Foggy Understanding: Sekonic 308S

KN4SMF

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I'm trying to acquire complete understanding of the usage of the Sekonic L 308S as a flash meter. There's with cord and without cord. I do have some limited experience in using it to meter as a free-standing flash meter without attaching it to the flash. I can't say that I've been satisfied. It seems that once a certain flash duration or room brightness is reached, the meter becomes inaccurate, or makes no sense. At least that's my assumption. I've reasoned that perhaps some interaction between ambient light and the flash itself possibly confuses the meter. I don't know. I've never tried hooking it up to the flash with a cord and setting off the flash that way. Does doing so lend itself to better accuracy at metering the flash? Or does hooking up to the flash with the cord do nothing more than a simple remote trip button for the flash, with no actual other benefit? i suppose the question i'm asking is, does the flash duration actually get transmitted through the cord to the meter? It is agreed (by me) that any power adjustment in an electronic flash is not really changing the brightness of the flash, but only it's duration. Thank you.
 

markbau

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I just replaced my ancient Luna ProF with a L 308S. I must agree, the meter is not as user friendly as my old Gossen. The main thing that makes no sense to me is why, in flash mode, it shows a shutter speed. Other meters I've used in flash mode simply show an aperture which makes perfect sense as (sync issues aside) shutter speed is irrelevant in flash work. I haven't used it with a cord but from my understanding all it does is allow you to do a test flash from a distance from the flash. On my old Gossen you could give multiple flashes and it would measure them all, (and give you an f stop for the total flashes) I suspect the L308S is doing the same thing in flash mode but the instruction book doesn't really make this clear. There are some Sekonic tutorials on youtube but they do not go into much depth.
 

bdial

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bernard_L said:
probably in order to give you a correct aperture setting that takes into account the ambient light
Click to expand...

My Minolta flash meter does that, and it will also show you percentages of ambient light and light from the flash.
I prefer using a sync cord with the meter, and it seems to be more reliable than using its flash standby mode. But either method should yield a good result, in theory.
The Minolta's manual includes this warning, which might be relevant to the OP's Sekonic;

 
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KN4SMF

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Recalling the instructions by memory that accompany the Sekonic, I believe they also say something similar, which raises my original question. Why would the cord method lend itself to better accuracy than without it? The obvious answer that would spring to mind is whether the cord is "hot" during the entire duration of the flash. Or does the cord simply trip the flash and go "cold" again regardless of how long the flash may still be happening after its initial trip?
 
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KN4SMF

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And that was what also struck me as off from the beginning. Why would it give a shutter speed? The next post after yours speculates it may be to take into account ambient light. But a f/stop reading alone would also do that. So it makes no sense. The Sekonic instructions leave more questions than answers. But anybody who has ever experimented with one can see that something strange is going on once a certain brightness level of ambient light exists. The flash meter reading becomes non-sensical.
 

Ian C

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To avoid problems, measure the flash and ambient portions of the light separately.

Set the shutter speed on the meter at 1/60 second or faster (within the shutter’s synchronization range) to preclude possible interaction between flash and ambient light. Triggering the flash in cord or non-cord mode should make no difference. The trigger signal to fire the flash is the only thing transmitted between the meter and the flash unit along the synchronization cord.

If you still have problems with your non-cord flash readings, simply use the cord with the meter set to 1/60 second or faster and within the shutter’s synchronization range.
 

bdial

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I've not used my meter for mixed ambient and flash lighting. However, the reason the shutter speed is relevant is that it is your control for how much the ambient light affects the exposure. Your aperture more or less governs how the strobe affects the exposure.Generally, unless you can vary the power of the flash, you only have 1 choice for the aperture. If the ambient light you want to capture is too low for that f/stop, then you'll need to reduce the shutter speed. Conversely, if you're in bright surroundings, you may need a short shutter speed to match a large aperture that might be dictated by the amount of light available from the flash. Generally focal plane shuttered cameras hit an upper limit pretty quickly in bright conditions, since you can't exceed the camera's max sync speed.

If you aren't using the flash for fill, however, you usually just ignore the shutter speed the meter might give you for the ambient exposure. In that case, you'd generally use the fastest speed the camera will support with flash, so as to minimize the affect of any ambient light.
 
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jim10219

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If you think about a situation where 25% of the light comes from fill flash, then the shutter speed will matter. That's why they have the shutter speed indicator. Generally, the flash sync cable is used so you can trip the flash from the position of the subject without moving the meter around and generating a false reading. The flash sync cable just sends a quick signal at the beginning of the flash, so it doesn't tell the meter anything about duration. So the flash sync cable shouldn't help with determining the duration of the flash, though I doubt any flash meter would actually cut off before the flash is finished.

They take a bit of getting used to, but if you play around long enough with it, you should be able to figure out how to get accurate readings with it. Mainly, you just don't want to move it around or walk in front of it to create a shadow while it's reading. I've never had accuracy issues with mine, though I use a Minolta Flash Meter V.
 
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KN4SMF

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Thanks for these answers. My brain is dense, but this info is slowly seeping in. My flash usage has only rarely been as "flash only". It's mostly always been a mixture of ambient and flash. Which now brings up the most important question of all. to preface it, my studio lights typically have a longer flash duration than the on-camera flashes with their strobo-eyes. The duration of the studio flashes and on-camera flashes in manual mode are closer to the duration to a flashbulb, which is quite long. But when hand-held or hot shoe mounted flash is used in automatic mode, then the duration can be very fast, like 1/70,000 of a second (to quote the old Honeywell Strobonar claims). And on my Sekonic, I have found that the readings are totally screwy when using flashes in auto mode. Of course I've only done it without the cord. So would using the cord fix this problem? As an aside, the doorbell analogy wasn't a very good one, as a doorbell button is hot as long as you have it pressed. Push one and see. First there's the "ding", but there's no "dong" till you let go.
 

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I'm not familiar with your meter but I agree with your assunption that flash power changes the flash duration. my flashmeter(Gossen LunastarF2) works like yours with and without cord;never got it to work with the cordso, I just push the 'meter' button and it goes into a waiting mode where it waits for the flash to fire and then displays a rating mixing ambient and flash and does so very reliably.Therefore, I never had a need for using the cord.
 

markbau

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Here is my take on it. My old meter only metered flash in flash mode, it was as if the ambient mode was turned off during flash measurement, which, to my mind, is how it should be. I have never done much work that mixed ambient and flash so it was never a problem. My main question now with a meter like the L308S is this: if it is "helping" me deal with flash and ambient at the same time, does that mean it is being affected by the modelling lamp? If so that is crazy as the modelling lamp goes out when the flash is fired. My expectation of a flash meter is it tells me what aperture to use for a given flash output, if ambient light is present I can meter that separately and combine the two myself. Sometimes "improvements" in equipment are not well specified.
 

MattKing

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Reading through the online manual.....
The major advantage of using the meter in corded trigger mode is that it takes out of the equation any issues you might encounter due to problems "triggering" the flash metering mode.
If you use the auto reset non-corded mode, the meter waits until it detects a sudden increase in light, then it makes its measurement, and then presumably stops making a measurement when it detects a decrease in light.
This means that long flash durations - such as from flash bulbs - require use of the corded mode.
It also likely means that very short flash durations - such as from auto exposure flashes - may create difficulty with triggering the flash meter mode, so may require use of the corded mode.
It also means that use of flash in high ambient light conditions may require use of the corded mode.
The manual also suggests that using the meter in situations where the ambient light is supplied by sources that turn off and on frequently - such as some fluorescent lights - may require use of the corded mode.
By the way, the need to set the shutter speed comes from the fact that the shutter speed determines the duration of the relevance of when the meter takes its reading - very important with flash bulbs.
 

jim10219

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If the flash is happening that fast, then that might pose a problem for your meter. Meters work by using some kind of photocell to convert light into electricity (or resistance or allow a transistor to conduct electricity). As such, there will always be some sort of slew rate associated with this action. They can only react so fast to changes in light. If the flash is flicking on and off before the meter can ramp up to get an accurate reading, then you'll have issues with inconsistency. You might have to set the flash to a higher power to get your reading, then calculate backwards to compensate for the lower flash settings. Either that, or use higher flash settings and either some kind of filter to reduce the power of the light coming off the flash, or set your lights further back and take advantage of the inverse square law (light power dimishes by half every time you double the distance). By doing either of the later, you wouldn't have to do any extra calculations, and could just go by what the meter says.

This would explain why I haven't experienced this problem. All of my flashes are pretty old and won't go anywhere near that fast.
 

jim10219

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Also, if your flash is set to a newer TTL setting (like what digital cameras use), or red-eye reduction, it can give you false readings if the meter doesn't have a setting to compensate for this. In those settings, there's a preflash triggered just before the main flash to allow the camera to get a light reading of its own. If the meter mistakes that for the actual flash, it'll show every flash power setting as the same because it's not reading the actual flash, but instead the preflash.

The original TTL settings in film cameras don't use preflash. They meter the light reflected off the film and cut off the flash when they hit the nessesary amount of light. So flashes designed for film cameras won't have this issue, but newer ones made for digital cameras might if this feature is engaged.
 

markbau

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I'm not really sure why you would use a flash meter with a TTL flash. I don't know about the OP but I'm talking about using it with a standalone Elinchrome monolight .
 

MattKing

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markbau said:
I'm not really sure why you would use a flash meter with a TTL flash. I don't know about the OP but I'm talking about using it with a standalone Elinchrome monolight .
Click to expand...
People do, of course, sometimes use TTl capable flashes with cameras that don't offer TTl flash capabilities. I expect that Jim was merely suggesting that the OP check to make sure that the settings on the flash were appropriate.
The OP referenced auto exposure flashes, so it seems clear that at least some of his flashes aren't monolights.
 

MattKing

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I've never had a problem with the modeling light distorting a flash meter reading, but I expect that is because I've never had to deal with a modeling light that was anything less than many, many, many stops less bright than its accompanying flash.
 
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KN4SMF

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One other thing the manual doesn't even mention at all is trip voltage when using the cord. I bought my 308S in about 2006. By that time, flashes had all gone to low trip voltages. I don't know when they started making flashes with lower trip voltages. The 80's, the 90's. Or later? Not only will I be using the meter with my late model studio flashes, but I'd like to know if I can also use it in corded mode with my 1976 Sunpak 611, which was made in the days if high trip voltages.
 
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KN4SMF

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Like was said in the OP. The manual doesn't discuss these things. If it did, I wouldn't be posting. I had to click show ignored content to see that last post. I might have known it would be useless.
 

John Koehrer

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Relying on my frequently faulty memory doesn't the 308s allow you to change readout mode? Aperture or speed?
 
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