Strobes

[Puffer Fish]

I hate to do two threads at a time, but as I am taking pictures with strobes anyway... might as well get this started.

I'm going to cover settings... what to look for in a strobe and specific problems, but first a small rant about specifications on these things:

If you have a Point and Shoot, then you need strobe that can mimic the preflash, not just ignore it.

For reasons I do not understand, this information is hard to get from the flash companies....

The lone exception is INON, but it is very valuable.

Why, because with the remote strobe firing, it will cause your camera to reduce the size of the flash, reducing batter usage,reduce the heat buildup and shortening the recycle time. And all are very good things.

The problem I have is finding out which do and which don't and how much of a flash that preflash is. So if someone knows that information, please post it..

[DevilDiver]

I am not sure if this covers all of the information you want but i have found this helpful. Check out this webpage and you should get a pretty good idea of the features offered on alot of the strobes on the market...........

Read to the left side of the page for links to a great article on strobes and an email adress for questions.

Underwater Strobe Comparison Guide - Digital Diver Network

Good luck!!

[dbh]

This should help some. Mfgs. seem to keep some info to themselves.

Underwater Strobe Comparison Guide - Digital Diver Network

Dave

[Soonerwink]

On my Oly sp350 I just set it to slave strobe with the lowest setting for the camera flash. I have only used it once but it seemed to work quite well.

[Puffer Fish]

Originally Posted by dbh

This should help some. Mfgs. seem to keep some info to themselves.

Underwater Strobe Comparison Guide - Digital Diver Network

Dave

Dave, the problem with that listing, and most other ones, is the issue of "Mimic" and just what that means.... With Inon... they use a very strong preflash to cause the camera to use it's lowest flash output... what and how do the other's do it?

Reading the Hartenberger site information, some strobes seem to be too slow to do this correctly....

As the biggest issue with a P+S is after you get by the the preflash issue, is how the camera will fire, this would seem to be very important...

[Puffer Fish]

I will have pictures tonight (sorry, was busy), but several words about using a P+S with a strobe.

The way a P+S works is to pick a set of settings, say 1/60 of a second @ F5.6 and then fire a preflash and measure the amount of light.

With a lot of light coming back to the camera, the flash duration is very short... with less light, the camera will increase the duration of the flash. It will do that, up to the point it completely dumps all the energy in it's capacitors.

The recycle time is fastest and the power usage is least when the strobe time is the shortest.

Problems:

If you use an external strobe, and block out the in-camera one from getting back to the camera (to reduce backscatter), the camera's strobe will be firing at maximum on every shot. Not good from a recycle time, battery usage and heat point of view.

That is where the mimic part comes in.. the strobe now flashes with the preflash and the camera thinks it is getting light back from camera and turns down the in camera strobe. Assuming it has the correct timing.

Getting a "skip the preflash" strobe is not good enough.

Problem is, don't know any details on most of the strobes except the INON, because the makers don't provide it, and most people don't know the details (me included)

[Puffer Fish]

Assuming you have a working strobe system, there is one other problem... back to the 1/60 second shutter speed. (it is the default fuji setting, for example).

Part of this is to allow time for the possibly long flash time and any timing issues between the shutter speed and the strobe.

But what if it is so light, that 1/60 of a second is too light? This goes back to using the lowest ISO setting and setting the camera with F8 (if you have it).

But even then, in shallow clear water, during the middle of the day, there will still be too much light...so no strobe is possible (a DSLR would not have this issue, by the way). Other than that, you will have a mix of outside light and the strobe

[bversteegh]

Follow the link below to Heinrich Weikamp's website - it has a good explanation of how different camera's control the strobe exposure calculation; and includes a table with measured pulse duration for several cameras.

HeinrichsWeikamp GbR

He builds an after-market TTL converter that is pretty sweet, BTW.

[Puffer Fish]

Originally Posted by bversteegh

Follow the link below to Heinrich Weikamp's website - it has a good explanation of how different camera's control the strobe exposure calculation; and includes a table with measured pulse duration for several cameras.

HeinrichsWeikamp GbR

He builds an after-market TTL converter that is pretty sweet, BTW.

He has absolutely amazing technology...which has to be installed in the strobe... and is pricy, but works great...

I have always been surprised that it was not being used by a major strobe mfg in a line of strobes...

Still does not address which strobes come with a preflash.

[Puffer Fish]

Been doing other stuff, but time to add some information.

Strobes are the one area where DSLR excel. Any point and shoot camera is going to have issues. You may be able to get around them, but it takes so thinking to do.

With a point and shoot, the usual default flash shutter speed is 1/60... that is because the amount of light put out by the in camera strobe is adjusted by changing the amount of time the stobe is "on".

So, you are starting with a shutter that is letting a lot of light in.

Next, many P+S don't have more than 2 f-stops... around 3 to around 5 is common.

The combination results in shooting,before the flash goes off, with 1/60th at say F 4. With an overcast sky, and ISO200 setting, that is a complete exposure, without the flash.... putting the flash in results in over exposure.

Also a 1/60 of a second is easy to get a blurry image, if you move at all.

For the above reasons, having a larger F range is important, as is a lower ISO number. Image stabilization also comes in handy.

Ideally, you would shoot at ISO 100 or lower, with the highest F number you have.. F8 is a nice number. That is about as good as you can do with a point and shoot.

There are three primary ways to use a strobe:

1. Flood flash, where the strobe is providing all you can see... backgrounds will be dark:



Not a big fan of this style.. but sometimes one has to use it, and if there is no water in view, works reasonably well.

2. Fill flash, where the flash lightens the area in front of you, but the water is still seen as, well water:



3. And lastly, just to provide color and the right focus on things:



Only the fish had any strobe light on it.




To do the last two, you have to balance the sun light with the amount the strobe puts out, and you may have to use a different f-stop.

It may also be, that with the 1/60 you have to use, it is not possible to actualy take a goo