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Big apperture (80-100mm) binoculars performance? Terrestrial viewing (1 Viewer)

Im waiting for the reply of a vixen BT81 owner ... i tell you a soon he answer. There's a italian review that says the glasses are between FPL51 and FPL53 ... will see ... i think a portuguese can understand the main italian text, if not use the translation tool on google.

http://www.davidesigillo.eu/test_vixen81.html
 
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More good news ... read (this would be my personal choice)

If these are the usual Sky-Watcher/Synta/Celestron/whatever versions, you CAN reach focus without any barlow or GPC with a Baader Maxbright or Mark V binoviewer, if you replace the focuser with a Kasai Crayford, attached via a Baader adapter, because this focuser is around 40mm shorter than the standard focuser.

With the Maxbright, this gives a max field on the 120 of around 2° and 1.7° on the 150. With the Mark V, the field increases to 2.7° and 2.2°, respectively.

I have replaced the focuser on my Synta/sky-Watcher 150mm f/8 with a Kasai Crayford and can EASILY reach focus with ANY eyepiece in my Maxbrights with over half an inch to spare with even my 25mm Zeiss microscope eyepieces, which require unusually much back focus. I can even use a Baader amici diagonal which gives a RACI image!

The focuser replacement is a five-minute job that requires no modifications and no tools except a couple of screwdrivers.
Click to expand...

http://www.cloudynights.com/ubbthre...=collapsed&sb=5&o=all&fpart=1&vc=1&PHPSESSID=

In theory, a skywatcher ED 120, 1200 eurosan the maxbright, cheaper and easiest to find than the denks ... 1400 euros in telekop express. Then the eyepieces.

pros: over the maks: well, nothing against the maks but i like the ED refractor vision ... a little more fov (40x with 82 afov) refractors dont need such cool down time, and are more resistant to lose collimation. Its a little bit more off road, lets say
contras: heavier and expensive, and less aperture than the C6 mak, much more expensive and heavier than the c5 ....

This combo results in a 85 mm binoculars, but remember, always keeping the resolution of the 120 original source.

I would like to compare this against a Docter 40x80 ... and see if it half of the price, despite the weight and package, is worth ... or even with including that :king:

oh i forgot, add the prism in all the BV combos ...
 
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Rui_Caratão said:
From what I could understand a few Vixen BT 81S-A owners sent them back and went to APM semi-apos http://www.cloudynights.com/ubbthreads/showflat.php/Number/5038087

View through Vixen BT81S-A with NLP? or NLV? eyepieces
http://youtu.be/fP-i9vDrM3w
Click to expand...

Forget it ... thats astro use, in terrestrial you dont find that problem. The guy is doing stargazing :t:

I finally contact with one owner, its says can reach 50x after CA begin to bother, wich is what i suspect. Maybe it can be pushed more in some situations, anyway is better than the chinese semi apo/quater APO etc, same prize and much lighter.
 
Cosme,

The 32mm plossels are 50-53º AFOV.
In your cost estimations you are forgetting the image erector. Which one you are planning to use?
A 120mm refractor on field use isn't practical - too long!...
Focal reducers don't work well on daylight use, specially on reflectors - they dont increase light availability and reduce contrast / image quality.
If you plan to only go until 70x a 80mm refractor is ok - with the binoviewer the light is split in 2 but the brain merge it again...;)
If you plan to use a diagonal or erecting prism that doesn't induce magnifications increase I would suggest you http://www.teleskop-express.de/shop/product_info.php/info/p1631_TS-80mm-f6-25-FPL-53-Triplet-SuperApo---2-5--Focuser---3-different-focus-positions.html or http://www.teleskop-express.de/shop/product_info.php/info/p5964_TS-90mm-f6-6-FPL-53-Triplet-SuperApo---2-5--focuser---3-focus-positions.html.
As I use the FSA-L2 that induce magnification increase I had to go to a faster model. However, latter I tested my bino-erector combo in a TS 80 and it worked well at <80x but with my TMB92 I can go over 100x... :t:
 
DRodrigues said:
Cosme,

The 32mm plossels are 50-53º AFOV.
In your cost estimations you are forgetting the image erector. Which one you are planning to use?
A 120mm refractor on field use isn't practical - too long!...
Focal reducers don't work well on daylight use, specially on reflectors - they dont increase light availability and reduce contrast / image quality.
If you plan to only go until 70x a 80mm refractor is ok - with the binoviewer the light is split in 2 but the brain merge it again...;)
If you plan to use a diagonal or erecting prism that doesn't induce magnifications increase I would suggest you http://www.teleskop-express.de/shop/product_info.php/info/p1631_TS-80mm-f6-25-FPL-53-Triplet-SuperApo---2-5--Focuser---3-different-focus-positions.html or http://www.teleskop-express.de/shop/product_info.php/info/p5964_TS-90mm-f6-6-FPL-53-Triplet-SuperApo---2-5--focuser---3-focus-positions.html.
As I use the FSA-L2 that induce magnification increase I had to go to a faster model. However, latter I tested my bino-erector combo in a TS 80 and it worked well at <80x but with my TMB92 I can go over 100x... :t:
Click to expand...

Hi David,

You can go almost 2 degrees in a 900/120 ed refractor without any path or corrector, using maxbrights bv, wich are only 23mm of clear apperture ...

Post number six. They key is use a short focuser.

http://www.cloudynights.com/ubbthre...9951/page/0/view/collapsed/sb/5/o/all/fpart/1
 
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