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CharlieInDayton
member
Reged: 12/28/05
Posts: 75
Loc: Directly above Earth's center....
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This is mainly an eyepiece query, even though the EP's in question will go in big binos...so I put it over here...
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It doesn't matter what you're looking at.
It doesn't matter what you're looking through.
It never looks like the pictures...
Charlie in Dayton
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edwincjones
Post Laureate
Reged: 04/10/04
Posts: 4419
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The down side of the TV zooms with binoculars is the narrow FOV.
edj
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n w arkansas
Binocular, Solar, General Amateur Astronomy
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grbrown
professor emeritus
Reged: 07/09/05
Posts: 643
Loc: Ampthill, UK, 52:02N 0:30W
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I'm with edj on this one. In addition, optical quality of many if not all zooms is seriously compromised, so taking into account their narrow FOV I never even considered them. 
For our BT100-45s we now have no fewer than four pairs of Siebert Ultras, in 24mm, 17, 13 and 9 FL, all with 65+ degrees AFOV. We don't do much astronomy it has to be admitted, and the 1.4mm exit pupil of our 9s is the lowest I reckon is practical in daylight. The 9s give us 66x. 
If you are looking to use a wide range of magnifications with your 80s, I suggest you have to consider a lot of EPs! You could half the number with Barlows, but a 2x would be more appropriate, using a suitable scale of EP exit pupil increments. Ours are in steps of [square root of 2 over 2], ie .707 (approx 4mm, 2.8, 2 and 1.4mm). 
Before going the Barlows route, check you have enough clearance above your prisms to get them in without the two coming into contact with each other. Measure from the top of the prism to top of focusser, with it screwed right home, to be on the safe side and contact your preferred Barlow supplier before making any commitment! Our 100s are OK for Siebert's 2x Barlow, but I never tried them and decided to go the EP way. 
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Graham
"one eye good, two eyes better...the more I look, the more I see"
BT100-45 degrees, plus 35,24,17,13,9mm Sieberts
15x80, 7x50 Steiners
12x50, 10x42, 8x20 Leica Trinovids
7x35 Minolta
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CharlieInDayton
member
Reged: 12/28/05
Posts: 75
Loc: Directly above Earth's center....
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I suppose I should have said that I already have the 8-24's...
Anyway...the advice about the fit of the Barlows will be taken into account. Measurements will be made.
The narrow(er) FOV from zooms doesn't seem to detract terribly from my viewing pleasure. Of course, in my newbietude, this may be a case of not knowing what I'm missing...sounds like it's time to start raiding everyone else's EP stash at stargazes in the name of experimentation.
Further commentary welcomed, especially on the subject of "What's better -- Barlows or the equivalent PowerMates?"
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It doesn't matter what you're looking at.
It doesn't matter what you're looking through.
It never looks like the pictures...
Charlie in Dayton
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later
sage
Reged: 01/16/05
Posts: 446
Loc: Posen, Michigan
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Going against the grain....and may I state that I agree with this statement,
" The narrow(er) FOV from zooms doesn't seem to detract terribly from my viewing pleasure. Of course, in my newbietude, this may be a case of not knowing what I'm missing"
Im happy with my click stop zooms.
Of course, I plan on aquiring a set of fixed mag EP's in the future. The quality of the BT100-45's still just amazes me everytime I look through them.
"optical quality of many if not all zooms is seriously compromised"
If the views I am enjoying are "seriously compromised" , then I am looking forward to even better views with a set of fixed mag EP's
Gary
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Galileo 15 X 70
Oberwerk BT100-45
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