Archived posting to the Leica Users Group, 2003/12/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Sorry for the earlier empty post. Here goes. A collegue and myself wanted to find out if we could get 80 line pairs per millimeter using a Leica and a Kenyon gyro stabiliser. We could not find those data in literature so last night, while also doing a test of Laphroig versus Lagavullin, we decided to give it a try ourselves. We scribbled some lines on a piece of paper with a group of line pairs one 1 cm per pair and the other 5 mm per pair. With a Noctilux 18 meters away we calculated the image on the film to be 36 and 72 line pairs per millimeter. We suspended the camera and running gyro from a bungee cord and started. First exposure was at 1/250 second and f1.0 going in stops to 1 second and f16.0. Then we tried the same sequence while handholding the camera and bracing ourselves in a doorway. By then we became to doubt the ability of a 4000 dpi scanner to resolve our results. While one would assume that 4000 dpi translates to 80 line pairs per millimeter,some knowledgeable people we asked suggested that 60lp/mm is about the best such a scanner can do. So we had to aim a little lower and did the same test with an aasummicron90 mm and the stabiliser starting at 1/60 and f2.0 . Although our test was hastily done it still yielded some suprises to us. The biggest being that the stabiliser clearly is able to permit shots at 1 second. Others were that the noctilux was still giving good results at f 4.0 and 5.6 and stayed that way until f16.(we realise that the focus shift of the lens could have been to our advantage at those apertures if we started out with a focus error). Also suprising was that at f 8.0 and smaller the summicron image is starting to fade. Lastly it shows that it is hard to find the testcard when handholding the camera. On the page the first column is the stabilised noctilux the second is the same handheld(stopping at 1/8th) and the last is the summicron. The film used was Kodak E100 GX . The question is to get rid of focusing errors .can one set the lens accurately at infinity just by putting the index on thatmarkingAnd if so at what distance would one have to put the target? http://www.leica-gallery.net/apekop/folder-6004.html best regards simon jessurun - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html