The Loreo 3d attachment.

Reviewed by Donald E. Simanek.

Always interested in stereo 3d photography, I bought one of the Loreo 3d "lens in a cap" attachments for my Pentax Digital SLR. Since no one yet is selling a digital stereo camera, this might be the next best thing, I thought. "Turn your digital SLR into a 3d camera" the ads say. Wow! For only $110. It's a good thing I got it from a vendor that offered a 30 day satisfaction guarantee.

The device is a neat little masterpiece of plastic engineering. Plastic housing, plastic lenses, and even plastic front surface mirrors inside. The only metal is the screws that hold it together. It may be ordered with bayonet mounts (also plastic) to fit major brands of cameras. These are not interchangable, so you must order a Loreo specifically to fit your camera. It is very lightweight, so it won't burden your camera bag.

Photos courtesy of Alexander Lentjes. The 3d Revolution

Its two plastic 38mm focal length lenses are about 9 mm apart. The front apertures have clear windows, to keep dust and moisture from reaching the delicate mirrors inside. These windows may be glass; I'm not sure. The mirrors redirect the light from the left and right front windows to the left and right halves of the camera's digital sensor. Unfortunately the images slightly overlap at the sensor's centerline. The manufacturer has arranged the mirrors so that they swap the left and right images. When used with a film camera, prints made from the film will be in L/R order for viewing with a simple optical stereoscope, without cutting or remounting. For those of us who prefer cross-eyed viewing on a computer screen, this feature is wasted. It just requires us to run the pictures through "Stereo Photo Maker" to swap the images again and crop out the distracting overlap area. Even worse, as the instruction sheet warns, "...under certain conditions stray light may still enter the left mirror. This will appear as flare..." To keep the device compact and stylish, the front windows have inadequate light masking. Something like a lens hood should have been included in the design.

This picture shows the limitations of this device. Even from across the street I could not get far enough away from this building to show more than a small portion of it. And then, being so far away, the building shows very little stereo depth, only the foreground tree branches betray that this is a stereo picture. Any device that splits the camera sensor into two parts necessarily reduces the angle of view by 1/2, and there's no way around it. Also, the taller-than-wide format isn't suitable for scenery and landscapes.

So how about a subject that is taller than wide. This Indian totem pole should fit that frame.

But he was too tall. He stands at the entrance to a city park. I'd have had to shoot him from across the street to get his full height (including the feathers in his headband), and then the photo would show even smaller 3d effect.

The Loreo adapter has two selectable apertures: f:16 and f:22. The inter-axial stereo separation is abou 6 cm (a bit smaller than the human eye separation which averages 6.4 cm). It has three focus settings: close-up (1 to 2.5 meter), mid-range (2 to 6 meter), and far (5m to infinity). That close up range might be useful for shooting smaller things, like this mechanical model. Indeed, that's the only use I have found for this device. The other possible use is head-shot portraits.

Closer than 1 meter? How about an old trick used in the 1950s. Prismatic close-up lens pairs were sold for standard stereo cameras to allow photographing very near objects. I happened to have a 4 inch diameter lens large enough to cover the entire front of the Loreo attachment, duplicating this method exactly. The result isn't pretty, as seen below.

The convergence of the chief rays introduces keystone geometric distortion and also greatly exaggerates the depth. This might be fun for "comic" effects, but not for much else.

Obviously the digital camera's autofocus does not function with the Loreo attachment, but its auto-exposure does, even for flash exposures. Set the camera on "aperture priority" and autoexposure selects the shutter speed. This picture should have been taken with bounce flash instead of direct flash, and a plain background would have been better.

In summary, this is an interesting toy, with some limited uses. But for general stereo photography it is severely handicapped. As with all image-splitter attachments it reduces the angle of view by 1/2. In effect it turns your expensive digital SLR into a stereo "box camera".

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Stereos for cross-eyed viewting in 3d Gallery One.
Still more, mostly taken with a digital camera in 3d Gallery Two.
Stereo view cards in 3d Gallery Three.
Home-built macro stereo camera, 3d Gallery Four.
Wildlife photography in your backyard, 3d Gallery Six.
A home-built digital stereo camera using mirrors 3d Gallery Seven.
Stereo with two synchronized digital cameras. [Coming soon.]
Return to the the 3d and illusions page.
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—Donald E. Simanek