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  1. #1
    WWPierre's Avatar
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    Default VERY Dissappointed Orion Long Eye Relief Telescope Eyepiece



    As a wearer of glasses, I have come to find that because of my need for high eye relief, long eyepieces combined with barlows is the best way to achieve magnification. I have a number of EPs between 20mm and 40mm that allow me to see the field stop with my glasses on. I use these with 2x and 3x barlows to achieve the equivalent of down to about a 3.5mm EP, and retain comfortable eye relief.

    My most expensive EP is a Siebert 30mm ultra, bought new, (about $180, by the time it arrived in my post box) next most expensive is my Tel Vue 3x barlow, (about $125 delivered) Other than those, $50 is pretty much the most I have paid, with around $30 being the mean. In short, my EP collection, while quite extensive, is pretty much low end.

    Thinking I should perhaps get a few at least medium quality EPs in the mix, I ran across an EP on eBay that seemed to fit the bill. this one.

    A $100 EP. I got it for about half that, and have been eagerly awaiting its arrival for the last couple of weeks.

    Well, it arrived today, and by happy co-incidence, the clouds went away and the sun came out.

    I got it out of it's (pretty much bombproof....**** even) packing and chunked it into my 80mm Vixen, put my eye to the eyecup, and beheld a tiny circle with blurry edges. I rolled down the eyecup, and I had to press my glasses against the eyepiece until my lashes contacted the inside surface of the lens before I could see the field stop. In a comfortable position, I estimate that the diameter of the vignetted image is about 1/3 of the size of the image when the field stop is visible.

    How is eye relief measured anyway? Logically, one would think it is the distance from the eyeball lens to the top surface of the first piece of glass in the lens. Using this criterion, the ER of this purportedly 20mm ER eyepiece is a mere 10mm. WTF??????

    Below is documentation of the eye relief of this new EP compared with a generic 20mm plossl which I use often and find comfortable. The methodology is to set the camera on a 10 second timer and look through the EP, moving close enough to just see the field stop. The top surface of the first glass is perhaps 1 or 2 mm below the surface you see.

    Comments welcome.
    Attached Images Attached Images
    Last edited by admin; 02-03-2012 at 07:30 AM. Reason: descriptive title please
    Meade 16" LightBridge; Celestron G-8N Bird-Jones/motorized EQ5; Orion 127 Mak/go-to EQ5; Burgess 127f8 refractor; Sky-Watcher 5" F/5 collapsible dob; 90mm Mak/motorized EQ2; Royal Astro 76/910-GEM; Meade 60x700 refractor/alt/az; Zhumell 25x100 Coin Ops; GalilleoScope. Celestron 8mm-24mm zoom; lots of fixed EPs,some good, some..not so much. A small collection of surveying instruments; a forest of tripods; Canon Rebel Xti. Confirmed gadget junkie; Custodian of the Magnetic North Pole (Send $1.00 to Pierre each time you use a compass.)
    49-41-37.03N 123-09-29.61W Calculated magnetic declination: 17° 39' East

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  3. #2
    skaven's Avatar
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    I agree with you that if the EP is advertised as 20mm of eye relief, your eyeball should be no less than 20mm away from the top surface of the last lens in the system when you are observing the entire field. Eyecups, plastic around the lenses, etc...I get that. But eye relief is measured from the glass, and from your description, it definitely looks like they're using some other measure of eye relief.

    The only thing I could think of that could possibly justify the delta is if Orion was using some other metric for eye relief -- such as "you can focus on the image when the eye is 20mm away" -- without regard to the field stop.

    Definitely a disappointment.

    For what it's worth, I ended up getting so frustrated by by glasses when out observing (regardless of eye relief issues, which on the Explore Scientific 82 degree series is quite short) that I got fitted for contact lenses. I only wear them when I pull the scope out, but I have to say it's quite liberating to not have to flick my glasses up and down (and constantly deal with the lenses fogging over) while observing.

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  5. #3
    WWPierre's Avatar
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    I posted the same observations over at Cloudy Nights, and it generated a lot of interesting discussion. I learned a lot.

    Towards the end of the discussion, there is a post from a fellow who owns an almost complete set of eyepieces of the same design. According to him, the short ER of the 18mm EP is an anomaly, and the others in the series have more comfortable ER.

    I have ordered a 14.5mm from Smart Astronomy, (he provided a link).
    Meade 16" LightBridge; Celestron G-8N Bird-Jones/motorized EQ5; Orion 127 Mak/go-to EQ5; Burgess 127f8 refractor; Sky-Watcher 5" F/5 collapsible dob; 90mm Mak/motorized EQ2; Royal Astro 76/910-GEM; Meade 60x700 refractor/alt/az; Zhumell 25x100 Coin Ops; GalilleoScope. Celestron 8mm-24mm zoom; lots of fixed EPs,some good, some..not so much. A small collection of surveying instruments; a forest of tripods; Canon Rebel Xti. Confirmed gadget junkie; Custodian of the Magnetic North Pole (Send $1.00 to Pierre each time you use a compass.)
    49-41-37.03N 123-09-29.61W Calculated magnetic declination: 17° 39' East

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  6. #4
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    Quote Originally Posted by skaven View Post
    For what it's worth, I ended up getting so frustrated by by glasses when out observing (regardless of eye relief issues, which on the Explore Scientific 82 degree series is quite short) that I got fitted for contact lenses. I only wear them when I pull the scope out, but I have to say it's quite liberating to not have to flick my glasses up and down (and constantly deal with the lenses fogging over) while observing.
    I tried the contact route, but I wasn't able to install them, even after trying 50or 60 times. I have been told I can have my eyes trued up with laser surgery. ..........perhaps.

    Meantime, I am having a pair of glasses made with the bifocal patch lowered so that the top of it doesn't go across the middle of my FOV when my glasses are pushed up as far as they can go.
    Meade 16" LightBridge; Celestron G-8N Bird-Jones/motorized EQ5; Orion 127 Mak/go-to EQ5; Burgess 127f8 refractor; Sky-Watcher 5" F/5 collapsible dob; 90mm Mak/motorized EQ2; Royal Astro 76/910-GEM; Meade 60x700 refractor/alt/az; Zhumell 25x100 Coin Ops; GalilleoScope. Celestron 8mm-24mm zoom; lots of fixed EPs,some good, some..not so much. A small collection of surveying instruments; a forest of tripods; Canon Rebel Xti. Confirmed gadget junkie; Custodian of the Magnetic North Pole (Send $1.00 to Pierre each time you use a compass.)
    49-41-37.03N 123-09-29.61W Calculated magnetic declination: 17° 39' East

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  7. #5
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    Quote Originally Posted by skaven View Post
    For what it's worth, I ended up getting so frustrated by by glasses when out observing (regardless of eye relief issues, which on the Explore Scientific 82 degree series is quite short) that I got fitted for contact lenses. I only wear them when I pull the scope out, but I have to say it's quite liberating to not have to flick my glasses up and down (and constantly deal with the lenses fogging over) while observing.
    As demonstrated by your avatar?
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  8. #6
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    Quote Originally Posted by John999R View Post
    As demonstrated by your avatar?
    Lol, noticed that too.
    Meade 16" LightBridge; Celestron G-8N Bird-Jones/motorized EQ5; Orion 127 Mak/go-to EQ5; Burgess 127f8 refractor; Sky-Watcher 5" F/5 collapsible dob; 90mm Mak/motorized EQ2; Royal Astro 76/910-GEM; Meade 60x700 refractor/alt/az; Zhumell 25x100 Coin Ops; GalilleoScope. Celestron 8mm-24mm zoom; lots of fixed EPs,some good, some..not so much. A small collection of surveying instruments; a forest of tripods; Canon Rebel Xti. Confirmed gadget junkie; Custodian of the Magnetic North Pole (Send $1.00 to Pierre each time you use a compass.)
    49-41-37.03N 123-09-29.61W Calculated magnetic declination: 17° 39' East

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    Quote Originally Posted by John999R View Post
    As demonstrated by your avatar?
    Heh, yeah...that photo was actually taken while I was on vacation in Boston. That's not even my scope...it was a junker Meade 10" that the ATMoB guys had sitting in a spare room near the door at their clubhouse; they pulled it out because I hadn't purchased my C10 yet and I wanted to see what the view was like through a 10" f/4.7 scope (I was worried about coma).

    Hence the gloves, hoodie, and coat (it was below freezing) and I didn't have my contacts with me...

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    Quote Originally Posted by WWPierre View Post
    I posted the same observations over at Cloudy Nights, and it generated a lot of interesting discussion. I learned a lot.

    Towards the end of the discussion, there is a post from a fellow who owns an almost complete set of eyepieces of the same design. According to him, the short ER of the 18mm EP is an anomaly, and the others in the series have more comfortable ER.

    I have ordered a 14.5mm from Smart Astronomy, (he provided a link).
    Good to know...thanks for following up!

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    You have the Explore Scientific 82 degree 30 mm which I am thinking of getting because I wear glasses (after 38 years wearing gas permeable contacts my eyes won't take them any more) but you say the eye relief is not too good - the spec is 21 mm. Were you referring to your 18 mm EP?

  12. #10
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    Both the 30mm and 18mm Explore Scientific 82 degree EPs may say they have ~20mm of eye relief, but the reality is that the last lens is like a bowl, so once you get your eye far enough down into the "bowl" to see the field stop, you're far beyond comfortable glasses-wearing distance. I find that I generally have to cram my face down into the eyepiece in order to see the field stop. That said, it *is* very comfortable to do this, as it doesn't actually mean my eyelashes are up against the glass or anything. But due to the shape, I think that in reality it's more like 10-15mm of usable eye relief from the flat surface at the top of the EP to your eyeball.

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    Meade HD-60 9mm, 6.5mm; 56mm; University Optics Orthoscopic 12.5mm, 9mm, 7mm, 5mm;
    ES 70° 15mm, 20mm; ES 82° 30mm, 18mm; ES 100° 9mm; Baader Hyperion 24mm; TV Nagler T6 13mm
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