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Subject: 請 指導 如何 選擇 bino [Print This Page]
Author: namsheetsim    Time: 7/02/2013 21:19     Subject: 請 指導 如何 選擇 bino

各位師兄師姐，我是一新丁，已有一個 Minox BV 8x25 (太太送的禮物)，覺不夠光，太太用的 BV 10x42 比較光, 我正研究什麼望遠鏡才適合我，但有些問題解決不了，請指教。 (前題: 不怕重量)

1.        My lay thinking makes me to think that a larger objective lens allows me to see more, but looking at the Field of View (FOV) of the Minox BV series, the FOV goes down with larger objective lens, from 421 f @ 1,000 yd (8x33) to 389 (8x42) to 342 (8x56).  Difficult to understand.

2.        My BV 8x25’s FOV is 358 yd @ 1,000 yd, while the BV 10x42’s FOV is 342.  But the image I saw in the 8x25 is smaller than the image in the 10x42.  Why?

3.        If I exercise my lay reasoning that a larger objective lens give a bigger image, similar to using a 19-inch computer monitor vs a 15-inch monitor (everything else equal), will I get a larger image with a 10x52 (e.g. the Minox BL 10x52 FOV 342 ft) compared to my wife’s BV 10x42 (FOV also 342 ft) ?

4.        If a larger objective lens gives a bigger image, can I choose a lower magnification but a bigger objective lens, e.g. instead of choosing BV 10x42, I choose BV 8x56, the FOV are the same, but to expect the ’56 will give a larger image of the shrunken in size by the 8x (instead of 10x)?  But then the brightness factor will increase from 17.64 (10x42) to 49 (8x56)!

5.        The twilight factor is most difficult to understand, a high magnification bino easily gives a higher twilight factor.  If I found that the colours are usually darkened (from blue to black, from brown to black etc.) when looking from underneath a tree in shade, and I want less colour distortion, do I need a bino with a higher magnification or a bigger objective lens?  E.g. the twilight factor of Minox BL 10x44 is 20.98 and that of BL 8x52 is 20.4, is the colour distortion less with the 10x44 or the 8x52?

多謝指教。
Author: thinfor    Time: 8/02/2013 10:04

Hi welcome to the forum.

From what you said, you seem to select binoculars in a scientific way.  Actually, you can get more detailed information in internet like Wikipedia:
http://en.wikipedia.org/wiki/Binoculars

For me, choosing binoculars have the following concerns:
i) Quality.  This is easy to know by observing other birders.  Swarovski and Leica of course are the best choices but also more expensive.  Minox and Olympus are medium brands and good too.  The good brand makes better lens with better coating and mechanism, just like Nikon and Canon lens usually provide better image quality.
ii) Weight.  Though binoculars are not extremely heavy stuff, prolonged birdwatching may cause tiredness, especially when you just hang your binoculars by your neck.

From my understanding, the expression A x B has the following meaning：
A = Magnification, B = Objective diameter
The above 2 parameters make the third and fourth criteria.
iii) Magnification - the greater the better, as the images will get closer.  A larger magnification leads to a smaller field of view.
iv) Objective diameter determines how much light can come into the binoculars to make brighter images.  It's very important as it directly affects performance.  For other parameters kept constant, your 8 x 25 should have a dimmer and vaguer image than a 8 x 42 binoculars.

For me, FOV is not so important in binoculars.  In photography, we may need wide angle to take shots that can give a wider view to exaggerate the object taken like scenery of mountain ranges, grassy terrain or desert.  But for birdwatching, we seldom need a wider view to see more birds because they are always so distant and we hope to be as big as possible!

So, to answer your questions:
1) May be a wrong concept, as (iv) said.
2) (iii) explains your observation.
3) Refer to (1).
4) Choose a lower magnification but a bigger objective lens - yes you can.  But usually there is a common range for the ratio of B/A, around 3-8.
5) I also don't know what is twilight factor.  But if you want to have a better lens that best truly reflect the color of the real objects, good brands usually have to be considered.  Like those big brand lens, they have many measures to prevent the optical flaws like diffraction and dispersion, e.g. specific coatings, aspheric lens design, lens made of fluorite, etc.  So the color distortion problem is not from A and B but the lens quality.  Of course, for same quality of lens, with a greater B, the image quality should be better.

Hope the above helps.

[ Last edited by thinfor at 8/02/2013 10:08 ]
Author: namsheetsim    Time: 8/02/2013 19:59

多謝提點, Thank You for your comments.
Author: akltsang    Time: 9/02/2013 10:24

1. The objective size determines the brightness and level of details of image.  It has nothing to do with FOV.

2. FOV is determined by eyepiece design.  You can have wide FOV 8x32(e.g. Nikon EII) or narrow FOV 7x50 (e.g. Fujinon FMTSX)

3. For bird watching, FOV, weight, waterproof, close focusing distance and focuser speed are more important.  Think about how you will use the binos.  For star watching, objective size, coating quality, magnification are more important.

Just my two cents.
Author: namsheetsim    Time: 9/02/2013 19:04

Thank you for your comments. 多謝指教。  Everyone has his own problem. Mine are:
1. i spot bird, raise bino, original view OFF the line = so i need a bigger FOV to increase the chance to keep the object in view
2. i have peripheral cataract, so in dim light, my effective 'pupil size' is smaller than my actual 'pupil size' (which is probably just ~ 5.5 mm because of my age) - so i need a bright bino as that will allow a smaller pupil in me - a.) the peripheral cataract part is not required to function, and b.) a smaller pupil means a deeper DEPTH of view.
So I will prioritize:
a. FOV, b. Brightness (8x preferred), c. Price, d. Weight.
Author: K_Chan    Time: 20/02/2013 18:33     Subject: Bushnell Legend Ultra HD

經師兄介紹、自己親眼看過，從Chicago網上訂購美國牌子Bushnell的Legend系列10x42雙筒，有ED鏡（extra-low dispersion)，約USD250，郵費另外。可以是另一選擇。Bushnell在香港有Office，網購但就沒有保養。在鴨記的代理fulibao有行貨，約HK$4200，一年保養。
要對眼(i)舒服、(ii)鏡清、(iii)robust。不太貴的，只有Zeiss的Conquest系列可以匹敵，也是ED鏡，九龍好生活有貨，$8800是合理，有十年保。“鵝仔" "萊啦" 可能更好，但沒有budget，故免問。
Binoculars Nikon Monarch 8x42，還有Olympus EXWP 10x42已有過。Nikon的在第二年爛掉，只不過是右眼focusing adjustor内裏的一條長幼型金屬pin斷折，修理要$1500，所以急急腳買了Olympus頂住，兩者好生活都是買$1800左右。但是Nikon雙筒的QC，令我三思“日本品牌”的將來。
一年保養，又有甚麽意思呢？最緊要，都是對眼利（或是視覺神經要掂)!
Author: namsheetsim    Time: 3/03/2013 11:35

多謝提點。但在新年時見鳥會 Minox promotion 已買了 BL 8x44, 感覺頗好。比太太的 BV 10x42 光。FOV 大些。但最好的是 focus 容易，景深大很多，舉鏡不用太多 adjustment 就找到目標,比 10x42 敏捷多了，tradeoff 是 image 細了少許，但暗影下的 image 明顯清楚很多.
Author: casualife    Time: 4/03/2013 13:20

一向沒有留意美國的望遠鏡，請問 Bushnell Legend Ultra HD 與 Olympus EXWP 比較，影像質素相差大嘛?
Quote:
Original posted by K_Chan at 20/02/2013 18:33
經師兄介紹、自己親眼看過，從Chicago網上訂購美國牌子Bushnell的Legend系列10x42雙筒，有ED鏡（extra-low dispersion)，約USD250，郵費另外。可以是另一選擇。Bushnell在香港有Office，網購但就沒有保養。在鴨記的代理fulibao有 ...
Author: K_Chan    Time: 14/07/2013 11:10     Subject: Bushnell / Nikon / Olympus / Zeiss

對不起，沒有check早前論壇。

三年前曾到尖沙嘴陳列室試過過BL Minox，覺得一般，有點over-Priced，包裝確實很精美。

如果比較Olympus EXMP 和 Bushnell Legend的10倍鏡，肯定是Bushnell清晰，層次好，惟色彩偏濃一點（紅色、黃色）。價格不同，Bushnell 用ED鏡片内地產，但Olympus日本產，我兩鏡都有用來觀鳥。

Nikon Monarch 5系列、7系列剛出台，前者近2000後者3xxx。我試過，7系列層次好多了，兩者都是ED鏡片，在内地生産，1年保養。三年前買的Nikon Monarch的8倍鏡（已經停產），剛好在第二年末期坏了，維修中心又對於雙筒望遠鏡既不熟行又不熱衷（500/4大炮或D7100等才是他們大茶飯），我心裏有陰影，決定放棄轉用Nikon雙筒。原來很多（大）牌子，都不是原厰提供維修，代理只做sales & marketing收錢，技術水平偏低。

鵝仔人人話好，十年保，但覺得marketing搞到over-priced，以顯示品質（現代市場策略，是價格決定質素，not vice versa)。心目中，Zeiss 的 Conquest 系列不錯（Victory 系列未試過），也是十年保，8xxx；他們今年出了Terra系列，據說也是ED鏡片，近4000，但香港無入貨，德國買同價，但有18%退稅（？）。

但，最重要，還是眼利。否則，俾台天文鏡我都無用。
Author: casualife    Time: 17/07/2013 13:08

謝謝詳盡分析。一向對"美國佬"的Bushnell有點偏見，看你的用後感應該可以一試.

或者可以分享一下在下使用 Minox HG 8.5x43 同 Zeiss Conquest HD 10x42 的感覺.
自己一直用舊款conquest 8x30 貪佢輕，後來太太有興趣觀鳥買左個 Minox HG 8.5x43. 當時有交換用，minox 影像較光和稍為清淅，我並不認同HG是如品牌所形容是"頂級質素"祗可說中上. 後來發覺8倍不夠又不想經常帶單筒便物色10倍鏡，不過不會再考慮 Minox，碰巧新款 conquest HD 發售便買了. 用後祗可以簡單講句，Zeiss 同 Minox 實在不同級數. HD 不單令我發現 Minox 的不足，相比之下我的8x30巳出現明顯距離，以 HD 的價位實在是合理. 現在我是有興趣一試 Conquest HD 的 8x32.

另外，絕對同意"眼利"是最重要的.

[ Last edited by casualife at 17/07/2013 13:27 ]
Author: HKBWS WY    Time: 11/01/2018 14:45

How to Choose Binoculars, According to Science – 15 Factors to Consider
- Jesse Miller

https://www.jenreviews.com/binoculars/


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