Last updated: 21 October 2005
Sent: Tuesday, October 18, 2005 09:02:50 From: Giuseppe Pellizzer (email@example.com) I wanted to report my preliminary experience with the Rini focal reducer (proptics.ieasysite.com/paul_rini_optics_006.htm) and my ETX-90. The focal reducer is a black aluminium piece. I find that the piece is well made and the optical quality looks good. It fits in the telescope like an eyepiece and then the webcam adaptor is inserted into it. That is, it is used pretty much like a Barlow, except that it reduces the focal rather than increasing it. It is not for visual use because of too much vignetting, but it works well with webcams. The reducer is labeled 0.5X and I wanted to check what reduction I was getting with it. The two Moon pictures that I sent you were taken with and without the reducer. Then, I have measured the distance between Moon features that I could find in the two pictures. The ratio of the distance (the units are not relevant here) measured in the picture with reducer and that in the picture without reducer gives the measured reduction. I found that the actual reduction was 0.34X. I could take the whole quarter Moon in two shots with my ETX-90 and the focal reducer, rather than having to take so many shots that I always miss a piece somewhere. So, all in all I think that this is a good focal reducer although it will reduce the focal more than what it is indicated on the barrel. Thanks again for your website, Giuseppe Pellizzer
Without Focal Reducer
With Focal Reducer
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