EOS 5D mkII v 20D, ISO ratings

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roisindubh

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Carl
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Hello to everyone,
have just upgraded from a 20D to the new 5D mkll and have been enjoying the benefits of what seems to be a fine camera. However one thing I have noticed in comparison to my 20D is that the 5D is approx 1 and 1/3 stops slower (darker) when shooting the same ISO100 and at f22 using the same lens. Is this because it has a larger sensor/wider ISO range etc etc? To me ISO100 is exactly that and I see no reason why it should differ from my other camera. Have I bought a faulty model or is it as i said due to the sensor?
I would be extremely grateful for any help/advice.
Best regards, Carlos : )
 
Hi welcome to TP sorry can't help with your question.
 
how are you comparing the 'proper' exposures, it could be the lcd on the back or the way the meter is calibrated?

and are you sure 1+1/3 as thats the diff between iso 100 and iso 250, do you mean a third of a stop as thats more of a calibration error

also might be best to ask in the equipment forum ;)
 
Welcome but maybe have a look around the site you may get an answer :)
 
welcome hope you sort your problem out on the forum :wave:
 
david1701 said:
how are you comparing the 'proper' exposures, it could be the lcd on the back or the way the meter is calibrated?

and are you sure 1+1/3 as thats the diff between iso 100 and iso 250, do you mean a third of a stop as thats more of a calibration error

also might be best to ask in the equipment forum ;)
Click to expand...

Hiya - thanx to everyone for replying - much appreciated. I think I need to be a bit clearer in what I say. I'm referring to the exposure meter on the viewfinder where it has stops of up to +2 and minus -2. In addition the EOS 5D has incremental stops of 1/3 between each full stop (hence my query of 1 and 1/3) (I seem to remember this is how our photographers would order their film from the processing labs in the good old days). Sooooo, when my 20D is set to ISO 100 and the 5D also at ISO 100, how come the 20D exposure compensation reading is at zero, while my 5D is at -1 and 1/3 focusing on exactly the same object with the same lens in the same conditions?
Is this any clearer? I think I need to brush up on my communication skills in future.

Anyway - thanx again for taking the time to reply.

Carlos from Manchester
 
a fairly massive difference, were they both set to the same metering mode? having one on spot and the other on evaluative would explain the difference if the exposures on foreground and background were different
 
What metering mode are you using. Remember the 5D mkII is full frame - so if you are using centre weighted average, or average metering modes - the 5D will be looking at more of the scene even when using the same lens.

Also make sure you dont have the "highlight tone priority" mode turned on, on the 5D (should be obvious as the iso figure will display something like D+100), not sure whether it will replicate what you have observed - but it is a possibility.
 
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Carl, I upgraded from a 20D to the 5DII at Christmas and I think I may be able to answer your question.

I battled with exposure problems on the 5DII for quite a while.
For example, brown seaweed on black granite is likely to result in half the screen flashing with the clipping indicator - including the center of the screen. It took 1.5 to 2 stops correction to fix this.
I never really was able to predict when this massive over exposure would happen. So I learnt to chimp like crazy and compensate as required.

Asking around it seems that my 40D photo-buddies complain about exactly the same thing. I'd heard them complain in the past but had always dismissed it as finger trouble. It looks like I'm now eating humble pie.
It seems that post-20D Canon changed the way the metering works. I don't find it as predictable as the 20D.

You may have noticed I've been using the past tense....
I realised both cameras were in matrix metering mode.
What I wanted was predictability - so I can expect the exposure to be spot on without having to chimp.
I flicked the 5DII over to center weighted metering.
It's not a perfect metering mode, but it's flaws are easily understood and it is 100% predictable.
Since I've made the change I've never missed my intended exposure by more than one stop and that's my fault, not the cameras......

Hopefully this helps.
Duncan
 
Carl, something else I fell obliged to comment on is that the 5DII is going to be a bit of a shock.
Initially I was very disappointed with the 5DII as I was expecting much better quality images. I was hoping for a quantum leap but all I got was a lot more pixels.

After a long hard look the problem turned out to be my technique.
In the eight months I've had the 5DII I've learnt a heck of a lot and I'm now beginning to reap the benefit of the 5DII's phenomenal image quality.
It's magical to see a 70x100 exhibition print that you can walk right up to and there is so much detail that even when you get to 6 inches away you still feel there is more detail there.
I call it an immersive experience and it's truly wonderful.
Only my most recent images produce prints of this quality.

I'm making this comment largely because you said in your OP about using f22.
On the 20D at f22 diffraction softens the image so much that it's only just tolerable at A3.
Last Autumn I spent a day creating abstracts using tripod mounted 20D set to f22 for maximum depth of field and left it there all day.
Looking back at those images I blew it big time. Diffraction caused all of them to be slightly soft even where I didn't need extreme depth of field.
They are fine at A4 but the 20D is capable of doing much better than that.
f22 is better on the 5DII but you still don't get the best image quality - here's a really good article on the subject.

The trouble is that to get the quality needed for immersive prints you start finding all sorts of problems that you can spot affecting image quality.
I discovered my 24-105 was a soft copy and after producing hard evidence sent it back to Canon; it's now a superb lens.
I've spotted motion blur caused by the 24-105 IS settling when on a tripod; they recommend turning IS off for a good reason....
If it's windy my tripod shakes enough to affect image quality. I've tested a Manfrotto geared head which is much superior and I need to upgrade my tripod.
I had very bad mirror shake with the 24-105 on the same dodgy tripod with a cable release; so bad I had to discard a whole set of images. I now routinely use either mirror lockup or live view without waiting to spot the problem first.

After a bit of navel gazing I've found the 5DII capable of producing utterly mind-blowing prints. Just don't expect them from day one!!!!!
Duncan
 
Greetings. Thanx again for all the replies. Problem solved by the looks of things.
Firstly I goofed, it wasnt 1 and 1/3 stops, it was more like 1/3-2/3 stops. Still a difference but not as significant. Secondly thanx to DuncanDisorderly who pointed out that his buddies using the 40D had experienced the same problem, and it turns out that after the 20D series Canon had changed the metering system. Thirdly, on a recent visit to Calumet and testing their 5D, my camera was found to be exactly the same, which confirms what Duncan had stated.

Huge sigh of relief. I have a wedding to shoot next week and am now a little more confident in my camera. One point though... what on earth is a 'soft copy' (as mentioned in Duncans post), and how would I know? So far I have been more than pleased with the results of my lens, nice and sharp, and have also used it on a recent 'Drink Awareness' poster campaign where the results were just short of stunning (under studio conditions). However I find the fact that you had in your possession a 'soft copy' rather perturbing as I am asuming it came straight from canon?!?!?!
Mmmm... the plot thickens.


Carlos
 
BRILLIANT - I've just read your article on aperture and light diffraction. Up to now I have been a stout supporter of f22 and getting everything in focus and sharp. Not anymore! I can't wait to experience the results of f11-f16 depending on lens/subject/circumsatnces) and the resultant extra shutter speed I can paly with.

: )
 
Carlos, soft copy... Right, here goes....
On the 20D I found the 24-105 considerably better than the kit lens but not as good as my 70-200 IS f4. Given the reviews all state the 70-200 is sharper than some L-series primes while the 24-105 is compromised in some areas I assumed this was normal.

However, when I stuck the 24-105 on the 5DII the results were completely different. In particular 24mm f4 the edges were extremely out of focus - enough to tell on a 6x4 print never mind pixel peeping. Again, the reviews do say 24mm f4 is prone to vignetting and edge softness so I didn't feel able to challenge Canon.

So I conducted thorough comparisons against two other 24-105 lenses and found they vignetted almost identically to mine but were vastly sharper at the edges. Pixel peeping showed the edges still weren't as sharp as the center of the frame but they were vastly better then my lens.

I talked to Canon who agreed it should be looked at by Elsetree - they were very helpful and efficient - full marks for customer service. My lens is now superb - at 24mm f4 it is sharper than the two I originally compared against. Although it took a lot of effort to gather enough evidence to present to Canon I'm now a very happy bunny. For some bizarre reason my 24-105 no longer vignettes - I wasn't expecting that but I'm not complaining!

Enjoy your 5DII - Duncan
 
I've just realised something important I should have mentioned.
I've been asking around and I've posted about my soft 24-105 on other forums.
Nobody else has reported problems.
Hopefully it's a one off - there is no indication of a general problem.
 
Nice one - as I said I'm pleased with my 24/105 but its good to check it out with whats out there. Shows we're not just putting up with what we're given by the manufacturers. It is a consumer society after all - lets be alert. Britain needs 'lerts' : )
Anyway, your replies have been very useful and its good banding round ideas with people such as y'self, i'd like to keep in touch an maybe share some shots/ideasetc etc.
Go'in away to do th weddin shoot Friday. Be back in a week or so to shoot 'a finger' - yep work, but someones gotta do it. No, its good, get's me pics around the nation so to speak.
Look 4wd to hearin from you.
Best regards, Carlos (thjackall)
 
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