SF20 output in TTL mode

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Hi Leica users.

I am asking if any one knows whether the SF20 Flash unit fires on all stops when operated in TTL mode.

We are told it does but in use, but using a meter, it seems to operate in zone form i.e. 2.8 - 5.6 - 11 and not in between and yes it is in TTL mode. Just the same as it does in auto only through the lens.

No one is able to answer this question at the dealers. I need to know if this unit is faulty or not. If one wanted to fire one stop under how can one tell if the unit may already be firing one stop under?

Just hoping someone may be able to help.-- Greg

-- Greg Pratt (gregpan@ozemail,com.au), May 28, 2002

Answers

Greg, you seem to be too caught up in theory. With any piece of equipment, you have to test, test, test. Shoot a half dozen rolls of film. Note each shot & all the tech data. Develop, compare, learn. At that point you will have some sense of how the SF-20 works. When I got mine, I spent two weeks doing just that before using it on any shot that counted. Come on!

-- Patrick (pg@patrickgarner.com), May 28, 2002.

Greg, I'm surprised by your question. Of course the SF20 will operate correctly at any given aperture in TTL mode as the output will be interrupted by the light measured from the emulsion by the TTL body's metering cell. Additionally, the output can be corrected +/- in 1/3 stop steps by pre-selecting the corresponding correction on the SF20.

-- Lutz Konermann (lutz@konermann.net), May 28, 2002.

If you're using a handheld flashmeter and not getting a reading in one-stop increments for each aperture, there is definitely something amiss. Of course once the flash reaches full power output, stopping the lens down farther will not change the meter reading; likewise if the flash is firing at minimum power, opening the lens up will also not change the reading. But in the normal range the flashmeter should indicate one-stop output changes at each f-stop, and 1/2-stop changes in-between f stops (though the meter might not agree with the same f-stop on the lens depending upon the meter).

-- Jay (infinitydt@aol.com), May 28, 2002.

Thanks for the answers so far folks. The reason for the check is to see if the recently purchased uniy is working OK. In this instance I don't have time to test/check by use, which I agree with. My normal flash of choice is a 60CT-1 I've used (with other gear) for years. I am well familiar with flash usage. This unit seemed puny to me but the physical size convenience and the decesion to use my Leice on this job, well away from home, prompted me to get the SF20 as a back up.

So much for explaining my self. The unit seems to work in TTL the same as in automatic, only through the lens. i.e. only at 2.8, 5.6, 11. I wouldn't have thought that metz (SF20) would have taken a short cut in manufacture, but who knows. The hand held clearly shows the descending (or ascending)transit of output reading as one turns the aperture ring, but in the three mentioned zones.

I don't mean to be picky but I do tend to shoot 1 stop under or what ever the situation requires. Not to the nearest zone.

I welcome any more imput? Thanks guys.

-- Greg Pratt (gregpan@ozemail,com.au), May 29, 2002.


Greg

The flash is "puny" but if you want a big one you have the 60. It is actually pretty powerful for its small size. I have to say, I am not quite sure why you cannot do a test. You can use a 1 hour minilab and look at the negatives. I have not noticed it playing up with half stops in the range f2-f8 at least. I never stop down more than this and I use 100 speed slide film so I am pretty sensitive to exposure issues.

-- Robin Smith (smith_robin@hotmail.com), May 29, 2002.



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