You're right, Leon. I forgot to think about flying insects. :-) Jostein
----- Original Message ----- From: "Leon Mlakar" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, May 11, 2005 9:14 PM
Subject: RE: reverse mounting lenses
Wireless flash and P-TTL are both useful but not essential. HSS, contrary to
what you implied, is not a good idea for stopping a motion.
At the speeds beyond the flash sync speed the shutter is never completely
open, hence a single flash pulse cannot expose entire frame. HSS works by
delivering a series of light pulses that are sync'ed with movement of the
gap in the shutter that let's the light to the film/CCD. This means that
the fast moving subject is "frozen" several times with several light pulses.
HSS is only good for fill flash on a sunny day if you want to shoot open to
reduce DOF.
To freeze the motion you're much better off using shutter speeds lower than
the sync speed. Remember, the duration of a single flash pulse is 1/2000th
of a second or less, depending on how much light is necessary. If you stop
down enough, the fast moving parts (wings?) of the subject will not get
recorded on the film/CCD so you'll see no blur.
See http://webs.lanset.com/rcochran/flash/hss.html for some examples and
more technical details.
Leon
-----Original Message----- From: David Zaninovic [mailto:[EMAIL PROTECTED] Sent: Wednesday, May 11, 2005 5:38 PM To: [email protected] Subject: Re: reverse mounting lenses
Pentax flashes can deliver TTL even with screw-mount lenses,but don'thave any hopes for P-TTL.
I would like to have P-TTL because of the wireless high speed flash option on my D. I will try to find some tubes that will transfer electrical contacts. It is much easier to shoot bugs handheld with flash set to 1/4000 speed and have a few tries to get the focus right.
