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Occasional Contributor
Posts: 23
Registered: ‎12-18-2018

5D Mark IV Auto ISO issues

[ Edited ]

Hello - I often shoot with friends who have Nikon and Canon cameras - at times we check each other for what their settings are.     For some reason my ISO is always running higher than theirs when the shutter speed and aperture is the same.     I know there's a lot of variables so this morning I got out my 7D (original), 5D Mark III and 5D Mark IV.

The lighting was the same - I mounted the Canon 70-200 f2.8 III lens on each camera, set at 200mm.    Each camera had the shutter speed at 1000 and the aperture at 5.6 - all set to M for Manual, same metering, etc.

The AUTO ISO reading was different on all three.     I expected the Mark IV to have the lowest ISO but it didn't.

7D read 500 ISO

MIII read 400 ISO

MIV read 640 ISO

What would make the MIV result in a higher ISO

I bought the MIV to have less noise/grain and that is not happening.

I hope I provided enough information.

Thank you

A friend told me to set the aperture and ISO and see what the shutter is so I set aperture at f5.6, ISO at 400.     Shutter resulted in:

7D 1250

MIII 1600

MIV 1250

I then put it in CA+ mode for kicks:

7D  640 f4 100

MIII 500 f5 100

MIV 500 5 100



Respected Contributor
Posts: 1,394
Registered: ‎01-25-2018

Re: 5D Mark IV Auto ISO issues

[ Edited ]

The real question is which camera is providing the absolute perfect exposure but I suspect they are all fine.  Your Mark III is setting the ISO 1/3 stop below the 7 and the Mark IV is 1/3 stop above the model 7 so there really is very little variance.  If all three cameras had absolutely perfect metering all would set the same ISO regardless of how each performs with respect to sensor noise level.


You shouldn't see any significant noise difference in the Mark IV between 400 and 640 ISO.  Better ISO noise performance comes at exposure primarily through the level of sensor technology with newer technology continually providing better performance, larger individual receptors, and the performance of the low noise amp used with the sensor.  Software makes a huge difference post process in whether the noise is a problem.  The Mark IV doesn't have to shoot at the lowest ISO to offer better noise performance than older cameras and as long as the overall exposure is correct for the combination of F stop, exposure time, and ISO then it is doing what it should.


I would hope that the Mark IV is providing good noise performance but there will always be noise in digital if you sharpen and crop heavily enough but modern high end digital provides very usable output at previously unheard of ISO.  I am very happy to have shot the last indoor soccer game of the season last week and I am looking forward to the outdoor games coming up because I can drop from ISO 10,000 down to the ISO 100 to 400 range while still slightly increasing shutter speed.  The players love the indoor shots and I do also until I compare them to what I get outdoors under better lighting.  Probably the greatest difference is the extent of cropping that is possible when shooting in good light.  Outdoors at ISO 200 a part of the image that covers 10% of the sensor can be cropped to a very nicely detailed image while at ISO 10,000 even a 60% crop looks pretty ugly by comparison to me. 


I shoot soccer primarily with a Canon EF 300 2.8 and in soccer with fast movement around the field that means rarely will the action perfectly fill the sensor so cropping is usually necessary.  I use a 70-200 F2.8 on the backup 1DX body which allows some control over what fills the sensor but even though the 70-200 2.8 is a great lens it can't hang with the 300 in focus speed and sharpness so I rely more on cropping and my placement instead of "zoom".



EOS 1DX M3, 1DX M2, 1DX, 5DS R, 1D M2, EOS 650 (film), many lenses, XF400 video
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