[dagaetch]

So I just got a new flash, a Yongnuo 560 III, to go with my K5ii. I've occasionally used the pop-up flash, but don't really know what I'm doing with an external one. Can anyone help me out, or point me towards a good tutorial for using a manual flash?

I've got the flash configured for basic shooting (M, on hotshoe, etc) and figured out how to adjust the power level and zoom. It attaches to the camera fine, and fires correctly when I take a shot. The thing is, on default Av settings, it's massively overexposed. Does the camera not automatically adjust for the flash? When I set the camera on manual and underexpose by a large amount, the picture comes out correctly (and very nicely with the flash). But I want to shoot on Av if possible....I guess I could program Ev comp to be negative, but that seems strange. Am I missing something?

Thanks! I'm hoping to use the flash at some upcoming work events, so it will be indoor portrait and candid shooting, if that makes a difference.

[jatrax]

I'm no expert but manual flash means manual flash. You have to adjust your settings on the camera and flash to get correct exposure. I do not think the camera will adjust the flash settings like it would on a P-TTL flash.

Here is a good amount of information: Strobist: Lighting 101

[Not a Number]

A manual flash usually has some sort of guide number calculator on them:

Strobist: Guide Number: Your Free Flash Meter

[OregonJim]

The key thing to remember is that, with flash, you are always making two exposures at once. One exposure is for the ambient light. You set this in the normal fashion to correctly expose the background. Then, you add the flash on top of that to add fill in selected areas. This is not related to the ambient exposure, but is separate from it. With a manual flash, you control the output power of the flash to complement the ambient exposure from the camera.

[THoog]

Does the camera not automatically adjust for the flash?

No, it does not with an old school all-manual flash like the YN-560III. The YN-560 isn't even a "dedicated" flash, with a pin to tell the camera that it is there, so as far as the camera knows, there is no flash. I'm afraid it's going to take some old-school methods and trial-and-error.

The YN-560III doesn't have an onboard calculator like in the Strobist article - it has a printed table in the back of the user manual. Here's a link to an online version:

http://speedlights.net/wordpress/wp-content/uploads/2010/06/YN-560-Instruction-Manual-42.jpg

Note that the "flash coverage" is for 35mm "Full Frame" Field of View, and there's a known typo - the "14mm" column should read "18mm", or maybe "with diffuser panel down".

To use the table, pick the column that most closely matches your Field of View, then read down the column to find the power setting for your distance to subject (whatever's closest). Take a test shot, check it, and adjust up or down as necessary. These values are based on fixed ISO 100, and the camera set to it's X-sync speed (1/180 for the K-5).

Here's where it gets tricky (for me): the table is for a f/1 lens. So for each f-stop slower than that (f/1.4, f/2, f/2.8, f/4) you would have to increase power or ISO one level.

This may seem awfully primitive, but that's why the YN-560III is so cheap compared to P-TTL flashes - there is NO automation. The photographer has to do all the work.

[Bob from Aus]

To do everything manually

keep the iso at 200 or less. You metering dial has a setting "X" It will keep the shutter at 180. Set the f stop to around 5.6. Set the flash to a quarter power and take a test shot. If it is to bright use a smaller f stop or reduce the power of the flash. if the subject is dark (unlikely unless it is far away) then increase the power. I find in manual mode I can get it right with one test shot.

With bounce flash you will need full power.

[Tanzer]

Errr, welcome to the world of manual flash.

As others have said, you will not have any automation whatsoever.

At your upcoming work events, you will have some time to prepare for the portrait shots since you will establish a working distance, which is a major factor in getting the flash power adjusted correctly. You can calculate based on guide number to start with, or just guess, and then adjust from there. Then take each portrait using the same distance and camera/flash settings. For a wider group of people, you might step back, in which case you will need to bump the flash power or open your aperture, but those are things you can kinda guesstimate once you establish your pattern.

For the candid shots, you will have a bit more trouble getting the exposure correct without some practice, since, well, some shots will be taken farther from the subject than others. If the ceiling is high, but not so high as to make the reflected flash too weak, then bouncing the flash off the ceiling will help a lot, because 1) it produces more even/natural lighting than direct flash; and 2) it increases your overall flash distance (by the inverse square law) which helps to minimize the variation in flash intensity that you would get with direct flash. That is harder to explain than to do.

Totally agree with OregonJim's approach, to consider the ambient lighting first whenever possible, then fill with flash. But if you have a slower lens, and/or the ambient lighting is dark like an evening cocktail party, that you might need to light primarily with the flash.

[dagaetch]

Wow, this is fantastic information. Thank you all! I knew a manual flash would require more work, and I don't mind that. Fortunately, I have some time to practice. I'm going to mostly shoot at the event with my new 50/1.8, which should help both by low aperture and by not fiddling with zoom distance.

I'll spend the next few days playing with it and I'll probably be back with more questions! :-)

[RGlasel]

keep the iso at 200 or less

ISO setting is just as critical as aperture when using manual flash. For $5 at any office supply store you can get a portable electronic Guide Number calculator. All you need is a way to calculate square roots. The hard part is knowing the distance that light travels from the flash to the subject and back to the camera, and how much of the light doesn't get reflected. To calculate the guide number for any ISO setting, multiply the guide number for ISO 100 in the manual by the square root of the result of dividing the ISO setting by 100. For ISO 200 multiply your guide number by 1.4 (1.4142135 is more accurate, but the extra precision is meaningless, because you are making assumptions about the reflectivity of your subject), ISO 400 multiply by 2, ISO 1600 multiply by 4. I can't believe this flash doesn't have a calculator built in.

on default Av settings

Probably the best camera setting for manual flash is M mode. If you want to use Av mode so the camera calculates a shutter speed for you, you will have to experiment to find out how much negative exposure compensation you need to get shadows filled in with flash without overexposing the subject. As long as your shutter speed is less than the duration of the flash at maximum power, you don't need to worry about the effect of shutter speed on flash output. This is also assuming your shutter speed isn't so fast as to cause trailing curtain synchronization problems, but if your shutter speed is below the flash sync speed, you don't need to worry about that either. If you end up with such a slow shutter speed in Av mode that you get blurry pictures from shaking, switch to M mode and increase the shutter speed to something like 1/60 second, but you will end up with darker backgrounds.

So, with your 50mm lens and your flash at full power, your aperture is (42 meters x square root (ISO / 100)) / distance to subject in meters. If the resulting aperture is narrower than you want, reduce the power of your flash, and use the guide number in the manual for that power level instead of 42. At ISO 400 and a subject 10 meters away you only need 1/16 power if you want to shoot at f1.8.