44 replies to this topic

[EdZ]

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

[EdZ]

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

edz

[Mr. Bill]

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?

[Mr. Bill]

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.

[Mr. Bill]

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!

[Mr. Bill]

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.....

[aporigine]

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

[Joad]

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?

[aporigine]

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

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.

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