FL-50R Flash HELP!!!

<p>Ok I got my new FL-50R flash unit and it's pretty and real powerful and all that, but can somebody PLEASE help me to decipher this Guide Number chart in the manual? I can find my way around using the flash on camera in the Auto TTL mode, but the reason for getting this flash unit was to get away from the full auto (aka real expensive point and shoot) camera stuff.<br>

I would like to be able to do manual work from time to time and I can't seem to get this Guide Number stuff down. I have the Aperture-Shutter Speed relationship under control but when I add this final piece, the puzzle falls apart!<br>

I have looked at the charts in the flash's manual until my eyes cross and I can't make heads or tails out of the info it says!</p>

<p>Wes,<br /> Assuming that FL-50R is essentially the same as my FL-50 (only without remote control function), you should be able to set the GN directly on the flash. Here's the procedure:<br /> 1. Push the "MODE" button on the rear panel of the flash until "MANUAL" is displayed on the LCD screen.<br /> 2. Operate the left dial until you get the GN you need. You can read out the GN directly at the bottom left section of the LCD.<br /> 3. When you zoom the flash head, the GN is re-calculated automatically. With the right dial, you can adjust the power ratio. The ratio is displayed right next to the GN.</p>

<p>Hope this helps.</p>

<p>Thanks Akira, that helps a little. But what I really need to know is how to set the Guide Number. I have the chart from the flash's manual, but I don't know how to read it! That's what I really need help on - figuring out the fool chart!</p>

Distance to subject should be about equal to guide number divided by aperture. So if the GN says 16 meters and you're shooting at f/8, then the flash will "correctly" illuminate a subject about 2 meters away.

 

In practice, you don't usually calculate this stuff. It doesn't take into account things like the presence of modifiers (umbrellas, snoots, etc.) anyway. Just guesstimate and then adjust based on the image/histogram. I vaguely recall someone wirting that there's a way to make the flash display power output (1/1, 1/2, 1/4, ...) rather than guide numbers, which may be less confusing.

<p>There's no shame in going TTL......the use of diffusers etc, plus bounce etc creates so many variables anyway.</p>

<p>Well I will agree that Guide Numbers have pretty much gone by the wayside with the new computerized flash units. But as a retired firefighter, I know that even the best laid plans often go wrong and going back to the basics is often the only way out.<br>

Yes bounces, umbrellas, and other light modifiers do have an effect on your light output, but I don't have any of those devices (yet) and am not a studio photographer. My work will mostly be travel, wildlife, and "street" photography. And if using Guide Numbers gets me in the ballpark, then that's a good enough reason for me to learn it.</p>

<p>Wes,<br>

As David explained, setting the GN on your flash means that you are fixing the relationship between the aperture value and the distance where the object is correctly exposed. If you set the GN to 16 and set the aperture to f8, you can correctly expose the object that is (16/2=)2m away. If you set the aperture to f4 with the same GN, you can correctly expose the object that is (16/4=)4m away. Or, if you want to expose the subject that is 5m away correctly, you should set the aperture to (16/5=) f3.2 (about 1/3 step slower than f2.8). If you raise the ISO value by one stop, you can get the GN multiplied by the square root of 2 (roughly x1.4), so GN16@ISO100 will be about GN22@ISO200, GN32@ISO400, about GN45@ISO800, etc. The system is quite simple.</p>

<p>The good thing about the full manual control of flash is that the exposure is not affected by the color (more precisely, the digree of reflection) of the subject which usually confuses TTL auto mode unless the exposure meter can recognize the color or the metering system can use the distance info.</p>

<p>The problem is that modern AF lenses often lacks the distance scale on the lens. Even if a lens does have the distant scale, the generally short focus throw of a modern AF lens inevitably squeezes the distant scale so much that it is nearly impossible to read out the precise distance especially between 2, 3 or 5m and infinity (say, on a standard zooms or standard primes), which means that you cannot calculate the aperture value correctly and thus you cannot expose the subject correctly.</p>

<p>So, I would think that the full manual flash exposure based on GN is mostly suitable only for the older MF lenses.</p>

<p>My thanks to all who responded. I guess the answer to this is that for the most part I will either do full TTL or at the most let the flash pick how it wants to fire.<br>

For those times when I want to go fully manual (for creative purposes or whatever) I will have to set the distance to start with and then work things from there.</p>

<p>If you go to Strobist.com you will learn to adjust manually by trial and error. They do not suggest TTL or light meters. Take a guess at your flash setting, shoot, look at your screen, adjust. Not much worry about f/8 or f/11. Just shoot and adjust. I do not remember them mentioning any effort to use guide numbers. They suggest to take full advantage of the digital technology by looking at the results in the screen.<br>

Then adjust.<br>

They say that you will get good enough soon to be within one or 2 adjustments on the first shot.<br>

Although I am just learning the technique, I am spending my time working with TTL</p>

 

<p>Thanks for the help Daniel and you're right about one thing - going digital is great for those who can take the time to shoot, adjust, and shoot again. No worries about spending a bunch of money on developing crappy pictures!<br>

But there are times that you only get one take and for those times you want to get "in the ballpark" if not better. These are the times I am talking about. If I'm shooting pics of flowers, I can take my time and get it right, but for action pics or people shots, you can't hunt and peck forever!<br>

It's for these pics I am trying to get things right the second time at least. I do have the Strobist and am learning lots all the time. But T.S. deals a lot with studio and portraits and I am more a travel photographer and "street" photographer. So I need to get a lot more familiar with my flash.</p>