What’s Your Preference?

Roger Dodger · #1 (**permalink**) 02-12-2011, 06:48 PM

When my new Sigma EM-140 Macro flash is attached and powered up on my Canon Rebel XSi, under external flash control settings, the camera won't let me select "ETTL II".

I assume I need to enable this setting to correctly use this flash unit.

Is my assumption wrong, or is there something wrong with the flash unit, or the camera?

Thanks!!

daft_biker · #2 (**permalink**) 02-13-2011, 04:14 PM

Does the lens communicate focus distance information to the camera?

I wouldn't worry about it....it should still work with ETTL?

Roger Dodger · #3 (**permalink**) 02-15-2011, 05:37 PM

Thanks for the feedback. As you can see, I didn't any help from anyone but you.

I finally concluded that the flash works, altho I can't "enable" the external flash setting for ETTL II, b/c the Canon camera only lets you do that for its proprietary Speedlites. My first response from Canon's online customer support was basically, sorry we can't help you b/c you should have bought a Canon Speedlight, and ended the message with "We hope this information was helpful". I responded back that "NO, it wasn't helpful", and rephrased the question, and then got a meaningful answer, i.e., that you could only enable that in camera setting with Canon's Speedlight.

A big part of the problem is my ignorance about external flashes and what ETTL II means and how it works. I couldn't navigate the Canon website to find it, and the url Canon sent me was no longer functional. So, I was able to find sufficient info at Wikipedia (I hope it's accurate).

It sounds like this flash unit is doing all the distance calculation internally, and doesn't communicate with the camera, other than letting it know that it's attached and powered on.
Now, I just need to use it some and gain familiarity with it, especially for macro work.

Thanks again for the response.

inkista · #4 (**permalink**) 02-15-2011, 07:03 PM

Hang on a mo'. [google google. PDF download. Check through user's manual...]

Use the "Mode" button on the back of the flash. Hit it until you see "ETTL" on the LCD.

While only certain Canon speedlights can be controlled via the camera menu, you can also set the flash to do what it should via its own LCD menu. In fact, some of Canon's own speedlight units (430EX and 580EX Mark I models) also need to be set this way. The flash control menu on dSLR bodies is a relatively new feature. Definitely not a feature I'd expect from a 3rd-party flash.

Silly questions: are you sure you've got the flash full seated properly on the hotshoe so that all the contacts match? And are you sure you've got the Canon version of the flash, not the Nikon or Pentax version?

Helpful definition:
ETTL-II: Electronic Through-the-Lens. Version II (digital).
What this basically means is that the camera can automatically adjust the flash's power output by using through-the-lens metering. Think of it as P mode for your flash. The camera tells the flash to send out a "pre-flash" burst of a known brightness, and meters it, then adjust the flash's power output setting to bring it up/down to where the level "ought" to be. Like most automatic modes, it's fast, it's easy, and it'll be in the ballpark, but because it's based on metering, it can be off and will be inconsistent as you change what goes into the frame.

Just like you use M mode on your camera for control and consistency, you'd also use M mode on the flash for the same reasons. The reason that the power levels on your flash are in powers of 2, (1/2, 1/4, 1/8, 1/16, 1/32, etc.) is because that equates to doubling the light (stops), just like doubling the iso or shutter speed, or moving one full stop up/down the f-number scale for aperture.

ETTL II was created for digital cameras, because the reflectance of light on film is different from light on a sensor, and the metering changed. If you're really interested in the history of TTL -> A-TTL -> E-TTL -> E-TTL II, you can read about it on the EOS Flash Bible.

But mostly what you need to know is that your camera speaks eTTL-II, and you probably want a flash that does the same thing.

The other thing you need to know about flash is that it's not like ambient exposure. It is not controlled by iso, aperture, and shutter speed the way that ambient light is. Flash illumination is controlled by iso, aperture, power output, and subject distance.

Note how a) shutter speed isn't part of that equation (the flash burst is faster that your top shutter speed, so no matter how long you leave the shutter open, you won't get more light from the flash). and b) subject distance is really really important. Light falloff with flash is described as following an "inverse square" law. That means that when you double the distance from the subject to the flash, you get 1/4 the light. Triple the distance, and you get 1/9th the light. Conversely, halving the distance quadruples the light, and 1/3 the distance will multiply the light by a factor of 9. So consider the effect this has with macro photography.

Last but not least, the biggest concept you have to learn with flash photography is that every image you take is going to combine both the ambient AND the flash illumination. So you still have to worry about iso/aperture/shutter speed for one, and iso/aperture/power/distance for the other. You're juggling both kinds of illumination, and working out how to balance them against each other. The best weapon you have to do this is shooting in full Manual mode on your camera. If you're not comfortable doing that, then you may want to take the time to learn. Otherwise, things like dragging the shutter aren't going to make much sense.

Roger Dodger · #5 (**permalink**) 02-15-2011, 07:37 PM

Quote:

Originally Posted by inkista

Hang on a mo'. [google google. PDF download. Check through user's manual...]

Use the "Mode" button on the back of the flash. Hit it until you see "ETTL" on the LCD.

While only certain Canon speedlights can be controlled via the camera menu, you can also set the flash to do what it should via its own LCD menu. In fact, some of Canon's own speedlight units (430EX and 580EX Mark I models) also need to be set this way. The flash control menu on dSLR bodies is a relatively new feature. Definitely not a feature I'd expect from a 3rd-party flash.

Silly questions: are you sure you've got the flash full seated properly on the hotshoe so that all the contacts match? And are you sure you've got the Canon version of the flash, not the Nikon or Pentax version?

Helpful definition:
ETTL-II: Electronic Through-the-Lens. Version II (digital).
What this basically means is that the camera can automatically adjust the flash's power output by using through-the-lens metering. Think of it as P mode for your flash. The camera tells the flash to send out a "pre-flash" burst of a known brightness, and meters it, then adjust the flash's power output setting to bring it up/down to where the level "ought" to be. Like most automatic modes, it's fast, it's easy, and it'll be in the ballpark, but because it's based on metering, it can be off and will be inconsistent as you change what goes into the frame.

Just like you use M mode on your camera for control and consistency, you'd also use M mode on the flash for the same reasons. The reason that the power levels on your flash are in powers of 2, (1/2, 1/4, 1/8, 1/16, 1/32, etc.) is because that equates to doubling the light (stops), just like doubling the iso or shutter speed, or moving one full stop up/down the f-number scale for aperture.

ETTL II was created for digital cameras, because the reflectance of light on film is different from light on a sensor, and the metering changed. If you're really interested in the history of TTL -> A-TTL -> E-TTL -> E-TTL II, you can read about it on the EOS Flash Bible.

But mostly what you need to know is that your camera speaks eTTL-II, and you probably want a flash that does the same thing.

The other thing you need to know about flash is that it's not like ambient exposure. It is not controlled by iso, aperture, and shutter speed the way that ambient light is. Flash illumination is controlled by iso, aperture, power output, and subject distance.

Note how a) shutter speed isn't part of that equation (the flash burst is faster that your top shutter speed, so no matter how long you leave the shutter open, you won't get more light from the flash). and b) subject distance is really really important. Light falloff with flash is described as following an "inverse square" law. That means that when you double the distance from the subject to the flash, you get 1/4 the light. Triple the distance, and you get 1/9th the light. Conversely, halving the distance quadruples the light, and 1/3 the distance will multiply the light by a factor of 9. So consider the effect this has with macro photography.

Last but not least, the biggest concept you have to learn with flash photography is that every image you take is going to combine both the ambient AND the flash illumination. So you still have to worry about iso/aperture/shutter speed for one, and iso/aperture/power/distance for the other. You're juggling both kinds of illumination, and working out how to balance them against each other. The best weapon you have to do this is shooting in full Manual mode on your camera. If you're not comfortable doing that, then you may want to take the time to learn. Otherwise, things like dragging the shutter aren't going to make much sense.

Thanks for all of the great info (especially since I have little experience with flash other than candid photos of the grandkids) with the on-bard flash, which I cover with paer to diffuse it.

The box says this flash unit is for Canon cameras. It's brand new.

I've learned the basics (off and on right and left lights, changing ratios of left and right light, and changing power output. I just need to set it up for some macro shots and try it out, especially in M mode (camera) with adjusting shutter and aperture, and distance, and output on the flash to gain enough experience to set it up reasonably quick before the bug moves or flies off.

And, again, I think that the only problem was that I'm so poorly informed on some of these topics. For example, I incorrectly assumed that when a third party vendor sells a product that is compatible with my Canon camera, it would work like a Canon product, i.e., in this case, that although the manual said the external flash control would only work with Canon Speedlites, since this flash was "For Canon cameras, at least my model", the camera would read it as a real Canon flash. But, not the case. Lesson learned.

Thanks again for the great response!

inkista · #6 (**permalink**) 02-15-2011, 07:45 PM

Quote:

Originally Posted by Roger Dodger

...I incorrectly assumed that when a third party vendor sells a product that is compatible with my Canon camera, it would work like a Canon product, i.e., ...

Actually, it does. The Canon macro flashes are the same way. They're much older units (being not as popular as the regular speedlites). The camera menu control thing only came in when the 580EX II and 430EX II were released about four years ago. AFAIK, the macro ring lights were not updated with this feature at that time. That's why expecting it in a 3rd party flash is so unrealistic. When Canon's own equipment doesn't have that feature, how can you expect a reverse engineered knock-off to add it?

Also, essentially, what you're grumbling about is having to move your eyes and fingers a few inches up to control your flash.

While menu control is nicer, and makes custom functions much less of a PITA, you still have access to all of your flash's functions.

Roger Dodger · #7 (**permalink**) 02-16-2011, 01:44 AM

Quote:

Originally Posted by inkista

Actually, it does. The Canon macro flashes are the same way. They're much older units (being not as popular as the regular speedlites). The camera menu control thing only came in when the 580EX II and 430EX II were released about four years ago. AFAIK, the macro ring lights were not updated with this feature at that time. That's why expecting it in a 3rd party flash is so unrealistic. When Canon's own equipment doesn't have that feature, how can you expect a reverse engineered knock-off to add it?

Also, essentially, what you're grumbling about is having to move your eyes and fingers a few inches up to control your flash.

While menu control is nicer, and makes custom functions much less of a PITA, you still have access to all of your flash's functions.

Nope, not grumbling about that. I just didn't think it would work if I couldn't tell the camera that it was there But, it did. Had fun working with it today and getting to know how to use it. It'll help get some good macro shots at f32 for good depth of field.

Roger Dodger · #8 (**permalink**) 02-16-2011, 02:08 AM

I'd post a picture but can't figure out how to resize the picture to 740 pixels on the widest length. My Photoshop elements gives me about 6 different units to resize my photos, but none of them are by pixels.

Roger Dodger · #9 (**permalink**) 02-16-2011, 02:29 AM

My default Mac picture manager let me resize by pixels, so here's a photo I took this afternoon of an orchid with my new Sigma flash and Kiron 105mm lens. No post processing other than about a 10% crop. This lens doesn't communicate any exig data, so I don't know the f stop, time, etc.