rob Zukowski , Feb 26, 2005; 12:16 p.m.
Just wondering from your experience which metering system you
prefer. I own the 7 film and the 5600d flash. I am still deciding
between the 28-70mm G 2.8 lens or the 28-75mm d lens. I know the d
activates the ADI system. Is the ADI system more advanced than the
TTL. I believe the G lens will use the TTL sysytem. Whey can't
Minolta make a 28-75 mm G D 2.8 lens to mike my life easier. Thanks
for your help.
Clinton Abe , Feb 26, 2005; 02:33 p.m.
Rob, The ADI system helps when you have a reflective surface in the background. If you were to take a picture of someone in front of a window and you focused on the person, you might get a big reflection of the flash from the glass which would cause the camera to reduce the output of the flash leading to an under-exposure of the main subject. With ADI, the camera knows that you are focused on the person and will disregard the reflection from the glass.
Another point to consider between the two lens. The 'G' lens is slow in focusing, even with the improvements Minolta has made to the AF over the years. If you have any other AF lens that you use, the 'G' will seem like it's taking forever to focus. You might want to try each lens before you buy.
A third factor is weight. The 'G' version is heavy, but it is a impressive bit of glass, if that's what you're looking for. The 'D' lens is smaller and lighter.
Matt H , Feb 26, 2005; 05:25 p.m.
Rob
The default flash-metering setting for the 5600D used with a D lens is ADI in conjunction with pre-flash metering. With a non D lens it will revert to pre-flash metering on it's own.
The pre-flash utelises the 'normal' 14 segment meter to evaluate the correct exposure rather than the 4 segment dedicated TTL flash meter. In theory this should produce more accuarate results. The ADI system gives extra feedback to help correct problems caused by excessively reflective surfaces in the picture.
By knowing the distance to subject, it is possible for the ADI sytem to calculate the correct flash output on its own but for some reason this only occurs when using the built-in flash. When using an accessory flash, the ADI is always used in conjunction with pre-flash.
Having said that, turning HSS off, setting bounce flash, using off-camera flash, rear curtain flash, multiple flashes or mirror lock-up cancels the ADI/Pre-flash and the whole thing reverts to TTL metering anyway.
So, if you use your flash as the main light source, on-camera, pointing straight at the subject, in conditions that may confuse the exposure system, then ADI can be useful as it 'throws a little extra into the mix' when the camera calculates the correct flash output.
Bill Tuthill 
, Feb 28, 2005; 12:34 p.m.
Best flash results are usually produced with modifiers (bounce,
reflector, softbox). When you rotate or tilt the flash head, it
cancels ADI. So you might ask yourself when you'll use ADI.
Only with a mirror in the background? (That occurs frequently, Not!)
Matt, maybe the 7 is different, but my camera does not do preflash
in regular TTL mode.
Rob, I don't know how fast AF needs to be for you, but I find that
with a 70-210/4 mounted on my 5, I occasionally miss shots due to
slow AF. Both this lens and the 28-70/2.8 G are rated "very slow"
on Photozone.de but telephoto lenses usually are slower due to
less DOF.
Matt H , Feb 28, 2005; 07:48 p.m.
Bill,
Sorry, I should have been more specific. The various flash metering modes I described are those used by the Dynax/Maxxum 7 film.
Steve Foster , Mar 01, 2005; 08:42 a.m.
I have a 7 film and 5600 flash unit. Although ADI is a feature when used with a D lens (I have 2). I can safely say I have never needed to use it. Direct on camera flash looks awful at the best of times. Even when using fill flash out doors I don't use it. I carry with me a white golf glove, whenever I need fill flash I put the glove on and bounce it off my hand. You could use a piece of card as well but I find the "glove light" is softer.
George Givens Jr. , Mar 14, 2005; 12:20 a.m.
Hmmm, I wonder what photographers did before there were things like ADI, pre-flash TTL, and TTL?
I never, never, never use my 5600HS(D) at 0 degrees. I almost always have my Omni-bounce on the flash and the flash head at a 45 or 60 degree angle. ADI, who needs it?
If I'm shooting wildlife or in a backlit situation with a distant subject I am typically in spot metering mode and manually adjusting my output with my choice of apertures. In cases like I just described ADI is a mute point.
The way I see it ADI is for beginners or people that rely on Program mode to get good exposures and who take snapshots with their subjects in a position they shouldn't be in the first place.
Don't get me wrong, I shoot in P mode too but only when I know my camera can handle the scene and my intervention is not needed. And sometimes in those cases I bracket, bracket, bracket.
