G9 vs 400D Exposure Differences

EMA747

EMA747

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Andy
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I have been shooting with my 400D and Canon 17-40 L for a long time now and love them both. I have bought a second hand G9 as a compact camera to take quick street photo sort of shots. I have been seeing some differences in the exposure settings for both cameras.

If I take two identical pictures of a particular scene with both the 400D/17-40 and the G9 I get different settings. For example I took something today and the 400D gave f8.0 and 1/400 while the G9 gave f8.0 and 1/200 to give a correct exposure. The save difference is also there for apertures, eg one give f8.0 and the other f6.0 (I think).

Why does this happen? Is it something to do with the physical differences to the lenses and the way they use the light?

Andy S
 
It's more to do with the way the two cameras meter the light. It's actually only a 1 stop difference which isn't unusual when comparing two cameras. Did the 2 images look identical or was there an obvious 1 stop difference in levels?
 
The ISO was the same in both. So was the metering mode.

The two images looked very similar but maybe not identical in levels. Not a big difference though.
 
I get similar, just tried it, with my 40D and two different lenses - both read 1/50sec at f/5 ISO400.

Canon G7 and Pano FX500 both say 1/30sec at the same. LCD images look the same in all cases, and histograms are virtually identical.

I suspect the lens apertures are maybe not exactly as stated in the readout, but more especially I've always been a bit suspicious that compact ISO is not quite the same as real ISO.

I think the error is too much for it to be some kind of mistake - that's about 3/4 of a stop shortfall on both my compacts.

I guess that with in-camera TTL metering we very rarely get to compare readings like we used to in the bad old days of film and hand held meters and manufacturers are maybe taking liberties. There are accepted standards and tolerances, and for example it's well known that very few zoom lenses are actually either as wide or as long as claimed - 5% shortfall is common and even more in unusual cases, but that kind of thing is rarely tested in reviews.

On the exposure front, the only time you would call it into question nowadays is if you were transferring flash meter readings to the camera, but who uses a compact to shoot studio flash? Out of curiosity I might just give that a go, but I kind of know the answer already and I guess I'm more disappointed than surprised :shrug:
 
Different cameras have different personalities in the way they meter. I find my G9 is usually spot on and my 450d over-exposes a little, mainly in high-contrast scenes. My 40d is similar to the 450d but the highlights aren't as blown out in high-contrast shots.

You just need to learn how the camera meters and then compensate to get the look you want.

George.
 
BadgerLover said:
Different cameras have different personalities in the way they meter. I find my G9 is usually spot on and my 450d over-exposes a little, mainly in high-contrast scenes. My 40d is similar to the 450d but the highlights aren't as blown out in high-contrast shots.

You just need to learn how the camera meters and then compensate to get the look you want.

George.
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Sure, that's the workaround.

But I think the point being made here is that the compact cameras need more exposure to produce an identical histogram and image. Whatever the reason, that is the outcome.

We make enough fuss arguing between the merits of f/4 and f/2.8 lenses, so I think we have every right to be a bit miffed at this revelation.
 
Most cameras don't actually deliver the ISO they claim and so there will always be changed in aperture/shutter to meet the actual ISO offered by the sensor. DxO Mark has "claimed" vs. "actual" ISO and there can easily be 1/2 stop difference, particularly at higher levels.
 
None of my cameras seem to give identical readings.

You should really be able to fine tune exposure to some permanent global setting in the menus where it will remain untouched - would be pretty easy to provide that function I'd think.
 
LOL .I've only skimmed the manual Paul - I'll have a look - that would be pretty cool if it has.

You bought a 50D then Kemo Sabe?
 
HoppyUK said:
Sure, that's the workaround.

But I think the point being made here is that the compact cameras need more exposure to produce an identical histogram and image. Whatever the reason, that is the outcome.

We make enough fuss arguing between the merits of f/4 and f/2.8 lenses, so I think we have every right to be a bit miffed at this revelation.
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I am so used to the controls on my 400D and know how to use them to get the required depth of field I am after. It's a pitty that I cannot do the same on the G9 though. Having to drop the f number down a couple of stops is sometimes not good and gives a depth of field that is a bit marginal for what I am after. The same shots on the 400D would have been fine.

I have only had the camera a few days though so maybe it's just that I have to get used to it. I was expecting something a little worse than the 400D in image quality but not in terms of it's shutter and aperture controls. :thinking:
 
EMA747 said:
I am so used to the controls on my 400D and know how to use them to get the required depth of field I am after. It's a pitty that I cannot do the same on the G9 though. Having to drop the f number down a couple of stops is sometimes not good and gives a depth of field that is a bit marginal for what I am after. The same shots on the 400D would have been fine.
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Depth of field with compacts is massive, due to the tiny sensor. Over four stops deeper, ie f/4 gives similar DoF to f/16 on a crop camera, more like f/20 in fact. It's very hard to get anything out of focus except with max zoom at close distance.

Check it out on here www.dofmaster.com
 
OK I just tested this out and it turns out my F5 spot meter is again 1 stop lower than the 1d mark II spot meter? Both were done at F2.8 with ISO 400 off a 18% gray card.

I've tried different lenses and the readings are exactly a stop out.

sid
 
sidxms said:
OK I just tested this out and it turns out my F5 spot meter is again 1 stop lower than the 1d mark II spot meter? Both were done at F2.8 with ISO 400 off a 18% gray card.

I've tried different lenses and the readings are exactly a stop out.

sid
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Hmm.....if you've tested both cameras by spot metering on a grey card youi've eliminated differences in metering patterns, so a whole stop is quite a lot, but then again not unheard of.

You really need to establish which is the more accurate exposure then adjust the ISO on the other camera to compensate - that's the time honoured way of doing it.

You could buy a hand held meter and then calibrate the cameras to your meter, but you can run round in ever decreasing circles with this stuff as there's no real guarantee that the meter is calibrated properly although it should be. So - what you end up doing is checking that meter against another... you see where we're going with this? :D
 
CT said:
Hmm.....if you've tested both cameras by spot metering on a grey card youi've eliminated differences in metering patterns, so a whole stop is quite a lot, but then again not unheard of.

You really need to establish which is the more accurate exposure then adjust the ISO on the other camera to compensate - that's the time honoured way of doing it.

You could buy a hand held meter and then calibrate the cameras to your meter, but you can run round in ever decreasing circles with this stuff as there's no real guarantee that the meter is calibrated properly although it should be. So - what you end up doing is checking that meter against another... you see where we're going with this? :D
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I checked the exposure with a canon 50e and it agreed with the 1D

Since the F5 is film, Its hard to see which one is right due to the latitude of film.

sid
 
sidxms said:
Since the F5 is film, Its hard to see which one is right due to the latitude of film.

sid
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There you go. That's another thing... film isn't digital and vice versa.:shrug:
 
I find it vaguely worrying that my mega expensive 'Tells you the time in Tokyo' meter with 1 degree spot, incident metering and more modes than you can shake a stick at - has a calibration facility. :D
 
sidxms said:
I've never actually tried slide film to see if that 1 stop possibly makes any noticable difference.
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Slide film is a bad example. The thing abouit slide film as you no doubt appreciate - is that when it comes out of the developing tank it's a final product with no adjustment possible, unlike negative film where you can make adjustments at the printing stage, with exposure times, paper grades etc etc.

Slide film was designed to be viewed back lit or projected, so that final product needs to be bang on exposure wise. Best practice was usually regarded as under-exposing by about half a stop to avoid over-exposure and enhance colour saturation. It's definitely less forgiving than negative film of exposure errors.

Having said that -look how things have changed now -if you scan that slide it now becomes a digital image and can be manipulated and adjusted like any other so it's probably not the issue it was unless you really do intend to project it.
 
CT said:
Slide film is a bad example. The thing abouit slide film as you no doubt appreciate - is that when it comes out of the developing tank it's a final product with no adjustment possible, unlike negative film where you can make adjustments at the printing stage, with exposure times, paper grades etc etc.

Slide film was designed to be viewed back lit or projected, so that final product needs to be bang on exposure wise. Best practice was usually regarded as under-exposing by about half a stop to avoid over-exposure and enhance colour saturation. It's definitely less forgiving than negative film of exposure errors.

Having said that -look how things have changed now -if you scan that slide it now becomes a digital image and can be manipulated and adjusted like any other so it's probably not the issue it was unless you really do intend to project it.
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Well do you think that the meter is faulty then? Does it matter?
 
sidxms said:
Well do you think that the meter is faulty then? Does it matter?
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LOL. Truthfully I could go nuts trying to calibrate all my cameras to one setting, half a stop difference is common, and as you said earlier, the exposure latitude of film is far greater than digital.

When it comes to digital, I've recovered from some monumental cock-ups in RAW processing. ;)

Photography isn't an exact science and never has been - see what the camera actually produces, that's the best test of whether it really matters. You can certainly spend way too much time worrying about it.
 
CT said:
LOL. Truthfully I could go nuts trying to calibrate all my cameras to one setting, half a stop difference is common, and as you said earlier, the exposure latitude of film is far greater than digital.

When it comes to digital, I've recovered from some monumental cock-ups in RAW processing. ;)

Photography isn't an exact science and never has been - see what the camera actually produces, that's the best test of whether it really matters. You can certainly spend way too much time worrying about it.
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Well as I said before, I only tried this because of the OP.

I've never had noticed this before. Infact I was checking if my OM1 had a meter problem and it appears that the F5 is actually off a bit.

Clearly print film (all that I have used so far) hasn't made me notice it but I'm tempted to try some slide film to see if it does matter.

sid
 
sidxms said:
Well as I said before, I only tried this because of the OP.

I've never had noticed this before. Infact I was checking if my OM1 had a meter problem and it appears that the F5 is actually off a bit.

Clearly print film (all that I have used so far) hasn't made me notice it but I'm tempted to try some slide film to see if it does matter.
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Slide film is very critical. More so than digital I would say. You need to get it within half a stop ideally and err on the side of underexposure.

With colour neg pretty much anything goes - when in doubt just over exposure it and the DIR couplers in the emulsion stop the highlights from blocking up very effectively. That is the reason why disposable cameras work with virtually no exposure control at all - they just over exposure everything and it still looks okay.
 
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