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25mm ES 100* confirmed? sale date? preorder?

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#1 stevenp_86

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Posted 30 January 2012 - 03:42 PM

im gona pick up one of these bad boys on the day of release, when will that be? how much?

#2 Dr Morbius

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Posted 30 January 2012 - 03:53 PM

Your guess is as good as mine, although it can't be much more than the 20mm.

#3 csa/montana

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Posted 30 January 2012 - 04:01 PM

Astronomics pre-order

#4 Jeff Black

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Posted 30 January 2012 - 04:23 PM

This morning, I cancelled the ES 24mm 82* I had ordered Saturday.... now I'm chompin at the bit for the 100* 25mm to get here!!

#5 Smithfr2000

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Posted 30 January 2012 - 04:32 PM

I thought 21mm focal length was the maximum physically possible in a 2" barrel ?

#6 Jeff Black

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Posted 30 January 2012 - 04:44 PM

There are quite a few 2" EPs over 21mm. I have a TeleVue 35mm Panoptic. I have 42mm and 50mm 2" EPs ordered and on the way now.

#7 Robert70

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Posted 30 January 2012 - 06:08 PM

how much? Very expensive if you ask me.

#8 Lane

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Posted 30 January 2012 - 06:37 PM

Now if it had 25mm of eye relief I could get excited too. But I suspect this will be yet another wonderful eyepiece that I cannot use being an eyeglass wearer :bawling:

#9 Jim Romanski

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Posted 30 January 2012 - 06:56 PM

I thought 21mm focal length was the maximum physically possible in a 2" barrel ?


It's not that you can't have an eyepiece with a focal length longer than 21mm. Televue stated that for their 100 degree Ethos eyepiece that 21mm was the practical limit. They said they didn't want to make one longer or they would have to compromise in key areas such as eye relief, weight and most importantly vignetting.

No picture, no specs except for the obvious ones and no anticipated release date???

I'll wait on this one and see how ES decided to make their compromises.

#10 Scott in NC

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Posted 30 January 2012 - 07:03 PM

From the Astronomics link that Carol kindly provided, I see that ES is also coming out with a 100 degree 5.5mm EP. That's exciting to me as well! :jump:

#11 Sarkikos

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Posted 30 January 2012 - 07:11 PM

An ES 100 degree 5.5mm might be worth reserving for the big "It's Christmas!" or "It's my birthday!" excuse.

:grin:
Mike

#12 faackanders2

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Posted 30 January 2012 - 08:19 PM

An ES 100 degree 5.5mm might be worth reserving for the big "It's Christmas!" or "It's my birthday!" excuse.

:grin:
Mike


You could always celebrate your "Un-Birthday" :grin:, but you may have to do the celebrating in the dog house. :lol:

#13 Joe Ogiba

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Posted 30 January 2012 - 08:39 PM

There are quite a few 2" EPs over 21mm. I have a TeleVue 35mm Panoptic. I have 42mm and 50mm 2" EPs ordered and on the way now.

I have an 80mm 2" eyepiece but I am sure he was talking about 21mm 100° AFOV 2" eyepieces. I guess the 25mm 100° will be using close to the maximum fieldstop in 2" barrel. BTW the 21mm Ethos has a 36.2mm fieldstop with a weight of 2.25 lb compared to my 40mm Pentax XW with a 46.5mm fieldstop.

#14 Darenwh

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Posted 30 January 2012 - 08:41 PM

Actually the 5.5mm will be out close enough to my wife's birthday that I could buy it for her!!

#15 Scott in NC

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Posted 30 January 2012 - 09:06 PM

Actually the 5.5mm will be out close enough to my wife's birthday that I could buy it for her!!


Hope she's an astronomer, too. Otherwise you'll really be in the doghouse! :tonofbricks:

#16 stevenp_86

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Posted 30 January 2012 - 09:09 PM

just like the time when homer gave marge that bowling ball

#17 Sean Puett

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Posted 30 January 2012 - 10:20 PM

That's a great idea. I'll get my wife the 5.5mm for mother's day. Do any of you have a room i can rent?

#18 Sarkikos

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Posted 30 January 2012 - 10:47 PM

The only thing worse than buying your wife something for her hobby, is buying her something for your hobby. :ubetcha:

Mike

#19 tmbuser6

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Posted 30 January 2012 - 11:15 PM

There are quite a few 2" EPs over 21mm. I have a TeleVue 35mm Panoptic. I have 42mm and 50mm 2" EPs ordered and on the way now.


Mr. Black, et al., I think the matter is a bit more complicated than you may realize. You see, it is already well established that the ES-100 design is at least /very/ similar to that of the Ethos, at least according to x-ray analysis. Basically, these eyepieces work with a negative-power Smyth lens group /ahead/ of the field stop, which is internal, about half way to the next lens, which is a positive meniscus. These 4 lenses operate together as a powermate-like group with the field stop placed within the group after the third lens.

Look at the bottom of any of these eyepieces and you will see that there is no external field stop present like in a normal eyepiece, and if you bring your finger up to the field lens while looking through, you will not find any point where you can bring your finger into focus looking thorough the eyepiece! That is because the focal plane is well inside.

It is this group which is both essential to and really the basis for the performance of the eyepiece. Due to the negative power of the Smyth lens group and the placement of the focal plane and field stop inside where they must be, the aperture of the Smyth group must be /larger/ than the field stop aperture. If you look hard into the bottom of one of these eyepieces, you may be able to tell that.

The net result of all of this is that this places an upper limit to the maximum focal length of such an eyepiece to be around 22mm if you wish to not have any vignetting. So, unless Explore has reinvented optics (I don't expect that to be the case), the only other option I can see is to allow for some vignetting to take place.

There were a great many people hoping for a 100 degree Ethos from TeleVue that was long enough to take the place of the 31mm Nagler so that they could retire that eyepiece in favor of an all-Ethos line of eyepieces, and they were hoping for something like a 24-25mm for that purpose, but the practical limit of the design without making compromises was 21mm due to the confines of a 2" barrel, that is why they didn't make it any longer. In order to make a longer focal length, you would need to go to a larger barrel.

And I suspect that was a similar constraint in ES choosing 20mm for their very similar eyepiece. SO, either Explore has chosen to allow a considerable amount of vignetting to occur in the periphery, or they have departed greatly from the original design, which I do not see happening while also maintaining equal performance. Therefore, we do not really know what we are buying here and I myself would be a bit hesitant to invest in one blindly before others have had a chance to sample the eyepiece and evaluate it.

The one maxim that holds true for all of optics is that there are no free lunches: You do not gain in one area without giving something up somewhere else. For ES to have crossed the 22mm threshold still within the limits of a 2-inch barrel, they must have made some compromises elsewhere. ;^)

I would expect the eyepiece to likely have both visible vignetting (limb-darkening around the edges), not be a true 100-degree AFOV, and/or probably have a loss of eye relief (smaller eye lens) as a consequence, which is already at a minimum in the present ES design.

Regards,

Wayne

#20 stevenp_86

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Posted 30 January 2012 - 11:40 PM

hmm...

#21 94bamf

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Posted 31 January 2012 - 12:16 AM

There are quite a few 2" EPs over 21mm. I have a TeleVue 35mm Panoptic. I have 42mm and 50mm 2" EPs ordered and on the way now.


Mr. Black, et al., I think the matter is a bit more complicated than you may realize. You see, it is already well established that the ES-100 design is at least /very/ similar to that of the Ethos, at least according to x-ray analysis. Basically, these eyepieces work with a negative-power Smyth lens group /ahead/ of the field stop, which is internal, about half way to the next lens, which is a positive meniscus. These 4 lenses operate together as a powermate-like group with the field stop placed within the group after the third lens.

Look at the bottom of any of these eyepieces and you will see that there is no external field stop present like in a normal eyepiece, and if you bring your finger up to the field lens while looking through, you will not find any point where you can bring your finger into focus looking thorough the eyepiece! That is because the focal plane is well inside.

It is this group which is both essential to and really the basis for the performance of the eyepiece. Due to the negative power of the Smyth lens group and the placement of the focal plane and field stop inside where they must be, the aperture of the Smyth group must be /larger/ than the field stop aperture. If you look hard into the bottom of one of these eyepieces, you may be able to tell that.

The net result of all of this is that this places an upper limit to the maximum focal length of such an eyepiece to be around 22mm if you wish to not have any vignetting. So, unless Explore has reinvented optics (I don't expect that to be the case), the only other option I can see is to allow for some vignetting to take place.

There were a great many people hoping for a 100 degree Ethos from TeleVue that was long enough to take the place of the 31mm Nagler so that they could retire that eyepiece in favor of an all-Ethos line of eyepieces, and they were hoping for something like a 24-25mm for that purpose, but the practical limit of the design without making compromises was 21mm due to the confines of a 2" barrel, that is why they didn't make it any longer. In order to make a longer focal length, you would need to go to a larger barrel.

And I suspect that was a similar constraint in ES choosing 20mm for their very similar eyepiece. SO, either Explore has chosen to allow a considerable amount of vignetting to occur in the periphery, or they have departed greatly from the original design, which I do not see happening while also maintaining equal performance. Therefore, we do not really know what we are buying here and I myself would be a bit hesitant to invest in one blindly before others have had a chance to sample the eyepiece and evaluate it.

The one maxim that holds true for all of optics is that there are no free lunches: You do not gain in one area without giving something up somewhere else. For ES to have crossed the 22mm threshold still within the limits of a 2-inch barrel, they must have made some compromises elsewhere. ;^)

I would expect the eyepiece to likely have both visible vignetting (limb-darkening around the edges), not be a true 100-degree AFOV, and/or probably have a loss of eye relief (smaller eye lens) as a consequence, which is already at a minimum in the present ES design.

Regards,

Wayne


Good stuff..

I think we are at an interesting point for Explore Scientific. It seems pretty well established that their other 100 deg AFOV eyepieces are pretty close to copies/clones of the TV Ethos line, whether people want to believe it or not(or care). It also seems well established that their clones/copies don't quite fully meet the quality/correction/execution of the Ethos line. This is what makes the 9mm 120 deg AFOV and the 25mm 100 deg AFOV eyepieces quite interesting. Two different focal length/AFOV combos that Televue has never produced. It really is a test to see if ES can match the quality/correction/execution of their other "copied" 100 deg AFOV eyepieces(20mm,14mm,9mm). I wish them well, and I hope they can do it. If either or both eyepieces have "issues" like vignetting or poor outer field correction, or other aberrations, it could hurt..

Ken

#22 Ernest_SPB

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Posted 31 January 2012 - 01:38 AM

I thought before that only reason for TV do not produce 25 mm Ethos is prevention of internal concurrence with their flagship 31 mm Nagler.

It looks like ES is free from the reason and does not afraid concurrence too much.

#23 tmbuser6

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Posted 31 January 2012 - 02:53 AM

Good stuff..

I think we are at an interesting point for Explore Scientific. It seems pretty well established that their other 100 deg AFOV eyepieces are pretty close to copies/clones of the TV Ethos line, whether people want to believe it or not(or care). It also seems well established that their clones/copies don't quite fully meet the quality/correction/execution of the Ethos line. This is what makes the 9mm 120 deg AFOV and the 25mm 100 deg AFOV eyepieces quite interesting. Two different focal length/AFOV combos that Televue has never produced. It really is a test to see if ES can match the quality/correction/execution of their other "copied" 100 deg AFOV eyepieces(20mm,14mm,9mm). I wish them well, and I hope they can do it. If either or both eyepieces have "issues" like vignetting or poor outer field correction, or other aberrations, it could hurt..

Ken


Ken, both the ES-100 and Ethos have been x-rayed and look too close (identical really) to be a coincidence. The Ethos has been taken apart and analyzed by people I know. Both the Ethos and the ES-100 have been rigorously tested side by side, and there is no doubt to me and others that the ES-100 is very good for the money, and very close, but the extra price of the Ethos buys you better optical quality which diverges apart more greatly the further off axis you go, and without the essential eye relief the Ethos has which makes it comfortable to use. THAT is what you are buying with the Ethos and giving up with the Explore. Not that the Explore isn't a good value, but surely no one thinks they are getting as good a design at hundreds of dollars less? Televue are the grandfathers of such designs and would not charge so much at their own peril of lost sales without good reason if they didn't have to.

When the 21mm Ethos came out, it came out under 22mm AS PREDICTED. The Ethos SX design at 110 degrees is just beyond the eye's range to see all at once. I see the 9mm 120 degree design as ponderously heavy and essentially pointless as no one will ever be able to see the entire FOV at once, so they are really paying for something they can never use. In practice, the view will never look any wider than an SX. In my opinion they are playing a numbers and marketing game with people. I've used hundreds of eyepieces over 46 years, I have yet to have any of them fog up for not being purged or sealed with o-rings. But if you had such a sealed eyepiece, you sure would be hesitant to take it apart, wouldn't you?

I think your assessments above are indeed quite accurate, and it will be interesting to read from those who plunk down $1000 and $500 on two really unknown and untested designs from a company which has, to date, seemingly built most of its laurels on the work of others, making less expensive copies. If we were talking about small sums of money I could understand it, but now we are talking about people pre-ordering a ONE-THOUSAND DOLLAR eyepiece that no one has ever even seen yet? And a $500 25mm eyepiece that TeleVue themselves would not build? Yes, expect to pay about $500 for it.

Frankly, it amazes me that when the 13mm Ethos came out in the fall 2008, most people were denouncing them as a gimmick, unnecessary and vastly too large, heavy and expensive; now folks are racing to enthusiastically buy a $1000 3 pound eyepiece with twelve lenses in it. That is like stacking an Abbe Ortho on top of another Abbe Ortho on top of another. But if anyone did that, they would be considered crazy, not revolutionary ;^)

The idea of a 7 or 8 element eyepiece has been around for a long time, but a 12-element design? That is a telephoto camera lens! That is four-fold the complexity of an 8-element design. Do you think there will be some ghosting issues and other losses there? ;^)

What are people really buying with these garish designs, good optics or merely an idea and a status symbol to hang on their telescopes? Something to think about before you mortgage the house. The greatest truth in optics is that there are no free lunches. You ALWAYS give something up to gain something somewhere else.

Regards,

Wayne

#24 rockethead26

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Posted 31 January 2012 - 07:43 AM

I've used hundreds of eyepieces over 46 years, I have yet to have any of them fog up for not being purged or sealed with o-rings.


But, as reported here on CN, others have.

But if you had such a sealed eyepiece, you sure would be hesitant to take it apart, wouldn't you?


So ES decided to purge their EPs only so no one would take them apart and look at the construction?

Frankly, it amazes me that when the 13mm Ethos came out in the fall 2008, most people were denouncing them as a gimmick, unnecessary and vastly too large, heavy and expensive; now folks are racing to enthusiastically buy a $1000 3 pound eyepiece with twelve lenses in it. That is like stacking an Abbe Ortho on top of another Abbe Ortho on top of another. But if anyone did that, they would be considered crazy, not revolutionary ;^)


And, history repeats itself yet again.

The idea of a 7 or 8 element eyepiece has been around for a long time, but a 12-element design? That is a telephoto camera lens! That is four-fold the complexity of an 8-element design. Do you think there will be some ghosting issues and other losses there? ;^)

What are people really buying with these garish designs, good optics or merely an idea and a status symbol to hang on their telescopes? Something to think about before you mortgage the house. The greatest truth in optics is that there are no free lunches. You ALWAYS give something up to gain something somewhere else.

Regards,

Wayne


Sound like what folks were saying when the 7-8 element EPs were first introduced. Nothing ever changes except change itself.

It will certainly be interesting to get some first-hand reports of the 25mm 100° and the 5.5mm 100°, not to mention the 120° 9mm.

With the ES company history of producing some really excellent eyepieces and refractors for a very fair price, I really don't think ES would introduce 3 new poorly designed EPs that would wreck their growing reputation just to out-do the competition.

Just my two cents.

#25 Darenwh

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Posted 31 January 2012 - 09:17 AM

Actually the 5.5mm will be out close enough to my wife's birthday that I could buy it for her!!


Hope she's an astronomer, too. Otherwise you'll really be in the doghouse! :tonofbricks:

It's my hobby but she likes going out with me. Still, I will be in the dog house but a few days in the dog house is a small price to pay for such grand views...






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