Hi--

>Now actually my real question becomes: what is the practical difference
>between TTL and ordinary auto flash? I have a Vivitar 285, and it has served
>me quite well with my Nikon manual bodies. The (simplified description of
>TTL technology seems easy enough to understand: the reading is at the film
>plane, using the camera's meter, and then at the "right" moment, the flash
>is shut off! Do I get center-weighted 60-40 metering? Now I get average
>metering using the sensor (covering say 30 degrees) on the flash. Is that
>the main difference? Really analogous to using TTL meters versus handheld
>meters?

Ummm, TTL does work much better with macro and tele, and it is more center-
weighted, so there is less of a problem with nearby subjects shutting down the flash too early. Also, any aperture (within the flashes power range) is
OK, including fractional apertures, so it simplifies use.

>About meters. In actual fact, I find most discussions on the Net about
>metering very confusing. When people say my camera has a great meter, do
>they really know what their cameras' meters are measuring? For example, it
>is never clear to me what 60-40 weighted average really means---except when
>the reading is from a uniform light source. Say you have a little candle
>emitting some light at 50 candle/ft^2. And everywhere else is having a
>luminance at 5 candle/ft^2. Suppose the candle just fills the entire
>"circle" of the 60% area of the meter, and no more. Will the meter then give
>a reading of 0.6 * 50 + 0.4 * 5 = 32 candle /ft^2?

Unknown - newer Nikons, and the F3, actually have most of their response
fairly uniformly in the large VF circle area (though it is usually not perfectly centered). Older cameras spread out the sensitivity area more,
which I think is better for quick metering.

>Here, on this occasion, if I use a TTL flash? Say, I even set the shutter
>speed at 1/15 sec, what kind of exposure will result?

The flash metering and ambient metering are mostly independent - if you
meter for full ambient exposure, the flash is added to that, and may cause overexposure.

>Maybe I'm reading too much Ansel Adams, but he did make spot meters very
>attractive---because at the very least, one can understand what it's measuring.

Yes, but it is often wrong! It takes a firm understanding of what it means to meter an area (color sensitivity of meter, placement of "grey" tone relative to others - it is slow, and there are pitfalls). There is no handy "middle grey" subject detail for an accurate quick spot metering. And
AA almost invariably modified the negative exposure when printing, with LOTS of dodging and burning, making one wonder why he didn't just go for an average-contrast negative, standard processing, and an averaging meter - same results, generally, but much simpler process.....

>>Ah, lessee, um, how do I make a million dollars easily and safely,
>>with a few hundred to start (in under a year, if possible.....)? ;-)

>Economists know this answer very well---impossible. Knowing the answer is
>one thing, really understanding why is the heart of the matter! That's why
>people do research about how the market works. (You can liken it to:
>everybody know what happens when you let go of an apple: it falls downward.
>Can you explain why?) In my experience with photo equipment market, one
>makes a good deal only if somebody else made a mistake. Here is my real
>story. I bought a Nikon F with an FTn finder from this shop. Just ten
>minutes after I gave me my credit card number and address, their manager
>called back and said the meter didn't work---they thought it did, but when
>they checked it out and packing it up they found out. Not having heard
>anything bad about the shop on the Net, I gave this guy the benefit of the
>doubt, and continued to listen. He said he should either cancel the order,
>or give me a discount. But then he said this was a very clean body. So I
>took my chance. The camera arrived---the meter wasn't reactive. But then I
>later found out it was just a bad battery contact! Here is an example of why
>the market favored me: the manager there made a mistake. Other than that,
>with any serious trader, you can "make a million dollars easily and safely."
>
>But of course relying on somebody else to make a mistake is not a very
>useful strategy.
> Albert Ma

The market (stocks) always struck me as a totally artificial condition, with lots of silly rules invented to make things more interesting (and profitable) for the insiders, but more mysterious and difficult to work with for the outsiders - and market "forces" border on the religious/occult - umm, much like subatomic physics, I guess..... On the last things you
said, I have been buying from Shutterbug for about 12 years, and used to find astonishing deals, often from people who bought when things were low, and decided to sell at an appropriate (for them) discount for used - or, like with your deal, the item would not appear to be very functional, or in good shape, but with a little effort on my part, would be useful to me -- all fair trades for the people involved, and I am always taking a risk when buying.
David Ruether