Different cameras - different light readings?

I was helping out on photoshoots for a brochure yesterday.  The first was an apartment.  I took a shot looking towards the window to get an idea of what shutter speed I would need to use to get the exposure right with an aperture of f8 and Bowens units.  The other photographer asked me for my settings as a guide - shutter speed, aperture and ISO, in manual mode - were given and she took a shot.  Her shot came out about 2 stops overexposed.
We checked the histograms and they confirmed it.

We were up against the clock so couldn't delay to figure it out and so made our necessary adjustments but it's been bothering me since.

There is a possibility that she wasn't using manual mode but I don't think so.  I've heard of differences in exposure results between different makers but are there different results between cameras from the same maker or am I completely off my trolley?   

There can be variations of exposure between lenses from the same manufacturer about 2/3 of a stop I have heard of.

2 stops seems excessive even between manufactured IMO

Was one a Nikon body and was the ISO 100? 

B

Thanks Brendan,
Hers was a Canon EOS 30D, mine a 5D MkII.
We were both using wide angle lenses - mine was an 11-18mm.  Not sure what hers was.
Paul T.

I would suggest she had a different ISO setting than yours.  This is 99% likely to have been the problem.

Hi Ross,
Unlikely as she asked me for the three settings.  On top of that she didn't want to go higher as she would get a lot more noise than I would.

I guess at this stage I should see if she still has the RAW files and check.

Paul T.

There are differences between cameras, between manufacturers and indeed bewyeen lenses. Some hand held meters allow you download specific camera profiles to them to allow you "calibrate" your meter to your specific camera. But two stops in the difference definitely suggests user error to me.

Suggest you check the EXIF on both photos to confirm.

That will eliminate (or confirm !) the possibility of user-error.

I wouldn't trust the ISO setting unless I saw it for myself Paul!   Brendan and I were at an event at Calumet recently, and 2 Nikon users 'thought' they were at ISO 100 when in fact they were 2/3rds of a stop away from it.   Something to do with L1, L2 and L3 in stupid Nikon cameras, rather then just telling you the ISO number...

If possible get her to check the EXIF info in the photograph and confirm the ISO, and aperture.   Those are the only 2 variables which would have affected a flash exposure.

There is also the possibility that the flash fired for you, but did not fire for her?   Maybe you had a connection to the flash and she didnt, therefore she only registered ambient light.

Thanks guys again!  Ross, we hadn't fired the flash units at this stage.  This was simply getting the exposure right for the windows and
then adding the flash later for the room.

I expect it's something stupid that I/she missed and we didn't have time to investigate - it was all very hectic!

Thanks for all your replies.  I'm trying to get her data from her.  Once I get something I'll post it here.

Paul T.

Lot's of useful information provided above, but one thing I haven't seen mentioned yet in relation to the lenses is the lenses maximum aperture. If both of you were using zoom lenses and both of the zoom lenses had variable maximum apertures, this may have been a factor in the exposure difference, particularly if setting the exposure manually. But without more details, I'm only guessing.

Well .................
I got the file from the 'lady' and I've put it with my photo and the result is below:



The EXIF data is identical with respect to shutter speed 1/50s, aperture f8 and ISO 1000.
I think I would concede that the difference may not be as severe as I originally thought but it still seems a lot to me.

Paul T.

Quite a considerable difference indeed, but as you point out now, certainly not 2 stops. I'm afraid the images, even with embedded EXIF don't tell the whole story as there are still many factors which can effect exposure.

JPG conversion - if you're shooting JPG, your camera will typically apply a curves adjustment and indeed can also change exposure, which can lead to a discrepancy. Similarly when converting, your WB choice can also effect exposure, even as much as a stop depending on the choice and the colours in the scene.

As Thorsten pointed out, the lens can also play it's part (I mentioned this at the tutorial acutally!).

If you had the two RAW files, I'd certainly be interested in having a look to satisfy my own curiosity?

Hi Ciaran,
I'll put the two raw files on my website and give you access.  My ISP only appears to want to allow me send e-mails - a restriction on the attachment sizes that I can't get them to tell me.

Thanks,
Paul T.

Another factor may be what parameters the 5DII was set to.  It has highlight priority, and if that was on, it would have ensured that highlights were not over-exposed.   With ISO1000, that may be a factor.

Ross

I'm not familiar enough with the 5D MkII to comment on this, so I'll ask a question instead. Does highlight priority also affect manual exposure images? From what little I know, I presume it does as it's something that alters the raw image data by the Digic processors before the file is finally written to the memory card.