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Scopestuff Anteres .5x Focal Reducer

Thought I would post the results of a test I did for ScopeStuff this week comparing their new Anteres .5 Focal reducer to my ATIK focal reducer.  Both of these reducers are the 1.25" nose piece types that screw directly onto your 1.25" eyepiece or the nose of your camera.  Both offer .4 to .6 reductions.

The point of my test was to compare them against each other and in my case, to see how they worked with the DSI cameras and more specifically, the larger CCD chip on the DSI-Pro II. 

For this test, I used each reducer on the same target thru my LX90 with my DSI-Pro II.  The DSI had my ATIK filter wheel on it and the Meade IR filter was selected.  Because of the high sky glow in this area, I also used my IDAS LPS filter on the front of each reducer while imaging.

Imaging Process:
For each set of images, I ensured that one star (my reference) was located in the same spot on the chip (since I had to remove the camera to change reducers).  I also setup guiding via another DSI to limit drift, wind effects, etc.  Each set of image consisted of 40 exposure of 30 seconds each of NGC2903 and the surrounding area. 
Post Processing:
From each set, I selected the best 20 images and stacked them in Envisage.  I then imported them into PhotoShop where level adjustments were performed to try to balance each image. I also applied a false flat to each (made from the original images) to try to reduce some of the evident vignetting.  No other adjustments were made including any changes to the stars, contrast, etc.  I did make some annotations on the images and save as JPEG (no compression).

Test Images:

Test Results:

  • FOV – The ATIK has a slightly wider FOV then the Anteres.  I measured this at a little less then 5% but both are in the same ball park
  • Vingetting – the Anteres was much better here.  Stars near the outer 20% or so of the ATIK show definite flaring.  Some of these stars were outside the FOV of the Anteres, but other could be compared directly those were better then in the ATIK image.
  • Contrast – The Antares appears to have better contrast then the ATIK.  While this is a little more subjective in nature, the vignetting with the ATIK contributed directly to this and shows as a much brighter core and dark corners.  The Antares was a much flatter field allowing for greater contrast at the center of the image.

Final Opinions:
I have used the ATIK reducer for a couple of years and have not had any issues with it.  However, this has always been with cameras having smaller chips then the new DSI-Pro II.  This increase in size made quite a difference in the capabilities of this reducer.  The Antares, on the other hand, handled the larger chip much better with greater contrast and far less vignetting.  While they are both quality reducers and even considering the slightly larger FOV of the ATIK, I would have to give this test to the new Antares overall.  It appears to work very well with the new cameras and is very capable at a good price.

Published Sunday, February 05, 2006 11:07 AM by E2Pilot


DrewS wrote:
You comment the Atik has a slightly larger field of view but more flaring and vignetting. Is that just two sides of the same coine as a function of the spacer you are using?

In other words, are the two FRs actually slightly different in strength, and would both get the same quality image if one used a spacer with each to match the FOVs?

I suspect that isn't the case, since the FOV difference is so slight, but I certainly get nice images with my Meade 3.3 FR with some spacers, but terrible vignetting and coma if I use to long a spacer/get to wide a FOV.

Drew Sullivan

2:35 PM on March 12, 2006

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About Stephen P Hamilton

As far back as I can remember, I was completely thrilled with all things having to do with flight, space, and some astronomy.  I am sure it came as no surprise to my family when after college, I joined the Navy to become a Naval Aviator.  Following Filght Training in Pensacola, FL, I moved to Virginia where I flew the Grumman E2-C Hawkeye, a carrier based Airborne Early Warning and Control aircraft.  It was on the long flights over the open ocean at night that I again became interested in Astronomy as I would spend my evening watching the heavens thru a pair of binoculars from my plane.

Several years later, I eventually got my first real telescope, a Meade ETX-70.  Since then, my collection of scopes and other "toys" has grown

a bit and my current primary scopes are the LX90 seen in this image and my LXD75 SN8.  These days, my real passion is astro-photography which, along with its many frustrations is also incredibly rewarding.  My primary cameras are my Meade DSI's (DSI, DSI-Pro, and DSI-Pro II), my LPI for planetary imaging, and my Canon 300D which serves double duty for both astro and non-astro photography.

I currently live in Chesapeake, VA where I am an Information Systems Consultant by day.  I belong the Back Bay Amateur Astronomers, our local astronomy club, and do presentations for local schools and public groups on astronomy.

I can be reached at

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