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jhors
Riddle me this
Reged: 07/16/07
Posts: 977
Loc: Tempe, AZ
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Greetings,
I am looking for experiences and advice regarding a DSO eyepiece in the 7-9mm range for use in a 10" f/4.7 Orion Dob.
I have a 26T5, 17T4, 13E, 9T1, and a 6R. I am looking for an eyepiece that will provide as much throughput and resolution as possible for DSO observation and note taking. Huge AFOV is not important.
Some EPs that I have been considering are: 7XW, 7.5 Tak LE, 7 & 9mm Genuine Ortho/UO HD Ortho, TV 8mm Plössl, and an Antares 1.6x barlow (for use with 13E). However, I am open to other suggestions. I have to admit that the 7.5 Tak LE is an early favorite in both a mathematical sense, splitting the gap between the 6 and 9mm EPs, and because I've heard good things about them.
I have been contemplating this for a long time and have analyzed myself into a corner. Any help would be much appreciated! I'm even interested in hearing how you ended up with the EPs you use in this range and the progression you went through to get there. 
Also, I am posting this here to emphasize my observing interest. I have little interest in lunar/planetary performance.
Thanks and CS!
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-Josh
Boyce Thompson Arboretum:
10" f/4.7 Dob
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AlanK
professor emeritus
Reged: 01/26/07
Posts: 510
Loc: Auckland, New Zealand
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Eyepieces these days, even those with multiple elements have very good throughput due to their high quality glass and coatings. The TV 7mm Nagler T6 and 8mm Ethos are my favorites in that range and one of the reasons is that an object takes longer to drift across their wide fields so there will be less nudging of the scope to keep it in the field. The other advantage is that they have a greater ability to frame multiple objects close by and allow you to see all of a large globular cluster and more of very large bright nebulae.
The advantage of the TAK LE 7.5 is that it does have less elements allowing slightly more light transmission so if you are trying to get close to the theoretical maximum then that would be the way to go.
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Clear skies!
18 inch f4.5 Obsession #1637
12 inch f5.4 reflector
Just another frozen astronomer
Kumeu Observatory
Auckland NZ
7,276 deep sky objects incl 4,670 ngcs
Who dares - observes!
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jhors
Riddle me this
Reged: 07/16/07
Posts: 977
Loc: Tempe, AZ
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Thank you for your input. I forgot to mention that I was also considering the 7T6. Just curious...has the Ethos made the 7 redundant or do you still use both of them?
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-Josh
Boyce Thompson Arboretum:
10" f/4.7 Dob
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AlanK
professor emeritus
Reged: 01/26/07
Posts: 510
Loc: Auckland, New Zealand
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Still use both as 8mm Ethos gives x258 and 7mm x292 in my case. Which one I use mostly depends on framing but the 7mm does get slightly deeper due to the higher power.
--------------------
Clear skies!
18 inch f4.5 Obsession #1637
12 inch f5.4 reflector
Just another frozen astronomer
Kumeu Observatory
Auckland NZ
7,276 deep sky objects incl 4,670 ngcs
Who dares - observes!
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PeterSurma
super member
Reged: 08/24/06
Posts: 117
Loc: Heidelberg, Germany
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I have a 9T6 and 5T6 on a 20" f/4 Dob. They work excellently for me (no glasses) in DS observing, although I do not tend to compare a lot.
If you like see
http://eyes4skies.de/Internet/Astro/BeobachtungsReports/BeobachtungsReports_files/BeobReport_2008_05_08_KABR_engl.htm
If you can afford Ethos EPs, why not, but the standard Naglers also have become a bit cheaper now, as Ethoses are emerging... Maybe that's the time to buy the Naglers... :-)
Good luck,
Peter
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Peter
Web: http://www.eyes4skies.de/home_EnglishVersion.htm
Scopes: From 3inch photographic APO to 20inch f/4 Dob
Edited by PeterSurma (07/03/09 11:02 AM)
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jhors
Riddle me this
Reged: 07/16/07
Posts: 977
Loc: Tempe, AZ
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Thanks Peter! I love the 9T1, but I have considered upgrading it to the T6. That might be a good route to go since that exit pupil is one I'm already fond of. The Ethos is an option, but it's out of the budget for now. I am willing to wait though if that is my best option.
Also, nice website! I enjoyed reading your observing report. You put a lot of time and information into it and have a style that's fun to read. I wish more of your reports were in English or that I remembered more from my 8th grade German class. Ausgezeichnet!
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-Josh
Boyce Thompson Arboretum:
10" f/4.7 Dob
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PeterSurma
super member
Reged: 08/24/06
Posts: 117
Loc: Heidelberg, Germany
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Hi + thanks :-),
yeah I wished I had more time to put all this into english, as the community would be a bit larger, but well, maybe once I go for it...
I'd really buy some first class EP since the time you actually spend on your scope is is so rare (at least for me it is). So I'd really like to have something good. I don't think you can beat T6 Naglers by large margins. Some people with glasses argue about eye relief of Naglers though, but if you don't have to wear glasses, I'd see no real reason not to get them. I simply doubt there is something much better or much cheaper (for the same quality). That - at least - was my reason to get them.
Good luck + have nice observations with you new EPs !
Peter
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Peter
Web: http://www.eyes4skies.de/home_EnglishVersion.htm
Scopes: From 3inch photographic APO to 20inch f/4 Dob
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Patricko
Carpal Tunnel
Reged: 01/30/07
Posts: 1501
Loc: SE New Mexico USA
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A vote for the 9mm Japan volcano top orthoscopic. I use it in my 60mm refractor to hunt DSO detail from my dark site.
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Clear skies,
Patrick
INTERNATIONAL DARK SKY ASSOCIATION
60MM TELESCOPE CLUB!
"You can always have better, but will you ever be happy with what you have?" - Me, myself, and I
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Jim Curry
sage
Reged: 10/29/07
Posts: 422
Loc: Maine
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I too use UO Abbe's for high power viewing. But I have driven scope so the rather narrow fov isn't an issue for me. They're low cost enough on the used market, try one. I just read a most interesting posting on the eyepiece forum, "UO Abbe" thread regarding someone who does threshold viewing with 22 & 30" scopes, he got rid of his ethos and kept his Abbe's. I too love doing threshold viewing to the limits of my modest equipment and after trying several brands of 5 & 6mm ep's settled on the UO Abbe's as the best (I did not try mono's or other higher priced ep's).
Jim
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Vixen 140 refractor
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rogerandgarf
sage
Reged: 06/01/05
Posts: 227
Loc: Arlington, Wa
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You may wish to consider a Brandon. Bill Paolini gave them high marks recently for showing nebular detail.
I tried a 24 Brandon in the 18" Starmaster on NGC 6946 the other night in average seeing/transparency conditions and was very pleased with its throughput and rendering of galactic core and arm detail; given the number of elements and the comparative tint and tone of the antireflective coatings, I'm looking forward to trying out the 16, 12 and 8mm as soon as I can.
My Supermonocentric lineup ends at 10mm, so the Brandons will fill that minimal-element void at an affordable price.
PS - I'm still not giving up the 7.5 Tak LE anytime soon.
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Roger Johnson
18"F4.2 Goto Starmaster
12"Antares Dob
Televue Genesis
5" Mak
ZAOIIs w/barlow
Denk II BVs/x switch
Swarovski, Leica, Canon IS,
Fuji, Obie bins/Unimount
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jhors
Riddle me this
Reged: 07/16/07
Posts: 977
Loc: Tempe, AZ
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Thanks Patrick and Jim!
The Orthos seem to be a low risk/high reward line of eyepieces so I think I'll try the 9mm and see how I like it.
Roger,
The 8mm Brandon is very intriguing, although that listed 1mm eye relief is pretty severe. They are definitely worthy of consideration in longer focal lengths though if I decide I want to shift that end of my case around.
What are your thoughts on the Tak. What is its primary purpose in your case with all those Supermonos?
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-Josh
Boyce Thompson Arboretum:
10" f/4.7 Dob
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ensign
member
Reged: 12/16/08
Posts: 30
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I have the Pentax 7XW and have been very happy with it in my F4.7 10" Dob as well as my 4" apo. Subjectively, "light throughput" seems to be very high with this EP. I mainly observe DSOs of all types.
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- Mike
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Modified 10" Sky-Watcher Dob
William Optics Megrez 110/EZTouch
Nagler Type 4 - 12,17,22
Pentax XW - 10,7
William Optics UWAN 28
Siebert Observatory class 40
Other assorted items too numerous to mention
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 12168
Loc: Los Angeles
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I think you want to have the following (at a minimum):
1)An eyepiece that gives you a field of view of over a degree. This will be, probably, a low power eyepiece, and you'll use it for M45, M44, M39, M31, Perseus Double Cluster, Veil Nebula, dark nebulae, etc.
2)An eyepiece that gives you a 30-40 minute field of view. This will probably be a medium power, and will be the right magnification and field for most star clusters (including globulars), most nebulae (e.g.M17, M16), some planetaries (e.g.M27, NGC7293), and a horde of galaxies.
3)An eyepiece that gives you a 20-30 minute field of view.
This will probably be a modestly high power eyepiece, and will be good for small planetary nebulae, small star clusters (including globulars), many small galaxies, and details in the larger DSOs.
Since your scope is a 10", I'd recommend that the above settle in on or about 60X, 120X and 180X.
Beyond that, it's a matter of taste. And you may have special eyepieces for *just* the planets and Moon. And you may find a "perfect" eyepiece for you straddles two categories I mentioned.
But the above would do you well on nearly every DSO except the very smallest and very largest.
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Don Pensack
12.5" Truss Dob, 5" Maksutov, Fujinon Binos
Sustaining Lifetime IDA member
Edited by Starman1 (07/12/09 08:11 PM)
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rogerandgarf
sage
Reged: 06/01/05
Posts: 227
Loc: Arlington, Wa
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Josh, I thought I would try the Tak line out of curiosity, based somewhat on Alvin Huey's choice of them for DSO viewing in addition to his choice of Supermono(centric)s.
I have read other posts by CN contributors which have not been so complementary of Taks, so I thought I would see for myself.
I appreciate the extra 10 degree fov from time to time, the warmer tone they produce, and their ergonomics. I may try some shorter fl Taks just for fun, but will have to wait for the money tree to resupply itself.
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Roger Johnson
18"F4.2 Goto Starmaster
12"Antares Dob
Televue Genesis
5" Mak
ZAOIIs w/barlow
Denk II BVs/x switch
Swarovski, Leica, Canon IS,
Fuji, Obie bins/Unimount
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