that it couldn't be done? The only conclusion that you could draw would be that I failed on that specific attempt.

Seriously - This is a rather pointless argument. History shows who innovates and who doesn't, pocketbooks determine market leaders. Sometimes they aren't the same folks. Unless you have FAR more power than I think you do, things don't happen according to your timetable. They certainly don't happen to mine.

I won't deny I ain't got nuttin. As long as you agree you don't either.

Anyway -

Quote:


So from the perspective of creating a line that can service all focal lengths





Having the eyepieces all in one line is a big deal to you? Really? It's never bothered me that I use different lines for different focal lengths. Heck, I even use different designs from different manufacturers. I must be a real heretic.

To me, looking at what you lay out just shows me that it takes time to successfully phase in a product line. I don't think you, I or Joe Internet can really predict the future here.

Just remember for the consumer's will to prevail, they need to have something to choose in the first place.

T


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BillP
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: Tom T]
      #5652486 - 01/30/13 02:44 PM

Quote:

Oh bull Bill and you know it. Nothing's changed (either in my argument, or in the years since I was last an active poster here) Bottom line is that it simply does not matter if it can or can't be done (yet) or if it's not profitable. My point is that there could be many different reasons, and it's not necessarily the sole one that you're putting forward.






Where the who-ha is that coming from Tom? I'm not putting forth reasons why it is not being done. I'm arguing with others who are giving discrete reasons like "it can't be done, etc.". That's a bunch of horse-hockey and you know it!!

My whole argument from the getgo is that the "can't" be done argument is nonsense. I put forth a supposition of a probable real reason, that the particular prescription of the Ethos does not lend itself to a 25mm incarnation. So take or leave my supposition all you want. I don't care. My only argument is that it is nonsense that it "can't be done". And further, I never ever care what any vendor says on the topic. No disrespect at all to the vendor. I am the consumer and the consumer's needs rule. If one vendor doesn't do it for whatever reason, like everything in the free enterprise system, another will come along and satisfy the consumer requirement. As the old expression goes...those that can do and those that can't don't. In the context of this discussion it is those vendors who can innovate do and those that can't don't. Simple as that. So when one vendor refuses to take on the challenge, another will almost always rise to the occasion...the beauty of the free enterprise system. And ps, I for one, as a consumer, will not hand over the reigns of control over to vendors. The consumer rules in this system of ours and that way it shall stay with every breath I have. RC made a similar point a while back....consumers always get what they "let" the market give them (i.e., don't let the market rule the consumer). So just standing up for the rights we own as consumers and not letting any nay-saying "can't" suppliers have their way...not with my dollars! And pps, there are consumers who like mixed sets, and others that like matched sets. Not demanding that either bow down to the other as both approaches are valid and both are REQUIRED. Not wanting to limit one class of observer's freedoms for another class of observers. So that's my bottom line and not budging...anyone saying "can't" do something is not a can-do innovator and vendors do not set directions consumers do...period. Nuf said as far as I'm concerned

And there are plenty of posts here on CN showing very much how some hate mixed sets and others love matched sets. In the end, for me personally, don't care about the internal optical prescription too much as long as the ER and AFOV characteristics are consistent. e.g., 50 degree class for TV is composed of their Plossls and Nagler-Zooms. A perfect pairing. Similarly, the Naglers achieve the full range of focal lengths with multiple lens prescriptions...T6's and T5s...Ethos with Ethos and Ethos-SX and the glaring hole in the 25mm slot


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BillP
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: Paul G]
      #5652512 - 01/30/13 02:56 PM

Quote:

Lumping the Naglers together isn't appropriate. The type 4, 5, and 6 Naglers are three completely different designs, and none of them cover the full focal length range.




I disagree with that...and so does the TV literature. The T6 design optimizes the 82 AFOV in shorter FLs, and the T5 design optimizes it for the longer FLs. This was and is the strategy they used. Then the T4 line was done to address those who need longer ER. So the Nagler T5 and T6 combination of prescriptions is the TV "solution" to a full range of 82 degree AFOV EPs with mid-ranged ER.

From the TV Site:

Why Are There 3 Types of Naglers?
To achieve the full magnification range over 82° apparent field of view requires two types: Nagler Type-5 with focal lengths of 31, 26, 20, 16mm and Nagler Type-6 with focal lengths of 13, 11, 9, 7, 5, 3.5, 2.5mm.

The Type-5 permits the largest true field possible (31mm has 42mm field stop), while the shorter focal length Type-6 models are parfocal, with similiar size and weight and all with a comfortable 12mm eye relief.

The Type-4 models feature about 18mm of eye relief and with the "instajust" eyeguard are best for eyeglass wearers or Dioptrx users in their 22, 17, 12mm focal length range. i]


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Jon Isaacs
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: BillP]
      #5652531 - 01/30/13 03:18 PM

Quote:

Plus, I need a 2" 100 degree eyepiece that gives widest TFOV capable with a 2" barrel.




So, what is your current eyepiece that fills this slot?

I was just reading where you said that for what you do, a 2mm exit pupil was about optimal. 2mm with a 21mm eyepiece is F/10.5. For anything faster, one needs a shorter focal length eyepiece to maintain that optimal exit pupil.

Jon


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Tom TAdministrator

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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: BillP]
      #5652545 - 01/30/13 03:28 PM

Quote:


My whole argument from the getgo is that the "can't" be done argument is nonsense. I put forth a supposition of a probable real reason, that the particular prescription of the Ethos does not lend itself to a 25mm incarnation. So take or leave my supposition all you want. I don't care. My only argument is that it is nonsense that it "can't be done".





So, even if it were to be shown to be completely impractical (due to size or cost) or perhaps even impossible because it does something like violate the laws of physics, you'd still maintain it's nonsense?

Quote:

And further, I never ever care what any vendor says on the topic. No disrespect at all to the vendor. I am the consumer and the consumer's needs rule.




Vendors or manufacturers / designers? It depends on who you actually mean, but I guess if you have no desire to listen to what the people who actually design and construct these things for a living (and have experience in dealing with the consumer market) have to say, those that actually have degrees and experience in the field then... I dunno. I guess if you at least say you don't trust them (for whatever reason), that's one thing. However I'd still listen - even if I have to put some filters in place.

The idea that anything can be done is absurd Bill. As is the idea that we know the reasoning behind why something hasn't been done.

Especially if you aren't willing to accept the answers from the folks who - um... haven't done it.



Quote:


Where the who-ha is that coming from Tom?





See above.


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rathbaster
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: Tom T]
      #5652773 - 01/30/13 05:01 PM

All this speculation could probably be ended the next time Al Nagler shows up at a star party.

Just sayin'

-Joe


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rockethead26
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: rathbaster]
      #5652784 - 01/30/13 05:07 PM

Quote:

All this speculation could probably be ended the next time Al Nagler shows up at a star party.

Just sayin'

-Joe




Nah, he never talks about future plans. Likes to keep everyone guessing.


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The Ardent
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: rockethead26]
      #5652857 - 01/30/13 05:45 PM

My new scope is an f/3.5

In this scope I wont be using anything longer than a 20mm Nagler T5 with my astigmatism.

I dont think the 35 Pan can be much improved upon. Its my favorite low power eyepiece of all time. But I wont use it in the new scope (hey 9mm exit pupil ) I dont even use it at all anymore. It was great in my f/5 dob and f/15 Maks.

Im excited with the new Delos as I will have high magnification AND an exit pupil >1mm.

My dilemma is whether to get the 17 Delos or Nagler T4. Do I need either since I like the 20T5?


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Paul G
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: BillP]
      #5653092 - 01/30/13 07:43 PM

Quote:

In the end, for me personally, don't care about the internal optical prescription too much as long as the ER and AFOV characteristics are consistent.




What existing eyepiece design covers the full range of focal lengths with consistent ER and AFOV?

Just because a consumer wants something doesn't mean it's possible or desirable for the manufacturer. In fact, manufacturers have been burned bringing products to market in response to a few vocal people on an internet group.


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Tom TAdministrator

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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: Paul G]
      #5653141 - 01/30/13 08:20 PM

Quote:


Just because a consumer wants something doesn't mean it's possible or desirable for the manufacturer. In fact, manufacturers have been burned bringing products to market in response to a few vocal people on an internet group.




I hope our next software package for the forums has a "like" button.

This is all too true. Often the most vocal voices are a distinct minority.


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johnnyha
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Re: Has Tele Vue Forsaken Long Focal Lengths? [Re: Paul G]
      #5653224 - 01/30/13 09:14 PM

Quote:

What existing eyepiece design covers the full range of focal lengths with consistent ER and AFOV?



Pentax XW.


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derangedhermit
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Re: Has Tele Vue Forsaken Long Focal Lengths? new [Re: johnnyha]
      #5653354 - 01/30/13 10:35 PM

Quote:

As far as the ES 100 line being a knockoff of Ethos, I though x-ray photos had long ago proven the obvious to be true?



I'm surprised this post is still here. I got a nastygram for a similar statement.


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