30D and 580ex ETTL strong flash output problem?

[nohnst]

Someone please help me understand if this is normal with direct flash, or could it just possibly be user error, or bad copy? My intention is to take pictures at manual setting, 1600 iso, 2.0 av, 30-40 shutter speed, with direct flash using a 580ex with no bounce flash. This is the type of setting I would normally use when I take pictures in low light enviroment, high ceilings, such as clubs and parties.

I just recently bought a 30D and I do not recall having a problem of strong flash output at high ISO settings when I use to have my 20D. My goal is to balance the ambient light with fill light.. and have a good enough shutter speed to prevent blurriness.

The pictures below are taken on a tripod, in a dimly lit room, approximately 3 feet from subject.

Picture 1 - ISO 1600, 2.0 aperture, 30 shutter speed, normal exposure, NO FLASH





Picture 2 - ISO 1600, 2.0 aperture, 30 shutter speed, normal exposure, WITH DIRECT FLASH





Picture 3 - ISO 100, 2.0 aperture, 30 shutter speed, underexposure, WITH DIRECT FLASH







Picture 1 has nice ambient background light.

Picture 2 is blown out with direct flash, using ETTL, and no FEC.

Picture 3 has good flash exposure on subject but background loses ambient light. In order for me to prevent the blow out in Picture 2, I have to decrease the ISO to 100, so I can get proper flash exposure. I even adjusted the FEC down to -3 and still get almost the same result. I thought ETTL was suppose to calculate the exposure and determine the proper flash output? And I don't think it's a speedlight problem because I have two 580ex's and they both have the same result. Anyone here ever get this problem?

[Moppie]

What was your range to the subject?
I shot the cat yesterday at ISO 1600 by mistake, at a range of about 2 feet, the flash simply couldn't run at low enough power to properly expose the cat.
I got a very similar effect to your No. 2 photo.
Shooting at ISO 100 solved the problem.
(this was a 550ex on a 30D).

[michael_]

if i am wrong please correct me (newbie flash user still) but dont you need to be above 1/250 in order to get a good exposure with the 580 as thats the flash sync speed?

[lostdoggy]

Originally Posted by CIDER

if i am wrong please correct me (newbie flash user still) but dont you need to be above 1/250 in order to get a good exposure with the 580 as thats the flash sync speed?

I beleve normal sync should be 1/250 or less High speed sync is another story

[lostdoggy]

30 sec seems to be a long exposure.

[Lotto]

I am with Moppie, minimum power could not be adjusted lower. Pull down the 14mm diffuser should get you by.

But why iso 1600 f2.0? Any 10W light bulb shows up in the picture would be completly blown out in that setting.

[Gatorboy]

Your first shot without flash is already exposed correctly, so of course your second shot with flash (adding more light) and keeping the same settings is going to produce a blown-out image.

[scottbergerphoto]

At ISO 1600, you have effectively increased the Guide Number of the Flash to 232 Meters. At f/2 that has a max distance of 116 Meters. At 3ft away, there is just no way the flash can shut down fast enough. You need to back off on your ISO or move farther away. What is the 580EX telling you on the back LCD what your mininmum distance is?

[Curtis N]

Originally Posted by scottbergerphoto

What is the 580EX telling you on the back LCD what your mininmum distance is?

Scott makes a great point.

The distance scale on modern flash units is an often overlooked tool. Learn to use it and your success rate will improve dramatically.

[Moppie]

Originally Posted by Curtis N

The distance scale on modern flash units is an often overlooked tool. Learn to use it and your success rate will improve dramatically.

I have to make a note to myself to check the back LCD for the Histogram, the top LCD for shooting settings EC, FEC, etc (as well as the viewfinder) and the flash LCD for distance guide, shooting mode, FEC etc


Im starting to realise why the 400D and the Sony Alpha have gone to one LCD.

[scottbergerphoto]

Whenever you use flash, you need to keep in mind that for each f stop/ISO combination there is a minimum as well as maximum distance for the flash. The flash Guide Number is for F/1 at ISO 100. As the ISO increases the minimum/maximum distance does as well.
ISO 100 to 200 = X1.4
ISO 100 to 400 = X2
ISO 100 to 800 = X2.8
ISO 100 to 1600 =X4

[Lunatique]

Hi, I was pointed to this thread by someone at the FM forums. I have the EXACT same problem--you can read about it here:
http://www.fredmiranda.com/forum/topic/475090

Here's another guy with the same problem:
http://photography-on-the.net/forum/...d.php?t=236512

Now we know we're not alone--what do we do? Contact Canon and get an explanation?

[Moppie]

Originally Posted by Lunatique

Now we know we're not alone--what do we do? Contact Canon and get an explanation?

How about stand further away and shoot at a lower ISO?

[Titus213]

Originally Posted by Lunatique

...Now we know we're not alone--what do we do? Contact Canon and get an explanation?

Put a cardboard milk carton over the flash?

I think you just got your explanation from Scott. You can back up, reduce the ISO, increase the f-stop. Or any combination of those items to suit your picture desires.

[René Damkot]

I've only had this kind of behaviour in three situations:
1- With direct flash, when being too close to the subject. (I guess that is the case here, and on the FM thread)
2- With bounced flash, when the preflash was too weak to be measured, so the flash gave full output instead of the 1/8 or so needed.
(You can test this by using FEL: If the display blinks instead of giving a flash reading, the preflash could not be metered)
3- Flash not properly on the camera. (Guess that is the case in the other thread on POTN)

Oh, and Lunatique: The red light indicates 'Fully Charged', while a green light indicates 'Ready for a Quick Flash' (max. 1/6 to 1/2 of full output) (Page 10 in the manual)