Do old speedlites work as auto thyristor?

Chan Tran said:

Modern flashes today remove the Auto Thyristor feature (only TTL is available) but most have the variable manual power.

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1. Actually almost all modern flashes use the THYRISTER to 'recycle' unused power back to the battery for faster recycle (and reduced battery depletion) after partial power flashes.
2. Many modern flashes may eliminate the PHOTOSENSOR AUTOMATION mode (known in Canon flashes as External mode) and assume the camera will issue nTTL partial power commands to the flash, in lieu of the flash measuring light with a photosensor and telling the thyristor to 'recycle power' when it detects 'enough light' on scene.

wiltw said:

1. Actually almost all modern flashes use the THYRISTER to 'recycle' unused power back to the battery for faster recycle (and reduced battery depletion) after partial power flashes.
2. Many modern flashes may eliminate the PHOTOSENSOR AUTOMATION mode (known in Canon flashes as External mode) and assume the camera will issue nTTL partial power commands to the flash, in lieu of the flash measuring light with a photosensor and telling the thyristor to 'recycle power' when it detects 'enough light' on scene.

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When I said "Auto Thyristor" I really meant the auto mode that uses the flash sensor. They eliminate this function and have better manual flash power control. Of course this feature also uses the thyristor. What I meant is that with the modern flash you either have a compatible camera or you don't have auto exposure.

Well, you misunderstood/generalized that term "Auto Thyristor" (put on those Vivitar flashes back then), but in Germany flashes with internal autoexposure feature were generally called (in translation) "computer flashes", which was way off...

My (dad’s) first auto flash that dumped the extra power was a German Bauer E-18A

And it’s not like it goes back to the battery. It’s the main capacitor which is not fully discharged so the recycle to full charge takes less time/energy. When you turn off the flash for a spell, the capacitor drains and you lose the power anyway.

And if you just let it on, the flash will keep the capicator on level, what will discharge the battery too... And with more modern flashes (90s) the flash may go on idle after a short time of not being fired, what will lead to the capacitator to leak over time nonetheless. At restart the battery will have to come up for this.

So there is no way out finally by no technology...

Mentioned this here before, but I'm not really an "event" shooter, but once commercial client pays my day rate when he has events. The night before, my Nikon DSLR died, which I had a dedicated flash for. I have a mirrorless that I use mostly for video (Samsung NX1, awesome camera) so I dusted off a 285 that had been sitting in a closet for a decade. Stuck a diffuser on it and did some tests with the NX. When I shot the gig, I really couldn't tell a difference from a TTL flash - the old Vivs were really very solid little workhorses.

As a side note, I butched up a busted Speedotron head to hold the Vivitar so I can use it with my speedo reflectors as a sort of a little extra battery-powered monolight. Had a last-minute Thrillist "Best Bartenders" gig and I had to shoot it at happy hour, at my favorite dive bar. So stands and cables would have been a nightmare. Clamped the 285 to a ceiling joist with an 11" grid head with mylar and a radio slave, and stuck a CTO gel on it, lit the BG with a tungsten fresnel behind the bar. Shot about 1/2 second for background blur and froze the subject with the flash. Really the handiest little thing, though its got no modeling light, a battery powered strobe with 4 power levels on manual that I can use my modifiers with is just dang cool!