Archived posting to the Leica Users Group, 1999/09/14
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On 14 Sep 99, at 16:24, Godfrey DiGiorgi wrote: > It certainly warrants more than this casual test. I can see that there is > cause to add another series of images taken with the Hologon fitted with > the ND filter and the Heliar set at f/16. At the next available > opportunity... :) Hi Godfrey, I am quite keen to view the next round of your Heliar vs Hologon + filter tests, however I don't believe that stopping down the Heliar to f16 would lead to a fair comparison. When the gradation filter is placed on the Hologon the actual aperture is still f8, but the effective aperture becomes f16 due to the light loss incurred by the filter. Closing down the Heliar to f16 (to equal the effective aperture of the Hologon) will lead to a loss of quality due to diffraction, therefore it becomes an invalid comparison. Cheers, Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 Fax +61-2-9554-9259 UTC(GMT) +10 Hours audiob@ozemail.com.au http://www.ozemail.com.au/~distudio/pagelist.html