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General Ccd Camera

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general ccd camera - The New

The New CCD Astronomy: How to Capture the Stars With a CCD Camera in Your Own Backyard

The New CCD Astronomy: How to Capture the Stars With a CCD Camera in Your Own Backyard

The New CCD Astronomy is the #1 source of information about CCD astrophotography. It contains everything you need to know to become proficient at CCD imaging. Hundreds of detailed illustrations show you how to select equipment, take pictures, and process your images with a variety of software.
This book cover everything you need to know: How a CCD camera works; How to achieve critical focus; How to choose the right equipment (mount, telescope, and CCD camera); How to autoguide, and more.
You'll also learn the secrets of color imaging, the art of noise reduction, many image processing techniques, and specialized techniques for planets, nebulae, galaxies, etc.
Free with purchase: a one-year subscription to the New CCD Astronomy web site, including: a complete online version of the book; additional fully-illustrated tutorials; discussion groups moderated by the author; searchable database of CCD imaging targets; and a number of free software tools to improve your CCD imaging results.

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Pentax "Ten Lens Shootout" 50mm Test - Wide Open


View the image at 100% after reading below, or you will go blind and learn nothing by looking at this small image above. lol

Premise: I wanted to know, unscientifically and for my personal edification, which of my 10, yes.. T-E-N Pentax mountable 50mm's is the best wide open. Secondarily I wanted to know about the bokeh of each, with emphasis on specular highlights such as points of light.

Method: I composed a simple yet attractive scene to challenge these lenses. A table in light with a dark background. I set a Kodak E100 box at frame center with my Konica Auto Reflex atop a photo album and another roll of film below them. In the rear by 3 feet an old white lamp and behind that by 10 feet a string of led Christmas tree lamps. Each shot was shot three times and the best shot picked for comparison snipping.

VIEWER"S GUIDE: What you see above are four rows of results.
The top row is CENTER sharpness at Wide Open. (blue film box)
The second row down is 3/4 to edge of frame sharpness at Wide Open. (camera body)
The third row is mid-frame bokeh Wide Open, with a small inset of the prism hump of the Camera for Chromatic Aberration (purple fringing) performance.
The bottom row is the same bokeh patch as the row above except that it is one f-stop down, again there is inset the prism hump sample.

Error: The f2.0 patch for the Pentax Super Takumar SMC f1.4 (third in from right) is incorrect, it is a needless duplicate of the f1.4 sample. :(
Note: the last two lenses were only shot wide open at f1.4 because they are automatic only and would require me gluing down the aperture pin for "stop down metering.

Gear: Pentax K100D 6MP CCD a ISO 200 mounted on tripod with I.S. turned off. K-mount-Screwmount adapter used for the 4 screw mount lenses.

Pentax-A 50mm f1.4
Pentax-M 50mm f1.4
Pentax-M 50fmm f1.7
Vivitar 50mm f1.8
Yashinon-DX 50mm f1.7
Sears 50mm f2
Pentax-M 50mm f2
Pentax Super Takumar SMC 50mm f1.4
Yashinon-DS 50mm f1.4
Yashinon-DS-M 50mm f1.4

As expected:
1. The Pentax-A f 1.4 has some of the most pleasant bokeh, even stopped down thanks to it's 8 blades.
2. As rumored online, the Pentax-M f1.7 is a very sharp lens, even wide open!
3. The off brand lenses are not as sharp across the frame.

The unexpected:
1. The Vivitar f1.8 (fourth column) is extreemly sharp and contrasty at frame center. BUT is the worst performer away from the center. It also has very low CA (purple fringing) on the prism hump inset samples, even less than the Pentax-A & Pentax-M lenses.
2. The Pentax-M f2 is no joke. It's a solid but quiet performer and seems to have great CA control.

The weird:
1. I assure you the bottom bokeh shot for the Pentax-M f1.4 is at f2. It appears from the bokeh though that it is not and is for some reason producing smaller circles of light than the "A" version of the same lens. Hmm.
2. The bokeh of the Pentax-M 50mm f1.7 is a little unattractive in my opinion when stopped down to f2. It has a type of curved aperture blades which create a bit of a "toothed" appearance to the bokeh.

If you want versatility, automatic aperture capability, maximum depth-of -field control (outside of splurging on a f1.2 lens) and bragging want general rights.....then the Pentax-A 50mm f1.4 is for you.
If you want center only sharpness and like a "swirlios" effect to your edge bokeh, then the Vivitar 50mm f1.8 is your wonky little buddy. Sharp and contrasty and cheap!
If you want a nice thin lens, with good sharpness across the frame and good CA (purple fringing) control and want an un-notable user experience, then the Pentax-M f2 is ready to please you, even at f2.
If you want a lens that gives you the smoothest barrel turn and most solid retro feel and "look" at the price of gaining more "glow" than more modern lenses...then the Pentax Super Takumar SMC 50mm f1.4 will give you the nice glow to your f1.4 people portraits.
If you want a "relatively unknown" lens that almost matches the legendary sharpness of the Pentax f1.7, and all this in a screwmount playful package...the Yashinon DX 50mm f1.7 will take you off to la-la land in a side-car of sharpness.

I want what I don't have. A nice Pentax-A 50mm f1.7. Why? The Pentax-M 50mm f1.7 performance is impressive!. And think about it.... if I want shallow depth of field while staying away from CA (purple fringing) and the typical "wide-open glow", then a good f1.7lens shot wide-open beats an f1.4 lens that must be stopped down to f2 anyways.
P.S.- I hope the aperture blades of the "A"version of the Pentax f1.7 are a bit better designed because the bokeh, specifically specular highlights are a bit disappointing.

Oh, more thing.. I want a Pentax digital FULL FRAME camera so I can shoot these as normal lenses!!!!

Enhanced Ida and Dactyl

Enhanced Ida and Dactyl

Date: 28 Aug 1993

This color picture is made with images taken by the Galileo spacecraft about 14 minutes before its closest approach to asteroid 243 Ida on August 28, 1993. The range from the spacecraft was about 10,500 km(6500 miles). The images used are from the sequence in which Ida's moon was originally discovered; the moon is visible to the right of the asteroid. This picture is made through the 4100-angstrom (violet), 7560-angstrom (infrared) and 9680-angstrom (infrared) filters.

The color is enhanced in the sense that the CCD camera is sensitive to near-infrared wavelengths of light beyond human vision; a natural color picture of this asteroid would appear mostly gray. Shadings in the image indicate changes in illumination angle on the many steep slopes of this irregular body, as well as subtle color variations due to differences in the physical state and composition of the soil (regolith). There are brighter areas, appearing bluish in the picture, around craters on the upper left end of Ida, around the small bright crater near the center of the asteroid, and near the upper righthand edge (the limb). This is a combination of more reflected blue light and greater absorption of near-infrared light, sesting a difference in the abundance or composition of iron-bearing minerals in these areas

Ida's moon also has a deeper near-infrared absorption and a different color in the violet than any area on this side of Ida. The moon is not identical in spectral properties to any area of Ida in view here, although its overall similarity in reflectance and general spectral type sests that it is basically made of the same rock types. These data, combined with study of further imaging data and more detailed spectra from the Near Infrared Mapping Spectrometer, may allow scientists to determine whether the larger parent body (of which Ida, its moon, and some other asteroids are fragments) was a heated, differentiated object or made of relatively unaltered primitive chondritic material.

Credit: NASA/JPL

general ccd camera

general ccd camera

A Practical Guide to CCD Astronomy (Practical Astronomy Handbooks)

High-performance charged-couple device (CCD) cameras have opened up an exciting new window on the Universe for amateur astronomers. This book provides a complete, self-contained guide to choosing and using CCD cameras. Beginning with a no-nonsense introduction to CCD cameras, the authors explain what determines camera performance and demonstrate how to use a CCD camera and accurately calibrate the images obtained. The book also presents a clear review of the software available for visualizing, analyzing and processing digital images. Finally, the authors navigate a series of key areas in astronomy where astronomers can make the best use of CCD cameras. This handy volume is packed with practical tips. It provides a clear introduction to CCD astronomy for novices and an indispensable reference for more experienced amateur astronomers.

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26.10.2011. u 10:49 • 0 KomentaraPrint#

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