Date: Fri, 30 Nov 2001 16:37:11 -0800
From: Andrew Kalman <aek@pumpkininc.com>
Subject: Suggestion for additional info on F3 flash pages
X-Sender: (Unverified)
To: leofoo@mir.com.my
Status:
Hello Leonard.
I have greatly enjoyed reading your F3 pages -- as a very early adopter (I received my F3 + MD4 + DA-2 as a graduation present in 1980), I have a real soft spot for my F3.
Anyway, I have recently come across some information re the F3's flash system that is not on your website and may be of use to other Nikon users -- perhaps you would like to include it at some later date?
The gist of it is this: the F3's TTL flash system is not only "mechanically" different from later ISO TTL systems (the whole "F3 foot issue"), it is also _electrically_ very different.
It turns out (see my thread "Nikon AS-17 flash coupler -- What does the ASA setting REALLY do? (long)" on rec.photo.equipment.35mm) that the F3 has a unique, first-generation and rather crude TTL system whereby the flash itself receives a signal from the F3's TTL SPD and combines it with the ASA setting on the camera to control the TTL flash's output. All this electronics is housed in the bodies of the SC-12, SB-12, SB-16A "adapter foot" and SB-17. This is very different from later / current generation ISO TTL flashes, which simply receive a "fire now" and "quench now" signal from the camera (e.g. F4, FE2, etc.). These F3 feet (like that of the SC-12) have a mechanical pickup inside them that keys off the ridge on the ASA dial. A few such accessories (like the SC-14 and AS-7) do not, mainly due to electrical and/or mechanical packaging considerations, but on these one must ensure that the adapter's ASA matches that of the camera. O/wise one has an effective +/-EV flash compensation scheme going ...
So it is for this reason, and not because of the peculiar flash mounting foot of the F3, that it took so long for the AS-17 to be produced. After all, Nikon could not simply make a "ISO TTL version" of the AS-4 by simply adding an extra contact. That wouldn't work, as ISO TTL flashes wouldn't understand the TTL signal, and may in fact have even been damaged by it. (This makes the report of the Vivitar TTL adapter hard to explain).
What the AS-17 does is basically translate the SPD TTL output and the set ASA to a more modern "quench now" signal for ISO TTL flashes like the SB-28. It has some electronics in it to do this, and that's why it's a bit more expensive than your average F3 flash foot accessory.
I hope you find this information interesting, and if you are still maintaining and updating the F3 pages, that you might consider it for inclusion into your beautiful site.
P.S. Is it at all possible to obtain the site on CD-ROM. I'm an archiving pack-rat, and would hate to lose this resource some time in the future when it is or I am no longer on-line.
I have greatly enjoyed reading your F3 pages -- as a very early adopter (I received my F3 + MD4 + DA-2 as a graduation present in 1980), I have a real soft spot for my F3.
Anyway, I have recently come across some information re the F3's flash system that is not on your website and may be of use to other Nikon users -- perhaps you would like to include it at some later date?
The gist of it is this: the F3's TTL flash system is not only "mechanically" different from later ISO TTL systems (the whole "F3 foot issue"), it is also _electrically_ very different.
It turns out (see my thread "Nikon AS-17 flash coupler -- What does the ASA setting REALLY do? (long)" on rec.photo.equipment.35mm) that the F3 has a unique, first-generation and rather crude TTL system whereby the flash itself receives a signal from the F3's TTL SPD and combines it with the ASA setting on the camera to control the TTL flash's output. All this electronics is housed in the bodies of the SC-12, SB-12, SB-16A "adapter foot" and SB-17. This is very different from later / current generation ISO TTL flashes, which simply receive a "fire now" and "quench now" signal from the camera (e.g. F4, FE2, etc.). These F3 feet (like that of the SC-12) have a mechanical pickup inside them that keys off the ridge on the ASA dial. A few such accessories (like the SC-14 and AS-7) do not, mainly due to electrical and/or mechanical packaging considerations, but on these one must ensure that the adapter's ASA matches that of the camera. O/wise one has an effective +/-EV flash compensation scheme going ...
So it is for this reason, and not because of the peculiar flash mounting foot of the F3, that it took so long for the AS-17 to be produced. After all, Nikon could not simply make a "ISO TTL version" of the AS-4 by simply adding an extra contact. That wouldn't work, as ISO TTL flashes wouldn't understand the TTL signal, and may in fact have even been damaged by it. (This makes the report of the Vivitar TTL adapter hard to explain).
What the AS-17 does is basically translate the SPD TTL output and the set ASA to a more modern "quench now" signal for ISO TTL flashes like the SB-28. It has some electronics in it to do this, and that's why it's a bit more expensive than your average F3 flash foot accessory.
I hope you find this information interesting, and if you are still maintaining and updating the F3 pages, that you might consider it for inclusion into your beautiful site.
P.S. Is it at all possible to obtain the site on CD-ROM. I'm an archiving pack-rat, and would hate to lose this resource some time in the future when it is or I am no longer on-line.
Regards, Andrew E. Kalman, Ph.D. aek@pumpkininc.com
Pumpkin, Inc.
home of Salvo, The RTOS that runs in tiny places.(TM)
http://www.pumpkininc.com
Relative: Another opinion from one of our Nikon F3
MB's Maintainer Hermann Graf <(hermann.graf@basf-ag.de)> To Andrew Kalman: "As
for your opinion concerning the F3's TTL flash metering, I agree with you that the
SBC meter cell signal of the F3 is directly transmitted to the flash unit, and not
only a "start/stop" signal. But I doubt whether there are much electronics
in the adapter AS-17. There is an extra ISO setting scale on the AS-17 to set the
film speed; why would this be necessary if the adpater "reads" the ISO
setting on the camera? BTW, the same is true for the SCA adapter from Metz for the
F3. My opinion is that the SBC analog signal coming from the F3 is only attenuated
proportional to the ISO setting on the adapter, probably by means of a potentiometer.
Highest possible ISO is 400, probably because there is no signal amplification, and
above ISO 400, the signal is to close to the noise level. In other words, this solution
could have been offered to us as early as in 1980, and more marketing thoughts had
been involved instead of technical ones. Herman
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