Flash and DOF

KiwiLight

Hey there! Just wondering if someone could help me out with my flash issue.

I shoot with a Canon 5D MII and 580 EX II. I have recently been trying to do a bit of event photography largely indoors involving a lot of group shots. Being a bit of a flash novice, I turn my camera to P adjust the WB and then focus my efforts on making people smile and look natural. I use a stofen difuser and bouce off ceilings where possible. Flash is on ETTL.

However, on P the camera seems to always default to 1/60 F4. The problem is that I find that the DOF at F4 is way to shallow when shooting rows of people. The back row will be out of focus....grrr. To overcome this I switched to AV and dialed in F8.... oh crap, now the shutter speed is 1/15 and I am making blury phots due to camera shake and moving targets. Shooting on a tripod is out of the question so I increase ISO to 1600 which then lets me shoot above 1/60 at F8... yay! Then its time to retouch and low and behold I now have to give noise ninja a workout.

Apologies for the long winded intro, but I guess my question is whether there is anyway to stay at ISO 100 and have a bit of DOF while shooting above 1/60. Is the ticket to increase the flash exposure compensation and decrease the auto exposure compensation?? I guess you could shoot in manual but I find that things are moving a bit fast to have to dial in exposure for every shot.

Any help appreciated.

Rich

jeffreaux2

Have you tried manually setting the aperture and shutter speed you want with maybe ISO 800?

Without flash this might be grossly underexposed, but with the flash set to ETTL it should make up the difference for a proper exposue....at zero FEC. You dont need to change settings for every shot in manual. If the settings would underexpose the image(even slighty) without flash...then switching the flash on and letting ETTL set the exposures will keep you from adjusting things.

What focal length are you shooting at?

KiwiLight

Excellent Point!
Your absolutely right.... ETTL should get me to a correct exposure if I shoot in manual. Thanks... I shall give it a go at my next event.

I typically shoot indoors with my workhorse 24-105mm f/4 IS L. Focal length is usually around the 'normal' range i.e. 40-60mm. I sometimes also shoot with my wide angle 17-40mm f/4 L.

Any other suggestions?

pathfinder

Shoot manual mode on the camera, ETTL ( or ETTL II ) on the flash, f5.6, 1/160th or faster, and adjust your ISO to get the lighting you need. You will find this much more more useful than shooting in P mode. Like Jeff said, do not avoid ISO 400 or 800, or even 1600 if they are not under exposed, they will be fine.

If you do this out of doors, be aware, you MAY need to adjust your flash to High Speed Synch. If you shots are over exposed, because you need a shutter speed higher than 1/250th out of doors, you need to turn on high speed synch.

I leave 2nd curtain flash turned on all the time as well.

KiwiLight

Very helpful
Yes, I think manual is going to be the ticket. I shall give it a whirl.

Is it just me or does it seem a bit strange to have to put your camera into manual to get a decent picture when using Canon's flagship flash and most recent dSLR. Maybe I am just used to dealing with less variables when shooting outdoors, but I would have thought at least one of the semi auto modes would be sufficient to give a decent DOF and allow you to hand hold at low ISO? I certainly can't complain about anything else with the EOS system.

I had to shoot in manual while at art school and hated it! Once I could shoot in the semi auto modes it was like being liberated. It kind of reminded me of when I made the transition from pencil to pen in grade school. I only use manual for maybe 10% of the pictures I take usually when dealing with zone control issues. The rest is AV and TV to a lesser extent. Anyhow, I digress!

Thanks for all your help!

pathfinder

As one of those of us who learned auto flash 30 years ago, I was really confused to find that shooting the camera in Manual Mode, and letting the flash automagically set the exposure, was very counter intuitive, which I think is what you are saying.

Canon does a very poor job of explaining why their flash system is set up the way it is. Once you grok the underlying philosophy, things make much more sense.

P mode assumes you are shooting snapshots of people, and programs for shallow DOF, and adequate shutter speeds to handhold. That is all it is for. I never use it.

Av mode - assumes you may be using a tripod, and sets the shutter speed according to the ISO and aperture to expose the background properly with ambient light. The flash will correctly expose the for ground subject, but you may find yourself with a 3 second shutter speed, unless it is fairly light out. Works very nice for balancing ambient and flash, if you know and understand it.

With Manual mode, you get the best of both worlds. You can choose the ambient exposure for the background, and make it lighter or darker by your choice of shutter speeds, and expose the subjects properly with flash. You can even drive the background to black when shooting with High Speed Synch with macro lenses in bright sunshine.

I have a sticky link at the top of this forum with a number of links about the EOS system flashes


I specifically recommend you read this one which is the most informative about the EOS flash system and how it is designed - http://photonotes.org/articles/eos-flash/index2.html

That is part 2 of a three part essay, all of which is quite helpful to learning the ins and outs of the Cann EOS flash system, which I think works quite well once it is understood.

KiwiLight

Great advice!!
Thanks Pathfinder, I will look into those resources to gain a better understanding of the flash system. I am sure that it all makes sense.

Take care and thanks for your help. I am sure I will be taking better flash photos from now on!

gvf

I have an older but top-end 35mm film camera, Minolta 700si.

It has a function called "Slow-Shutter-Synch". This allows the flash to operate but the setting remain for what the exposure would be without the flash.

So, at night, say with light from the moon and streetlights illuminating the whole scene somewhat, and a person in the foreground you want lit well, the flash would go off at setting of say, 1/2 second at f8 or whatever you wanted it to be from a light reading of the natural light. So, you get the foreground figure well lit from the flash, and the background lit in natural light. maybe your camera has that capability? Check the manual.

pathfinder

This is precisely what the EOS system with the flash in ETTl and the camera in Av mode does.

ziggy53

Pathfinder has a great elaboration on the Canon EOS flash system here:

http://dgrin.com/showthread.php?t=70330