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skysurfer
member
Reged: 10/05/09
Posts: 16
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Here are some pics of my Anglefinder (AF) adapter. I have this device normally for pointing my Canon EOS-40 to the sky and I discovered that it just contains a prism which redirects the image by 90° behind an eyepiece without mirroring it. So I held it behind my 15x70 and saw it worked. Very useful during opportunities when a telescope cannot be used.
Then I made a wooden adapter with an outer diameter equal to the inner diameter of the rubber eyecups of the bino EP. I lathed this from a piece of hardwood (I am lucky to have a lathe but without one you can also make such an adapter) and glued an SLR camera eyepiece adapter to it (last picture).
What is very important is that the angle finder should be exactly aligned with the optical axis of the binocular otherwise coma and color errors will occur. I had to tape off the outside of the adapter with duct tape to prevent sagging (and intruducing optical errors) keeping it aligned. Use the left eyepiece of the binocualers as this has no individual focusing (which may introduce extra play).
Due to cloudy weather here I tested it on trees far away (dark branches to bright sky a rather high contrast test). The Angle finder has a switch of 1x and 2.5x the 'original' power. At 2.5x the image was still rather good it showed 35x power and only slight blue fringes as color errors, which is good for an objective designed for only 15x power. However, in both cases (1x and 2.5x) the apparent FOV is omly 30-40°.
Advantages:
- Quick setup when you have no telescope available
- No neck problems as you have a diagonal and provides an erect image.
- when you make this adapter twofold and buy another AF, you have a nice binoviewer.
Disadvantages (compared to a 'real' scope):
- Small FOV
- more glass-air transitions which means more light loss.
- probably slightly more color errors when the AF magnifies the image
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Two eyes (5-7mm in full darkness)
TS 15x70mm binos
TeleVue Genesis 100mm f=500mm
Orion XT-10i 250mm f=1200mm
Canon EOS 40 w/85mm f/1.8, 50mm macro f/2,5
Edited by skysurfer (11/07/09 11:50 AM)
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Mark9473
Post Laureate
Reged: 07/21/05
Posts: 3211
Loc: 51°N 4°E
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Interesting! Could you expand a bit more on the advantages and disadvantages when compared to the binocular as such? Is this a way to make an angled binocular (for two eyes)?
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Mark
Leica 8x20; Vixen 8x42; Swift 8.5x44, 10x50 and 20x80; TS 7x50; Orion 15x63; Docter 15x60
WO Megrez II 80 FD + Baader 90° T2 Amici
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GlennLeDrew
Pooh-Bah
Reged: 06/18/08
Posts: 1269
Loc: Ottawa, Ontario, Canada
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The angle finder is a self contained telescope, and operates afocally when attached to a camera viewfinder (or bino, 'scope, etc., as we see here). At the 1X setting you get a non-magnified view when used by itself, and when attached to an eyepiece the magnification also remains unchanged. As noted, these devices have small AFoVs because they need not cover an angle larger than that subtended by the the camera's viewfinder.
As to using a pair to make an angled bino, yes you can. But adapting them so as to remain rigidly fixed in position and aligned, good luck! I'd say forget it for a bino which employs center focus due to the inherent floppiness of the assembly. Even an IF bino would give one fits.
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Home-made 11X50 right angle bino, 8.1 deg. FOV
Modified 26X100 bino, 3.5 deg. FOV
Home-made Mk II RA bino, using interchangeable objectives and eyepieces
My Gallery
Mediocre minds discuss people. Good minds discuss events. Great minds discuss ideas.
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Mark9473
Post Laureate
Reged: 07/21/05
Posts: 3211
Loc: 51°N 4°E
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Thanks Glenn, I think you've confirmed my own expectations. But I have a few binoculars I'm not using anymore, and it sure would be fun to try this out.
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Mark
Leica 8x20; Vixen 8x42; Swift 8.5x44, 10x50 and 20x80; TS 7x50; Orion 15x63; Docter 15x60
WO Megrez II 80 FD + Baader 90° T2 Amici
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skysurfer
member
Reged: 10/05/09
Posts: 16
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In the meantime I did a 'real' sky test yesterday, but the slightest misalignments results in color errors. So I have to update the coupling between the eyepiece cup and the AF.
@GlennLeDrew: The AF is a small telescope in itself ? That means that when I using it with my binos (or even with an SLR where it is designed for) I have two telescopes in series. An SLR is also a small telescope when you use the optical viewfinder.
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Two eyes (5-7mm in full darkness)
TS 15x70mm binos
TeleVue Genesis 100mm f=500mm
Orion XT-10i 250mm f=1200mm
Canon EOS 40 w/85mm f/1.8, 50mm macro f/2,5
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Luigi
Post Laureate
Reged: 07/03/07
Posts: 4940
Loc: MA
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Some bino companies make a multiplier attachment for their bins, which works on the same principle. I bought and tried a 3x Zeiss multiplier with Zeiss Victories and a few other bins. It worked, but the image quality in terms of sharpness and contrast was significantly poorer than with a small dedicated scope of the same aperture and magnification. Putting the light through two objectives, two prism systems, and two eyepieces takes it toll.
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17.5" f/5 Dob. IM-715 MCT. 120ED. Lunt 60mm Ha.
Zeiss, Leica, Fujinon, Nikon, Pentax, Bushnell bins
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GlennLeDrew
Pooh-Bah
Reged: 06/18/08
Posts: 1269
Loc: Ottawa, Ontario, Canada
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To carry this idea to a further extreme, take a small bino/monocular/finder such as, say, a 5X24 and hold it up to the eyepiece of a bigger bino or 'scope. This is one way to find the limit of on-axis resolution of an instrument, and I'd imagine this is more or less what EdZ does.
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Home-made 11X50 right angle bino, 8.1 deg. FOV
Modified 26X100 bino, 3.5 deg. FOV
Home-made Mk II RA bino, using interchangeable objectives and eyepieces
My Gallery
Mediocre minds discuss people. Good minds discuss events. Great minds discuss ideas.
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