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Explore Scientific 3" 30mm Prototype

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#26 Gord

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Posted 13 December 2012 - 10:30 AM

The diagonal already has a 3" output and appears as though the mirror would fully support that size. If this is done right, the input size could be swapable (just thread on a new nosepiece) and work with various different scopes focuser sizes.

For example, 2" is the common standard, but there are ones at 2.4" (TV), 2.5" (APM?), 2.7" (A-P & Tak), 3" (FT), 3.25" (Celestron's SCT's), 3.5" (FT), 4" (A-P), etc. You could just have one diagonal design and various different nose pieces. Then people could pick which ones work for their setup (or multiple setups). Some would not offer all the benefits (ex. 2" etc), but it's at least giving options and these would really not be a huge cost to manufacture.

As I said in the thread on the EP forum, I hope we might see some other options in the large format. I'm guessing that some simpler designs (relatively speaking) more along the lines of super or ultra-wides (68-82 deg) would be cheaper than the 100deg so a wider field option in the 50-60mm FL would be possible. The $1200 price option is higher (but not unreasonable for what this is), but something with lower specs (ex. a 55mm 68deg) in the $500 range would be quite paletable and useful to the big cat/refractor owners. Not that much more than the big 2" Plossl's, or the 41mm Panoptic for example.

Clear skies,

#27 dcoyle

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Posted 13 December 2012 - 10:44 AM

I would be concerned about the twisting torque that weight could pose.

It seems to me that if a new standard is established for 3" focusers, it ought to have something like a compression ring lock or splines, not a few #6 screws, to keep that 8 pound baby from rotating. Splines could be at every 20 degrees, so one could set the diagonal at various orientations to facilatate veiwing in different positions.

Dan

#28 frebie

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Posted 13 December 2012 - 11:16 AM

Concerning the weight and safety, Scott thought a lanyard on the eyepiece with a D-ring carabiner on the end for connecting to the scope might be useful to keep the eyepiece from hitting the ground in case of an accident. What say you? It works with DSLR bodies when imaging.

#29 Jobryant

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Posted 13 December 2012 - 05:52 PM

More info here http://www.youtube.c...h?v=nnjlmxHQfmw

#30 pbsastro

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Posted 13 December 2012 - 06:32 PM

Concerning the weight and safety, Scott thought a lanyard on the eyepiece with a D-ring carabiner on the end for connecting to the scope might be useful to keep the eyepiece from hitting the ground in case of an accident. What say you? It works with DSLR bodies when imaging.

What about a parachute on the eyepiece, plus an air-bag for the landing? I would drop it on purpose often to enjoy the ride :grin:

Sorry couldn't resist

#31 pbsastro

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Posted 13 December 2012 - 06:46 PM

More info here http://www.youtube.c...h?v=nnjlmxHQfmw


What a beauty. Can't wait to get one.
The field lens is bigger than I expected, which is a good sign that we will get a totally unvignetted, 100% illuminated, field of view.
ES rules!

#32 pbsastro

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Posted 13 December 2012 - 07:13 PM

... think about a 40mm-75deg....


You already have (almost) that eyepieces: Pan41, SWA40, XW40...


You may be right. I already have the XW40, which I find perfect by the way. I just usually prefer the 100 deg views of the 17 Ethos.
The XW40 has about 46mm field stop, about same as Pan41. So 52mm of the 40-75 may not be a big enough step to justify it.
However I think a smaller AFV eyepiece allows to use more of the eyepiece barrel, so it should be possible to fit a larger 75 deg eyepiece in the 3" barrel than what is possible with 100 deg. Say 62mm. That would translate to a 54mm-70deg or a 50mm-75deg.
But 50mm may be too much focal length for me.
So I think my preferred companion to the 30-100 would be a 20mm-120deg (or 17-120), weighting about the same as the 30-100, so that the scope would keep balance when changing eyepiece. The perfect pair!

#33 pbsastro

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Posted 13 December 2012 - 07:20 PM

The 30-100 is getting famous. One of these days we may get to see it on TV.
Sorry couldn't resist again. :grin:

#34 Jim7728

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Posted 14 December 2012 - 08:46 AM

From the video: 6.25 degrees TFOV with the ES 80ED!

I think I want one :evillaugh: or at least check out in person at NEAF.

#35 EFT

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Posted 14 December 2012 - 09:33 AM

Concerning the weight and safety, Scott thought a lanyard on the eyepiece with a D-ring carabiner on the end for connecting to the scope might be useful to keep the eyepiece from hitting the ground in case of an accident. What say you? It works with DSLR bodies when imaging.

What about a parachute on the eyepiece, plus an air-bag for the landing? I would drop it on purpose often to enjoy the ride :grin:

Sorry couldn't resist


Something a kin to what the Spirit and Opportunity rovers used when they bounced onto Mars would probably do the trick. :)

#36 junomike

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Posted 14 December 2012 - 12:50 PM

One important thing! Filters? I guess we all have to replace our Filters with 3" versions? Can't put a 2" Filter on a 3" eyepiece!

Mike

#37 dscarpa

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Posted 14 December 2012 - 02:10 PM

It would be wise to wear steel toed boots when using it. David

#38 coopman

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Posted 14 December 2012 - 08:16 PM

Just what the Dr. ordered - an eyepiece that will turn any scope into a diving duck.

#39 APM M.Ludes

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Posted 15 December 2012 - 05:19 AM

CHROMA Filters in USA makes UHC, O-III, Deep Sky and other filters in big sizes, they made my full 150 mm size for the big Fuji :-)

#40 mclewis1

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Posted 15 December 2012 - 10:56 AM

Suggestions/Options:

How about one of those Medic Alert things ... just in case the eyepiece/diagonal combo pulls a small refractor over on it's side? - "help I've fallen and can't get up".

An airbag in case it's dropped - you could probably incorporate one around the outside edge without it changing the size and shape at all.

An arrow indicating which end to look into - because it's not going to be obvious when this thing is used on a small refractor.

Handles to hang onto so you don't fall into that big black hole.

Long term financing, something on the order of a small bank bail out.

Name and number of a good divorce attorney - because you're gonna need one when the CFO finds out you spent over $1000 on "another eyepiece".

#41 faackanders2

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Posted 15 December 2012 - 07:38 PM

Make the widest TFOV 3" eyepiece possible for 100 AFOV and 82 AFOV and 70 AFOV, to take full advantage of 3". I don't feel I would ever be able to afford a 120 AFOV max TFOV.

P.S. These may be the eyepieces people will build telescope around (3" refractors, 3" reflectors, and 3" SCTs).


Anybody know what would be the theoretical widest TFOV eyepiece focal length for a 3" diameter 70 AFOV, 82 AFOV, 100 AFOV, and 120 AFOV eyepiece? Also what would be their exit pupils?

#42 Starman1

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Posted 15 December 2012 - 08:20 PM

OK, 3" is 76.2mm.
It's likely an eyepiece barrel for that large and heavy an eyepiece will be 2mm thick, maybe 2.5mm thick counting threads.
That means the maximum field stop would be 71.2mm.
With a negative/positive design, that might result in vignetting, so I'll go with a more conservative maximum of 70mm.
With NO distortion (of course unlikely), that would mean
an apparent field of:
99 degrees in 30mm
90 degrees in 35mm
82 degrees in 40mm
75 degrees in 45mm
70 degrees in 50mm
With a little distortion at the edge, the apparent fields could be slightly larger than that in each focal length. For example, the 24mm 1.25" widefield eyepieces would have a field of 59 degrees instead of 68 were it not for some distortion.
Which means 100 degrees for the 30mm 3" is entirely plausible, even if the effective field stop is less than 70mm.

#43 edwincjones

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Posted 16 December 2012 - 07:58 AM

oh no
I went from 1.25" to 2",
back to 1.25" for binoviewers
now I have to go to 3"
:question:

#44 Thomas Karpf

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Posted 21 December 2012 - 11:26 AM

Should we expect that Explore Scientific will soon be selling refractors with 3" focusers (and 2" inserts and 1.25" inserts)?

#45 faackanders2

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Posted 23 December 2012 - 12:56 AM

OK, 3" is 76.2mm.
It's likely an eyepiece barrel for that large and heavy an eyepiece will be 2mm thick, maybe 2.5mm thick counting threads.
That means the maximum field stop would be 71.2mm.
With a negative/positive design, that might result in vignetting, so I'll go with a more conservative maximum of 70mm.
With NO distortion (of course unlikely), that would mean
an apparent field of:
99 degrees in 30mm
90 degrees in 35mm
82 degrees in 40mm
75 degrees in 45mm
70 degrees in 50mm
With a little distortion at the edge, the apparent fields could be slightly larger than that in each focal length. For example, the 24mm 1.25" widefield eyepieces would have a field of 59 degrees instead of 68 were it not for some distortion.
Which means 100 degrees for the 30mm 3" is entirely plausible, even if the effective field stop is less than 70mm.


If I got a 3" focuser, I would probably be most interested in a 50mm 70 AFOV for widest TFOV, folo :question: :jump:wed by either 40mm 82 AFOV or 30mm 100 AFOV.

#46 faackanders2

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Posted 23 December 2012 - 12:58 AM

Should we expect that Explore Scientific will soon be selling refractors with 3" focusers (and 2" inserts and 1.25" inserts)?


If you build it, they will come.

#47 faackanders2

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Posted 23 December 2012 - 01:00 AM

What is the AFOV of this ES 3" 30mm prototype?

#48 Astrojensen

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Posted 23 December 2012 - 03:49 AM

100°


Clear skies!
Thomas, Denmark

#49 Cyclop_si

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Posted 25 December 2012 - 08:32 AM

.... The 30mm will be the first in a series of 4 or 5 3" 100 degree eyepieces. ES is contemplating a 40mm as the next in the series and would like CN feedback on what other focal lengths might be desirable...


I agree that it would be smart move for ES to offer 35-40mm 100° eyepiece next, since I think this would maximize 100° potential in 3" format. Also, I think many APO and SCT users would prefer this focal length over 30mm, since difference between existing 30-31 mm 82° and new 3" 30mm 100° eyepiece might not be beneficial enough for potential customers to mess with bulk and weight of new system. Contrary, 35-40mm 100° eyepiece would give them significantly increased TFOV to deal with related cost, bulk and weight. This eyepiece would give reasonably small exit pupil for most APOs (f/7 and slower) and SCT users of course.

For large SCT users, I think 3" eyepiece with 45-50mm 82° and also 55-60mm 70° would be interested as well.

#50 faackanders2

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Posted 26 December 2012 - 11:47 PM

.... The 30mm will be the first in a series of 4 or 5 3" 100 degree eyepieces. ES is contemplating a 40mm as the next in the series and would like CN feedback on what other focal lengths might be desirable...


I agree that it would be smart move for ES to offer 35-40mm 100° eyepiece next, since I think this would maximize 100° potential in 3" format. Also, I think many APO and SCT users would prefer this focal length over 30mm, since difference between existing 30-31 mm 82° and new 3" 30mm 100° eyepiece might not be beneficial enough for potential customers to mess with bulk and weight of new system. Contrary, 35-40mm 100° eyepiece would give them significantly increased TFOV to deal with related cost, bulk and weight. This eyepiece would give reasonably small exit pupil for most APOs (f/7 and slower) and SCT users of course.

For large SCT users, I think 3" eyepiece with 45-50mm 82° and also 55-60mm 70° would be interested as well.


30mm 120 AFOV, 40mm 100AFOV, 50mm 82AFOV, 60mm 70AFOV really would be pushing the limit of maximum TFOV for given power. They probably would all require a paracorr coma correcttor.
But hopefully they would allow 2" filters to be screwed in the eye side of the eyepiece also; till we have enough 3" eyepieces to upgrade filters also.






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