How To Understand & Use Eyepiece View Simulations from "Eyepiece" by Steve Waldee Copyright (c) 1991-2007, Stephen R. Waldee - All Rights Reserved These pictures were developed back in the period when Windows 3.0 had just been introduced. We used a 16-bit monochrome HP scanner to render graphics images from black and white photos and drawings, and later a very rudimentary 8-bit color scanner for color prints. These files were processed by a number of DOS graphics editing programs, notably "Neopaint"™, and also by a very early Windows program called "Photofinish"™ by ZSoft. The rendered versions (16 level grayscale, and 256 level color) were employed in the graphics function in "Eyepiece" to show full screen, at a coarse resolution that was just barely acceptable in the early 1990s on typical 8-bit VGA color monitors with 13" screens. Today, on true-color displays of 17 to 21 inches diagonal size, the images are unpleasantly ugly and non-representative (unless, perhaps, viewed from way across a large room!) So, some forbearance had to be applied by the user of the "Eyepiece" program's simulations, when the software was run on a modern PC. We have attempted to overcome this problem by re-casting the pictures into small size on one webpage for each object. On our test displays ranging from 14 to 19 inches, the results are more believable. Yet, because the "daytime" type of vision works very differently from dark-adapted sight at night, using a telescope, there are many remaining disparities between a true "sky view" in an amateur telescope, and what may be seen on most computer monitors under normal day environs, with ambient light all around the computer. Viewing these pictures in the dark does not help, because of the competing high-contrast elements onscreen: menu bars, text, background colors. Even the "raster" of the screen (its faint residual glow, visible when the picture is black) can interfere with fine details of contrast. Furthermore, the dynamic range of the eye is very wide -- it can see, it is said, a range of 90 decibels, or a variation of intensity of 1,000,000,000 times, from the faintest starlight to the brightest image seen during a sunny day. Although color images may have as much as 32 bits resolution with later versions of Windows™, the operating system's screen display grayscale dynamic range for black & white images, however, is even now only 8 bits or 256 levels (as explained here on the MS Knowledge Base.) At the time we developed the "Eyepiece" software, we were limited to an even more restrictive 16 levels of gray, and 256 levels of color. These images do not look absolutely realistic in a modern Windows context. So, be aware that these simulations are not scientifically developed at the limits of current standards; in addition, they are also affected by the setting of contrast and brightness of your monitor display; how big your screen diameter is; how close you view them; and ambient light in your room. Thus, what may look fairly realistic on one system, is grossly exaggerated and unnatural on another. Of particular significance are: the faintest background nebulosity; and the sky darkness across the entire eyepiece field. These elements are very hard to quantify and render in a simulation, and then to represent reliably on uncounted multitudes of computers viewing these images, all over the world... Here is the original Help panel that opens up in "Eyepiece" the first time you bring up the "View" menu to see the pictures. The article mentioned above about dark adaptation is now on our websight, and may be found here. It has a link to a discussion of the "Purkinje effect" observed first by a 19th century physiologist: the loss of color sensitivity under dim light conditions. It is important for beginning observers to realize that they may not necessarily be able to see the faintest nebulosity when starting out as a novice telescope user. Dark adaptation is critical; furthermore it is probably necessary to develop the skill to be able to interpret what you see in your eyepiece view as being meaningful. (Is that faint smudge of light a "real object" or just a reflection caused by a poor eyepiece; is it a visual illusion; or is it unrelated to the object you're trying to discern?) A good article that may advise you is found here, written by Alan McRobert of Sky & Telescope Magazine. In the section "The Fine Art of Observing", Alan explains many of the issues related to why celestial objects often appear as mere "faint fuzzies": the small bits of light that are rendered by an amateur telescope. Alan's followup article, here, provides more specific details of what you'll do in a typical observing session in order to see, for example, Messier objects; and how to choose the right magnification for planets, versus deep-sky objects with larger diameter. So, please consider our eye-view simulations not to be scientifically accurate and absolutely calibrated, objective replications, but rather as an attempt to render approximately what one might see, under certain specific conditions -- if you allow that there are large differences between these simple pictures, and the infinitely more nuanced abilities of your eyes to perceive the range between light and dark, and fine details. Press BACK key, or click for the Eyepiece Simulation View Menu. Last edited: Friday 9 March 2007 at 6:27 pm. Copyright © 2007 Stephen R. Waldee - All Rights Reserved. All Trademarks or Copyrights are © or Property of Their Respective Copyright Holders. 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