brocknroller
Carpal Tunnel
Reged: 10/16/03
Posts: 1983
Loc: Bedford Falls, Pa.
|
|
As binofans who wear eyeglasses have learned, the adveristed eye relief on bins is often more generous than the useable ER. But with 27.4mm ER, these Discovery 7x50 binoculars could have a 7mm lens recession and still deliver enough ER for most eyeglass wearers. However, from the price, I would guess they are not FMC or of good quality.
http://www.discovery-telescopes.com/d-binoculars.html
This bin has the highest ER I've seen listed. Any other bins out there with VERY high ER for eyelgass wearers with thick glasses and/or deep-set eyes?
Brock
--------------------
Press: Are you a mod or a rocker?
Ringo: I'm a mocker
|
fellers
Pooh-Bah
Reged: 12/29/05
Posts: 1094
Loc: NY by ADK park
|
|
I have learned to stay away from cheap binocs as you will eventually run into problems which will require you to send back or junk them.
I am looking for a decent pair of binocs now because I have just recently run into a problem with my cheapos.
The more I get inot astronomy the more I realize you definately get what you pay for in this hobby.
--------------------
MVAS Observatory
Old Forge
The farmer allows walkers to cross the field for free, but be aware that the bull charges.
"SUA SPONTE"
|
patter1
professor emeritus
Reged: 01/19/05
Posts: 597
Loc: Canada
|
|
I'm skeptical about that 27.4 mm eye relief spec... even if it doesn't take into account the eyecup/recess. Most 7x50s are in the low 20s at most.
Oberwerk 7x50 and 8x56 are listed at 24mm.
--------------------
Patrick
8" f/6 NewStar dobsonian
Orion Starblast 4.5" f/4 mini dobsonian
42mm SuperView, 17mm Nagler T4, some other cheapies
Omcon 7x50, Oberwerk 11x56, Olympus DPS-R 7x35, Olympus Magellan 8x25
homemade 50mm right-angle bino-scope prototype
|
brocknroller
Carpal Tunnel
Reged: 10/16/03
Posts: 1983
Loc: Bedford Falls, Pa.
|
|
Discovery makes good quality Dobsonians but are selling cheap Chinese bins under their label. It's becoming a trend, with Astrophysics now offering a line of Chinese bins under their label.
Perhaps the ER distance was a misprint and should read 24.7mm ER? That would sound more reasonable.
But all this is moot (or "mute" as a friend would say), because the exit pupil on 7x50s is too big for my eyes and my skies. Wish I could get that much useable ER in a good quality 10x50.
Brock
|
Refractor6
Post Laureate
Reged: 10/20/04
Posts: 3653
Loc: Vancouver B.C. , Canada
|
|
The Orion 9x63 mini giants I just made reference to on another thread have 26mm eye relief. I wear my glasses when using binos and I find these quite comforable to use with the cups up and get the whole field of view.
-----------------
Stan
Takahashi FS-102 NSV
Antares 152 f/8 prototype
Antares 152 f/6.5
Antares 127 f/6.45 prototype
Orion 9x63 mini giants
Pentax 20x60 PCF WP
|
patter1
professor emeritus
Reged: 01/19/05
Posts: 597
Loc: Canada
|
|
I checked the Orion 9x63, and yup it says 26mm. I wonder if that's accuarate, or 'optimistic'. I would expect it to use the same eyepeieces as the 8x56 (18mm) but who knows.
--------------------
Patrick
8" f/6 NewStar dobsonian
Orion Starblast 4.5" f/4 mini dobsonian
42mm SuperView, 17mm Nagler T4, some other cheapies
Omcon 7x50, Oberwerk 11x56, Olympus DPS-R 7x35, Olympus Magellan 8x25
homemade 50mm right-angle bino-scope prototype
|
Refractor6
Post Laureate
Reged: 10/20/04
Posts: 3653
Loc: Vancouver B.C. , Canada
|
|
Quote:
I checked the Orion 9x63, and yup it says 26mm. I wonder if that's accuarate, or 'optimistic'. I would expect it to use the same eyepeieces as the 8x56 (18mm) but who knows.
All I know is for eye glass wearers such as myself the Orion 9x63 mini giants have very comforable eye relief and as stated earlier with the cups extended I have no problem taking in the whole field of view. Compared to other older binos I replaced with relatively short ER these have definitely been the ticket for me wearing glasses when observing.
-------------------
Stan
Takahashi FS-102 NSV
Antares 152 f/8 prototype
Antares 152 f/6.5
Antares 127 f/6.45 prototype
Orion 9x63 mini giants
Pentax 20x60 PCF WP
|
EdZ
Professor EdZ
Reged: 02/15/02
Posts: 18806
Loc: Cumberland, R I , USA42N71.4W
|
|
Quote:
I would expect it to use the same eyepeieces as the 8x56 (18mm) but who knows.
What makes you think they use 18mm eyepieces, or the same eyepiece for that matter?
If an 8x56 binocular had an 18mm eyepiece, then the focal length of the objective would be 8x18 = 144mm. That would give an f ratio of 144/56 = f/2.6!
I've seen a few 7x35s and 8x42s at f/3.6 or f/3.8, and one 10x50- at f/3.7, but I've never seen any larger binocular less than f/4 and many are f/4.1 - f/4.2, with giants more like f/4.4 to f/4.7.
Just doing rough calculations I come up with eyepieces about 25mm to 28mm. That seems to be much more in line with the extremely long eye relief.
FWIW, for hand held use, with glasses, I find binoculars with more than 16-18mm of usable eye relief TOO LONG.
edz
--------------------
Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21
|
btschumy
Vendor - Southern Stars
Reged: 04/13/04
Posts: 1708
Loc: Longmont, CO, USA
|
|
I think he's talking about 18mm eye relief, not focal length.
--------------------
Bill Tschumy
Southern Stars
|
EdZ
Professor EdZ
Reged: 02/15/02
Posts: 18806
Loc: Cumberland, R I , USA42N71.4W
|
|
I see.
BTW, as it works out an 8x56 and a 9x63 are the exact proportions to allow using exactly the same eyepiece and keep the f# of the binoculars exactly the same.
edz
--------------------
Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21
|
patter1
professor emeritus
Reged: 01/19/05
Posts: 597
Loc: Canada
|
|
Yes, I should've wrote '18mm eye relief'. If the stated eye relief specs are correct (big assumption), then that alone indicates that they're not the same eyepiece. But I've read that some binocs (one example might've been the Fujinon 10x50 and 16x70 IIRC) having the eaxct same eyepieces. Presumably for reasons of economy.
>>>for hand held use, with glasses, I find binoculars with more than 16-18mm of usable eye relief TOO LONG.
We're all different; my 11x56s (stated as 19mm er... don't know if that's gross or 'useable') isn't nearly enough; with my glasses on I have to mash my face & glasses right into eyepieces to see the entire field, and even then just barely. (I trusted the seller when he said that it's 'plenty enough' for use with glasses). The only way to know for sure is to try in person. But I like the term 'useable' or 'effective'... much more meaningful than a measurement from the lens.
|
Refractor6
Post Laureate
Reged: 10/20/04
Posts: 3653
Loc: Vancouver B.C. , Canada
|
|
I agree we are all different in the issue of ER. I find the long ER on the Orion 9x63's very easy to view with when the rubber cups are extended with my glasses on for both day and evening viewing as already mentioned. Each to his own. Best to try and see what suits you before buying a pair with long ER.
----------------
Stan
Takahashi FS-102 NSV
Antares 152 f/8 prototype
Antares 152 f/6.5
Antares 127 f/6.45 prototype
Orion 9x63 mini giants
Pentax 20x60 PCF WP
|
Previous
Index
Next
Threaded
Edit
Reply
Quote
[Re: