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Ready to purchase - Orion 20x80 or 25x100?

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#51 Erik D

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Posted 04 May 2005 - 03:21 PM

15-20 years ago nearly all water proof military spec binos in 7X50( or Zeiss 8X30 ) were available in IF only. It was easier to seal IF binos These days most of the premium European water proof binos are Roof Prism with INternal center focus. A well designed, top quality CF bino should be every bit as good as IF bino.

I have had a pair of Celestron Water Proof RP binos for many years. Didn't mind the IF too much till I took up birding about two years ago. It's really inconvenient using IF binos for terrestrial observation if you have to change focus frequentyly.

I don't mind IF in astro binos but I'd prefer CF binos for most other applications. I was condisering the Burgess 25X100 S2 because it had CF but Bill Burgess told me his is no longer offering the S2. The Burgess S2 was introduced at NEAF 2004 but I am not sure if it ever went into volume production.

Erik D

#52 DJB


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Posted 05 May 2005 - 12:44 AM

Hello all,

I prefer IF. My eyes have nearly a five diopter spread between my near-sighted eyes, so I simply set 'em and forget 'em. My FUJI FMT-SX just cuts the mustard, whereas the Miyauchi Binon has more than adequate adjustment for my eyes (both "standard" 7x50mm's).

I agree with EdZ on the advantages of both systems. However, I have always detested the CF focus bridge that retains the two oculars for the CF bino. It can get alignment/travel jitters, unless we are talking a very beefy design, indeed.

I understand the CF units can be nitrogen filled/purged if an internal focusing design is implemented. Also the CF bino is generally better for birding and scanning where fast focus change is an advantage.

I have to believe that the military has investigated this to a degree in the past--probably has to do more with a waterproof design than most else. Otherwise, why would the military folks use the IF design almost exclusively?

Take care all,


#53 Guest_**DONOTDELETE**_*

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Posted 05 May 2005 - 07:09 AM

In the example of military bins, big ones which could be used for example with border monitoring (like the 20x120 Nikons recently seen on Ebay) or the BT100, it could be simply that engineering restrictions prevent the use of CF once a certain sized it reached. Can you imagine the BT100 with CF? I'm not saying that it is mechanically impossible, but the IF may be much easier production-wise for the larger binoculars.

Just guessing...

#54 Apracticalguy


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Posted 13 May 2005 - 02:47 PM

Let's keep talking!


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