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Baader Maxbright II with SV Access 80mm

refractor equipment
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#1 gul1337



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Posted 27 July 2020 - 09:38 PM



Two nights ago, I managed to try Baader Maxbrigtht II with my 80mm APO  -  SV 80 Access. It worked pretty well.


My SV80 Acces has WO Rotolock installed - it gives about 10mm more back focus than original M63->2" Adapter.


I tested it by drift time with 12.5 guiding eyepiece, with Baader 32mm T2 diagonal, with 1.25"eyepiece holder or directly connected to diagonal

The numbers below are not exactly accurate as I used my phone as a stopwatch :), but it should be pretty close.


Bino -> diagonal -> T2/1.25" nose =  not enough backfocus

Bino -> diagonal -> T2/1.25" nose -> 1.6x WO OCA  = 2x 

Bino -> diagonal -> T2/1.25" nose -> 2.0x WO OCA  = 2.5x

Bino -> T2/1.25" nose -> diagonal -> T2/1.25" nose ->2.0x WO OCA  = 2.6x


Bino -> T2/1.25" nose -> 1.6x WO OCA -> diagonal -> T2/1.25" nose = not enough backfocus

Bino -> T2/1.25" nose -> 2.0x WO OCA -> diagonal -> T2/1.25" nose = 2.2x (just 4 mm of back focus left)

Bino -> T2/1.25" nose -> 2.25x Baader Zoom Barlow -> diagonal -> T2/1.25" nose = 4.2x


I tried it with Baader Zoom, and it works really well, Jupiter looked really nice especially with 2x WO GPC in front of diagonal, with Baader zoom at 8mm it gave me around 180x magnification, with 0.4mm exit pupil it still looked Great!. Zoom was working nice, after little practice it was possible to zoom in two eyepieces at once with the image being merged all the time.


I have also tried my ES24mm 68deg, but somehow viewing through them was not as comfortable as through Baader zoom, it was very sensitive for eye placement, I had to look precisely into the center of the eyepiece to keep it merged. My 24mm pair was bought 2 years apart, so maybe this is the reason. When looked straight, there was no problem to combine images, and when looking to the side, somehow it was putting a strain on eyes. Something like this did not happen with my 20mm 66 deg WO. Maybe they are "too fat" for me, and they are getting a little in the way of my nose.


The best eyepiece pair was Baader Classic Ortho 18mm. For me, it was easiest eyepiece pair to work with, and with 2.25x Barlow Jupiter looked really nice. The strangest thing was that 18mm Ortho was much more immersive then 24mm 68 deg, It is strange, but it felt "wider", maybe it was just how comfortable eye placement is with it.


But I think that the winner is Baader Zoom, It allows us to easily locate target and zoom on it. With manual AltAz Mount, it works just great!.


I'm wondering If Baader 1.7x OCA  would work in this configuration, Will there be enough back focus? Did anyone try?

Is there any point in getting 2.6x Baader GPC ? or keep WO 2x GPC in front of the diagonal?


Clear Skies!




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#2 alphatripleplus


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Posted 29 July 2020 - 07:12 AM

Moving this over to Binoviewers for a better fit.

#3 betacygni



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Posted 29 July 2020 - 05:40 PM

While I’ve not used that exact scope/configuration, the 1.7x glasspath is typically the safest bet to work on most refractors. Below is a list from the glasspath manual about the focus requirements:

Glasspath Compensators:
#4A: 1.25x, focus gain: approx. 20 mm
#4B: 1.7x, focus gain: approx. 35 mm
#4C: 2.6x, focus gain: approx. 65 mm

So the 1.25x is hardest to get to work (needs focuser racked in more), while the 2.6x racks focuser out quite a bit, I’ve heard of some needing extensions for it, 1.7x is in the middle.

As for needing the 2.6x glasspath vs just using your Barlow, sounds like you’d most likely have similar results. In theory the glasspaths correct better for the prisms in the binoviewer then a standard Barlow, though in regular use that might be a subtle difference.

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