Attaching Opticals to Your Camera Lens for
High Magnification Imaging using Monoculars, Binoculars and Spotting Scopes
by Bill Benz

It can be shown that if a TTL (thru the lens viewing) camera lens is held up close to the eyepiece of most any optical device, such as a monocular, binocular, or spotting scope, one can see the subject in the eyepiece thru the view finder of the camera. You can also take a picture of what you see in the view finder by holding the camera close to the eye piece. This however becomes quite difficult when you have to hold the camera and the optical device at the same time while trying to focus and click the shutter.

The Lens to Eyepiece Connection

If you can hold your camera up to the eyepiece and take images this way, how can one hold the eyepiece of an optical device so that it will become an integral part of the camera lens?

To quote Trevor Anderson in his article Photographing Through a Microscope the following three criteria should be used:

"Three criteria are important. First, the method must be safe for both the optics of the camera and the microscope. If there is any possibility of scratching these, the adapter must prevent this unhappy event. Second, the method must be stable to prevent camera shake. Third, the adapter should block extraneous light from entering the camera from the gap between the lens and eyepiece"

The LE-Adapter

Some fifteen years ago I invented and patented a device that meets Mr. Anderson’s criteria. I named it the LE-Adapter (the LE standing for "lens to eyepiece"). Its a device that couples a camera lens to the eyepiece of most any optical unit whose eyepiece is less than 1.7 inches (43mm) in diameter. The LE-Adapter consists of an annular anodized aluminum ring that has three "sizing screws" located 120 degrees apart and a spring steel band that centers and locks the eyepiece to the camera lens.

This lens adapter also has a 37mm "coupling ring" as well as 52mm threads to match the filter threads of most digital cameras. Step-up or step-down rings are available from local camera stores if the camera does not have these two filter thread sizes.

Front view of the LE-Adapter showing the three "sizing screws" and the spring steel band.	Rear view of the LE-Adapter showing the37mm coupling ring and the 52mm threads.

The procedure for attaching the lens of a camera to the eyepiece of an optical device is relatively simple. First one threads the 37mm "coupling ring" or the 52mm threads onto the filter threads of the camera. Then the three "sizing screws" are set so that the spring steel band is adjusted to the approximate diameter of the eyepiece. The eyepiece is then inserted into the LE-Adapter and the screws are individually turned to center and firmly lock the eyepiece to the camera lens. To remove the camera and the LE-Adapter from the eyepiece, one merely loosens one of the "sizing screws" (while holding onto the optical device!) and slips the camera off of the eyepiece.

LE-Adapter mounted on a Nikon 990	Monocular coupled to Nikon 990

Eyepiece Vignetting

One of the inherent problems with any lens to-eyepiece coupling device is vignetting. That is, if the cameras telephoto lens can not be zoomed to a focal length which puts the lens effectively inside the eyepiece the image will have a shaded ring around it. See the pictures below. The picture on the left shows a Nikon 990 at half its full telephoto setting when the camera is attached to an eyepiece and the picture on the right shows the camera zoomed to its full telephoto setting wherein the vignetting effect is eliminated and a full image is captured. (For additional explanation of focal length see Understanding Lenses).

Nikon 990 Image at Half Telephoto	Nikon 990 Image at Full Telephoto

Aperture Vignetting

Another cause of vignetting with high magnification optics attached to the lens is the "aperture vignetting effect". To obtain properly exposed images the aperture of most digital cameras lenses partially open and close in relation to the intensity of the amount of light impinging on the light sensor within the lens. The brighter the subject... the smaller the size of the aperture of the lens will become to adjust the camera for proper exposure. When an eyepiece is coupled to the lens of a camera and the aperture closes down the resulting image will be framed by the aperture of the camera. See the picture of the Nikon 990 monitor showing the outline of the aperture.

Aperture set to f/7.0.

Focusing

When using a high magnification device attached to the LE-Adapter the following steps are recommended.

1. Focus the optic on the object before inserting it into the LE-Adapter. This will allow one to be in approximate focus after inserting the eyepiece into the LE-Adapter.

2. Set the camera in the aperture preferred mode and the zoom setting to full 'optical' telephoto.

3. Fine focus the optic and try using the autofocus setting for the sharpest focus. If the ‘autofocus’ mode does not work satisfactorily... set the lens to manual focus and infinity and use the focusing control on the optic to obtain a sharp image.

It should be noted that the quality of the image is highly dependent on the quality of the optics. Higher quality optics should always result in images that will record the truer colors and result in higher resolution recordings.

It also should be noted that when you attach a high magnification optic to your camera lens with the LE-Adapter, the magnification of the camera will be multiplied by the magnification of the optical device. That is, if one attaches a 20X spotting scope to an 8X lens the combination of the camera and the optic will result in a total magnification of 160X. This high magnification combination will also result in a very narrow field of view. Therefore it is best to use a lower magnification device.

I have found the 8x32 Walters monocular (sold by LensPlus) to be a very a good match with the Nikon 990 camera. The combination of the two results in an optical magnification of approximately 16X. A number of the images shown in the Image Gallery were taken with this combination.

Nikon 990 with Walters 8x32 Monocular

Supporting the Camera Lens

The heavier the optical device that one attaches to the camera, the more consideration one should give to..."should I hang the camera on the scope or should I hang the scope on the camera?"

The light-weight Nikon Coolpix and cameras that are similar in weight can normally be attached to a scope mounted on a tripod without additional support.

When one moves up to the heavier cameras like the Sony C1000 or the Olympus E1000 and a heavier optical device like a spotting scope...the consideration here is..."should I attach the camera to the tripod...or attach the scope to the tripod?"

The LE-Adapter support bar is an example of a device that allows one to put the camera or heavier optics on a tripod. See the photo below that shows an Olympus C-2100 mounted on a tripod with a 3 pound Bushnell 15x by 60mm spotting scope attached to its lens with the LE-Adapter and supported by a support bar.

Nikon 990 with Bushnell scope.	Olympus C-2100 with Bushnell scope

Preferred Camera Type

Until the digital camera manufactures can design a hood for the camera monitor or a monitor that one can use to view subjects in daylight...the camera of choice has to be one that you can compose your images by viewing thru the lens.

There are a growing number of camera accessory suppliers on the Internet that are starting to help resolve this problem by designing hoods that attach to the tripod threads in the bottom of the camera or are held on by velcro strips attached to the sides of the monitor.

Conclusions

For quality daylight high magnification pictures you need:

1. A Digital Camera that...

• ...has a monitor with a hood or thru the lens viewing (TTL) capabilities.
• ...has zoom capabilities that will eliminate vignetting and can be set in the aperture-priority mode.
• ...has a remote control or a timer to allow the camera to steady itself after the shutter button is pressed.

2. A sturdy tripod.

3. A method for coupling a high magnification device to your camera lens.

4. A support bar to support the camera lens when using heavier optics such as a pair of binoculars or a spotting scope.

Image Gallery

The following images were recorded using the LE-Adapter with various optics. Comments on what cameras were used and the optical devices that were attached to their lenses are also included.

Berries taken with Nikon at full telephoto.	Berries taken with Walters.
Night Heron taken with Nikon at full telephoto.	Night Heron taken with Bushnell 10 x 50.
This image was captured with a Sony TR101 camcorder set to wide-angle. The nest in the center of the picture is about 250 yards away.	This image was captured with the same camera set to full telephoto with the 10X50 scope.

This page was put together by Dennis Curtain

Copyright by Lens Plus