These specific settings are for the Canon 20Da. They will be identical for the Canon 20D. Most will be similar for other cameras, such as the Canon 350D except some will not be available. Most cameras offer variations on these settings, although some may be named differently.

More information can be found at www.dpreview.com which usually has extremely detailed reviews on most digital cameras and their operation. Read your owners manual. Play with the camera in the daytime to learn how it works. It will be hard to learn how to use it at night in the dark, possibly in the cold, at your scope. While trying to take pictures the LCD screen with the menus will frequently be someplace inconvenient to view. You don't want to keep taking the camera on and off the scope because this will lead to dust on the sensor and wear and tear on the lens mount and possibly change the focus that you have worked so hard to achieve.

In the dark most cameras offer an illuminated top control panel and viewfinder display. This is ok to use, but should be turned off during exposures. Some cameras offer the option to light up the display inside the viewfinder during an exposure, this should definitely be turned off.

Use the eyepiece shutter or eyepiece cover during long exposures. This prevents any possible stray light from entering the viewfinder, and making its way to the sensor. This is probably not a problem at night unless you occasionally use a light to check the progress of the exposure time on the top of the camera.

Critical settings for Astrophotography

• Exposure Mode - Set to Manual
• Auto Focus - Turn Off for lenses, doesn't apply to scopes
• White Balance - Set to Daylight
• Motor Drive - Set to Single Shot
• ISO - Set based on Temperature.
  • 60F to 75F set to ISO 1,600
  • 40F to 60F set to ISO 800
  • Below 40F set to ISO 400
• File Type - raw
• Resolution - 3504 x 2336
• Long-Exposure Noise Reduction - Set to off if separate dark frames are shot.
• Mirror Lockup - Set to On for high resolution planetary imaging

Most of the settings critical for long-exposure deep-sky astrophotography will be discussed in detail in subsequent sections.

Canon 20D / 20Da

* A red asterisk indicates a setting that is important for astrophotography. The following settings are the ones that I recommend.

Top of the Camera Settings

Exposure Mode Dial* - Set to Manual Exposure.

Basic Zones

• Fully Automatic Exposure - Looks like a green rectangle on the mode dial. Fully automatic mode where the camera has complete control over all parameters.

• Portrait - Looks like a woman's head with big hair. Uses a shallow depth of field to blur the background to make the subject stand out.

• Landscape - Looks like mountains with a cloud over them. Used for scenic landscapes.

• Close-up - Looks like a flower. Used for close ups of small objects.

• Sports - Looks like a highly styled runner. Used for sports when a high shutter speed is required to stop action.

• Night Portrait - Looks like a person from the waist up with a tiny star over his shoulder. Uses a slow shutter plus to correctly expose for the available light and a fill flash for a person in the foreground.

• Flash Off - Looks like the flash symbol with a line through it. Used to turn the flash off.

Advanced Zones

• P - Program Auto Exposure. The camera picks the shutter speed and aperture, but you can change ISO or shutter speed or aperture and the camera will compensate by changing other parameters to achieve correct exposure.

• Tv - Time Value. Shutter speed priority. You pick the shutter speed, the camera sets the aperture.

• Av - Aperture Value. Aperture priority. You pick the aperture, the camera sets the shutter speed.

• M - Manual. You set both shutter speed and aperture.

• A-DEP - Automatic Depth of Field. The camera detects the nearest and farthest subjects based on the autofocus points and sets the aperture to ensure that all subjects are in focus.

Auto Focus - Set to One Shot. Controlled by the main dial by the shutter button.

• One Shot
• AI Focus
• AI Servo

White Balance - Set to Daylight. Controlled by the main dial by the quick control dial (big dial on the back of the camera). This color balance is only applied to JPEG images, but the setting information is stored in the raw file also and is applied as the default when the image is opened in Canon's Digital Photo Professional. It can be changed in DPP and other programs that can handle raw format files such as Photoshop.

• Auto (3000 - 7000 K)
• Daylight (5200 K)
• Shade (7000 K)
• Cloudy (6000 K)
• Tungsten (3200 K)
• Fluorescent (4000 K)
• Flash (6000 K)
• Custom (2000 - 10000 K, set by frame selection)
• Kelvin temperature (2800 - 10000 K)

Drive - Set to Single shot. Controlled by the main dial by the shutter button.

• Single shot
• Continuous 5 frames per second for up to 23 frames in JPEG
• Self-Timer

ISO * - Speeds range from 100 to 1600 (3200 if H is enabled in Custom Function 8). Controlled by the quick control dial (big dial on the back of the camera). For long-exposure astrophotography, these are some simple recommendations:

• Heavily light polluted skies - use ISO 200 or 400
• Faint objects under dark skies - use ISO 800 or 1600
• Bright objects under dark skies - use ISO 400

Metering - Set to Evaluative. Controlled by the main dial by the shutter button. Doesn't matter for deep-sky astrophotography.

• Evaluative
• Partial
• Center Weighted Average

Flash Compensation - Controlled by the main dial by the quick control dial (big dial on the back of the camera). Doesn't matter for deep-sky astrophotography.

• +/-2 EV
• 1/3 or 1/2 EV steps (Custom Function 6)

Menu Items

Quality * - Set to the RAW. If you have a large compact flash card or lots of space on your hard drive if you are writing the files directly to the computer, use raw + Large / Fine JPEG. This allows you to examine the JPEG for things like focus and framing without having to apply adjustments to the raw file to see what is there. If you open the files in Photoshop's Adobe Camera raw or Canon's Digital Development Pro, or Nikon View, or have Images Plus set up to automatically open a raw and apply a non-linear curve, you won't have to do this, but remember not to save the file and overwrite the original.

• RAW - 3504 x 2336
• RAW + Large / Fine JPEG - 3504 x 2336 RAW + 3504 x 2336 JPEG Fine

Red-Eye on/off - Set to Off. If set to on, it allows use of the red-eye reduction lamp before a flash shot.

Beep - Set to Off. If set to On, the camera beeps when auto focus is confirmed, and when the self-timer is used. Doesn't matter for deep-sky astrophotography.

Shoot w/o Card - Set to Off. The camera will not fire without a memory card in it. This is good insurance against accidentally forgetting to put a card in the camera.

AEB (Auto Exposure Bracketing) - Leave set to the default setting of 0.

WB SHIFT / BKT (White Balance Shift / Bracketing) - Leave set to the default settings. This can be used to fine-tune the color balance of images if they are shot in JPEG mode.

Custom WB (White Balance) - Can be used to set a custom white balance by shooting a white or gray card. You can also try to use it by shooting an autoexposure of the sky on AV Mode (Aperture Priority) and then selecting that frame to set the custom white balance on. This can remove undesirable color from the sky background in light-polluted areas, but changing the white point will yield inaccurate star colors.

Color Temp. - The color temperature can be manually selected, such as 5200K for daylight balance. For astrophotography various settings can be used to try to correct for a sky background with light pollution, but again changing the white point will yield inaccurate star colors.

Color Space - Set to sRGB if you have no idea of what a color space is. If you understand color management thoroughly, set to Adobe.

Parameters - Contrast, sharpness, saturation and color tone can be individually adjusted. The default it to apply increased contrast, sharpness and saturation to JPEG images. This however is probably not the best setting for astrophotos because it may increase the noise. Set to Parameter 2 to set these to defaults of zero on each. You can also set up a custom set with your own settings. If you are using high ISOs under warm temperatures, you can try turning the sharpening down to help with the noise. These settings are only applied to the data that is written to a JPEG file, but the info is also saved to a raw file, and applied when the raw file is converted if left at the defaults in the conversion program. With a raw file, all of these parameters can be changed after the image is shot and before it is converted from raw.

Protect - This setting is used to protect a file and lock it so that it cannot be accidentally erased.

Rotate - Rotates an image thumbnail that was shot vertically so that is displayed correctly on the back of the camera. This setting is also saved with the file and used when the image is opened. The image is not actually rotated in the camera, it is only tagged for the correct orientation based on the in-camera orientation sensor.

Print Order - Specifies on the compact flash card which images are to be printed and then number of prints in a Digital Print Order File (DPOF) for output to a printer or service that supports DPOF.

Auto Play - Play an automated slide show of the images on the compact flash card that can be viewed on the LCD on the back of the camera or on a separate monitor via the video out plug on the side of the camera.

Review Time - Set the length of time, 2, 4, 8 seconds or hold as long as the shutter button is pressed, for display of images on the back of the camera after they are shot.

Auto Power Off * - Set the amount of time the camera stays on before it turns itself off. The camera can be turned by on by pressing the shutter button

Auto Rotate - Rotates vertical images so they are displayed with the correct orientation on the back of the camera and when thumbnail images are displayed in the camera's image viewing program.

LCD Brightness - Sets the brightness of the LCD display on the back of the camera.

Date / Time - Sets the date and time in the camera. This information is added to the image files.

File Numbering - Set to Continuous. Sets the method of numbering image files. There are two numbering schemes. Continuous keeps sequentially numbering the files even when a compact flash card is changed. Auto-reset starts the numbering at 0001 every time a compact flash card is re-inserted into the camera.

Language - Sets the language for the menus.

Video System - Set to NTSC for the US, PAL for Europe. Sets the type of video system that will be used by the video out on the side of the camera. Choices are NTSC and PAL.

Communication - Set to Normal. Sets the type of communication protocol used by the USB connection. Choices are Normal and PTP.

Format - Formats the card in the camera. All of the data on the card is erased when it is formatted.

Custom Functions

• 01 Set Button Function: Set to 0 (No function)

        0: Default (no function)
        1: Change quality
        2: Change parameters
        3: Menu display
        4: Image replay
  

• 02 * Long-Exposure Noise Reduction: Set to 0 (Off) if the ambient temp is below 32F, or if you plan to shoot separate dark frames. Use 1 (On) if you are only shooting a couple of frames of bright objects.

        0: Off
        1: On
  

• 03 - Flash Sync Speed in AV mode: - Set to 0 (Automatic)

        0: Automatic (slow sync)
        1: 1/250 sec Fixed (when using flash)

• 04 - Shutter Button / AE Lock button: - Set to 0 - pressing the shutter button half-way starts the AutoFocus (AF) and locks the AutoExposure (AE). Pressing the * button locks the AutoExposure.

        0: Shutter button: AF     * button: AE lock
        1: shutter button: AE     * button: AF
        2: Shutter button: AF     * button: AF lock and no AE lock
        3: Shutter button: AE     * button: AF, no AE lock
  

• 05 - AF assist beam: - Set to 1 (Does not emit the AF assist beam). This only applies when the on-camera flash is raised. If you shoot a lot of flash in the dark, set to 0.

        0: Emits
        1: Does not emit
        2: Only ext. flash emits
  

• 06 - Exposure Level Increments: - Set to 1 (1/2 stop increments)

        0: 1/3 stop increments
        1: 1/2 stop increments
  

• 07 - Flash Firing: Set to 1 (Does not fire the flash)

        0: Fires
        1: Does not fire
  

• 08 - ISO Expansion: - Set to 1 (Off). This allows the choice of ISO 100 and ISO 3200 in addition to the normal range of ISO 200 to ISO 1600.

        0: Off
        1: On
  

• 09 - Bracket Sequence / Auto Cancel: - Set to 3 (Disable) - If the camera is set to auto-exposure bracketing in the shooting menu, the sequence will be minus, zero and then plus compensation. The amount of compensation in stops is set in the AEB shooting menu, and can be set up to plus or minus 2 stops. Auto-exposure bracketing is normally canceled automatically for the next frame. Disable stops the automatic cancellation and keeps auto-exposure bracketing on for the next shot.

        0: 0, -, + / Enable
        1: 0, -, + / Disable
        2: -, 0, + / Enable
        3: -, 0, + / Disable
  

• 10 - Superimposed Display: - Set to 0 (On)

        0: On (highlight AF points on focusing screen)
        1: Off
  

• 11 - Menu Button Display Position: - Set to 1 (Previous). The same menu is displayed even if the camera is turned off.

        0: Previous (top if camera is powered off)
        1: Previous
        2: Top
  

• 12 * - Mirror Lockup: - Set to 0 (Disable) - For long exposure astrophotography on a good solid mount mirror lockup can be turned off. For high-resolution planetary photography it should be set to 1 to enable mirror lockup. The first press of shutter release flips mirror up and the second press starts the exposure. When enabled the camera's self-timer duration is set to 3 seconds.

        0: Disable
        1: Enable
  

• 13 - AF Point Selection Method: - Set to 1 - The multi-controller on the back of the camera selects the auto-focus point. The multi-controller is the small joystick-type button above the larger quick command dial on the back of the camera.

        0: Normal - the camera picks which autofocus point to use.
        1: Multi-controller direct - you pick with the multi-controller button.
        2: Quick control dial direct - you pick with the quick control dial.
  

• 14 - E-TTL II: - Set to 0 (Evaluative Through The Lens (TTL) Flash)

        0: Evaluative
        1: Average
  

• 15 - Shutter Curtain Sync: - Set to 1 - The flash fires immediately before the shutter curtain closes. With 1st curtain sync, the flash fires immediately after the curtain clears the sensor. This is used for different flash effects when subject movement is involved.

        0: 1st curtain sync
        1: 2nd curtain sync
  

• 16 - Safety Shift in AV or TV: - Set to 1 (Enabled). If the camera cannot set a correct exposure in Aperture Priority or Shutter Priority mode, it will over-ride the user settings to give a correct exposure. This doesn't really apply to astrophotography, but it can be useful for daytime photography.

        0: Disabled
        1: Enabled
  

• 17 - Lens AF Stop Button Function: - Set to 0 - For super telephoto lenses that have autofocus lock buttons on them, pressing this button will lock the focus.

        0: AF stop
        1: AF start
        2: AE lock while metering
        3: AF point:M - Auto/Auto - ctr
        4: One Shot - AI Servo
        5: IS start
  

• 18 - Add Original Decision Data: - Set to 0 - This requires a special Data Verification Kit to prove that the image is original and has not been manipulated in any way. This is used in law-enforcement photography.

        0: Off
        1: On
  

Clear Settings - You can clear all of the camera settings or just the custom function settings.

Sensor Clean - This setting flips the mirror up and opens the shutter so the sensor can be cleaned. The camera has to be turned off to cancel this setting. Be sure to use a fresh battery or plug into a 120-volt adapter so that the shutter doesn't close when you are cleaning the sensor as this can damage the sensor, shutter and mirror.

Firmware Version - Displays the current firmware version in the camera. Also allows the firmware version to be updated with the proper software on a compact flash card.

Download manuals, software and firmware for the camera on Canon's support page for the 20D.