Scopetronix 14mm and 18mm eyepiece/adapters
A Review by Gregory Pruden
I had the privilege to test two new Scopetronix digital camera eyepiece/adapters for use with Nikon Coolpix cameras. These wide angle eyepieces, available in 14mm and 18mm focal lengths, have screw off eyecups that are easily removed in the dark and the eyepieces can then be threaded into the 28mm filter threads on the lens of most Nikon digital cameras and into the lens adapters of some others like the Coolpix 5000. The eyepieces are a hybrid design and offer excellent nearly parfocal wide views with the eyecups in place and excellent optical and physical connection to the camera when used photographically.

The 14mm (14.497mm) is 5 element 4 group optical arrangement eyepiece with a wide apparent field of view of 66.2 degrees. The 18mm uses a 4 element 3 group arrangement with an apparent field of view of 66 degrees. The views through both eyepieces were very good for the price $119 (14mm) and $99 (18mm) and would be decent eyepieces alone without their photographic double duty with digital cameras. I did not have another medium power eyepiece to compare with these but they had slightly more contrast than the Meade 24.5 SWA or 26mm Super Plossls with similar edge performance to the SWA.

I tested the eyepieces with my Nikon Coolpix 995 digital camera in my three telescopes; a Meade 10" F/10 LX200GPS SCT, a Synta 80/f5 refractor, and a Synta 90/f5.6 Mak-Cas. My first concern was vignetting as most adapter solutions cause serious vignetting requiring significant zoom to remove it. To my delight there was negligible vignetting even at the widest zoom setting when used with all three scopes and the LX200 and 80/f5 had only a few pixels in the top left corner while the Mak had a little more in both the top and bottom left corners. These eyepieces had considerably less vignetting than the William Optics DCL28 that I normally use which produces a strong black ring around all four corners. The more vignetting, the more zoom or focal length in the camera and the longer the required exposures for deep space objects. Using these Scopetronix eyepieces the digital camera astrophotographer will be able to use the widest zoom which will improve most deep space object images.
This cropped image from the image below right shows the ever so slight vignetting in these eyepieces!


14mm with 254mm LX200GPS


18mm with 254mm LX200GPS

18mm with ST80

14mm with Nikon 5000 (no scope)

14mm with 90 f/5.6 Synta MakCas

18mm with 90 f/5.6 Synta MakCas
The above images were all taken at the widest zoom or 8.2 focal length on Nikon 995 and a friend's Nikon 5000 digital cameras.
These eyepieces have a number of threads which allows for a sturdy connection and the 995 did not slip when attached as it has with those adapters and other eyepieces with fewer threads. The glass of these eyepieces and camera lens is placed very close together, which is why there is so little vignetting, and the images have a more even distribution of background light which will also improve deep space images and does not leave odd hot spots, or gradients in the images. I was very pleasantly surprised by this even light distribution as my William Optics DCL28 always requires synthetic flats if the image's histogram is severely stretched.
With other eyepiece/adapter and camera/scope combinations the difference between the focused image in the camera and the eyepiece visually is usually extreme such that removing the camera to locate an object would require focusing to actually see the object. With my camera, scope, and these new eyepieces I could remove the camera and locate a new object without first refocusing which is very convenient. With other adapters/eyepieces no dim objects would show and the central obstruction is visible in dim stars requiring refocus for locating objects and refocus again with the camera. I never even knew that this was possible. This combined with the easy to remove and replace rubber eyeguards switching from visual to photographic use is a breeze. Note: Your camera/scope combination may not yield this same benefit.

The Coathanger - 18mm with ST80 at full wide on Nikon 995 (see full size)
Ptolemaeus - 14mm with LX200 at full Telephoto on Nikon 995 (see full size)

M57 - 18mm with LX200
Plagued by poor seeing and transparency during the testing these images are the best I could do
   

I have always preferred a threaded eyepiece as opposed to an adapter, no Allen wrenches in the dark for me, and these new eyepieces provide even more choices for the adapter challenged folks like me. The 14mm combined with the optical zoom (4x) of the Nikon 995 will provide an excellent high power eyepiece with my main scope when the digital camera zoom is in a telephoto position. I have been looking for a high power solution and the 14mm digital camera eyepiece fits this bill quite well. Images of the moon using this eyepiece even in poor seeing showed craterlets and other features near the resolution of my 10" SCT. For small refractors or other fast scopes the 14mm or 18mm may be all that you need depending on your digital camera's optical zoom. The 18mm will provide an excellent medium power solution for the f/10 telescope but will excel with the rich field refractor and the Mak for fast wide views (2 degrees) with the digital camera.
Calculated Image FOV with 2540mm SCT and the Nikon 995
Wide Telephoto
18mm 21' x 16' 10' x 7.6'
14mm 17' x 12.7' 4.5' x 3.4'
Calculated Image FOV with 400mm Refractor and the Nikon 995
Wide Telephoto
18mm 2.2° x 1.7° 35' x 26.4'
14mm 1.6° x 1.2° 27.4' x 20.6'
Calculated Image FOV with 500mm Mak Cas and the Nikon 995
Wide Telephoto
18mm 1.8° x 1.3° 28' x 21'
14mm 1.4° x 1.0° 22' x 16.5'
You can calculate the FOV of these eyepiece with your setup here

My only complaint about these eyepieces is that there are not longer focal length versions currently available. I would love to see a 30, 35 and/or 40mm version of these eyepieces and maybe a really high power 10mm. They provide a sturdy, vignette free connection, with even background distribution, they are extremely convenient, and produce excellent digital camera images.

Visit http://www.scopetronics.com/new.htm for more information.