Archived posting to the Leica Users Group, 1999/10/01
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Godfrey is indeed correct. A very few cameras have had 1/30th bothered by mirror slap, but the majority of known and used SLR cameras, succumb to mirror slap vibration at the speeds of, as Godfrey said, 1/2 - 1/15 sec. Any exposure longer that 1/2 sec overpowers the insignificantly small portion of that exposure that occurs during the vibration. Likewise, a 1/30th and shorter exposure is actually over before the vibration can get mechanically transmitted to the lens, etc., to cause motion blur. This is a well tested fact. Jim At 10:37 AM 10/1/99 -0700, Godfrey DiGiorgi wrote: >> If one is an SLR and one a rangefinder I definitely lock up >> the mirror on the SLR; there is a huge difference in not having >> mirror vibration being another variable. >I have seen this statement so many times and it's just so much total >bullshit. The ONLY time that mirror slap on any modern, well-designed SLR >is of any concern at all is at a very very few shutter speeds (usually in >the 1/2-1/15 sec range) where the *possibility* of a resonant vibration >could happen *with some lenses*. Usually very long lenses or when the >camera is mounted for astrophotography or photomicroscopy use. > >The photo posted was a hand-held snap, most likely at some shutter speed >like 1/60 second with a lens set to approximately 35mm focal length, >mounted on a Nikon F5. There is simply no possibility at all that mirror >slap induced vibration could be detected in any analysis of these photos. > >Godfrey >