|Denkmeier Optical Coupling System
| Visually optimized scopes can present a special challenge for imagers, as the focal plane is often formed so close to the tube
that cameras or CCDs cannot be accomodated. This can be partially resolved with the use of a relay lens or Barlow to "pull"
the image from the OTA, though creating a larger image scale and increased EFR in the process.
Denkmeier Optical has developed a low-amplification 2" Optical Coupling System that, while primarily intended to complement
their binoviewer line, may provide relief for "back-focus challenged" scopes as well. Having been fortunate enough to get one
of the proto-types, I've included a few test shots to illustrate its capabilities. While the A/B images themselves were taken
within moments of each other, only rough processing was done, so variations of image quality do exist.
These shots are from a Canon D60 digital SLR and 203mm f/5.9 Mak-Newt using a Denkmeier OCS or TeleVue 2x
Powermate (for the reference images). Focus was shifted outwards out from a -12mm (inside) position to a +25mm (available)
TeleVue 2x Powermate Denkmeier OCS
The above images were equally resized (about 20% of the originals) but not cropped, and illustrate the low amplification of the
Denkmeier OCS (about 1.25x with the center spacer removed).
The grayed-out background image is from the Denkmeier OCS while the insert is a 2x image from the
TeleVue Powermate (images resized but uncropped). The Denkmeier image is shown below in normal color
The Denkmeier OCS does a spendid job as a low-amplification relay lens, with a slight amount of field curvature seen in the
stars around the edges and mild vignetting (most likely from the MNs small secondary).
In another example of image scale, the foreground Denkmeier sun uses a 2x Powermate shot as a backdrop, each was an
uncropped 3072 x 2048 pixel image (re-sized down to 800 x 533 for web display). Were it not for my hap-hazard job of centering
(Oops!), the OCS image would have fit snuggly within a single frame! Foreground image is at 1/500th sec, background is 1/250th
at ISO 100.
I continue to use and enjoy and my TeleVue Powermates, but with its low amplification factor and preservation of a faster focal
ratio, the OCS fills a much needed niche in my artillery... it looks to be a keeper!