TTL flash metering is not the same a TLL AUTO FLASH. TTL flash metering gives you the correct fstop value to use with a fixed (usually maximum output) flash power.
TTL Auto flash on the other hand uses a fixed fstop and adjusts the flash power DOWN to match that fstop via TTL. Not the same and not as good when you need maximum light.... JCO -----Original Message----- From: Paul Stenquist [mailto:[EMAIL PROTECTED] Sent: Monday, November 15, 2004 8:41 AM To: [EMAIL PROTECTED] Subject: Re: A Question About Macro Lenses Most SLR cameras made in the last 25 years or so can do TTL flash metering. The LX does it quite nicely. When checking exposures with a DSLR, you don't want to rely on the image review. It can be very misleading. You really have to look at the histogram. On Nov 15, 2004, at 8:30 AM, J. C. O'Connell wrote: > TTL is fine but a lot of people do > Macro with strobes (myself included), > and I am not aware of any SLR cameras > that can do TTL flash metering. > > My technique is I use a flash meter, calculate > bellows factor exposure compensation, and determine > a base fstop. But even then I usually bracket > unless I have used exact same lighting setup, film speed, lens and > magnification, etc. > > I would imagine with a DSLR its just a matter > of running a few exposures and adjust fstop > until you get what you want on the image review > screen. > > JCO > > -----Original Message----- > From: Rob Studdert [mailto:[EMAIL PROTECTED] > Sent: Monday, November 15, 2004 8:46 AM > To: [EMAIL PROTECTED] > Subject: RE: A Question About Macro Lenses > > > On 15 Nov 2004 at 7:23, J. C. O'Connell wrote: > >> Unless the 125mm zoomed out to 62.5mm at 1:1, it is >> going to need exposure compensation. > > Of course you are correct, I was simply drawing a relative comparison > to > > another lens. > >> What you have is essentially >> a variable aperture zoom with that lens, how do >> do you know what exposure compensations to use? > > I don't really care but I do know now that relative to a "non-zoom" > macro lens it requires about an extra half stop when approaching 1:1. > I haven't used > external meters for macro photography since the late 80's. Then I had a > 67 and > bellows and I was glad to get my hands on a TTL prism. > >> Does the lens barrel have exposure compensation >> markings on it? > > No > >> At least with a fixed focal length and aperture you >> can calculate the correct compensations based on magnification or >> bellows extension, but with variable aperture those techniques won't >> work... > > ..or you (I) could use the TTL metering, which I do quite > successfully. > > > Rob Studdert > HURSTVILLE AUSTRALIA > Tel +61-2-9554-4110 > UTC(GMT) +10 Hours > [EMAIL PROTECTED] > http://members.ozemail.com.au/~distudio/publications/ > Pentax user since 1986, PDMLer since 1998 >
