超低倍天文雙筒望遠鏡 Vixen SG 2.1x42 vs 裕眾 2.3 x 40

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TONGKW
中子星
文章: 1923
註冊時間: 週二 13 9月, 2005 14:35
來自: Hong Kong

超低倍天文雙筒望遠鏡 Vixen SG 2.1x42 vs 裕眾 2.3 x 40

文章 TONGKW » 週五 19 6月, 2015 23:27

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我很久以來都想擁有一台這類超低倍天文雙筒望遠鏡,
多謝Wongsir安排團購今日剛收到一台裕眾的 2.3 x 40。
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與這直接比較的會是:-
裕眾2.3 x 40天文雙筒望遠鏡(售價HK$650.00)
Vixen SG 2.1x42 天文雙筒望遠鏡 (售價HK$1,470.00)
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售價有頗大差別,不知在星空下使用時,兩者的光學表現如何。
最好有一晚來個比試
在外國網頁找到兩者一起的照片:﹣

Front View of Vixen SG 2.1x42 vs 裕眾 2.3 x 40
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TONGKW
中子星
文章: 1923
註冊時間: 週二 13 9月, 2005 14:35
來自: Hong Kong

文章 TONGKW » 週五 19 6月, 2015 23:28

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Side View of Vixen SG 2.1x42 vs 裕眾 2.3 x 40

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TONGKW
中子星
文章: 1923
註冊時間: 週二 13 9月, 2005 14:35
來自: Hong Kong

文章 TONGKW » 週五 19 6月, 2015 23:29

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Rear View of Vixen SG 2.1x42 vs 裕眾 2.3 x 40


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TONGKW
中子星
文章: 1923
註冊時間: 週二 13 9月, 2005 14:35
來自: Hong Kong

文章 TONGKW » 週五 19 6月, 2015 23:30

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Carrying Case of Vixen SG 2.1x42 vs 裕眾 2.3 x 40

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Eddy So
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文章: 11326
註冊時間: 週四 04 12月, 2008 22:35
來自: 中男海

文章 Eddy So » 週五 19 6月, 2015 23:47

[Good Job] 剛剛試過這個裕眾的 2.3 x 40,效果不錯,看多了許多星星!

Water
紅巨星
文章: 401
註冊時間: 週一 23 6月, 2014 01:40
來自: H.K.

文章 Water » 週五 19 6月, 2015 23:51

Vixen SG 2.1X 42 的出射光瞳面積較 SKY ROVER Opera Glasses 2.3X 40 大3倍。

TONGKW
中子星
文章: 1923
註冊時間: 週二 13 9月, 2005 14:35
來自: Hong Kong

文章 TONGKW » 週六 20 6月, 2015 10:41

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一間外國的代理是這樣介紹這類天文雙筒望遠鏡。
QUOTE
BLUE PLANET OPTICS
Introduces the Unique 2.3x40 Constellation View Wide-Bino
Want the widest possible field of view
when sweeping the Milky Way under dark
skies? Then consider Blue Planet Optics’
new and truly unique 2.3x40 binoculars.
The Constellation View Wide-Bino weighs
just 10.4 ounces and features eye-relief of 7
mm and a field of view at 1,000 yards of a
very wide 1,370 feet. That’ll grab some sky!
You'll notice from the accompanying
photo that there is no room in the assembly
for either roof or porro prisms. Because the
twin optical systems operate in Galilean
versus Keplerian mode, none are needed,
which results in the very compact, light-
weight assembly. The Galilean system does
not invert the image, so prisms are not nec-
essary to create an erect image.
Obviously, the low magnification fac-
tor of 2.3 versus the 40-mm aperture of the
objective lenses results in a large exit pupil
of 17 mm, reducing the effective aperture
of the system by an extent that depends
upon the user’s eye pupil dilation.
However, the large exit pupil results in ease
of eye placement and the small magnifica-
tion factor eases hand-held use of the
binoculars.
We’ve heard the experience of using
these binoculars described as more “binovi-
sion” than the typical binocular experience.
For more information or to order,
please visit www.blueplanetoptics.com.
UNQUOTE
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Kasai 2.3x40.jpg
Kasai 2.3x40.jpg (112.79 KiB) 已瀏覽 11647 次

TONGKW
中子星
文章: 1923
註冊時間: 週二 13 9月, 2005 14:35
來自: Hong Kong

文章 TONGKW » 週日 21 6月, 2015 17:36

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在外國及國內的業餘天文綱頁上找到一些這類低倍廣角双筒鏡的使用者報告,
看來這2款低倍廣角双筒鏡的整體表現相比之下各有千秋,
現時本港的天文愛好者也都有數十台這類低倍廣角双筒鏡,
在使用後請大家在這裡表示一下意見,使大家得以分享心得。
﹣﹣﹣﹣

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Vixen SG 2.1x42 双筒望远镜,一位國內天文愛好者使用報告
(請注意,這只是那位用者的意見)。
QUOTE
终于盼来了。开发这款 Vixen SG 2.1x42 小镜子,前后折腾了快一年,终于露面了。这是一款以观看星座为目的而开发出来的。是一款真正的星座镜。
Made in Saitama,是埼玉县。因为该款产品所用全部零配件,包括组装成品都出自该县。 实际上,生产厂家就是著名的天文双筒专家“宫内光学”!
对于伽利略式望远镜来说,没有固定的出瞳距离(眼点高度)和视场角。眼睛越向目镜方向靠,视场角就越大。眼点为 8mm 时,视场角大约11度;眼点为5mm 时,视场角大约是15度;如果你把眼睛凑到目镜表面大约 2~3mm 的话,能得到的最大视场角大约是28度了。
好了,现在,我们来谈谈它的光学表现:
1》中心清晰度:非常好,干净利落,清晰锐利。
2》良像范围:由于是伽利略式望远镜,没有一个清楚的黑白分明的视界环,所以比较难以确定,大体上而言,良像范围在 45% 到 50 %之间。
3》边缘像质:当然不好了,因为是伽利略式光学结构的局限性所决定的。
4》周边畸变:比较不明显(至少比想象的要少的多)。当初认为,伽利略式嘛,周边枕形畸变肯定严重,但是实际观看后发现,畸变实际上并不明显。
5》色差:中心像部分的色差非常少,肉眼几乎难辩。这可能跟伽利略式望远镜没有使用棱镜有关吧。
6》观看舒适度:首先,为了得到最大视场角,眼睛必须贴着目镜的感觉。另外,目镜瞳孔对于眼睛瞳孔的同心度要求也比较高,稍有偏离,色差的困扰就会出现。所以总的来说,观看的舒适度并不高。
7》景深:除 了外观精致,中心清晰,视场角大等亮点之外,景深也是该款产品的一大亮点。从最近距离的 2 米到无穷远,都无需再扭动目镜框调焦。可以说是我玩望远镜这么多 年以来遇到的景深最大的一款双筒望远镜了。景深大到这种程度,就跟双调啊中调啊的没有关系了。一旦确定好左右视度位置,就永远都不用再调整了。无论看远看 近,都不用调整。真方便!如果周边像质能再好一点的话,那就真是活脱脱一个完美的肉眼延伸器了。
原来非常昏暗的地面景物,也变的明亮可视了
观看星座:抬望眼,哇!整个猎户座尽收眼底,怎一个爽字了得。
当然了,观看星空的感觉肯定比不上 7x50 或者 7x42 等产品的效果。跟肉眼直接观看相比较,在 Vixen SG 2.1x42 的视界里,星点的数量明显增多了,星点的状态也非常令人满意(50%以内视场)。但是跟 7x50 或者 7x42 相比之下,效果还是不可相提并论的。Vixen SG 2.1x42 毕竟是星座镜,观看肉眼基本可辨的星座效果非常明显,但还是不太适用于流览星空银河之用。毕竟效果不够震撼。
超大视场角的一款星座镜,目前为止世面上出现的最专业的星座镜。
景深也是该款产品的另一大特色,一旦调整好左右视度位置,从最近距离的2米到无穷远处,均可聚焦而无需再做调整。是目前为止我遇到的景深最大的一款产品。从这个意义上来说,它甚至比带有中调结构的产品都方便。小小的个头,却有着410克的体重,是缺点,也是优点(全金属制造)。另外,表面处理做的非常精细,是优点,也是缺点(容易碰伤留下痕迹),用手接触后都会留下指纹痕迹,真舍不得用。表面喷沙再稍稍粗一点点就好了的感觉。
缺点是视界环模糊(伽利略式望远镜的通病),为了得到最大视场,眼睛要往目镜上凑,结果很容易在目镜表面留下污痕:
UNQUOTE
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TONGKW
中子星
文章: 1923
註冊時間: 週二 13 9月, 2005 14:35
來自: Hong Kong

文章 TONGKW » 週日 21 6月, 2015 17:37

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Kasai 2.3x40 双筒望远镜,一位外國天文愛好者使用報告
(請注意,這只是那位用者的意見)。
QUOTE
A week ago, the mail brought my Kasai 2.3x40. I bought it instead of the Vixen 2.3x42 because in a German Forum I had read the Kasai (probably made in Russia), despite being only about half the price of the Vixens, provided better edge performance as well as viewing-comfort. Since the Kasai's oculars' opening is restricted to 8mm, centering the eyes is easy which could exactly be one (or maybe "the") reason for what I mentioned before.
In my boyhood, I must have had over average night sight, for example being able to locate 13 stars in the Pleiades by naked eyes.
While meanwhile having grown over sixty, this ability has greatly decreased and today I can perceive only the six brightest stars and, due to suffering from astigmatism, am hardly able to properly locating (sketching) them.
Sharpness : On rights side very good, and since I did not specially study the edge => also esthetically pleasant.
With left eye never comparably sharp. Notice: My left eye suffers much more from astigmatism than my right one.
When I rotate the binocular 180 degrees (=>upside down), thus swapping left to right, the situation remains the same.
Conclusion: It's my eyes' fault and not the instrument's optics'!
Explanation: A Galilean refractor does not restrict your eye-pupil => you always watch with its full aperture. This way eye-astigmatism is fully revealing its disastrous consequences.
Whereas in a telescope, you will hardly (or not at all) notice it as soon as your telescope-eyepiece's pupil-diameter goes under 2.5mm.
Here my observations in yesterdays very transparent skies after midnight:
First of all, thanks to Saint Peter who, other than when we buy big instruments, did not seem to have become jealous at all of this little thing and hence, obviously has permitted the weather to be really first class yesterday evening.
M45 (Pleiades): 13 stars down to magnitude 6.5, location included (I could have drawn properly), however 7 of them mainly "blinking" more or less avertedly.
Hyades: wonderfully framed together with M45 in the same field
Orion: All the four brightest stars framed in one field! Many more stars than are visible to me naked eye.
M42: Clearly visible as a diffuse object "around a star".
Auriga: All of the five stars forming the pentagon beautifully enclosed in one field!
M37,36,38 (M36 and M38 much harder than M37) all visible and locatable.
M35, M41, M67 very easily visible and identifiable as diffuse objects (not mistaken for stars).
Jupiter with Ganymede included (was the most elongated of all the 4 Jovian moons yesterday evening).
Conclusion : under the stars (with both eyes): I am absolutely (!) excited about this little instrument's fully re-activating my boyhood's eyesight that I have already believed to have lost forever...
UNQUOTE
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TONGKW
中子星
文章: 1923
註冊時間: 週二 13 9月, 2005 14:35
來自: Hong Kong

文章 TONGKW » 週日 21 6月, 2015 17:38

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一位外國天文愛好者比較其擁有的 Vixen SG 2.1x40 vs Tento 2.3x40 使用報告
(請注意,這只是那位用者的意見)。
QUOTE
Widefield Binoculars ﹣Comparision of Vixen SG 2.1x42 vs Kasai 2.3 x 40
I have looked at them up online, and certainly see a family resemblance. But the Kasai 2.3X40 delivers the claimed 28 degree FOV (64 apparent) when one's eyes are snugged up very closely to the eyepieces. I wonder how much better one can do compared to the (assumed to be conservative) stated FOV of ~12 degrees for this unit? Hopefully rather more so, which the large objectives are after all there to provide.

A reminder: A Galilean's FOV scales as the diameter of the objective. At given power, double the objective diameter and you double the FOV. Provided the eyepiece has sufficient diameter at given separation from the eye. To maximize FOV, get the eye as close as possible; unlike the positive eyepiece, there is no external exit pupil and hence no fixed eye point.

The seeming too-large 'exit pupil' here is a consequence of the large objective chosen to expand the FOV. The light bundle for any one image point occupies only a portion of the objective, this effective diameter equaling the magnification multiplied by the observer's iris diameter. Forever farther off-axis image points, the location on the objective for the relevant light bundle moves ever farther from center to edge. This is in the very same manner that most wide angle camera lenses operate.

I got the Vixen SG 2.1x42 last Friday from Mikasa Camera and have been carrying them ever since. The FOV does not increase appreciably between having your eye comfortably placed (the above 8mm seems accurate,) and smushing your eye right up next to the glass. I've never looked through a Widebino to be able to compare. I'd be happy to try any technique you all might suggest to figure out the gain. They focus closer than 2 meters, as I am 5'10" and can focus on my knees. This website has some nice pictures taken through the thing. I was curious about these too, and am very happy with them. Construction is certainly top-notch.

The Vixen SG 2.1x42 has big eyepieces compared to the ~8mm diameter on the WideBino! This is why for the latter there is a marked difference in FOV coverage depending on eye distance. In this guy the more than generous eyepiece diameter permits comfy eye distance without cutting into the FOV. And the smaller AFoV does help here, too.

With the WideBino, in spite of the small eyepiece diameter, there is much sensitivity to eye centration if aberrations are to be minimized. This is due primarily to the quite strong curvature on its eyepiece surfaces. This Vixen appears to have gentler curves, which suggests greater latitude on eye centration. Can this be verified, or at least be provisionally confirmed?

Initial impression of field of view was surprising. If eyes are comfortably positioned over the eyepieces then the true field appeared larger in the Vixen. Squeezing the eyes into the Widebino eyecups was required to get a similar field to the Vixen. No exact figures to go on but the Vixen is the more comfortable instrument. The night I first compared them I found that the Vixen was also less critical on eye placement, where the Widebino requires very careful setting of inter-pupillary distance. The conditions I last compared them under had a first quarter moon in the sky but star images at center of field appeared tight in both instruments. Keeping the eyes concentrated on the center of the field and moving the binocular to sweep up objects yields the most pleasing views.

My WideBino (the original Russian version) has had its rearmost perforated cover plates removed, which permits minimal eye distance. And so I can just fit within its FOV the entirety of the Big Dipper, and Scorpius (row of three brighter claws to tip of stinger). This confirms the claimed 28 degree TFoV, albeit via 'extraordinary' measures. With eyepiece perforated plates in place, the max. FOV is about 22 degrees.
My Russian unit does indeed have 'frosting' on the eye pieces. This is a fairly wide, ground conical taper on the edge, which restricts the diameter of the rearmost surface. I presume this was done as a means to aid eye centration. I'd not call it a baffle of any sort, for it does scatter light rather obnoxiously. I painted these conical, ground surfaces black, which very greatly improved things.
The rear, black, perforated caps simply unscrewed. But these also retain the knurled sleeves, which easily fall off now. I placed small strips of masking tape on the inside walls of these sleeves so as to somewhat fill the gaps between them and the eyepiece barrels. This holds the sleeves in place via friction, but with sufficient freedom to turn for focusing.
Interesting that Vixen states a mere 12 degree FOV, while the full Dipper fits within, confirming at least a 25 degree FOV.
Regarding magnitude gain, this is easily calculated. We will initially assume virtually 100% transmission efficiency. And that the binoculars always operates at the user's pupil diameter, we know sky brightness remains the same, and hence the brightness gain on point sources scales as the square of the magnification.
At 2.1X, the areal increase on the entrance pupil is 2.1^2 = 4.41. The magnitude equivalent is LOG(4.41) * 2.5 = 1.61.
We might subtract at most 0.1m, to account for transmission loss.
Note that for users who are rather farsighted or nearsighted, the eyepieces at infinity focus will be located farther from or nearer to the objectives, respectively. This will result in a respective slight increase or decrease in magnification.
UNQUOTE
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TONGKW
中子星
文章: 1923
註冊時間: 週二 13 9月, 2005 14:35
來自: Hong Kong

文章 TONGKW » 週日 21 6月, 2015 17:40

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另外一位外國天文愛好者比較其擁有的 Vixen SG 2.1x40 及 Tento 2.3x40。
(請注意,這只是那位用者的意見)。
QUOTE
I got my very own pair of Vixen SG 2.1x42 in the mail today from Optics Planet. I just went out and compared them to my Tento 2.3x40 Owl Eyes under overcast daylight skies. What I've found so far:
1. I can get 27.5° TFOV out of my Tento 2.3x40 with the eye lens thread-on caps still on (I measured on the night of 4/26/2015, using Stellarium, and could fit Pollux and the Moon at the very edges of the FOV and still see them both. I have to remove the caps to get a TFOV approaching the Vixen.
2. The eye placement of the Vixen SG 2.1x42 is less critical.
3. The Tento 2.3x40 is sharper than the Vixen SG 2.1x42 once you get about 40-50% out in the FOV all the way to the edge; in the center they appear the same. In the Vixen SG 2.1x42, there are odd bands/rings of varying and increasing blurriness/defocusing (it's like there are 3 bands, and each one steps it up) as you get further out that I can easily see beginning in the outer 50%.
4. Either I can see metal particles all around the eye lens in the Vixen SG 2.1x42, or it's the ground edge of the eye lens; I'm not sure. I can't see them looking straight thru at all, but, if I tilt the binoculars just a bit, I can see them, but this is from inches away, so I'm not viewing thru them, only inspecting.
5. The Vixen SG 2.1x42 is (obviously) heavier than the Tento 2.3x40.
6. The focusing of the Vixen SG 2.1x42 is much, much smoother.
7. Chromatic aberration is more noticeable in the Tento 2.3x40; it's not a lot, but it's there.
8. The Tento 2.3x40 has a very slight yellowish-green tint to the view; the view of the Vixen SG 2.1x42 appears natural.
9. You're gonna immediately get eyelash oil on the eye lenses of the Vixen SG 2.1x42 unless you don't have eyelashes; it'll take a little bit longer with the small opening thread-on caps on the Tento 2.3x40.

OK, I was finally able to compare the Vixen SG 2,1x42 with the Tento 2.3x40 under the night sky a few nights ago:
1. I can get 32.75° TFOV out of the Vixen SG 2.1x42; I could fit Vega and s Hercules at the edges of the FOV.
2. Those bands/rings of defocusing/blurriness in the Vixen SG 2.1x42 seem to make for some very noticeable and highly annoying edge of field brightening.
3. The Tento 2.3x40 is sharp over the majority of the FOV; the Vixen SG 2.1x42, not so much, by far - it's sharp over maybe 50% of the FOV, then, it blurs off steadily to the edge.
4. Stars look like the default Stellarium view (brighter stars are bigger) in the Tento 2.3x40; in the Vixen SG 2.1x42, they focus down to further pinpoints. I find the Tento 2.3x40 view more pleasing by far at night based on this as well as #2 and #3 above.
5. The big surprise, and I only kept comparing this attribute for the entire time I was out - the Tento 2.3x40 shows MORE stars & objects (goes deeper) than the Vixen SG 2.1x42 in a given patch of sky. Maybe it's due to the extra 0.2x magnification, I really don't know. M13 was visible direct (but faint) with the Tento 2.3x40; it simply wasn't there in the Vixen SG 2.1x42 - at all. In Virgo, ω Vir (m=5.20) and 4 Vir (m=5.30) were directly visible in the Tento 2.3x40; they were only barely visible using averted vision in the Vixen SG 2.1x42, and they blinked in and out even then.

And three more daylight observations:
1. The Vixen SG 2.1x42 is ever so slightly sharper in the center of the FOV.
2. The Vixen SG 2.1x42 shows slightly better contrast than the Tento 2.3x40.
3. The up close view (~10' away) of the Vixen SG 2.1x42 appears sharper, more vivid, and has more contrast than the Tento 2.3x40.
UNQUOTE
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skyfiction
主序星
文章: 153
註冊時間: 週六 23 8月, 2014 12:04

文章 skyfiction » 週三 22 7月, 2015 19:41

haha..我又學咁多位師兄買入個3x34既望遠鏡玩下.......hehehe......

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