24 replies to this topic

[jrcrilly]

http://www.astromart.com

[EdZ]

It's easy at Cloudynights to do so. Just hit 'Preview Reply', then click 'URL' under 'Instant UBB Code'. A window will pop up where you can cut and paste the URL from your link. Be careful not to add your URL to the 'http://' already in the pop-up window. Your URL can be as long as you like in the pop-up window. Next click 'OK' and another pop-up window will open for you to enter the name of your link as you want it to appear in your post. Enter your link's name and click 'OK'. That's it. Your link will appear as the name you entered, but lead to the link you entered.

For example, here's a link to Cloudynight's Variable Star Forum . Try it. It's easy!
Tom(pegster) 2-16-05

[EdZ]

A comprehensive explanation of Binocular Summation, how binoculars, telescopes and telescope/Binoviewers all compare and the benefits that can be derived from each.
Binocular Vision Summation
A compilation of writings on Binocular Summation. Includes several noteworthy posts of imporant information on vision.


Beamsplitter Transmission Variances Affect Binocular Vision Summation
read the entire thread for a great info


Do you have issues merging images? Read this.
"Training" your eyes to merge images is simply training your eyes to accept eye strain.

[EdZ]

Calculations are presented for several examples of Binoviewer/Scope , Monocular Scope and Binocular to help users compare Equivalents of Monocular and Binocular Aperture.

Also
Data collected from three different models binoviewers shows how binoviewer clear aperture restricts field of view. Field of View is compared for Binoviewer/Scope, Monocular Scope and Binoculars. A summary is given for lowest power acceptable (non-orthoscopic fov) field of view for binoviewers and then that is also give as a binocular equivalent.
Binoviewers and Binoculars (equivalents)

[EdZ]

Binoviewers and Clear Aperture
If selecting one of the 20mm CA binoviewers on the market, not only is there a light loss at the outer edges of the field stops, but also the Maximum True Field of View that you can get will be restricted to eyepieces with field stops about 22-23mm max.

Which binoviewers are actually the same?
Here's a series of measurements some that are the same

Which are the same? Which are different? Where are they made?
Keep in mind, these are actually the same binoviewer. The "BODY" of the Burgess C and the Stellervue BV3 are exactly the same. In fact both of these are exactly the same as the WO binoviewer and the Orion binoviewer and the older Moonfish BV. They appear to be the same as the Celestron and the Antares binoviewers. At various points in the past some of these older binoviewers had only 18mm clear aperture. The Stellervue, Orion, WO and BurgessC all have 20mm clear aperture. The only thing different about these binoviewers is the eyepiece holders. So, if one happens to have a brighter side than the other, that may be just luck of the draw.

Binoviewers that are not the same as those listed above include Baader Maxbright, BW-Optic, Lumicon, Televue, Seibert and Denkmeier.

edz


Here's the same binoviewer seen commercially available from a half dozen different dealers. It's shown here with options for every available configuration I've seen from any American dealer (1 screw, 3 screw and twist lock collets) .
United Optics - Kunming



Eyepiece FS Diameters for Binoviewers



Is there a scope that's best for binoviewing?
This post in the Binoviewer forum starts out " A few things you should know about binoviewers and scopes". This post explains not only how clear aperture affects the field of view, but also how the various attachments to the binoviewer nose change from the specified magnification factor when used in different scope/diagonal configurations. It is my experience, some people that are using binoviewers with an SCT scope have no clear idea what magnification they are using or what they are getting for true field of view. This post helps explain some of the above.

The Focal Length of an SCT scope
It is almost always NOT what is stated by the manufacturer. That is nominal focal length of an SCT. The calculations are complex, but the concept is relatively easy to understand. If you want to find the actual focal length of your SCT, read the next link about Drift Timing Eyepieces.

Drift Timing Eyepieces to Determine True Operating Magnification
You cannot trust the manufacturer stated power factors for binoviewers. There are just too many pieces in the light path that have an affect on the operating focal length. this is especially significant for SCT scopes, where many people are not even aware that the operating focal length is longer than the nominal stated, and that SCT focal length varies with every little turn of the focuser knob. You can determine YOUR operating power factors with your binoviewers. Here's how.

[EdZ]

If the images are not merged, tollerance for that miscollimation is entirely dependant on the magnification in use. Generally, everyone can tollerate some small misalignment and the eyes will merge the images. Tthe higher you go in power to more stringent the requirements

Miscollimation Allowable Errors

You can measure miscollimation by observing a double star. You need to know the separation of the double. An even double works best. When you observe the pair and watch for the merging of the images, compare the mis-match of each star (or the amount it does not merge), to the separation of the double. I've used this method to measure collimation down to about 10 arcseconds.

For reference 1 inch at 100 yards is just slightly less than 1 arcminute, and this is about 3x to 4x worse than the least problematic allowable error.



edz

[Jeetoo]

An interesting web site I stumbled on from International Light, Inc.

Light Measurement Handbook by Alex Ryer

link broken

Here is the updated link..

http://www.intl-ligh...ght measurement

I hope it works