question wrt YS-D2 on manual

[ReadyDiverOne]

+1 on @Interceptor121

Chris, this sentence don't make sense: "You want enough flash that the flash exposure is correct whether you are at the surface 100 feet deep or in the dark"

As has been repeatedly pointed out, exposure on land and exposure underwater are two totally different things: a good exposure in a dark(ened) room may work at 30 feet if you are 3 feet from your subject, but it may not, depending on how much ambient light there is, how clear the water is, how and where the strobes are positioned, etc. And that exposure certainly won't work at 100 feet. Thus, if you need 1/160 at 30 feet to properly expose the background as a nice blue color (assuming aperture at say F6.3), your strobe setting is likely going to be quite low powered, say around 8 or so. Of course, those setting won't work AT ALL if you drop down to 60 or 90 feet: you will need to lower your shutter speed and or open your aperture to get the background ambient light right, and increase your strobe power to light the foreground.

So, as @Interceptor121 says, there is just no way to replicate this on the surface and the manual contains no reference to or instructions regarding using the GN numbers for setting manual exposure. As I have said in several posts, if you ask the experts at backscatter and bluewaterphoto, they will tell you that the GN indicators are just rough indicators of power output and must be adjusted manually given numerous changing factors, including how much light there is, what your shutter and aperture settings are, where and how the strobes are positioned, etc. There just isn't any magical formula that says, if you are 100 feet, shooting 1/100/F6.3/ISO 100 the GN should be X. There just isn't and you certainly can't create a reliable formula in a dark room on land.

 

[tursiops]

+1 on @Interceptor121

Chris, this sentence don't make sense: "You want enough flash that the flash exposure is correct whether you are at the surface 100 feet deep or in the dark"

As has been repeatedly pointed out, exposure on land and exposure underwater are two totally different things: a good exposure in a dark(ened) room may work at 30 feet if you are 3 feet from your subject, but it may not, depending on how much ambient light there is, how clear the water is, how and where the strobes are positioned, etc. And that exposure certainly won't work at 100 feet. Thus, if you need 1/160 at 30 feet to properly expose the background as a nice blue color (assuming aperture at say F6.3), your strobe setting is likely going to be quite low powered, say around 8 or so. Of course, those setting won't work AT ALL if you drop down to 60 or 90 feet: you will need to lower your shutter speed and or open your aperture to get the background ambient light right, and increase your strobe power to light the foreground.

So, as @Interceptor121 says, there is just no way to replicate this on the surface and the manual contains no reference to or instructions regarding using the GN numbers for setting manual exposure. As I have said in several posts, if you ask the experts at backscatter and bluewaterphoto, they will tell you that the GN indicators are just rough indicators of power output and must be adjusted manually given numerous changing factors, including how much light there is, what your shutter and aperture settings are, where and how the strobes are positioned, etc. There just isn't any magical formula that says, if you are 100 feet, shooting 1/100/F6.3/ISO 100 the GN should be X. There just isn't and you certainly can't create a reliable formula in a dark room on land.

You still seem to be confusing purely ambient light on land with mainly strobe underwater.

 

[bvanant]

I haven't the YS manual right here but it is my experience (tested in the pool) that while the published guide numbers should be taken with a grain of salt (or maybe more) the relative outputs on the label are correct. That is one stop difference is a factor of 2 less or more light depending on the direction of the dial turn. This is accomplished by adjusting the time duration of the flash during firing, It seems though that there are two discussions going on here, one about strobe power and one about strobes plus ambient light. As Chris and Tursiops keep pointing out, adjust your shutter speed for water color i.e. ambient and adjust your strobe power to illuminate your main subject. Shutter speed ( mostly ) has zero impact on strobe exposure, f stops can control ambient a bit but mostly interact with strobe power and DOF and ISO changes everything.
Cheers
Bill

 

[ReadyDiverOne]

My goodness, has no one read my posts?? This is EXACTLY what I said. Oy. And I NEVER said that the strobe controls didn't work or weren't accurate. Amazing.

 

[bvanant]

" they will tell you that the GN indicators are just rough indicators of power output and must be adjusted manually given numerous changing factors, including how much light there is, what your shutter and aperture settings are, where and how the strobes are positioned, etc." To my reading this suggests that the strobe controls are not accurate. Sorry for the confusion.
Bill

 

[ReadyDiverOne]

Both are true statements: first, the controls are accurate in terms of increasing or decreasing power by X amount; but second, how a particular power setting will actually affect the exposure does NOT correlate in any specific formulaic way to aperture or ISO. Hope that clears it up for you.

 

[Chris Ross]

It makes perfect sense to me - the strobe exposure needs to be strong enough that the contribution from ambient light is negligible to get the strobe light to be the expected colour temperature. That exposure does not change with ambient light conditions unless the ambient light is strong enough to overpower the scene at max sync speed and your chosen aperture, which is unlikely unless you ISO is high and right at the surface. The classic thing to do underwater is expose your scene and have enough shutter speed that the BG water looks good, you are generally pointing up for the brighter light and anything on the reef or subject beyond the range of the flash is generally quite dark.

All this is assuming you are the same distance from your subject and that distance is close enough that the water has a minimal impact upon the flash brightness.

I found the single issue with my photos has been the flash is not strong enough or conversely contribution from ambient too high - this comes from considering the overall exposure - it's quite easy to get a well exposed photo where the flash is not strong enough and underwater it looks OK, it's not till you start shooting with enough flash power and see the results that it becomes more obvious. Considering the flash as a separate exposure and getting your strating point on land forces you to turn up the flash. You then go under water and it'll be pretty close if the ambient light is too much turn it down half a stop or so.

 

[M DeM]

@Chris Ross and @tursiops, I guess I wasn't clear or maybe we're saying the same thing. First, regarding shooting your strobe in a room above water--I assume we're talking shooting in Manual and RAW. My point was that I don't see how one can replicate how dark or light the underwater conditions are by turning off the room lights or dimming them. As you know, the light or lack thereof underwater can change very dramatically in 10 feet or so, and so if you're at 100 feet it may be a lot darker (depending on whether is is clear or cloudy up top or not) than it is at 50 feet. And light is not light at depth; it is totally different in terms of strobe use. So I think it would be hard to replicate those variances in a dark(ened) room, and I've never heard anyone (eg, from backscatter or bluewaterphoto) recommend that approach. Everyone I've spoken with--and all the Internet sites I've researched--suggest getting shutter and aperture where you want and then experimenting with the strobes' power output.

Second, and very much relatedly, as you know, at depth, one uses shutter speed to "dial a blue" and to achieve the color one wants in the background, since the strobes will light the foreground irrespective of shutter speed. So the faster the shutter the darker blue the background. As noted, the shutter speed will not affect the strobes, since they fire far faster than the shutter ever could, so the amount of light provided by the strobes is almost entirely a function of the power setting you have them on. Now, let's say that you like the way the background of your shot looks shutter-wise, and you're happy with your aperture, but when you fire the strobes your foreground is too dark or too hot. Above water, without strobes, if you like your speed and aperture settings, then maybe you adjust your ISO or even your exposure compensation. But neither of those work well underwater: as noted, adjusting your shutter will only affect the BACKGROUND and not the foreground where the strobes are firing. Similarly, increasing ISO or EV will increase light receptiveness for the ENTIRE photo, meaning both the background and the foreground will be more (or less, as the case may be) exposed. But again, that's not what you want, we've agreed you like the way the background (shutter speed) looks and the aperture. Moreover, because the strobes are so powerful, increasing the ISO or EV even a little bit usually results in the foreground getting blown out--strobes are really really sensitive to increased ISO.

So for all these reasons, you want to first dial in your shutter and aperture at the lowest ISO you can achieve that makes the background look good/blue, etc., and then use the strobe power levels to get the foreground exposure the way you like it.

Here are a few examples where I used this technique: https://flic.kr/s/aHsmFrVnhn

I hope this makes sense. Thanks.

Ps. One additional note: the YS-D2s are so powerful I have yet to encounter a wide-angle shot I could not get with them on or near full power, see, e.g., the very wide shot of the fans in the link.

HOLY CRAP - those photos look like you took a tank into a studio! Amazing!!! Can I ask what length arms you are using? (Not that I'm insinuating that the arms that makes the photos so great -- obviously it's the person positioning the arms).

 

[M DeM]

I think around it differently. You have two exposures - flash and ambient and you want flash to be dominant in the foreground. When you're setting flash exposure I could care less about the shutter speed - as long as it's fast enough that you get the little input from ambient light. Set up your exposure in a darkened room subject about 30cm away +/- set your aperture f8 for m43, f11 for APS_C, f16 for full frame, and base ISO that's about what you need to deal with dome ports and having a chance to get the corners as sharp as they will be. Adjust flash until your subject is exposed correctly. Stop there and use that as your first setting underwater. You are only trying to get the first half of the exposure dialed in.

When UW, take an reading on the BG, and take some test exposures and dial in your shutter speed. Take your first shot and adjust flash output as required.

Doing it that way you start with enough flash power, you can get a good histogram that with the exposure weighted too much towards ambient light and that looks OK at first glance UW. If you start out with a flash setting that gives the right exposure you avoid falling into that trap. Your first iteration after the first test shot is to try it with more flash .

I actually have a question about metering -- I have a film background (as in "motion picture film" rather than "still photography") so most often I used a spot meter, then moved/scrimmed/diffused the lights to taste.

So when I started doing photography, I kept it on spot metering. It's what I'm used to.

But underwater..... I'm really not getting great results. It's almost like it's way more contrasty underwater. I was told I shouldn't use spot-metering, just "center weighted" metering. What are your thoughts?

 

[tursiops]

Here is the starting point recipe:
Everything -- camera and strobe -- are on manual.
1. Use as low an ISO as conditions allow. This likely will be 100-400.
2. Use f/5.6 for point and shoots, f/8 for m43, f/11 for 1-inch sensors, f/16 for full frame. Smaller f-stops risk diffraction effects. Go one f-stop smaller if you must, for depth-of-field.
3. Use a shutter speed that exposes the water for your desired background color...light blue, dark blue, black, your choice. You may be limited in how fast your shutter will sync with your strobe.
4. Adjust the strobe power and position so your foreground is exposed correctly.

This is not hard, and for different subjects at similar depths requires only adjusting the strobe power.

Why not use some automatic mode on your camera, like A or P or whatever your system calls it? Because that mode is not designed for underwater shooting, and will attempt to expose the scene using ambient light, which causes two undesirable things to happen: (1) the camera will likely choose a slow shutter speed and/or a high ISO, because it is pretty dark down there. The former gives you motion blur, the latter gives you a noisy picture (today's equivalent of the old grainy pictures). (2) When your stobe fires, it adds light on top of the ambient-light exposure, so you get an oveexposed result, all blown out.