On 11/12/06, Mark Cassino <[EMAIL PROTECTED]> wrote: > I'm looking forward to trying out SR for macro work as well. I don't > expect that it will allow me to do much with available light shooting, > but if it lets me slow down the shutter speed by a stop or two that > opens up a lot of opportunities to better balance flash and ambient light. > > I currently use a monopod and A* 200, flash, and *ist-D. At 1/250th of a > second I can usually count on the shot being sharp. At 1/125th the > percentage of successful shots drops off significantly. At 1/60th, even > with the monopod and flash, it's difficult to obtain a critically sharp > shot.
I don't expect SR to work miracles either but as you say even a little help can go a long way. > I've read the thread and I'm not sure what you mean by 'effectively is a > 137mm.' I thought that the A* lens, via the use of floating elements > etc, was using a some degree on internal focusing to focus close. As > such, it actually gets shorted in focal length as it is focused closer. > So it _is_ a 137.5mm lens at 1:1, no? Which is why it does not need > 200mm of extension to get to 1:1. You are correct, my use of "effective" relates to the actual FL at the particular magnification. > You raise an interesting question. I take a pretty empirical approach to > this sort of stuff so I'll be running some tests. I will be too, I'm just too busy to actually go out and shoot at the moment :-( > On a slightly different subject - I was surprised to see in the manual > that Pentax recommends turning of SR when you have the camera on a > tripod. Surely a truly long lens setup on a tripod (eg 400 - 800 mm) - > would benefit from SR, especially if the lenses is on a ball head > (remember Paal's comments on that?) or if it is not 100% locked down (I > usually shot birds with the lens in a semi-mobile mode.) I suspect that's because of the limited bandwidth of the SR system. In other words the SR system is quite slow, it's designed to compensate for the relatively low frequency movements encountered during normal hand holding. Mirror shock is often a source of ringing when shooting on tripods as most are resonant and under-damped. I expect that the SR system may over-react to these high frequency oscillations and may cause the SR system to overshoot in attempting to compensate. Given that the pre-fire timer mode disables SR I guess that they thing pre-fire is of far greater benefit for tripod shooting than SR which makes sense. -- Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://home.swiftdsl.com.au/~distudio//publications/ Pentax user since 1986, PDMLer since 1998 -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
