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Canon-Nebulosity Tutorial for Beginners - page 3 / 9





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Capturing Images

Step #1: Turn on the Canon EOS camera. The Canon Utilities window will automatically open. Allow it to open and then click “Quit”. We found that if one tries to run Nebulosity with Canon Utilities open, you will get an error message. The two programs do not like each other. Now double click the Nebulosity icon. The Nebulosity window will open with a large black screen. Click the “Files” tab drop-down menu at the upper left corner of the window. Near the bottom of the list, click “Preferences.” Click “Acquisition Mode” and click the down arrow on the right and select, “RAW acquisition.” Next, click “DSLR Long Exposure Adapter.” Click the down arrow on the right and click “Shoestring DSUSB.” If you don’t select this option, the camera will only give you a maximum of 30-second exposures. Leave all the other settings alone unless you know what you’re doing.

Warning! If you do not make the necessary selections in the “preferences” section to RAW Acquisition, the Canon EOS will take the photos in JPG color format. Processing those images will be a daunting process. I know, the first time I tried to take images, I pulled my hair out for two days wondering why my laptop ran out of memory. Each of my carefully guided 30 images was an incredible 45.5 MB in size. To process that many images at the size, I would need a Cray computer!!

Step #2: On the right side of the screen under the “Camera” heading, click the down arrow for the drop-down menu. Select “Canon DIGIC II DSLR.” It will take a second or two for the computer and camera to shake hands. If a cable connection is bad or you simply forgot to connect the camera, you’ll get an error message.

Turn your telescope to a relatively dim star near the target. Please don’t try to focus on Sirius, Venus or other ridiculously bright object. You are now going to focus the camera, but you’ll need a star at about magnitude 7 or dimmer. It’s not like focusing the camera for a snapshot with auto focus (AF). Focusing a digital camera is a bit different than daylight snapshots. The CMOS in the DSLR is much more sensitive to light than your eye. We want the dim star to use as few pixels as possible. This will take some time and a lot of practice, but you will be rewarded with exceptionally sharp digital images if you will take your time with focusing. Craig Stark has made focusing very easy in Nebulosity. The pixel algorithm does all the work for you. All you need is a lot of time and patience.

Step #3: Focusing the camera. On the right side of the screen, under exposure>duration, select "1 or 2 seconds” or any short duration you feel is appropriate. (If the duration in parenthesis says, “(ms)”, go back to file>preferences> uncheck the box for “use msec not seconds.”) Leave Gain and Offset alone and leave the number of exposures to 1. Nebulosity will continue to exposure your focus star at the time you have selected until you press “Abort.” To get a rough focus, look through the Canon viewfinder and focus visually as best you can. Now press “Frame and Focus.” Don’t be alarmed at the image.

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