5D and Flash built in underexposure?

[ben_rubinstein___mancheste]

Has anyone noticed if the 5D underexposes the flash by 2/3 of a stop

like many believe the 20D does? I tried the 5D out in the store today

in a flash shootout between it and the D2X (in leu of the D200 which

doesn't exist yet) and it seemed to be underexposing by a

consistent .75-.9 of a stop with both full and fill flash, straight

and bounced.

 

The D2X was worse in full flash but I've no idea how to use it so I

can't draw any conclusions. The resolution is give or take the same

with the D2X having more of a film look to the resolution and

sharpness. Dare I say that the 5D was (slightly) better with noise at

iso 400?

[PuppyDigs]

"Has anyone noticed if the 5D underexposes the flash by 2/3 of a stop like many

believe the 20D does?"

 

Opinions seem to be all over the place so I suspect much of the exposure problems

are due to differing tastes and/or techniques.

[chris_floden]

You might Google "K" factor in regard to the underexposure. Nearly all digital camera manufacturers calibrate "level" at a point that is actually .85 (or 15% under 18% gray). The "K" factor has been present for a number of years, but as the digital quality increases, it becomes more apparent.

[ben_rubinstein___mancheste]

It was consistent at least otherwise I wouldn't have bothered running the 'your technique was wrong' gauntlet sometimes seen here. It was worse for white and better for black or course but the standard exposure seemed under by a .75 exposure adjustment in both ACR and DPP. Just wondered if anyone else had seen it. As far as taste goes, you're right of course, some people judge screen exposure which 'looks' brighter than judging exposure from a print, but I usually print so I'm judging by both.<div></div>

[lotsawa]

The image on the right looks a bit overexposed to me.

 

Also, how should the camera judge the brightness of the shirt? If you did AE lock on the face the exposure might have been better.

 

Or may be I got something wrong.

[PuppyDigs]

The left image looks like balanced fill flash (perfect!) whereas the right one looks

slightly overexposed (flash is brighter than ambient). I prefer the natural look of the

left image. The right one looks too much like a flash snapshot.

[steve_dunn2]

<p>FWIW, I've noticed that flash pictures taken with my 20D and 420EX often need either positive FEC or a boost in brightness when converting from RAW. I haven't keep tabs on how much, but the suggestion of 2/3 of a stop seems to be in the right ballpark at least. Not having a 5D, I can't say how it handles this.</p>

[gluteal cleft]

I once had a 300D which, when used with an external flash, would underexpose all images by about 2 stops. I tried it with various flashes that were all known to work on other 300D bodies. I sent it back for a refund, waited a couple of months until the 350D was out, and ordered one of those.

 

The moral of the story is that there can be body-to-body defects with flash.

 

steve

[ben_rubinstein___mancheste]

Puppy, it's exactly the same image just processed with a plus exposure, how could it have a different fill balance?

[rodney_gold1]

All digital cameras will err on the side of underexposure with flash as blown highlights cant be recovered. If you use the flash correctly , your shots will be spot on , however the Canon flash system is pretty much complex and is not a set and forget type thing.

It uses a centre weighted metering system for flash that can be confused by light or dark stuff , much the same as the metering system , IE shoot a white cat and you will get underexposure as it tries to make it grey.

Apart from that , in certain modes NEVEC is applied

http://eosdoc.com/manuals/flash/NEVEC/

Your best strategy to using flash oin the 5d is this

1) Use manual mode to control the ratio of ambient to flsh and to have control of shutter speed and DOF. The closer your metering is to ambient the more natural the pic.

2) Set the flash CF from evaluative to averaging , this will average the centre weighted metering and generally produce a brighter pic.

3)Fill the frame with the subject

4)Understand that focus and recompose will no longer have the subject where it was before and whatever is in centre frame will be metered for , thus the * button is used when the camera is pointed at the subject or a neutral coloured item to lock flash exposure to what you want exposed for.

5) Dial in FEC if you feel things are too dark

If you use this strategy , you are almost guaranteed to get a very high percentage of properly exposed flash shots.

Of course , Canon could have included a sort of thyristor circuit (auto mode) on its flashes for mere pennies and given its shooters the best of both worlds.

If you use flash for more than just the occasional group shot etc , like for macro or multiflash wireless or fills etc , then the value of the Ettl II system is huge and makes for really effortless shots.

It really is an excellent system on the 5d.

[ben_rubinstein___mancheste]

So Rodney, you are saying that the ETTL II system is excellent based on having to have one of the focus points over the face (not easy with the 5D), not focus recompose, be ready to do it again, only take pictures where the subject fills the frame etc. Sounds pretty crap to me. Don't know about you but I actually use my cameras in real live weddings and certainly can't afford this kind of palaver. Not that I don't appreciate your help.

 

NEVEC is a pain in the neck, I shoot almost 100% in manual so it isn't usually a problem though. The above shot was taken at manual settings of 1/125 f5.6, the ambient was 1/100 f2.8 which is why puppy's comment makes even less sense, the only way for their to have been a proper fill lighting would be if the flash was underexposed heavily and the whole thing brought back up in the raw convertor.

 

I've used auto flash for a while on both the 10D and 1Ds, far better than ETTL I. I'm playing with ETTL II and it seems to get it right the majority of the time when I compensate for black/white, but with a consistent underexposure of 2/3rds that I've mentioned.

[rodney_gold1]

So Rodney, you are saying that the ETTL II system is excellent based on having to have one of the focus points over the face (not easy with the 5D), not focus recompose, be ready to do it again, only take pictures where the subject fills the frame etc. Sounds pretty crap to me. Don't know about you but I actually use my cameras in real live weddings and certainly can't afford this kind of palaver. Not that I don't appreciate your help.

 

Ettl II doesnt require the focal point to be over the subject , it meters centre weighted. I actually wouldnt use this system for group shots at weddings and the like , its way too complex , I actually use a Nikon Sb25 with an auto feature on the flash which fires fine on my Canon for this type of shot , in fact it has a front flash as well as the main flash so on bounce its better.

I get blown highlights occasionally , it's somewhat of a sledgehammer approach but its very consistent and a set and forget. If you had the time at an event or wedding you would get better pics with an ETTL II flash , but there is no time to futz around. Something like a metz or the like would be better.

 

I've used auto flash for a while on both the 10D and 1Ds, far better than ETTL I. I'm playing with ETTL II and it seems to get it right the majority of the time when I compensate for black/white, but with a consistent underexposure of 2/3rds that I've mentioned.

 

Just wack it up in FEC , a lot of ppl do that.