Jesper Hansen , Sep 13, 2010; 02:45 p.m.
Recently I photographed a teen party with my Canon 50D. I would really like some input about how to do this kind of low-light job right.
Here are some of the problems I encountered:
Starting out with reasonable light, I used Sigma 50mm 1.4, high ISO and no flash to keep the mood. Autofocus was quite unreliable though. When light levels dropped further, autofocus stopped working, especially the Sigma lens AF was completely useless. Isn't there supposed to be some red AF assist light in these situations?
Did manual focus for a while, and then light dropped to very low. Pulled out the 540EX flash, and the 17-85 IS. Was unable to do indirect light with the flash, since the roof was like 8 meters up. So, pointing the flash straight forward, and dialed in -1 in flash level compensation, to try to keep it down, and also -1 in exposure compensation to not aim for "normal" light level in the pictures.
The flash refused to do ETTL, simply stating "TTL" in the display instead, and it did not reflect the correct zoom distance of the lens, nor the compensation levels. Insisting on firing the full load everytime, exposure was way off. Normally ETTL serves me well, I often use both one and two flashguns and the ST-E2 master. What happened to my 540EX here? And still AF did not work at all.
In the end I stopped using the 540EX, and used the built-in flash instead. The built-in flash gave me pre-flash to help the autofocus, and the exposure was now in accordance with my compensation settings. Probably the most usefull pictures of the night, even though I would normally do much to avoid the flash-on-camera pictures.
Are the AF and ETTL problems normal? Why would the 540EX not do at least as good a job as the built-in flash?
How do you guys normally handle low-light focusing, and how do you get reasonable pictures retaining just a little bit of the mood when doing nightlife pictures?
All advice welcome - thanks,
Jesper.
Mark T , Sep 13, 2010; 02:53 p.m.
i use manual focus, and a light that i turn on while focusing and then off once i have the subject in focus..
and i use all my flash in manual..none of that ttl voodoo guessing game.
Nadine Ohara - SF Bay Area/CA 
, Sep 13, 2010; 03:06 p.m.
You describe multiple issues here.
1. Read Jeff Spirer's excellent article.
http://photo.net/learn/club-photography/photographing-bands-musicians/
2. AF assist from the flash is only with One Shot autofocusing. If using AI Servo, it does not operate.
3. You cannot expect the 'regular' autofocusing to work well in low light. You could use the ST-E2 only, if taking no flash pictures, just to get the focus assist, but again, you must use One Shot focusing.
4. You must be talking about the 580EX II flash, as a 540 flash is probably a 540EZ, which does not work with digital cameras. The 580EX II was firing full blast and only in TTL because the contact between flash and camera was faulty. This is a fairly common issue with this flash. The redesigned rubber gasket on the flash sometimes causes problems withe the flash contacting the hotshoe correctly. Research it--plenty has been written about it.
5. Or, your hotshoe plate could be loose. You can tighten the screws yourself.
http://www.conraderb.com/flashrepair/
6. You can still bounce flash pretty far using high ISO. A 30 foot ceiling is not necessarily too high, although the color/value of it may be a problem. You can bounce off walls, or off other people and things around you, such as off tablecloths, or the floor. I have found that in very dark situations, pulling the wide angle diffuser out to spray the light in a wide pattern, actually helps.
7. I use off camera flashes in these situations, plus diffused, direct flash, or bounced off a white card or other objects as described above.
8. You can try using zone focus for the images with no shutter/focus lag. You may find the following interesting.
http://photo.net/photography-lighting-equipment-techniques-forum/00XEeL
Jesper Hansen , Sep 13, 2010; 03:24 p.m.
@Mark - respect, but I don't have the skill or experience to pull that off yet :)
@Nadine - thanks, your answers and links are extremely helpfull. And of course it is the 580EX II flash. It never failed me before - I'll check the hotshoe.
I almost always do OneShot AF. Do I understand you correctly that the 50D is not capable of any AF assist on its own, but mounting the ST-E2 would do this? That is new to me, but vital knowledge for a situation like this. Thanks.
Nadine Ohara - SF Bay Area/CA , Sep 13, 2010; 03:30 p.m.
Jesper--no, the 50D is very capable of AF on it's own. However, no camera, no matter how sophisticated, is going to easily autofocus in very dim light. Perhaps you are confusing AF with AF assist--these are two different things. When an external flash is mounted to the 50D, it is, of course, capable of utilizing the AF assist, which comes from the flash, not the camera.
When you have this kind of situation, a wide aperture lens (usually a prime) is going to help, but slightly. What you really need is the AF assist from an external flash or, as I described above, the ST-E2 can be used just for the AF assist pattern.
Jesper Hansen , Sep 13, 2010; 03:46 p.m.
@Nadine, got you, that's what I wrote: "Not capable of doing any AF *assist* on its own" :)
Nadine Ohara - SF Bay Area/CA , Sep 13, 2010; 04:12 p.m.
You can also set up an external flash to give AF assist but not fire.
Jesper Hansen , Sep 13, 2010; 06:18 p.m.
Great info - basically the 580 could help me out all through the event - both with and without flashing.
I also found your description of the no flash at high ISO custom setting. If I understand it correctly, simply switching to a high ISO would mean that flash would be disabled, but I would still benefit from the AF assist. Selecting a low ISO again would enable the flash. Seems like a great setting for low light event fotography.
Thanks for all your great advice.
Nadine Ohara - SF Bay Area/CA , Sep 13, 2010; 06:23 p.m.
Jesper--no, high ISO and the flash not firing are not linked in the custom function setting. What I meant above, with high ISO, was that combined with a wide-ish aperture, your flash will have more 'reach', meaning going up to a 25-30 foot ceiling and back would be easier and do-able.
The custom function which prevents the flash not firing is just for when you may want the focus assist for dark/dim conditions, but not the flash. You can set this either with the flash custom function, on the flash itself, or through the flash control menus in the camera. The flash firing or not is not linked to high or low ISO.
