Hi Dominic -_______________________________________________Do you know why this is? Isn't just a clear filter. Since it's needed for the lens to reach focus at infinity, it seems to me that it's acting more like a corrector of some sort?Weird....Chris----------------------------------
Chris Cook
Astronomical & Nightscape Photography
www.abmedia.com/astroHi Chris !Yes you should have this filter or the other colored filter to have the focus at infinity. You can make the test visualy in daylight , you'll see that you should have the clear filter for a good focus !Let us know when you'll have an astrophoto with this lens that I find verry useful.Clear skies !DominicIt would seem to me that the clear "filter" is needed for this reason... (If I'm wrong, chime in) All filters slightly shift the focus point. The degree of shift is dependent on the thickness of the filter. The fisheyes have colored filters built into them because you can't put a filter over the outside of the lens like you do on a "normal" lens. Thus when the colored filters are not being used, something has to take their place in the optical path because it is designed from the ground up assuming that one of these filters will be in the light path, either a colored one or the clear one for "no filter".Robert Reeves reeves10@swbell.net
520 Rittiman Rd. www.robertreeves.com
San Antonio, Texas 78209 210-828-9036
USA 29.484 98.440 200 meters
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Dominic Cantin
http://spacew.com/gallery/DominicCantin
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