The Sun, with sunspot group 1024, a member of new solar cycle 24, was photographed on July 6, 2009. It was shot with a Canon 1000D (Digital Rebel XS) DSLR camera through the Stellarvue SV70ED 70mm refractor with eyepiece projection at f/32 at an equivalent of 2,240mm of focal length and a 1/500th second exposure at ISO 400.

This type of astrophotography is used when a high amount of magnification is needed, such as for planetary or lunar or solar close-up photography. Increasing the magnification means increasing the effective focal length of the telescope. The focal ratio also increases, slowing down the speed of the optical system. Eyepiece projection is rarely used for deep-sky astrophotography.

Eyepiece-Projection Adapter

Eyepiece-Projection Procedure

• Locate and center the object you want to photograph in a regular high power eyepiece.

• Put the eyepiece in the eyepiece-projection adapter and attach your camera.

• Focus your camera with Live View.

• Shoot a test exposure.

• Examine the results with the LCD on the back of the camera.

• Make adjustments.

• Shoot a lot of frames in the hope of lucking out and getting one good sharp one during a moment of good seeing.

The amount of magnification is determined by the spacing of the eyepiece to the sensor. Varying the distance between the eyepiece and focal plane of the camera changes the magnification of the system.

The correct exposure for close-ups of lunar craters and solar sunspots can usually be determined by a simple meter reading in the camera since the subject will usually fill the entire frame with eyepiece projection.

WARNING! - NEVER ATTEMPT TO VIEW OR PHOTOGRAPH THE SUN WITHOUT PROPER AND SAFE FILTRATION! INSTANT AND PERMANENT SEVERE EYE DAMAGE COULD OCCUR.

The correct exposure for the planets can be determined by trial and error through test exposures, and examining the image on the LCD on the back of the camera.

Focusing

Focusing can be difficult for eyepiece-projection photography. Because of the long effective focal lengths, focusing in extremely critical, but the slow focal ratios produce a very dim image. If your DSLR has it, Live View is the best way to focus with eyepiece projection.

An eyepiece-projection adapter used with a diagonal to reach focus.

With some refractors, it may be difficult to get the eyepiece to focus at all without some type of focuser extension. Most refractors are made to be used visually with a diagonal. If a diagonal is not used, the focuser may not have enough "out" travel to reach focus for an eyepiece.

It is also possible that you won't be able to reach focus with a diagonal and eyepiece-projection adapter because the focuser does not have enough "in" travel to reach focus because the eyepiece is an inch or two behind where it would normally sit in the diagonal.

You will just have to test your particular setup and see if the eyepiece you plan to use in the eyepiece-projection adapter will come to focus. If it won't you will have to purchase an extension tube.

Note that if a diagonal is used, the image will be mirror reversed. This should be corrected during image processing before the image is presented for viewing.

When you employ the high magnification associated with an eyepiece-projection setup, you are normally trying to do high-resolution work of the planets, Sun, Moon, or double stars. When you magnify an image to this degree, you also magnify everything else, such as bad seeing, poor focus, vibrations, and poor tracking. Slower focal ratios mean longer exposures which compound these problems.

If you are shooting the Sun (with proper safe solar filtration), or planets in the daytime, you may find it is very hard to see the LCD screen because the surroundings are so bright it washes out the screen. It can be helpful to use a black cloth, or even a coat, over your head and the camera to block out this stray light, and help you see the LCD for Live View.

Eyepiece Projection - The Bottom Line With eyepiece projection astrophotography, a special adapter is used to hold an eyepiece that projects the telescope's image onto the sensor of your camera. This method is usually used for high-resolution and high-magnification lunar, solar, and planetary photography.