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First Light with the Big Guns

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#26 EdZ

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Posted 01 August 2005 - 12:14 PM

You will find there is considerable variation in the diameter of various eyepiece insert barrels. This is all well documented in the thread on Eyepieces for the BT100.

30mm Ultimas won't fit at all.
the stock eyepieces are a tight fit.
Every TV eyepiece that I've tried slides in like it was buttered, but is still very secure.
Some UO orthos went in so tight, I need to wrap them with a cloth and use pliers to pull them out.

I like the secure snug fit of the eyepieces. There are just certain ones I don't use any more.

edz

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Posted 01 August 2005 - 12:27 PM

Yes Ed, I am hearing from others about this EP fit phenomenon. I darn near had to pull out a set with pliers! I could not find a "set" of TV's that would work, the EP that came with the purchase were pretty bad and I would not use them anyways, EVEN if they DID fit my IPD (which they do not). I am willing accept this minor annoyance, because without set-screws, there probably just is no other choice. If Kevin does not suggest that perhaps the Miyauchi 71 may be better suited for my intended use, then I am certain the replacement pair they send will be spot on perfect!

Gary

#28 EdZ

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Posted 01 August 2005 - 01:11 PM

How could the supplied eyepieces "not fit" your IPD, when they are able to be adjusted throughout the entire IPD range?

edz

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Posted 01 August 2005 - 01:27 PM

Because the barrels are so large I cannot squeeze my face in close enough to use them. I had to buy all "thin-barreled" eyepeices.

Gary

#30 Mr. Bill

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Posted 01 August 2005 - 02:07 PM

Gary...

Casually read thread so I might have missed, but did you try observing through the left assembly with your right eye to eliminate individual eye differences as suggested by edz?

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Posted 01 August 2005 - 02:25 PM

Yes, I switched eyes and eyepeices (taking eyepeice from right and inserting it into left to r/o eyepeice problems).

Is it possible that perhaps the Miyauchi f/8 71mm might be better choice for Moon? (not withstanding this particular problem I am experiencing)

Gary

#32 Mr. Bill

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Posted 01 August 2005 - 03:01 PM

Yes, I switched eyes and eyepeices (taking eyepeice from right and inserting it into left to r/o eyepeice problems).

Is it possible that perhaps the Miyauchi f/8 71mm might be better choice for Moon? (not withstanding this particular problem I am experiencing)

Gary


Certainly can't hurt to go to a slower focal ratio to minimize objective aberrations; CA, SA, spherochromatic, and lateral color. All things otherwise being equal (coatings, glass)

Of course, you're losing aperture for DSO viewing.

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Posted 01 August 2005 - 03:13 PM

Yes, I realize that, but when I seriously evaluate my needs, I have the 10" Meade for my DSO work, and wanted the bino's for my quick grab and go, which is my backyard stuff, lunar observation and terrestrial viewing. (can't do DSO stuff from my light polluted skies)

Gary

#34 Mr. Bill

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Posted 01 August 2005 - 04:35 PM

Yes, I realize that, but when I seriously evaluate my needs, I have the 10" Meade for my DSO work, and wanted the bino's for my quick grab and go, which is my backyard stuff, lunar observation and terrestrial viewing. (can't do DSO stuff from my light polluted skies)

Gary


Sounds like "analysis paralysis" time.....

Been there, done that....good luck!

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Posted 01 August 2005 - 06:42 PM

LOL...i will just put that decision into the hands of Kevin, and follow his recommendation...let him do the "analysis" :)

Gary

#36 Mr. Bill

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Posted 01 August 2005 - 08:34 PM

LOL...i will just put that decision into the hands of Kevin, and follow his recommendation...let him do the "analysis" :)

Gary


Good choice....he's The Man IMO.....

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Posted 02 August 2005 - 06:51 AM

Having ANY kind of abberration on the Moon will just not be acceptable to me at all inasmuch this is the primary purpose for the decision to buy these bino's

If this is truely your requirement, then you bought a sub-par binocular. The BT100 will show a slight amount of CA. I have only seen this on the moon and even then there is only a razor thin amount of color on the limb. The FOV is not completely sharp from edge to edge. It nearly is, about 95% out. According to your requirement you may this to be unacceptable as well.

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Posted 02 August 2005 - 08:09 AM

A little CA is not all that distrubing to me, and a minus-violet filter could resolv that issue i beleive. I followed Ed's (and others) suggestions and gave them another try, both daylight and nighttime. There is something terribly wrong with these optics! If i look thru the matching finderscope, those lens are crystal clear with excellent thru-put of light transmission. THe binoculars are "dark", really losing LOTS of light, not to mention overlays the entire view with a "thick" yellow haze. The back focus star pattern gives an elongated oval. ( i dont know the technical terminology well enough to express this scientifically). If the optics in the bino were as good as in the finder scope..i would be tickled pink! LOL

Gary

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Posted 02 August 2005 - 08:49 AM

Of all the optical problems that are inherent with bins, CA should be the least of anyone's worries. The rest of the things you are observing does sound pretty bad and atypical of the other BT100s. I hope your replacement comes quick and painless.

#40 aporigine

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Posted 02 August 2005 - 02:12 PM

Regarding Miyauchis -
I have the 20x100 "Galaxy" non-fluorite. I am enjoying them, but they have some glaring excursions from optical and engineering perfection. Since I can only compare them to other binos I've owned, I hesitate to really nail down what bugs me about them. What follows is the subjective review of one pair by one old coot.

1) Very very fussy in re eye placement - these binos are intolerant of more than a millimeter off-axis.
2) Small "good" field. I estimate 25% of the field to be usably sharp when a star is focused in center field. In the outer 75%, star images show severe radial streaking and chromatic smear.
3) CA on Moon and Jupiter isn't subtle. Definitely worse than in my achro Obie 20x90s. Moon has a rim that's violet in some places, tennis ball green in others.
4) Eyepieces! I'm not sure how much of the above color/sharpness porblem can be blamed on them. Mechanically they are way too loose. i tried various greases and waxes to stiffen their action. What I did end up doing was to finally apply aquarium silicone to the focuser threads. This didn't freeze the eyepieces, but the silicone "boogers" rolling around in there gave a good feel to the focuser - it's a little less prone to being knocked out of focus, and the focusing action is smooth.
Since my overriding interest is DSOs, these flaws are not Mission Critical for me. I am pleased how "bright" the field images are. It's like owning an old Porsche - it does some things very very well, and others ... well, one adjusts. At this price however I'd expect a Lexus - all the features without all the "character".

How this translates to the smaller Miyauchis I don't know.

cheers aporigine

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Posted 02 August 2005 - 02:34 PM

I spoke with Helen today who had relayed my problems to Kevin (whom is out of town until next Monday). She conveyed to me that he was extremely embarrassed that I should have recieved such a poor example of what these bino's are capable of, and that when he returns next week, he will hand select and personally star test (and lunar test) a set of bino's and ship to me the BEST that his company has to offer! He further told Helen to convey to me that these bino's are absolutely fantastic on the moon, so he is really perplexed as to the causal factors of my subpar optics, but will insure i get a superb example! (this is exciting!) It's good to know that he believes these to be excellent for lunar observation, and her message to me has put my mind at ease. In two weeks, I will give an update on the new pair :)

Gary

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Posted 02 August 2005 - 02:52 PM

That sounds like Kevin alright. It's a shame that you received sub-standard hardware, but it's great that Kevin will hook you up. I would be curious to hear about what he sees when he tests the BT100 you are returning. It would be satisfying to know that your claims are real! (and that you're not crazy.)

#43 Joad

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Posted 02 August 2005 - 04:00 PM

Regarding Miyauchis -
I have the 20x100 "Galaxy" non-fluorite. I am enjoying them, but they have some glaring excursions from optical and engineering perfection. Since I can only compare them to other binos I've owned, I hesitate to really nail down what bugs me about them. What follows is the subjective review of one pair by one old coot.

1) Very very fussy in re eye placement - these binos are intolerant of more than a millimeter off-axis.
2) Small "good" field. I estimate 25% of the field to be usably sharp when a star is focused in center field. In the outer 75%, star images show severe radial streaking and chromatic smear.
3) CA on Moon and Jupiter isn't subtle. Definitely worse than in my achro Obie 20x90s. Moon has a rim that's violet in some places, tennis ball green in others.
4) Eyepieces! I'm not sure how much of the above color/sharpness porblem can be blamed on them. Mechanically they are way too loose. i tried various greases and waxes to stiffen their action. What I did end up doing was to finally apply aquarium silicone to the focuser threads. This didn't freeze the eyepieces, but the silicone "boogers" rolling around in there gave a good feel to the focuser - it's a little less prone to being knocked out of focus, and the focusing action is smooth.
Since my overriding interest is DSOs, these flaws are not Mission Critical for me. I am pleased how "bright" the field images are. It's like owning an old Porsche - it does some things very very well, and others ... well, one adjusts. At this price however I'd expect a Lexus - all the features without all the "character".

How this translates to the smaller Miyauchis I don't know.

cheers aporigine


I have read in other places (including the Oberwerk site) that the Miauchi non-flourite 100mm have a significant CA problem. When it comes to lunar viewing, my big Obies show a slender yellow fringe on the rim of the moon that goes away when I look directly at it and doesn't affect what I'm viewing at all. Not a hint of CA at the terminator nor in any crater shadow.

BTW, aporigine, your post may contain the first use of the word "boogers" on Cloudy Nights. Is there a CN historian in the house? :lol:

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Posted 02 August 2005 - 04:23 PM

NW....yes, I am very curious as to what his findings will be...and if he says they are absolutely fine, then I will know beyond a shadow of a doubt that HE is crazy!

Joad...that is not CA, it's a booger on your lense! lol

Gary

#45 aporigine

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Posted 02 August 2005 - 05:34 PM

Hi Joad
What a way to make history on CN! You made me lol. :bow:

I can live with the CA in the Miyauchis. I would imagine that many other consumers would find it more annoying. The optic bears a nice silkscreened "label" certifying that the objectives are Semi Apochromats. This seems to be an instance where the term is semi-useless at best, and semi-misleading wouldn't be too hard a term. If they didn't specify "four elements in three groups", I would have guessed that a Semi-apo has 1 1/2 elements. :grin:

What bothers me most is the smearing of star images outside the smallish Sweet Spot. How much of this is the fault of the eyepieces I cannot say. I am provisionally blaming the eyepieces, nominally Erfles but pretty seriously "doggy" compared to my scope and Obie eyepieces. I have taken to calling them Arfles. ...Since I am a DSO fan, I can comfily work with/around these subjective flaws.

And yet ... I wonder if I can substitute non-Miyauchi eyepieces. The fov of the Galaxys is 2.5 degrees, yielding an afov of a quite well-balanced 50 degrees for my tastes. Good fifty-degree eyepieces are legion ... could I find a way to adapt a pair of 25mm oculars to the bino body? That might be a winter project for me.

cheers aporigine :watching:


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