Due to the number of questions Ive received I feel the need to do a step by step guide on how I set up and use the MT-24EX. But before I dive in there are a few things that you need to understand
Ive spent a lot of time experimenting with the MT-24EX and looking for a way to get the light I want from a flash that, out of the box, is really harsh. I started by learning how a flash works from reading the HiViz web site
and reading the tutorials at Strobist
like Aperant Light Size
. There is a huge difference between getting good results with a flash and understanding how youre getting the light that youre seeing in your images. If youre not willing to invest a little time to read those two sites then, IMHO, you should stop reading this tutorial now. Odds are Im going to confuse you in the long run because youre not going to understand what youre doing and youre not going to understand why the things that I do work
The last disclaimer before we get into the nuts and bolts of things: I am not now, now will I ever be, the last word on any photographic discipline. There are a lot of ways to get from point A to point B and Im only giving you one of them my way. Take what you read here and elsewhere and experiment. Make your photography look like its coming from you and not me otherwise you will always be walking in my shadow
Lets get started by going over what Ive learned about ratio control on the MT-24EX. With ratio control you can vary the power of the flash heads to create deeper shadows, but it has some limitations...
With E-TTL flash metering the camera will send out a pre-flash that's used to determine the exposure for the scene, and then it sets the power of the flash heads for the main flash burst. With ratio control your telling the flash to take the total amount of light that the camera want's to use for the scene and send more of it out a single flash head. But the total amount of light that the flash produces is the same with or without ratio control, in other words ratio control is not the same as flash exposure compensation (FEC). So with ratio control enabled you run the risk of over exposing part of the scene, and it's been my experience that the E-TTL pre-flash is not affected by ratio control (or if it is it doesn't have any effect on how the camera is metering the scene).
You do not need ratio control to get good shadows, so turn it off. The only time you should have ratio control enabled is if the flash heads are 180 degrees apart on the flash mount and even then if you have the heads angled differently you still dont need ratio control. If you do feel the need to use ratio control then dont set it higher than two to one and keep in mind that I do not use it
I usually have one flash head at the top of the lens (the key) at the 11 O'clock position and the other flash head is off to the side (the fill) at about the 2 O'clock position (relative to me) on the flash mount that Canon supplies with the MT-24EX. I also use a Kaiser Adjustable Flash Shoe to get the key flash higher, and at a different angle, than the key to cut down on glare. If both flash heads are mounted directly to the Canon flash mount then the angle between the flash heads, subject, and sensor will be the same -any shiny surface is going to cause problems since both flash heads will be hitting the same spot at the same angle. The Kaiser Adjustable Flash Shoe is not "keyed" to clip into the Canon flash mount, but I cut two groves in mine with a Dremel tool so that it locks in place like the MT-24EX's flash heads.
The angle of the individual flash heads can also make a big difference. I usually keep them both pointed directly at the subject and at the same angle. If Im getting some glare that I dont like and I have time to correct it then Ill angle the flash head thats causing the problem either toward the lens or toward the subject it depends on the scene. Also the magnification that I have the MPE-65 set to determines how I have the flash heads angled, and its kinda tough to show it in a photo so Im going to do my best to explain it.
If you own the MT-24EX then you know that the flash heads make a clicking sound when you move them up and down. So as a starting point push the flash heads all the way down so that they are pointing toward the lens. For life size bring both flash heads up one click. For twice life size and higher magnification leave both flash heads all the way down. My method of angling the flash heads at the various magnifications keeps them pointed directly at the subject, and it keeps the flash duration short. In some situations you might what to change the angle to eliminate bad reflections, but the angle that I set the flash heads to works most of the time.
You can also turn the flash heads from side to side, and you might want to depending on how close the subject is to the background. The way that E-TTL metering works is that there is a pre-flash before the main flash fires that the camera's light meter uses to set the exposure for the scene. If very little of that pre-flash makes it back to the camera (it can happen if the background is more than 6" or about 15cm from the subject) then the background will be very dark or black and the subject will be over exposed because the light meter gets fooled into trying to expose the background. But if you turn the flash heads toward the subject, especially the fill light (the one that I position on the side of the lens) then most of the pre-flash will hit the subject and the meter will give you a correct exposure.
Because the light from the MT-24EX is so harsh the trick to getting the quality of light that I want from it has been to get the flash heads pointed right at the subject, get them as close to the subject as possible, and to diffuse them. I tried several different things, but currently I have a some Rolux diffusion material from a Bogen Diffusion Kit hot glued directly onto the flash heads and on top of that I put a Sto-Fen diffuser set over the Rolux. I also wrapped Gaffers tape around the Sto-Fens to keep light from bleeding out the sides and to force more light out of the front of the Sto-Fens. The end result is that people are starting to think that my images are taken in natural light and that tells me that Im on the right track. My goal when I started experimenting was to get flash photos that didnt look like flash photos. But keep in mind that Im still learning, still experimenting, and that you should do the same
One final note: Getting the flash heads close to the subject gives me a flash duration that is extremely short and enables me to freeze the motion in a scene. The resulting images are razor sharp and have a lot of detail. So if youre not getting the sharpness that you see in my images you might have your flash too far away from the subject, or your diffuser is better at blocking the light from your flash than it is at diffusing it...