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is anyone planning on buying the ES100 30mm?

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#26 faackanders2

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Posted 13 March 2013 - 11:39 PM

Definitely NOT in the market for this......BUT I think it will find a home. 20 years ago no one would have believed a $500 100' would dind a home. Back a bit no one had a 2" focuser.

Once the EP is here I would bet it finds buyers and they will prompt other manufacturers to make scopes that will work with it. Just the same as years ago no one made F5 newts with 2" focusers.

For E is peobably more of a Formula 1 product, it gives them credibility to say "we are advanced, we are cool, we have the biggest and best etc etc' its pebably worth the development cash just to be able to put it on the shelf even if they never sold a single one.


If they build it, they will come ...

#27 Scanning4Comets

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Posted 13 March 2013 - 11:53 PM

If they build it, they will come ...


...Not for everybody.

#28 Sean Puett

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Posted 14 March 2013 - 07:41 AM

If you plan to get a 24" f3 why wouldn't you want a 3" focuser and secondary to accomodate the ES100 30mm (you would get for your other scope)? It might save you from having to transport so many scopes.


The reason that I (and I believe most people) would not want this eyepiece in a dob is because you would need to increase the size of your secondary to have decent illumination at the 75% to the field stop. What good is the extra fov if if dims noticeably? How much larger a secondary are you willing to tolerate? Is it worth it? All these are questions that need an answer before even considering this eyepiece.

For the refractor, my scope's balance changed quite a bit just from adding the feathertouch upgrade to the existing Televue focuser. Trying to go from a 1.5lb eyepiece to a 7lb eyepiece would require sliding the scope in its rings. I would have a 5.5* tfov though.

I love the concept of this eyepiece. I don't want anyone thinking I am bashing ES in any way. I am not. I think this eyepiece would be great in Rob's 10"f15 refractor. Rob is a local CNer with an observatory who would probably not want this eyepiece because he likes simple eyepiece designs better but, it doesn't stop me from fantasizing about that giant refractor with this eyepiece.
If you have a newt and want to get this eyepiece, running the numbers through the NEWT program should answer a lot of questions about illumination and secondary size. I may try that with my Z12 later just to see what it looks like. Some of the big super fast dob have giant secondaries already and may be able to use this eyepiece with just a larger focuser.

#29 Sean Puett

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Posted 14 March 2013 - 09:19 AM

After running my Z12 through NEWT, I think it could illuminate this eyepiece well without a larger secondary. Some of the premium scope's with smaller secondaries optimized for contrast might need to increase the size though. The 30mm ES100 costs twice what I paid for that telescope though...

#30 gatorengineer

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Posted 14 March 2013 - 09:48 AM

Realize that exit pupil above 7mm is wasted, so below F4.5 (after paracorr), this does not make sense. F4 and below for me without coma correction is entirely unuseable anyway, if I want to see seagulls I go to the beach. There are no visual 3" comma correctors out there yet. So using this on a dob faster than 4.5 is not economically justified as there are other options out there the 25 100 or the 31 82 degree....

On a long F ratio refractor, why not use a giant plossl as a finder EP? long refractors are purpose built scopes and wide field isnt the purpose.

The application of this eyepiece is to newts slower than F4.5, and ""Fast"" refractors F5-F8 say that take a 3" EP, or for those folks who will accept the illumination issues with stopping this down to 2".

On these big slow dobs, if I have to upgrade my secondary from 3.5" to 4" it isnt a big deal, as I am well less than 20% CO...

#31 Sean Puett

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Posted 14 March 2013 - 09:57 AM

That seems to be the consensus. The 3" paracorr would probably cost as much as a tv85, maybe more. Refractors do seem to be the only option unless the big cats come with 3" focusers now.

#32 johnnyha

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Posted 14 March 2013 - 01:28 PM

Meanwhile, the 30/100 will be master of the 7" apo and C14HD.


I am honestly having a hard time seeing how this could possibly work with a C14, at least without significant modifications?

#33 pbsastro

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Posted 14 March 2013 - 08:05 PM

If you plan to get a 24" f3 why wouldn't you want a 3" focuser and secondary to accomodate the ES100 30mm (you would get for your other scope)? It might save you from having to transport so many scopes.


f/3 and 30mm => 10mm pupil. My limit is 5.5mm pupil. That is 17mm Ethos.
Each scope has its unique characteristics. When I go out, I only take one scope.

#34 pbsastro

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Posted 14 March 2013 - 08:11 PM

If they build it, they will come ...


...Not for everybody.

Very true. But the same can be said about all the equipment you list.

#35 pbsastro

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Posted 14 March 2013 - 08:22 PM

Meanwhile, the 30/100 will be master of the 7" apo and C14HD.


I am honestly having a hard time seeing how this could possibly work with a C14, at least without significant modifications?


Johnny, no modifications needed. C14 and C11 come with 3" opening. Both have a 52mm illuminated circle with illumination above 70% at the edge.
By coincidence (maybe not) the ES30/100 eyepiece has a 52mm field stop.
With Edge version we have flat field and coma correction, so C14HD and ES30/100 is a match made in heaven. Even the weight is not so significant in this size scope.

Pedro

#36 Sean Puett

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Posted 14 March 2013 - 09:31 PM

We have another winner. Where do you buy a 3"diagonal though? I am sure someone makes one but, I have not seen any for sale. I haven't looked...

#37 Scanning4Comets

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Posted 14 March 2013 - 09:43 PM

That seems to be the consensus. The 3" paracorr would probably cost as much as a tv85, maybe more. Refractors do seem to be the only option unless the big cats come with 3" focusers now.



Adding a 3" paracorr to a 7.5 Lb EP hanging off your focuser would be even more insane, :lol:

#38 gatorengineer

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Posted 15 March 2013 - 08:11 AM

Suggest you look at what the baffle tube diameter is which is reported to be 2.1" Now treat that as a 2.1"field stop 14" or so inches in front of the eyepiece. You will find that you edge illumination is exactly 0 for the 3" 30.... Sorry to be the bearer of bad news. The visual back opening on large cats is irrelevant, its the baffle tube that counts.

#39 Sean Puett

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Posted 15 March 2013 - 08:55 AM

No argument here. The scopes that I would want to use an eyepiece like this in (giant dobs) are not really a good match for it. I am too picky to ignore bad edge correction in any form. I can't use my 30mm ES82 without a paracorr at f5 anymore because I am spoiled now. 100* would show even more coma (I believe) because it is just that much bigger afov.

I do think that this eyepiece will be great if you happen to have the right set up for it but, and this is just my opinion, most people won't want to go with this big piece of awesome engineering. What would be cool is if it does sell enough that they make longer focal lengths for those giant refractors because the 10"f15, in example, focal length is 3810mm that is 127x mag and roughly .78 tfov with only a 2mm exit pupil. It would be an excellent fit for that scope but a longer focal length would be nice as well. Since this whole line of thought is fantasy anyway, why not?

#40 Sean Puett

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Posted 15 March 2013 - 03:09 PM

Suggest you look at what the baffle tube diameter is which is reported to be 2.1" Now treat that as a 2.1"field stop 14" or so inches in front of the eyepiece. You will find that you edge illumination is exactly 0 for the 3" 30.... Sorry to be the bearer of bad news. The visual back opening on large cats is irrelevant, its the baffle tube that counts.


That is unfortunate. Now we are back to just long giant refractors and dobs above f6. (f5 for those not used to a paracorr). What about big standard cass scopes? A few amateurs have them. The Goldendale observatory was donated by an amateur and has a 24" cass in it.

#41 M44

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Posted 15 March 2013 - 03:33 PM


I am not in the target market for this eyepiece. But I was wondering what would be the weight of 3" diagonal that is supposed to come out this summer? Couple of pounds or more?
A total weight of diagonal + EP is 10 lbs?

#42 johnnyha

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Posted 15 March 2013 - 07:45 PM

Suggest you look at what the baffle tube diameter is which is reported to be 2.1" Now treat that as a 2.1"field stop 14" or so inches in front of the eyepiece. You will find that you edge illumination is exactly 0 for the 3" 30.... Sorry to be the bearer of bad news. The visual back opening on large cats is irrelevant, its the baffle tube that counts.

Yup, that's what I was getting at... Also I imagine with a fork mount you might have a few clearance issues.

It's also quite possible that the extra fl added to the C14 by the length of the 3" diagonal would negate the advantage over a 2" 25mm 100* eyepiece - you may end up with similar magnification.

#43 gatorengineer

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Posted 16 March 2013 - 10:38 AM

large standard cassegrains will generally have the same baffle tube issues as Schmidt newts, but it would depend on the particular instrument. Sieberts page shows a 24" cass that takes them...

For those wondering 3" EPs are NOT new to the hobby, siebert has been selling them for years and few large amateur refractors I know use them, he also sells 3" diagonals, although I suspect that Explore will see those as well shortly...

#44 pbsastro

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Posted 16 March 2013 - 04:23 PM

Suggest you look at what the baffle tube diameter is which is reported to be 2.1" Now treat that as a 2.1"field stop 14" or so inches in front of the eyepiece. You will find that you edge illumination is exactly 0 for the 3" 30.... Sorry to be the bearer of bad news. The visual back opening on large cats is irrelevant, its the baffle tube that counts.


I am happy to be the bearer of good news. That is not right.
If you have a 2.1" (53mm) baffle, obviously you do not get 0 illumination at 52mm. If fact, if placed at 14", I estimate 70% illumination.
Did you really mean a 53mm baffle blocks all the light of a 52mm circumference?

Also my info is that 2.1" (53mm) is the corrector CA, which is placed 7.4" (188mm) from focus (ideal 146mm back focus).
The baffle front ID is 2.25" (57mm), placed at 15" from focus (ideal 146mm back focus).
I estimate that to give about 75% illumination at 52mm circumference. Error margin 5%. So at least 70%.

Official numbers from Celeston (white paper) for C14HD (and C11HD) are 100% at 16mm and 83% at 42mm.
On a side note, 2007 Ken Hutchinson analysis of the standard C14 gives 73% at 52mm circumference.

Finally, the visual back opening is not irrelevant. Both the baffle and the opening must have the proper size. One without the other will not work. What you probbaly meant is that it is irrelevant if larger than a minimum size, but that is true for every baffle regarding vignetting.

#45 pbsastro

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Posted 16 March 2013 - 05:03 PM

I think the reason people keep repeating ES30-100 field illumination problems is that it is being regarded as a 3" eyepiece when in fact is is just a 2"+ eyepiece in a 3" body, as the Ethos 21 is a 1.5" eyepiece in a 2" body.
ES 30-100 has a 52mm field stop while the Pan 41 or Plossl 55 have 46mm field stop. Only 6mm difference!
So illumination requirements are not very different.
Now correction is another matter, as the extra magnification of 100 deg will show field edge errors more than 70 deg and 50 deg.
And weight is also much more than the Ethos 21, which has a small 36mm field stop, very far from 46mm, the 2" limit.
But regarding illumination ES 30-100 is just a 2"+.
So most scopes that can handle a Pan41 can deal with the ES30-100 illumination.

Both C11 and C14 have about 70-75% illumination at 53mm and then illumination falls out rapidly, resulting in practice in a 53-55mm field.
So, the ES30-100, with its 52mm field, is exactly tailored to give all C14 and C11 capabilities.

Some people asked for 40-100 or 30-120. Those eyepieces, beside the prohibitive weight (much more than 30-100), would be much difficult to use in available telescopes, and would be ruled out for C14 and C11.

Now a 20-120 would be nice, which I estimate to have the same weight as 30-100. Although a 25-120 would have the same 52mm field stop as the 30-100, it would be much heavier than 30-100, and more demanding on field edge due to extra magnification. The 20-120 would have 42mm field stop, the same as Nag31...
I am so used to the Ethos now, that I am starting to find 100 deg is a little narrow... oh boy...

#46 gatorengineer

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Posted 17 March 2013 - 04:59 PM

This topic has been covered before...

http://www.cloudynig...5673585/page...

Fully illuminated on a c14 is 10mm or 16mm depending upon who you believe in the above thread.......... Test your assumption, by trying to hold a 31 nagler up behind a 1.25" holder see how it looks.....

If it makes you feel better, my TV NP127 cant fully illuminate a 31 nagler, and I can see the difference with an 127IS scope, in a side by side which I have done.

#47 johnnyha

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Posted 17 March 2013 - 05:24 PM

pbsastro - thanks for the detailed explanation, it gives me a much better understanding of how that works. Makes sense to me now that the C14 would work with the 30ES100*.

#48 Shneor

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Posted 18 March 2013 - 01:29 AM

Not me. Exit pupil too large, focuser diameter too large, trusses too long.
Clears,
Shneor

#49 Ava

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Posted 19 March 2013 - 01:58 AM

According to the EdgeHD white paper the 9.25" has 90% illumination at 42mm, while the 11" & 14" have 83%. If they have a similar falloff curve towards 52mm the 9.25" could potentially be even better suited (brighter at the edges) for the ES30 100.

The 8" on the other hand has 83% at 28mm. I wonder what the edge illumination has fallen to at the edge of the pan 35s 38.7mm field stop...

#50 Dunkstar

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Posted 19 March 2013 - 05:48 PM

Celestron lists the baffle tube diameter of the C9.25 as 46mm so you'd risk some vignetting with this eyepiece in that scope, whereas the baffle tube of the C11/C14 is listed at 54mm.






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