沙鹿的星空

[yao]

大小懸殊的40mm目鏡, 大的是Meade SWA 40mm 70度目鏡(取自CN)

[yao]

幼稚園等級難度的手持雙星, 10X??以上雙筒一定要試

Nikon SP 18X70手持(躺睡袋+墊枕頭)成功解析雙魚座的亮星:
雙魚座Psi1 Piscium(Psi1 Psc, ψ1 Piscium, ψ1 Psc)

尋找難易度: 10%-15%左右非常容易
成功解析度:  0%-5%(ψ1Psc A 與ψ1 Psc B 完全沒難度, 幼稚園等級難度)
顏色: 藍白
美麗度: 85%(兩顆星亮度, 顏色超相近.......炯炯有神的一對藍白眼睛橫空出世於黑暗背景中)

Psi1 Piscium (Psi1 Psc, ψ1 Piscium, ψ1 Psc) is binary star in constellation of Pisces. It is approximately 280 light years from Earth, based on its parallax.[1]

The two components of Psi1 Piscium are both A-type main-sequence stars.[3][5] The primary has an apparent magnitude of 5.273, while the secondary is slightly dimmer, with an apparent magnitude of 5.455.[2] The primary itself is a close binary, with two A-type stars that orbit each other every 14.44 years.[3]

Psi1 Piscium is moving through the Galaxy at a speed of 22.5 km/s relative to the Sun. Its projected Galactic orbit carries it between 22,800 and 24,300 light years from the center of the Galaxy.[8]

[yao]

8X手持雙筒(朗峰平場pro 8x42)可分解的雙星: 船帆座gamma(實際上是四合星)

不但可以分解, 而且也能看出gamma 1與gamma不同的顏色

[yao]

APM 150 mm 45 ° ED-Apo Bino for 2 Inch Eyepieces
volume weight: 50,00 kg
products weight: 18,70 kg
delivery time: 2-3 months
product number: APM-ED150-Bino45-FK61
8.490,00 EUR
Netto Export Preis: 7.134,45 EUR

https://www.apm-telescopes.de/en/binoculars/giant-binoculars-100mm-aperture-more/apm-150-mm-45--ed-apo-bino-2-inch-eyepieces

現在是ED版本的, 之後會出SD版本的(似乎欲眾天虎今年五月已出)

[yao]

可能是說明雙筒亮度與顏色最詳細的一個網站

www.greatestbinoculars.com/allpages/articles/coloursandbrightness.html?fbclid=IwAR2rgrbWtAY89riHAMfNFJh447kuLjZ-HOW4R5q5hcZAlD7L0ZSfJNgUUgI

[yao]

轉發

业余天文望远镜小史｜50年代的美国梦

read:https://mp.weixin.qq.com/s?__biz=Mzg2NjA4Nzc1OQ%3D%3D&mid=2247483714&idx=1&sn=4d852767b2b50eaf36553eed4d596d01&chksm=ce516762f926ee74379ef30b6fb20c7913d45d10e631c4d49e14a245cb2dcbead8ab52a4724f&scene=21&fbclid=IwAR3tycD8bVaGjiIMvzn8X9mtQJTHIEnvtRQ3eNBwCD4pLxW8Y2-jB3XvhqM

[yao]

(續前)Optical Craftsmen前幾年還出好幾個型號的超平價赤道儀, 如今似乎再也找不到了???

https://uncle-rods.blogspot.com/2012/07/parades-gone-by.html?fbclid=IwAR33LvPpfAHtKTikufZYNpK0oWGeiADL5WOQUB-BAABoSrivlBq1xbXPRis

現在Edmund分成兩個公司

Edmund Optics(最出名的是Edmund RKE目鏡, 尤其28mm)
Scientifics(最出名的是Astroscan)
Edmund RKE目鏡與Astroscan應該都是Edmund時期的產品

圖一 Edmund RKE 28mm(floating in space)
圖二 現在的 astroscan

[yao]

大犬座HD 56577
冬季的輦道增七(顏色與亮度對比稍遜半籌)

尋找難度: 15%大犬delta至大犬tao至HD 56577
(apm ed 20x70, 3.3度平場視野)
分解難度: 25%(躺著手持apm ed 20x70)
美麗度: 85%(主星為黃, 伴星為藍)

Right ascension
07h 16m 36.83423s]
Declination
−23° 18′ 56.1398″
Spectral type
K4 III

圖一 輦道增七(實際上類似大犬座HD 56577, 只是主星羽辦星顏色對比比較淡些)
圖二 大犬座(HD 56577在大犬tao或是NGC 2362上方不遠處)

[yao]

可變換目鏡(倍率)手持雙筒鏡口徑上限為85mm

實務1. 2047天文工作室去年推出一款85mm ED雙筒，廠商宣稱正常情況下可手持，以終極手持雙筒鏡來販售。

實務2.Docter ED 40x80在clouynights的雙筒論壇上有一活躍的同好對手持結果感到滿意。

實務3.我自己也有手持25X100幾個月過，結果還可以。例如20X80看不到的M1手持25X100就看的到。我猜與Docter ED 40x80相比雖然倍率小，但是Docter的重心更好把握+Docter的筒徑小更好抓握...........所以兩者手持難度應該差不多。

當然雙筒手持最好是配合躺椅+枕頭。雙筒手持配合睡袋+整頭也很讚。

當然10X50與20X70與40X80手持巡天的滿足感是不同檔次.......。

是何檔次??EDZ雙筒(松本除外)指數: 夜間非極暗天體可視的總數量=倍率X實際口徑的開平方X雙筒鏡品質(約1.2-0.

圖1. 2047天文工作室85mm ED雙筒
圖2. Docter ED 40x80
圖3. 早期astrocan

[yao]

透過雙筒望遠鏡看晚霞最漂亮的是一直變換的顏色與一直變換的雲層如細私紗綢般的結構

用高倍與低倍看的感覺各不相同(nikon 8x30 eii vs takahashi 22x60 apo)

nikon 8x30 eii看晚霞會有點色差..........

[yao]

Iota Cancri

方式: 手持。

器材: Apm 20x70 ed。

尋找難易度: 5%-15%(找到M44後就很容易。由M44至Gamma Cancri至Iota Cancri。

分解難易度: 5%。(30角秒間距)

好看度: 75%。(視器材與天氣而定。當然與上架與否/個人喜好/個人期望度/個人視力...........而定)。

顏色: 極亮白而帶黃的主星G-type與極亮白而帶藍的伴星 A-type。亮度差10倍(2.55等/4.02 vs 6.57)。當然透過

Takahashi 22x60看的顏色會更漂亮。

Iota Cancri (ι Cnc, ι Cancri) is a double star in the constellation Cancer approximately 300 light years from Earth. According to Sky-Map.org, it also has the name Decapoda.

The two stars of ι Cancri are separated by 30 arcseconds, changing only slowly. Although no orbit has been derived, the two stars show a large common proper motion and are assumed to be gravitationally related.

The brighter star, ι Cancri A, is a yellow G-type giant with an apparent magnitude of +4.02. It is a mild barium star, thought to be formed by mass transfer of enriched material from an asymptotic giant branch star onto a less evolved companion. No such donor has been detected in the ι Cancri system, but it is assumed that there is an unseen white dwarf.

The fainter of the two stars, ι Cancri B, is a white A-type main sequence dwarf with an apparent magnitude of +6.57. It is a shell star, surrounded by material expelled by its rapid rotation.

維基圖片

[yao]

雙筒望遠鏡的實際總集光力應該是下面那樣算吧??

雙筒望遠鏡的實際總集光力=有效亮度比率(brightness ratio)x 雙筒透光力x 實際有效口徑的面積

1. FUJINON 16X70實際總集光力=72%X95%(廠商公布數值)X4900 =4335.16
2. Oberwerk 15x70實際總集光力=66%x85%(假定數值)x3965(實際口徑)=2224.36
3. Takahashi 22x60實際總集光力=89%x95%(假定數值)x3600=3043.8

https://www.cloudynights.com/articles/cat/cn-reports/binocular-reports/comparing-binoculars-go22x85-wo22x70-tak22x60-r2333?fbclid=IwAR1Re-7PVsrqgSFr-29j03AsrnWvMZy3o0B-swybrBXWqXQvLZtLgpPys00

[yao]

Olympus EXWP I 10x42這只雙筒很有名, 也廣受好評, 曹大貓咪似乎也有推荐過

2018 10月底, Olympus 8x42 PRO與Olympus 10x42 PRO推出, 主要標榜中價位($469.00)高透光(94%)
結果All bino測出的透光力是84.7+/- 1%

實際上中心透光率超過94%的量產雙筒也了了無幾

For a Schmidt-Pechan pair of binoculars that costs less than 500 Euro it was a really bold declaration; after all a level of 90% is rarely exceeded even in devices 2-3 times more expensive.

似乎Fujinon等鏡子也有這種問題(至google輸入關鍵字 astro talks earnest)

[yao]

以下梅西爾以APM 20X70 ED在沙鹿都看的到(手持)

M107與M20除外(SQM=21.5用APM 11X70看107沒問題)

M70難度很大(前幾年好一些)

M11(M26左上)與M80(M4右上)圖上有圈圈但沒標示

[yao]

瞳孔距離(Pupillary Distance)測量儀測出的瞳孔距離絕非雙筒鏡使用者的真正使用瞳孔距離

Cloudynights上是說看遠處要另加瞳孔距離測量儀數值1-2mm

網路上是說說看遠處要比看近處另加2-4mm

圖:雙筒顏色與亮度