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  1. #1
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    Default First night out with my Nagler! (and a question)



    It has been a few days since my first night out with my new Nagler EP (17mm, 2 inch barrel). It was a hazy night, and I was hoping for a better first light report (eh..."first" light report that would really be a second light report...which would have been cheating anyway ). BUT, it's just getting cloudier and yuckier outside with each passing day, so that isn't going to happen.

    First impression: Wow! That field of view! Peripheral vision is useful again! The edges of the field are far enough out of the way that when you're concentrating on an object in the center of the field, the edges almost shimmer out of view. They are never completely gone, but if you ignore them, you will forget that they are there. This is actually similar, in my opinion, to looking through a pair of glasses and seeing the outside edges of the frames...similar AFOV, too. There is no doubt that the frames are in your field of view while you wear your glasses, but if you're focusing on what you're looking at rather than the frames themselves, then you forget the frames are there.

    When looking near the edge of the field, the opposite edge does disappear from view. This is in stark contrast to my Plossls, where I can see the entire field the whole time, plus plenty of black surrounding the field of view, without moving my eyes around or using peripheral vision.

    I did not notice any coma even at the edges of the field. Stars were pinpricks (or, as pinpricky as I could make them through the haze). I compared the Nagler with my 25mm Plossl looking at the Orion Nebula, and the Nagler seems to have higher contrast than the Plossl. Both EP's split the Trapezium with no trouble, so there's no edge for either EP there.

    The only negative is that I like to rest my hand (or my eye) against the scope because it helps me hold my head steady. Unfortunately, with that huge EP in place, even touching the OTA set the view to shaking. However...when I disassembled everything, I noticed a screw loose on the focuser that I didn't remember ever tightening, so I think I just didn't secure the EP properly in the first place. I HOPE that's what it is. Otherwise, this is really going to cut into my enjoyment of this otherwise fantastic EP, and keep me from buying any more 2 inch EP's in the future.

    The last target of my viewing session was Jupiter, because it had spent most of my observing time hiding behind some trees. I took the chance to peek at it when it was visible through some branches. With the Nagler unbarlowed, Jupiter was crisp even at the very edge of the field of view. The haze had improved somewhat by then, but the tree wasn't cooperating, so I only got a few minutes of Jupiter that night. I look forward to the next clear night I get, so that I can really observe Jupiter with my new EP.

    This leads me to my question. I got a 2 inch Zhumell barlow lens to use with the Nagler. Worked beautifully on every target I tried...except for Jupiter. I couldn't focus on Jupiter with the barlow in place. All I got was a fuzzy white disk. What gives? Did I just catch Jupiter in a moment of particularly bad haze? Was there a twig in the way that I just didn't see? (Stupid tree.) Does my focuser just not have enough travel? Also, I noticed that the barlow lens itself unscrews from the rest of the tube. Am I supposed to screw that into the EP using the threads that were put there for filters? It didn't come with instructions
    Moya: Orion XT8i
    9x50 Correct-image Finder Scope, Telrad
    TeleVue Nagler 17mm

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  3. #2
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    The Jupiter problem is more than likely caused by simply bad atmospheric conditions. Jupiter is a big, bright object and if the atmosphere is even just average, you are going to have lots of light scatter which causes the blurriness. In reality, it will take a night of INCREDIBLE seeing to be able to barlow that eyepiece on Jupiter.

    You picked a heck of an eyepiece there, many people say that the Nagler 17T4 may be the best eyepiece made by Televue that isnt an Ethos. Congratulations on your purchase!
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  5. #3
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    Hi Zardi,

    Thanks for the report!

    Re. Jupiter:
    It could either be due to too high magnification or atmosphere conditions, or a little bit of both...

    Normally, I'm not a big fan of Barlows, as they tend to degrade views in the EP, a little.
    Chris
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  6. #4
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    Zardi, congrats! Glad you're liking your new Nagler 17mm T4 and that you're one of the many observers who appreciates a wide 82-deg. field of view with no problem at all. With regard to the use of a barlow, is it a 2x one? Your scope with a focal length of 1200 should work well with an 8.5mm equivalent or 141x power (17mm barlowed 2x), as this review of the same scope as yours:

    Orion Skyquest Intelliscope XT8 - Review

    has his scope working with a 10mm eyepiece used with a 2x barlow (or 5mm equivalent), to quote:

    Jupiter: .. .. Since I already had the 10mm with the Barlow in the focuser, I redirected the scope towards the southeastern sky.â€* It just broke the edge of my roof so I could take a look.â€* Wow! (Recurring theme, right?)â€* Not only could I make out the 2 equatorial belts, but also I could make out several other cloud belts to the north and south of the 2 main belts. I also observed what I think were 5 satellites orbiting Jupiter, but I'm not sure.â€* Very impressive!
    So I see no reason why your 17mm barlowed 2x should not work on Jupiter. It is possible that because of that particular barlow that you're using, there is not enough in-travel. What you can do is to unscrew the bottom barlow element and screw it on to the filter thread of you 17mm Nagler - if the barlow you are using is 2x, using the bottom barlow element will result in a 1.5x equivalent barlow or 11.3mm, and you might be able to focus. I've done that with a scope that can't focus using the full barlow, but when I try using the bottom lens element only and screw it to the filter thread of the EP, it works fine. Try this with your set and tell us if it works.

    Best,

    Hernando
    Last edited by ibase; 01-11-2011 at 04:38 PM.

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  8. #5
    Zardi's Avatar
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    Thanks for the replies! I was able to go out last night. It was hazy again, but at least I was able to test some of the issues I had.

    The Jupiter problem is more than likely caused by simply bad atmospheric conditions. Jupiter is a big, bright object and if the atmosphere is even just average, you are going to have lots of light scatter which causes the blurriness. In reality, it will take a night of INCREDIBLE seeing to be able to barlow that eyepiece on Jupiter.
    Very helpful, thank you! I noticed some of the symptoms of poor seeing when I tried again last night. Jupiter was very shimmery (like a desert mirage) most of the time, but I got little glimpses of the equatorial belts from time to time. At least I know it isn't the EP.


    Normally, I'm not a big fan of Barlows, as they tend to degrade views in the EP, a little.
    I noticed some chromatic aberration last night while viewing Jupiter with the barlow (though none on the moon, strangely). Is this the fault of the barlow, the EP, or of poor seeing conditions? Normally I would blame my glasses, but I had taken them off. I hope it isn't the EP, considering its cost.


    With regard to the use of a barlow, is it a 2x one?
    Yes, it is a 2x Zhumell brand barlow lens.


    What you can do is to unscrew the bottom barlow element and screw it on to the filter thread of you 17mm Nagler - if the barlow you are using is 2x, using the bottom barlow element will result in a 1.5x equivalent barlow or 11.3mm, and you might be able to focus.
    Thanks for the info I tried this, but didn't have enough out-travel. I also tried barlowing the EP with the barlow completely assembled, and I was able to focus this time. It must just have been horrible seeing conditions last time.
    Moya: Orion XT8i
    9x50 Correct-image Finder Scope, Telrad
    TeleVue Nagler 17mm

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    When you were viewing Jupiter, how high above the horizon was it? Your description (very shimmery..like a dessert mirage; some chromatic abberation) of how you were seeing the planet seems to suggest that it was at a low altitude - even the best eyepiece in the world won't be able to give a sharp image under such a condition, which happens when the object is below 30-degrees north of the horizon - too much turbulence as your line of sight to the planet is cutting through a thicker part of the atmosphere with all the dirt and impurities that causes the shimmering or boiling effect. The ideal time to view Jupiter is when it is high up in the sky where your line of sight slices through a thinner segment of the atmosphere (thinnest is directly overhead or at zenith position); so try viewing Jupiter at its highest in your location and the view will probably improve considerably. Hope this helps.

    Best,

    Hernando
    Last edited by ibase; 01-13-2011 at 07:56 AM.

  10. #7
    Zardi's Avatar
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    Jupiter would have been 30-35 degrees above the horizon when I was viewing it, so I bet you're right. The highest it will get currently is about 50 degrees, though, and it's only going to get worse.
    Moya: Orion XT8i
    9x50 Correct-image Finder Scope, Telrad
    TeleVue Nagler 17mm

 

 

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