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Message: <blockquote data-quote="JGobeil" data-source="post: 1234777" data-attributes="member: 24649">Prime focus digiscoping protocol - V. 1.0(Revised 08.07.02 20:00 EST)PLEASE FOLLOW EXACTLY ALL THE INSTRUCTIONS IN THIS PROTOCOL AND DO NOT CHANGE ANYTHING. We won’t be able to compare meaningfully if we don’t use the EXACT same settings.1- To begin this experiment, the test will be limited to a DSLR connected directly to an astro refractor scope. Nothing else: no teleconverters or barlows.  Use spacers ONLY if they are required to get the target in focus.  As soon as we are satisfied with the protocol we will open it to other setups.2- The DSLR must be set to its standard settings. Of particular interest is the internal sharpness setting which should be set at the DEFAULT VALUE. It should be set at its maximum megapixel value if any choice is offered.3- The target to be used is a standard ISO 12233 test chart. The file containing the target in JPEG form is available here.  Right click on the image and copy.<a href="http://julesgobeil.com/private/ISO_12233-reschart%20-%20resized-a.jpg" target="_blank">http://julesgobeil.com/private/ISO_12233-reschart - resized-a.jpg</a>Only this file should be use as a source for the target. This target has those dimensions:10.0 x 5.65 inches (254.0 x 143.51 mm) at 300 pixels/inch (118.11 pixels/cm).  The complete image should be included in the target, do not crop out anything.  This size will fit A4 and Letter size paper with an adequate margin for all printers. After printing, the dimensions should be checked to make sure they are the same as the original file.4- Find an adequate place to photograph the target under sunny conditions with little or no wind. Put the target on a firm background like a cardboard box or a piece of wood and fix it solidly so that it doesn’t wobble and its surface is perfectly flat.   You must put it at a distance where the target will exactly fill the width of the viewfinder – no more, no less.  The sun should be facing the target – behind your back when you take the picture. Make sure that the target is perfectly vertical and that the camera is at the same height as the target. Use a sturdy tripod and head - lock everything so it doesn’t move. 5-  If possible use mirror lock-up and timer activated shutter or remote cable. Set the camera at ISO 400 and adjust the shutter speed for proper exposure.  Take the photograph using RAW if it is available – if not, use JPEG at the highest resolution possible.  Focus with extreme care and take 3 pictures, keeping the one with the best resolution.6- Resize the COMPLETE photograph of the target to 800 megapixels wide and convert to JPG if you shoot RAW.  DO NOT CROP AND DO NOT PROCESS IN ANY WAY. NO SHARPENING PLEASE ! Attach this picture to your post (Picture 1). 7-  Using the photograph you made in step 5 (before resizing),  Make a 800x800 pixels crop of the middle top portion of the target in your picture which is marked by a square, exactly as shown below.  Convert it to JPG, no compression.  Also attach this picture to your post (Picture 2).Here is how it is done in Photoshop:Start with your picture before resizing to 800 pixels (after Step 5)Select the Crop ToolUse those parameters (top left of screen, below the menus)- Width: 800- Height: 800- Resolution: leave  value empty and select Pixels/inchSelect the area with the mouse – it will be squarePress Enter to selectVerify that it is 800 x 800 pixels (Menu: Image / Image size)Save it as   picture2.jpg  , no compression8-  Using the photograph you made in step 5 (before resizing),  Make a 800x800 pixels crop of the lower right portion of the target in your picture which is also marked by a square, exactly as shown below.  Convert it to JPG, no compression.  Also attach this picture to your post (Picture 3).9-  Studying the target, evaluate the BEST resolution number.  This is the highest number where you can see WHITE SPACE BETWEEN ALL FIVE LINES. 10- Publish your picture with the following information:Make and model of DSLR:Make and model of scope:Type, make and model of camera adapter:Length of spacer needed to reach focus: Focal length of complete setup in mm:Measured distance between target and telescope in meters:Evaluated resolution number:Speed setting of camera:ISO:Original picture format (RAW, JPG) and resolution (mpx)Date and time:Weather conditions (sun and wind):Other pertinent information:Pictures 1,2 and 3:</blockquote>

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