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Equipment Discussions >> Binoviewers

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Geo557Moderator
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Reged: 10/10/07

Loc: SE GA
Re: Binotron-27 - That was it for me new [Re: Never2Busy4You]
      #5733355 - 03/15/13 01:04 AM

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Fogboundturtle
professor emeritus


Reged: 05/20/09

Loc: Burnaby, BC
Re: Binotron-27 - That was it for me new [Re: Geo557]
      #5733768 - 03/15/13 10:06 AM

Geez. This is only a binoviewer. No need to get all emotional and such. I took the denk 21 eyepieces because it calibrated to be used with the binoviewer.

I am not working for or paid for by DenkMeier.


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teskridg
Pooh-Bah


Reged: 01/15/08

Loc: PA
Re: Binotron-27 - That was it for me new [Re: Fogboundturtle]
      #5741194 - 03/18/13 05:19 PM

I use the Earthwins with power x switch and an 11" SCT. I can't say I notice reduced aperture/resolution with the lowest power position, but 24mm Panoptics and 32mm Plossls do vignette somewhat in the reduced, lowest power x switch position. This is not the case with 30mm Plossls and I would expect there would be no vignetting with the 21mm Denkmeier eyepieces also. This vignetting isn't too disagreeable but it is present. Tim

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GlennLeDrew
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Binotron-27 - That was it for me [Re: teskridg]
      #5741676 - 03/18/13 08:33 PM

If one has any doubts about aperture loss, there are two ways to check.

1) The flashlight test. With eyepiece installed and focused at least near to infinity, shine a bright, compact light source straight into the eyepiece from a distance of a foot or two. Measure the diameter of the circle of light emerging out the front end.

An alternative: install a short focal length eyepiece so as to get an exit pupil Of about 1-2mm. Shine a green laser straight into the exit pupil, with the laser housing in contact if you wish. You will likely have a brighter circle of light to measure the diameter of. If the aperture is not fairly come telly illuminated at once, your laser beam is of narrower diameter than the exit pupil; increase the magnification.

2) With eyepiece installed and focused at least near to infinity, look into the front of the scope. Note the small image produced by the eyepiece. Move your eye laterally until the *center* of that image just becomes clipped, either by a baffle or the primary's edge. If a baffle edge clips the image center before it has reached the edge of the primary, aperture loss is occurring.


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