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Baader Amici Diagonal?

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#1 Michael Rapp

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Posted 15 October 2013 - 05:47 PM

Hi all,

Anyone have an experience with the Baader Precision Amici Prism Diagonal?

I've got an amici finderscope, but when I get down to where I want to star-hop with the eyepiece, the mirror view kills me. I guess I have to unlearn two decades of reflector star-hopping. :)

I'm wondering just what aberrations and to what extent the Baader Amici diagonal would show. I can only hope that at nearly $300 it's nearly aberration-free.

#2 M13 Observer

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Posted 15 October 2013 - 08:44 PM

Hi all,

Anyone have an experience with the Baader Precision Amici Prism Diagonal?

I've got an amici finderscope, but when I get down to where I want to star-hop with the eyepiece, the mirror view kills me. I guess I have to unlearn two decades of reflector star-hopping. :)

I'm wondering just what aberrations and to what extent the Baader Amici diagonal would show. I can only hope that at nearly $300 it's nearly aberration-free.


It works pretty good. It does show a very small distraction (diffraction) spike due to the roof prism on bright stars but is pretty decent otherwise.

#3 The Ardent

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Posted 15 October 2013 - 09:32 PM

This report inspired me to upgrade my finder with the Baader Amici:

http://www.cloudynig...hp?item_id=1308

#4 AllanDystrup

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Posted 16 October 2013 - 01:36 AM

I've been using the Zeiss Amici 4x eyepiece turret for a long time -- it's optically perfect and a joy to use in star hopping.

Some months ago I ordered a Baader T2 Amici diagonal, primarily for use with my Baader MaxBright bino. Though the roof edge of the prism was clearly visible, the prism was performing well on terrestrial objects and the sun and moon, BUT the edge showed up as an obvious dark line in star tests and as a noticeable pair of spikes on bright stars, -- rather distracting on high magnification double star observations.

I returned the diagonal to Baader, and received a new one with a letter stating :

"We where able to see the fault at the optical bench.
We have no idea why this slipped trough our QI.
The new prism was tested to perform optically to our standards.
We think with this prism there should be no issue."


I'm satisfied with the astronomical performance of the my new Baader T2 Amici diagonal. It's on level with my Zeiss Turret.

Roof prisms are technically demanding to produce to the high precision required for astronomy, and although this should be reflected in the quality inspection (as it certainly is in in the price), always be sure to check that the performance of your buy matches the advertized quality.

In the case of Baader you are in safe waters though, -- my experience of their handling of my 'lemon' prism was totally satisfactory : no hazzle replacement, fast and kind service.

And the prism is a joy to use for star hopping and moon bino'ing ! Warmly recommended for visual astronomy :-)

Allan

#5 RAKing

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Posted 16 October 2013 - 07:08 AM

I use the Baader Amici prism when I'm looking at the moon or when I'm star hopping.

I have never seen anything through the Amici that I would consider to be a flaw. I swap this diagonal back and forth with a Baader mirror diagonal and I sometimes forget which one I'm using in my little Traveler. :)

I use 1.25 inch Clicklock eyepiece holders on these and they make a great lightweight set with the smaller Panoptics and Naglers.

Cheers,

Ron

#6 Michael Rapp

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Posted 17 October 2013 - 08:07 AM

Thanks for the advice and reports. This has moved up a bit on my wish list, especially if star-hopping in a mirror diagonal continues to drive me crazy.

I could see myself leaving it "permanently" attached to a low-power wide-field eyepiece, and then when the target is found, swapping out both eyepiece and diagonal for a higher power eyepiece on a mirror diagonal.

#7 Cyclop_si

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Posted 17 October 2013 - 01:24 PM

... and then when the target is found, swapping out both eyepiece and diagonal for a higher power eyepiece on a mirror diagonal.


Why swapping amici with mirror diagonal when going high power?

#8 Michael Rapp

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Posted 17 October 2013 - 03:07 PM

Well my assumption is that the amici would be primarily to make my refractor a RACI finderscope.

When I've found the object, I no longer need the correctly-oriented image, so I would switch to a mirror diagonal that, again, I assume would have higher light transmission and less abberations than the amici diagonal.

#9 Bill McNeal

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Posted 17 October 2013 - 05:01 PM

I would switch to a mirror diagonal that, again, I assume would have higher light transmission and less abberations than the amici diagonal.


I don't think this is a safe assumption to make. I'm under the impression there have been improvements in erect image diagonals for image quality.

#10 The Ardent

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Posted 17 October 2013 - 05:47 PM

Why don't you use the 66 as a finder?

#11 GlennLeDrew

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Posted 17 October 2013 - 10:09 PM

Even a perfectly made Amici prism's roof line must introduce at least a subtle horizontal diffraction spike on brighter objects.

If you want to undertake a *very* sensitive test for wavefront quality and accuracy of the 90 degree roof angle, place the prism in front of a small refractor. Any errors are much more magnified than they are as when under normal use just ahead of the eyepiece. If the image looks at least reasonably decent, and (for roof prisms) there is no obvious image doubling, the diagonal is good.

And this test works for all diagonals.

#12 Mark9473

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Posted 18 October 2013 - 02:37 AM

My experience is that the Baader amici gives very pleasing lunar and planetary views, but if you want the cleanest airy pattern on stars then definitely switch to a conventional diagonal.

#13 AllanDystrup

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Posted 18 October 2013 - 03:25 AM

I'll add that a Amici prism made to the highest (~Zeiss) quality standards :
* will show clean star diffraction patterns, and
* will be well suited even to high magnification double star viewing.

Allan

#14 Mark9473

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Posted 18 October 2013 - 06:25 AM

Oh, then something must be wrong with the Baader/Zeiss one I got.

#15 Michael Rapp

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Posted 18 October 2013 - 01:38 PM

Why don't you use the 66 as a finder?


You know I was thinking about this the other day. I've got a dual mounting plate....the 66 can give me a 4 degree FOV with my largest 1.25" eyepiece and I already have an amici prism for it that seems to be decent....






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