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02-04-2009, 08:22 AM   #1
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Non-ttl / manual flash confusion

Howdy!

I'm having a bit of confusion with determining shutter speed when using non-ttl hotshoe flash in auto or manual mode. I just picked up 2 flashes, a Sunpak auto 821 and an Alfon 540.

I have shot a few rolls with the Alfon in non-ttl auto mode. All of those pictures turned out fine with the shutter speed at either 1/125 or 1/60, and the lens aperture at the setting recommended by the flash. BUT, just because the images turned out decently doesn't mean I know what the hell I'm doing!

How can I determine what shutter speeds I need to be using? Obviously the flash unit has no idea what the lens is set at... so how can it calculate the right amount of light to shoot? Is it all just a guessing game when it comes to non-ttl flash?

Any input would be greatly appreciated.

02-04-2009, 09:04 AM   #2
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Shutter speed has no impact on flash output (as flash is nearly instantaneous)... You just have to stay below the sync speed (altough you can go above on carefully controlled cases!).

Now, once you sync both iso and aperture values between the flash and the body, auto flash will rely on this to quench its output once the needed amount of illumination is reached.

EDIT : you can go above the sync speed when you don't need flash on the top or bottom of you scene...
Say you want to shoot someone lying on the beach, with a half-half horizon, the subject staying below the horizon line: then your flash would be totally useless on the upper half of the picture!

So you can use 1/250 without blacking out some important part (but you'll have to handle your camera upside-down, as flash is synced with the top of the picture).

Last edited by dlacouture; 02-04-2009 at 09:10 AM.
02-04-2009, 09:16 AM   #3
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It may be nearly instantaneous but the shutter has to be fully open.

The shutters in film cameras, because of how they open are synched at 1/60 (and some at 1/125) and the settings on the flash for aperature are calculated based upon distance, aperature and that synch speed. If you use a fast shutter speed, it may not expose the whole frame. With my older flashes I still use 1/60 on my K10D and get the best results using what the flash "calculator" suggests.
02-04-2009, 09:18 AM   #4
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QuoteOriginally posted by dlacouture Quote
Shutter speed has no impact on flash output (as flash is nearly instantaneous)... You just have to stay below the sync speed (altough you can go above on carefully controlled cases!).

Now, once you sync both iso and aperture values between the flash and the body, auto flash will rely on this to quench its output once the needed amount of illumination is reached.

EDIT : you can go above the sync speed when you don't need flash on the top or bottom of you scene...
Say you want to shoot someone lying on the beach, with a half-half horizon, the subject staying below the horizon line: then your flash would be totally useless on the upper half of the picture!

So you can use 1/250 without blacking out some important part (but you'll have to handle your camera upside-down, as flash is synced with the top of the picture).
With all my cameras the shutter travels left to right. So how is it synched to the top of the frame?

02-04-2009, 11:33 AM   #5
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What camera body are you using here?

The vertically traveling shutters often used to sync at 1/125, the horizontal ones at 1/60. This was in the old days. Improved electronic shutter controls etc have increased the max sync speed in more modern times.

The point is: the camera body has a manufacturer stated max sync speed.

In auto mode the flash uses its own sensor to measure, say, f/8 worth of light in front of it. When that amount of illumination is reached, the flash turns off. So the camera needs to be set at f/8 to get correct exposure. The shutter speed on the camera doesn't determine the exposure - except in fill flash situations perhaps - but a longer shutter speed can let you do some effects or balance between flash and ambient background light.

Before the thyristor auto flash days, you had to figure out the appropriate f/stop to set the lens based on distance, ASA etc, using the flash unit guide number. Like many photographers, I ended up taping a little table on the flash as a cheat sheet.

TTL flash looks to 'improve' the flash sensor based control by using the camera's own light meter to measure the illumination. Theoretically this can result in a more accurate exposure; in practice under most circumstances there's not much difference between TTL and flash sensor.

But you know photographers, we'll pay extra $$ for the capabilty to shoot that one shot in a million...
02-04-2009, 11:52 AM   #6
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My two bodies are: K1000 SE and a Ricoh KR-5 SuperII.

The K1000 has a sync speed of 1/60, and the Ricoh is 1/125.

I think I'm understanding more now... but how about a scenario question:

I shot a roll in a pretty dark room at a subject about 3 feet away. I had the Ricoh's shutter speed at 1/125, the lens aperture at 5.6 per the flash's recomendation, and the flash was on auto mode. I was shooting 200 speed film. All of the pictures turned out, but they weren't anything special or interesting.

Let's say I'm in the exact same scenario... but I slow down the shutter significantly, say to 1/4. What changes can I expect? Will the picture be drastically lighter? Blown out? Or will the foreground look more-or-less the same, and the background will have more ambient light?

I'm also very interested in party/bar/nightclub photography and shooting live bands. These are some of the things that have sparked these questions. I've watched Codiac(chris)'s tutorials on the subject and it's helped a bit with ideas. Still a lot of flash ponderings to be done on my part though.
02-04-2009, 01:25 PM   #7
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Dragging the shutter

QuoteOriginally posted by Sasquatch Quote
My two bodies are: K1000 SE and a Ricoh KR-5 SuperII.

The K1000 has a sync speed of 1/60, and the Ricoh is 1/125.

I think I'm understanding more now... but how about a scenario question:

I shot a roll in a pretty dark room at a subject about 3 feet away. I had the Ricoh's shutter speed at 1/125, the lens aperture at 5.6 per the flash's recomendation, and the flash was on auto mode. I was shooting 200 speed film. All of the pictures turned out, but they weren't anything special or interesting.

Let's say I'm in the exact same scenario... but I slow down the shutter significantly, say to 1/4. What changes can I expect? Will the picture be drastically lighter? Blown out? Or will the foreground look more-or-less the same, and the background will have more ambient light?

I'm also very interested in party/bar/nightclub photography and shooting live bands. These are some of the things that have sparked these questions. I've watched Codiac(chris)'s tutorials on the subject and it's helped a bit with ideas. Still a lot of flash ponderings to be done on my part though.

Shooting at a speed slower than the maximum sync speed of you camera is known as "dragging the shutter". It is a perfectly valid and useful technique. It is normally used when you wish to stop the action or fully light an object in the foreground, but not lose detail in the background.

By shooting with a slower shutter speed, more of the background will be visible, due to the ambient light. The person or object in the foreground will be exposed by the flash. As others have said, the shutter speed has little effect on the flash exposure, since electronic flashes typically have a shutter speed of 1/1000 second or faster. Automatic or TTL flashes vary the flash duration to as little as 1/50,000 second for closer objects.

Of course, this technique, like any other can be misused, overused or used in an inappropriate manner.

If there is enough ambient light to expose the foreground object, and it is moving, you may see a "ghost" image of the object. The slower shutter speed lets the moving object appear on the film and the flash then freezes it. With most film cameras, the flash is synched at the instant that the shutter is fully open. Since the shutter is fully open for 1/60 second or more, while the flash is only on for 1/1000 or less, there is plenty of time for the subject to move, resulting in a blurred ghost image after the flash.

On a few film cameras (definitely NOT the K-1000) and many dslrs, there is an option to synch the flash to the trailing shutter. That is, the flash will fire an instant before the shutter begins to close. This means that the ghost image will lead into the flash-frozen image.

I believe that, if the proper ambient light exposure is within two stops of the flash exposure, you run the risk of ghosting. That is, if you're shooting with flash at 1/125 @ f/5.6, but your light meter says that ambient light will be exposed with 1/30 @ f/5.6, then you may see the ghost. If ambient light requires 1/8 or 1/4 at f/5.6, you probably will not see the ghost.
02-04-2009, 03:22 PM   #8
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Simple point to think about, related to shutter speed.

Most cloth shutters are horizontal moving shutters, limited to 1/60 th. Newer cameras use metal vertical travelling shutters with a sync speed of either 1/90 or 1/125.

as someone oted, as long as you are below the sync speed, the acutal speed is not important. This is not quite true,. if you want flash to really do it all, then your shutter should be at maximum and the lens stopped down so exposure without flash is about -4 stops.

If you want the flahs to fill shadows, you should set the calera (shutter and apature ) to about -1 stop, and then the auto sensor on the flash will do the rest.

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