DVL-Digest 748 - Postings: Index CCD Size and Depth of Field VAIO phone home. That's a bad Sony, bad, bad, bad. CCD Size and Depth of Field - "Perry" You could write what I know about optical physics on the back of a postage stamp: 1) The minimum aperture (largest f-no) in an optical chain dictates the overall f-stop. For video cameras this is the splitter block at about f1.6. For complicated reasons to do with their design, you cannot make the current di-chroic splitter blocks any faster. 2) Therefore putting an f1.2 lens on the front is 'wasted', it can only pass up to f1.6 3) Aperture stop doesn't 'attenuate' all light, only that passed by a faster element. Think of it like a clipper, not an attenuator. 4) f-stop is based upon 'perfect' lenses, real lenses let through less light. Film guys measure this with 't-stop' values but it never caught on with video. 5) I'm not sure exactly what a Frasier lens is, but the only 'Snorkel' or 'Periscope' lens I ever used had a MAXIMUM aperture of f22 (if I recall) and so had an incredible depth of field. It was normally used for model shots, so this was as well. Incidentally, for model work it may need to be used as low as f60 which results in very little light getting through - this means either very high lighting levels or long exposure times. High lighting levels can cause problems of heat so ergo - film cameras live on with stop frame animation computer controlled model rigs. Perry Mitchell Video Facilities http://www.perrybits.co.uk/ VAIO phone home. That's a bad Sony, bad, bad, bad. - "Perry" Way back, a colleague in my office (in UK) was given a beta copy of the first Microsoft IE browser to test. The company had a wide (1MB/s+) Internet connection. During the install process his machine connected to an MS site in UK and stayed connected for many minutes with intense HD activity until my friend decided to force a disconnect. The rumour was that every browser install would also do a complete HD scan for illegal MS programs! Perhaps we'll never know, and the next version he got had lost the scan. Perry Mitchell Video Facilities http://www.perrybits.co.uk/ (diese posts stammen von der DV-L Mailingliste - THX to Adam Wilt and Perry Mitchell :-) [up] |
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