I have a question, I have been told you can't use the old film flashes on digital camera bodies. One of my friends said he saw chart that Nikon put out that said the SB25 would work with the current digital cameras without burning out the body. I tried it on my D300 in Programed mode and the flash was set in the TTL mode and it seemed to work fine. I didn't want to push this any further until I new more for sure. I also have a D90. At some point I will probably buy a SB700, but I'm not ready to do that now.
Did you actually take a photo with it set to TTL as the SB-25 will only work in Manual or non-TTL Auto flash modes. Otherwise, the SB-25 is compatible with the D300 (and D90). See the "Optional Flash Units" section in your D300 manual, particularly page 360.
The SB-25 uses Film TTL Flash Control and the D90 and D300 use i-TTL Flash Control and unfortunately they are Not compatible with each other. That said, the SB-25's sync voltage is safe for use on All Nikon DSLR's. You will be limited to Non-TTL Auto Flash mode or Manual Flash mode. For the most consistent results use Manual exposure mode and Manual ISO. You can use the Calculator built into the SB-25 to set the Aperture based on the flash to subject distance.
Thanks for the info, I'm glad to hear it will work in manual and non-TTL modes.
I'm pretty sure that when I tested the flash on my D300 I had it set in the TTL mode. I was sitting in my living room which is about 21' by 15'. Had a 60 watt light bulb in a lamp on one side of the room to my left. The photo's I shot were at the oppose end of the room which was semi dark. Maybe 18" away. The shots looked pretty good. I will have to test it further in different modes and see what kind of results I get.
Again, thanks for your help, I at least feel safe in using the unit on these bodies without doing any damage.
TTL mode simply cannot work correctly, although as noted, it does work safely. The SB-25 is a film TTL flash. These worked by opening the shutter, firing the flash, and a sensor read the amount of light being reflected off the film emulsion. During the exposure. When the light reached the appropriate amount, the camera sent a signal to the flash to tell it to quench the flash tube.
This does not work on DSLRs for (at least) three reasons. First, there is no film emulsion behind the shutter any more. Instead of a matte-finish film emulsion, there's a shiny glass filter covering the digital sensor, which has quite different reflective properties. Second, the TTL flash sensor is no longer in the mirror chamber, since capturing the light reflected off the film is no longer possible. And finally, the quench signal is obviously no longer transmitted, since there is no sensor.
DSLRs use new flash metering techniques that involve firing a pre-exposure metering flash pulse, reading that with the in-camera metering cells, and then adjusting the flash output accordingly. This is called iTTL (all of the current models) or dTTL (D1, D1h, D1x, D100, all ancient history now).
Because the SB-25 doesn't know how to participate in iTTL, and the cameras are not equipped to do film TTL, none of the TTL modes work when older film-era flashes are combined with DSLRs. This means that the only modes that work are manual (which has no metering), or "auto" in which the flash does the metering based on a sensor located in the flash itself.
_____ Brian... a bicoastal Nikonian and Team Member
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