Do old speedlites work as auto thyristor?

[kingbuzzie]

Definitely a newbie question. I'm severely lacking when it comes to flash operation, and it's about time I learn more. Do old speedlites work as "Auto Thyristor" flashes on non-canon cameras? I did some google searches, and the term "Auto Thyristor" doesn't come up in reference to old speedlites (only vivitar, sunpak).

 

[KN4SMF]

The thyristor flashes came about in the mid 70s at various times according to manufacurers. It was a design that cut off flash duration without dumping the excess juice in the storage capacitor as wasted energy. On a dedicated flash you don't lose the thyristor advantage just because you mount the flash on another camera, if that answer your question.

 

[kingbuzzie]

The thyristor flashes came about in the mid 70s at various times according to manufacurers. It was a design that cut off flash duration without dumping the excess juice in the storage capacitor as wasted energy. On a dedicated flash you don't lose the thyristor advantage just because you mount the flash on another camera, if that answer your question.

I suppose it does. Thanks!

 

[Chan Tran]

I started in 1976 and when shopping for flashes I found the majority of the flashes available at that time had "Auto Thyristor" feature. Simple one had but 1 choice for aperture per ISO. More elaborate ones can have 5 or 6 aperture choices. They are generally compatible to all cameras. Until the 80's about the only camera with TTL flash was the Olympus OM-2. Dedicated flash units didn't do much, they basically set the shutter speed to max sync speed automatically and perhaps light a ready light in the viewfinder and with the same light provide sufficient exposure signal after the flash fired.

 

[removed account4]

Hi KB

Lumeduyne also makes something like a Thyristor and it's pretty handy!

John

 

[AgX]

Do old speedlites work as "Auto Thyristor" flashes on non-canon cameras?

That thyristor thechnique is one within the evolution of flash autoexposure. It has nothing to do with camera models. It is a pure flash feature, independant of camera.

 

[Bill Burk]

Very old speedlights were manual and fired their full charge each time. As flashes became smaller, they could be run by AA batteries or rechargeable NiCd's hardwired into the flash unit.

The earliest automation featured a built-in sensor in the flash unit itself which would sense sufficient exposure and then "dump" the rest of the charge like KN4SMF said. It wouldn't need the camera body to tell it when light was sufficient as AgX says.

Relatively speaking they chewed through batteries / charges. As a consumer it was a pain to discover how short your battery life and you felt it in terms of how long you had to wait for the "charge" indicator to tell you you were ready for the next shot.

The thrysistor was actually a good, real benefit to users of small portable flash units. It's really a magic bullet! I'm very glad the technology was either generic or widely licensed because it really works!


If you turned down the power (used a larger f/stop) or worked closely (needed less flash for the shot), you were rewarded with an orange glow just a few seconds after your last shot.

At first, you would have to mount the flash in a shoe and aim it straight forward. To solve that issue, and make it easier to use bounce flash, there was a trend towards making the sensor face forward even if the flash was tilted (like the Vivitar 283).

Pentax made the Spotmatic IIa with a "strobo-eye" on the camera, Vivitar gave a cable you could put in the camera's hotshoe and mount the sensor onto, so you could connect the flash to the camera and aim it anywhere while the light returning to camera was measured through the remote sensor.

TTL flash came on the scene much later, like with the Olympus OM-2. The Olympus flash also had a tiny sensor that would work if you didn't put it on an Olympus hotshoe.

 

[AgX]

Relatively speaking they [non-thyristor auto-exposure flashes] chewed through batteries / charges. As a consumer it was a pain to discover how short your battery life and you felt it in terms of how long you had to wait for the "charge" indicator to tell you you were ready for the next shot.

Well, to be fair they acted on this issue just as the manual models, not better, not worse. Just as the preceeding manual models they consumed a full charge at every flash.
So they were no disappointment, but instead a benefit.
Only in hindsight, after the emergence of tyristor flashes, they looked like a pain.

 

[Bill Burk]

So right you are AgX.
And also to be fair, when you need the full flash output, even a thrysistor model chews through batteries like the rest of them.
But I have the VariPower module on the Vivitar, and when I dial it down to 1/32 power, I can fire repeatedly within seconds, all night long.
How many hypes have we been offered as photographers that turned out to be less amazing than the claim.
The thrysistor lived up to its.

 

[KN4SMF]

Very old speedlights were manual and fired their full charge each time. As flashes became smaller, they could be run by AA batteries or rechargeable NiCd's hardwired into the flash unit.

The earliest automation featured a built-in sensor in the flash unit itself which would sense sufficient exposure and then "dump" the rest of the charge like KN4SMF said. It wouldn't need the camera body to tell it when light was sufficient as AgX says.

Relatively speaking they chewed through batteries / charges. As a consumer it was a pain to discover how short your battery life and you felt it in terms of how long you had to wait for the "charge" indicator to tell you you were ready for the next shot.

The thrysistor was actually a good, real benefit to users of small portable flash units. It's really a magic bullet! I'm very glad the technology was either generic or widely licensed because it really works!


If you turned down the power (used a larger f/stop) or worked closely (needed less flash for the shot), you were rewarded with an orange glow just a few seconds after your last shot.

At first, you would have to mount the flash in a shoe and aim it straight forward. To solve that issue, and make it easier to use bounce flash, there was a trend towards making the sensor face forward even if the flash was tilted (like the Vivitar 283).

Pentax made the Spotmatic IIa with a "strobo-eye" on the camera, Vivitar gave a cable you could put in the camera's hotshoe and mount the sensor onto, so you could connect the flash to the camera and aim it anywhere while the light returning to camera was measured through the remote sensor.

TTL flash came on the scene much later, like with the Olympus OM-2. The Olympus flash also had a tiny sensor that would work if you didn't put it on an Olympus hotshoe.

The Honeywell Strobo Eye Spotmatic IIa was in the same sales brochure at the time with the Strobonar 772 and 882 which were 1971-1972 technology before thyristor circuitry came along I know this because I slept with that brochure practically under my pillow every night. Actually the first I remember about ever seeing "Auto Thristor" was the Vivitar 283 line. That was I guess about 1974-75 or so. No later.

 

[AgX]

The thyristor was introduced in a flash by Sunpak. In 1973 (If that matters.)

 

[Bill Burk]

Here's a fun read, Doug Kerr is always worth reading...

http://dougkerr.net/Pumpkin/articles/Thyristor_Flash.pdf

 

[MattKing]

One of the consequences of thyristor technology was that for a lot of flashes, if only a small portion of a full charge was needed, the flash duration was shorter. This means that if you are looking to stop really fast action, a thyristor flash used close to a subject can provide the result you need.
You actually have to be careful some times that you don't end up with a flash with such short a duration that you see the effects of reciprocity failure when exposure is too short (the opposite of the situation we normally struggle with). You have to be working at the extremes of permitted operation with powerful flashes before that latter problem occurs.

 

[AgX]

One of the consequences of thyristor technology was that for a lot of flashes, if only a small portion of a full charge was needed, the flash duration was shorter.

But that already was the case with the preceeding technology.

 

[KN4SMF]

But that already was the case with the preceeding technology.

Yes it was. And I might add that electronic flash used in auto mode will always have you bumping your nose against the stone wall of reciprocity. Flat lifeless photos compared with flashbulbs, which had their own problem of forcing you to lose all control of both depth of field and fill light.. Long ago I found that a flash like my Sunpak Auto 611 was best used with the stobo-eye attachment sitting at home in the junk drawer. Used in manual mode and choosing from the power ratio dial, I can meter a scene and shoot by ambient light standards, and throw in just enough light to fill as needed. Only when it is too dark to do that, do I let the flash become the main source, or only source of light. That way you avoid reciprocity problems, and the dull lifeless photos that come with it. I don't know of any of the older non-thyristor units that had manual variable power capability. Of course many of the auto thristor flashes don't give you a dial for manual variable power either. A good Sunpak flash spoiled me forever. And here it is 43 years from the day I bought it, and it's still the cat's pajamas.

 

[AgX]

And I might add that electronic flash used in auto mode will always have you bumping your nose against the stone wall of reciprocity. Flat lifeless photos compared with flashbulbs, which had their own problem of forcing you to lose all control of both depth of field and fill light..

Could you go into detail on this issue?

 

[KN4SMF]

Could you go into detail on this issue?

I can't, because there was a lot of plain opinion and speculation in what I said. I always thought that color photos shot with portable electronic flashes were often bluish and dull compared to how I remember with flashbuulbs. It was years before I thought if a reason to explain it. Reciprocity comes into play, I reasoned. Might be a load of baloney, but is as good as any other reason I ever thought of.

 

[Chan Tran]

Yes it was. And I might add that electronic flash used in auto mode will always have you bumping your nose against the stone wall of reciprocity. Flat lifeless photos compared with flashbulbs, which had their own problem of forcing you to lose all control of both depth of field and fill light.. Long ago I found that a flash like my Sunpak Auto 611 was best used with the stobo-eye attachment sitting at home in the junk drawer. Used in manual mode and choosing from the power ratio dial, I can meter a scene and shoot by ambient light standards, and throw in just enough light to fill as needed. Only when it is too dark to do that, do I let the flash become the main source, or only source of light. That way you avoid reciprocity problems, and the dull lifeless photos that come with it. I don't know of any of the older non-thyristor units that had manual variable power capability. Of course many of the auto thristor flashes don't give you a dial for manual variable power either. A good Sunpak flash spoiled me forever. And here it is 43 years from the day I bought it, and it's still the cat's pajamas.

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

 

[AgX]

TTL autoexposure still works with the thyristor, the flash has not changed at all, except for AF light, camera-controlled zoom etc. and that they may have no own sensor any longer.

 

[Chan Tran]

TTL autoexposure still works with the thyristor, the flash has not changed at all, except for AF light, camera-controlled zoom etc. and that they may have no own sensor any longer.

I meant that the newer flashes tend to eliminate the auto mode which uses the flash own sensor and thus it has to be used with a compatible camera. Of course TTL and manual power control still uses the thyristor to control the flash power.

 

[MattKing]

In my experience, the quality of illumination from electronic flash (or flash bulbs, for that matter) is almost completely related to how that light is reflected and/or modified.
If the flash (electronic or bulb) has a small, focused reflector in order to maximize range, the light from it can tend toward the "dull, lifeless" end of the quality spectrum.
Point sources aren't very flattering - just look at the results from flashcubes!
Most of my portable flash work has been with Metz hammerhead flashes - largish reflectors and enough power to permit bounce and diffusion. The resulting light lends itself to flattering illumination.
Prior to using the Metz units - first 402s, then 60CT series units - I used Vivitar 283s. The result from those weren't bad, especially when bounced, but the Metz flashes were much better.
As a practical matter, I haven't encountered short duration flash reciprocity problems, because I don't do close-up flash work. It is only in that circumstance that the issue arises.

 

[BrianShaw]

The thyristor was introduced in a flash by Sunpak. In 1973 (If that matters.)

Well you learn something new every day... I always thought that was a Vivitar innovation.

 

[AgX]

But who presented when the first autoexposure flash?
To my information it were Rollei and Honeywell in 1960.

 

[removed account4]

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

Not so sure about that, Lumedyne has an electric eye for their flashes. It is called the HAHM ( Autoexposure Handle Module ) probably still made and used with modern lights. I have had one since it was first released ( early/mid 2000s? ). It allows you to do asymetrical lighting if you have 2 flashes plugged into the same pack ( other wise it splits it in half ) and it allows you to trim your lights from 2WS to full power. Lumedyne still makes great lights, and this feature might be incorporated into their new systems.

 

[AgX]

But if you look even at the modern Metz on-camera flashes, which are rather conservative, they only got TTL-autoexposure or manual mode. They no longer got an own sensor for selfsustained autoexposure.