Need explanation or tips for YS-25 Auto

[wwu123]

Hello,

I just completed a dive trip with an external strobe for the first time, a Sea & Sea YS-25 Auto. Having never used even a non-"Auto" strobe before, I'm wondering what exactly the "Auto" part of the strobe is supposed to be doing, because Sea & Sea doesn't really explain it anywhere.

I was using it with a new camera, a Canon SD500. The SD500 doesn't have manual aperture or shutter control, so what I observed in my EXIF data was that with the internal flash on (to trigger a strobe fiber-optic cable), the camera invariably was set to f7.1, 1/60 sec, regardless of the various scene modes available on the camera. I assume that the internal flash fires for not the full 1/60 sec but something much shorter and variable to get the right exposure, because when shooting with the internal flash only, the subjects generally came out properly exposed whether 3", 6", or 12" away.

However, when shooting with the YS-25 Auto and the internal flash masked, I found that to get the right exposure I basically had to manually adjust the dial roughly in accordance with distance - down at the lowest level 2 for a macro shot, up at 11 at a few feet away. Thus it felt like a purely manual control.

The Sea & Sea instructions say to match up the number with the aperture (with this camera, that would be f7.1), but that didn't seem to work at all. So what's the "Auto" supposed to be about, or does it not apply to my camera? If it doesn't, am I just as well off buying a manual strobe that is 1) pre-flash compatible and 2) can trigger off a fiber-optic cable?

I was pretty happy with the YS-25 Auto. Since I was mostly shooting from 3-18" away, by the end of the week I was able to guess the right position for the knob for a given shot to within one stop or so. Just not sure I was using the strobe to its fullest potential.

 

[gert7to3]

I have the YS-25 DX which is the previous model of the YS-25 Auto. You have indeed worked out the function of the "auto" feature on the strobe, ie: manually adjusting the power control for particular distance exposures. The "auto" part of the YS-25 exposure is that the strobe limits its energy output on user selectable power levels below level 7 (or Level 11 for your newer strobe) and that it can be set to ignore pre-exposure flashes. As to your camera's EXIF data, f7.1 @ 1/60 sec. would be a very normal flash setting.

Exposure has two variable components, light and time. Your camera stops down its lens to f7.1 to control incoming light and give you the best depth of field. It relies on the strobe to blast out enough light to properly expose the subject.

1/60 sec. exposure time merely means the camera's shutter will open for 1/60 of a second and your strobe will fire for a few 1/1000's of a second during that 1/60 sec. interval. When the strobe triggers within the 1/60 sec. time interval, your camera and strobe have achieved flash synchronization and you will have an image exposure.
At f7.1, the lens aperture won't let enough light in to obtain any eposure from the 1/60 sec. interval that the shutter is open, but where the flash isn't firing.

Since the YS-25 Auto strobe is being triggered by the camera's internal flash, save your battery by setting the camera flash to its lowest level. You're simply triggering your YS-25 not exposing anything with the internal flash. My YS-25 DX had some mumbojumbo that the camera's internal flash intensity would somehow control the external strobe's output. This never seemed to work, but varying my power control levels did.

 

[bobf]

An "auto" strobe has a sensor built into its head that records how much light is reflected back from the target. Once a user defined, predetermined amount of light is recorded by the strobe, the external flash will shut itself down. That explains the term "auto". IOW, the strobe "automatically" shuts itself down when it feels it has received the predetermined amount of light requested initially by the user.

The user determines how much light he wishes the strobe to accept prior to shut down by selecting from a variety of "aperture settings" found on the strobe. The theory is to begin by selecting the same aperture number on the strobe and camera. Then, if the user decides that the strobe should offer more or less illumination after the initial test exposure, he may then choose to alter the "aperture setting" on the strobe, choosing an alternative setting that will offer more or less light output. In that way, as gert7to3 implied, it becomes more of a "manual" strobe as opposed to anything one might confuse with "auto".

One downside of an auto strobe in my opinion is that in order for it to work, you must aim the strobe directly at a target so that the light reflected off the target will reach back to the sensor built into the strobe head. This may be part of your problem. That is, the light emanating from your strobe is not making it back to the sensor due to aiming.

btw.........auto strobes have the light recording sensor built into the head......ttl has the light recording sensor (in theory) behind the lens, such the term "through the lens".........

hth,
b

 

[Mario007]

Can this flash be turn solid on to use for video recording too?