Max f/4 Lens + TTL Flash

Started Jul 25, 2008 | Discussions thread
Shop cameras & lenses ▾
Peter Kwok
Peter Kwok Senior Member • Posts: 2,292
Pre-flash wide open, shoot after stop down

Pre-flash measurement is taken while the lens is wide open, just as you view the scene thru the VF. In fact, you can see the pre-flash in the VF. So, a f2.8 or faster lens should yield better measurement.

The actual flash occurs after the mirror flips up, the lens stops down and the shutter fully opens. Thus, shooting at f5.6 has nothing to do with pre-flash with a f2.8 lens.
--
Peter Kwok
http://www.pbase.com/peterkwok

 Peter Kwok's gear list:Peter Kwok's gear list
Canon EOS M Canon EOS 5DS Canon EF 70-200mm f/4L IS USM Canon EF 16-35mm f/4L IS USM Tamron SP 45mm F1.8 Di VC USD +3 more
Post (hide subjects) Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow