Why the bad shot with 17-40mm f4?

[sheldonnalos]

**** By Diffuser I mean the built in element that swings down over the bulb of the flash. Not Stofen. Am I using the wrong term?

 

No, you are using the right term. I just wrongly assumed it was a Stofen. The diffuser you are using is for when you need to use a very wide lens and want full coverage from direct flash (ie. a 17mm on full frame or a 10mm on a crop camera). It's not really necessary otherwise. You should, however, use the little white reflector card built into the 580EX. It's a very handy thing when doing bouce flash.

 

**** One problem I have in the P (Program) mode is that I thought it would default the flash as the main light source. That's what I wanted so how do I make it so?

 

Program mode does work to have the flash as the primary light source in lower light conditions. Unfortunately it defaults to f/4.0 and 1/60 as the exposure, which still allows in some ambient light. Stopping the lens down to f/5.6 or f/8.0 and increasing the shutter speed helps to completely eliminate the ambient light. Once you take out the ambient light, the problems with camera shake, subject movement, and white balance strangeness are greatly mitigated.

 

**** Mazza suggested above to go with F8 or F11. Can I adjust to this aperture manually in P mode? I didn't think I could.

 

In Program mode you can somewhat adjust the exposure settings by playing with exposure compensation. However, it is much preferable to set the exposure in Manual mode, and then let the ETTL II flash algorithm determine the correct amount of flash output to light up the scene. The flash is measured entirely separate from the aperture/shutter speed settings, and is controlled by the Flash Exposure Compensation setting. That is why you can leave the settings constant by using Manual mode, and let the flash do all the work.

 

Mazza's suggestion of f/8.0 or f/11.0 is ok, provided you keep the shutter speed up using Manual mode. If you use Aperture Priority (Av) mode, the shutter speeds will be very slow. Stopping the lens down to f/8.0 or f/11.0 gets you additional depth of field, but it does have one downside. The flash has to put out more light to expose the scene, which leads to longer recycle times between shots. I've settled on f/5.6 and ISO 200 as a good middle ground between best performance and faster flash recycle times. Shooting at f/5.6 gives enough depth of field for your average indoor candid, and gets the lens into the aperture range where it performs the best (f/5.6 to f/11.0 is usually the range where a lens will give its sharpest results). ISO 200 also gives faster recycle times, and isn't really any grainier than ISO 100. If you shoot at f/8.0 or f/11.0, there is also the possibility that the flash might not have enough power (ie. with a higher ceiling).

 

One other tip for getting faster flash recycling is to use NiMh rechargeable batteries instead of alkalines. Not only are they cheaper in the long run, they also recycle the flash almost twice as fast.

 

**** Should I be shooting the flash in ETTL mode with no adjustments?

 

Yes, plain ETTL mode on the flash with no adjustments. You can then control the Flash Exposure Compensation setting directly from the camera. (Top right button, see the 20D manual for complete details). Again, I find a setting of around + 1/3 stop to be about right for FEC.

 

**** Thanks for all the help guys. I have a wedding coming up for a friend and I really need to get these indoor settings working for me.

 

You should also read the EOS Flash Bible at www.photonotes.org for a more detailed explanation of the quirks of the Canon ETTL flash system. That will help out greatly, especially with the upcoming wedding.

[jonathan_gentry]

Thanks so much. I was trying to figure this out on my own and obviously that was not the best choice. I bought the flash a few months ago but most of my shooting has always been natural light.

 

Thanks so much for the detailed response Sheldon. f/5.6 it is (unless I need deeper depth of field.) So I set that in M mode and any suggestion on shutter? 1/125 sec?

 

Someone also made reference to A-DEP mode. Is this recommended?

[steve_dunn2]

<p>A-DEP is not a bad way of getting enough DOF to cover whatever's in the centre of the frame, but it has its drawbacks.</p>

 

<p>Since it's automatic, you don't get the opportunity to tell the camera which things are part of the subject and which aren't. If it's under one of the AF points, it's part of the subject as far as the camera is concerned, even if you disagree. Previous bodies occupying the advanced-amateur slot in the product lineup have had DEP, which lets the <em>photographer</em> tell the camera what the nearest and farthest parts of the subject are; while I didn't use DEP mode all that often, I am annoyed at Canon for removing it, since I now cannot use it at all. At least they've put a sort-of substitute into the 20D; they removed the depth-of-field mode entirely from the 5D.</p>

 

<p>Its idea of DOF may be different from yours. Anything that is within DOF, but not at the precise distance at which the lens was focused, is technically not in focus; however, it's close enough that it looks like it is. The dividing line between "close enough that it looks like it's in focus" and "not quite close enough so it looks slightly out of focus" is not well defined; it depends on a number of factors including how much you're enlarging the image and how picky you are. Canon has programmed the camera with one setting for this. That setting may or may not be the same as what you want it to be.</p>

 

<p>And since you're using flash for your lighting, that pretty much kills A-DEP; if you set the camera to A-DEP and use flash, you get P (page 82 of the manual).</p>