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Message: <blockquote data-quote="Paul Corfield" data-source="post: 1847199" data-attributes="member: 19132">Imagine the image leaving the barlow as an ever increasing cone. By moving the barlow slightly further from the camera, the cone covering the sensor is enlarged and the softer parts of the image at the edges of the cone can be made to fall outside the edges of the camera sensor. This also has the effect of increasing the magnification because less of the image is now hitting the sensor. It works with teleconverters too. I found with my Kenko 1.4X teleconverter that I can put a 60mm macro tube between it and the camera and the magnification is boosted to 2X.I'll do some more tests with the Antares 1.6X barlow just to be sure I had the focus spot on. Wont be able to post anything till Monday as I'm away doing a show this weekend.Other big 2" barlows that I know of are the 2" Televue Big Barlow and the Orion 3 element Apo barlow. Also some made by Siebert Optics might be ok. All these are in a higher price bracket though so I've not been able to afford those yet.The Antares 1.6X beats my best 2X teleconverter. Don't know how it would compare to the Canon one though.Paul.</blockquote>