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ISO / Sensitivity accuracy

In a new addition to our reviews we are now measuring the actual sensitivity of each indicated ISO sensitivity. This is achieved using the same shots as are used to measure ISO noise levels, we simply compare the exposure for each shot to the metered light level (using Sekonic L-358), middle gray matched. We estimate the accuracy of these results to be +/- 1/6 EV.

Unlike the EOS 350D (Rebel XT) the EOS 400D (Rebel XTi) proved to be slightly less sensitive (by a third of a stop) which means that its actual sensitivity is as per the indicated sensitivity.

Indicated
sensitivity
Canon EOS 400D
(actual sensitivity)
Nikon D80
(actual sensitivity)
Sony DSLR-A100
(actual sensitivity)
ISO 100 ISO 100 ISO 100 ISO 125
ISO 200 ISO 200 ISO 200 ISO 250
ISO 400 ISO 400 ISO 400 ISO 500
ISO 800 ISO 800 ISO 800 ISO 1000
ISO 1600 ISO 1600 ISO 1600 ISO 2000
ISO 3200 n/a ISO 3200 n/a

UPDATE 18/Dec/06: In our original review a mistake was made in the measurement of ISO sensitivity, this has now been corrected and the releveant pages of this review updated.

ISO Sensitivity / Noise levels

ISO equivalence on a digital camera is the ability to increase the sensitivity of the sensor. The works by turning up the "volume" (gain) on the sensor's signal amplifiers (remember the sensor is an analogue device). By amplifying the signal you also amplify the noise which becomes more visible at higher ISO's. Many modern cameras also employ noise reduction and / or sharpness reduction at higher sensitivities.

To measure noise levels we take a sequence of images of a GretagMacBeth ColorChecker chart (controlled artificial daylight lighting). The exposure is matched to the ISO (ie. ISO 200, 1/200 sec for consistency of exposure between cameras). The image sequence is run through our own proprietary noise measurement tool (version 1.4 in this review). Click here for more information. (Note that noise values indicated on the graphs here can not be compared to those in other reviews). Room temperature is approximately 22°C (~72°F), simulated daylight lighting.

Canon EOS 400D (Rebel XTi) vs. Nikon D80 vs. Sony Alpha DSLR-A100

  • Canon EOS 400D: Canon 50 mm F1.4 lens, Aperture Priority, Manual WB,
    Default Parameters (Standard PS), JPEG Large / Fine
     
  • Nikon D80: Nikkor 50 mm F1.4 Macro lens, Aperture Priority, Manual WB,
    Default Parameters (Normal), High ISO NR (Normal), JPEG Large / Fine
     
  • Sony DSLR-A100: Minolta 50 mm F1.4 lens, Aperture Priority, Manual WB,
    Default Parameters (Standard DEC), JPEG Large / Fine
Canon EOS 400D
ISO 100
Nikon D80
ISO 100
Sony DSLR-A100
ISO 100
(125 equiv.)
Canon EOS 400D
ISO 200
Nikon D80
ISO 200
Sony DSLR-A100
ISO 200
(250 equiv.)
Canon EOS 400D
ISO 400
Nikon D80
ISO 400
Sony DSLR-A100
ISO 400
(500 equiv.)
Canon EOS 400D
ISO 800
Nikon D80
ISO 800
Sony DSLR-A100
ISO 800
(1000 equiv.)
Canon EOS 400D
ISO 1600
Nikon D80
ISO 1600
Sony DSLR-A100
ISO 1600
(2000 equiv.)
Canon EOS 400D
n/a
Nikon D80
ISO 3200
Sony DSLR-A100
n/a

As you can see there is no discernable difference between the EOS 400D, D80 and DSLR-A100 up to ISO 400 (except for slightly better sharpness from the EOS 400D image). The EOS 400D continues this sharp detail all the way up to ISO 1600 but does have noticeably more chroma noise than the D80 which employs better chroma noise reduction. At higher sensitivities the EOS 400D delivers more detail but with slightly more chroma noise, the D80 less detail but a cleaner more 'film like' appearance to noise grain, the DSLR-A100 has the noisiest image although has good detail at ISO 800.

Luminance noise graph

The graph below is a little complicated but what it tells us is that noise levels between all these cameras (and the EOS 350D thrown in for comparison) are similar up to ISO 400. At ISO 800 the D80's noise reduction suddenly drops noise levels although they return to a similar level as the EOS 400D at ISO 1600.

Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity on the vertical axis.

Luminance noise graph (zoomed, only 10 MP cameras)

The graph below is based on the same data as above except it only shows ten megapixel cameras and the standard deviation range (vertical axis) has been reduced to a maximum of six. A difference in standard deviation less than one would be quite difficult to distinguish in a normal everyday shot.

Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity on the vertical axis.

Chroma (color) noise graph

In addition to measuring luminance noise we now also measure chroma (color) noise. The D80's stronger chroma noise reduction keeps levels lower at ISO 800 and 1600, however the 400D is still relatively low and at least predictable.

Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of color on the vertical axis.

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Comments

Total comments: 5
reanim888

The Canon 400D remains a very good first dSLR, with a balance of automatic, semi-automatic and manual controls to progress through as your creative photography skills improve.
I think it's very important for every Digital Photo Camera!

1 upvote
Sam Spark

I think all of the camera makers (Canon, Nikon, Sony, etc.) have been doing the same thing… just making minor, poor, or inconsequential upgrades to their cameras. I think they all got caught blindsided by the smart phone market.

1 upvote
canonaholic

Was a great little thing

Comment edited 45 seconds after posting
0 upvotes
512A385C4A114355B73DB0DC6598F611

I want to know if kiss digital 400D can be used to shoot videos and movies. Can it also be used to shoot on long hours?

0 upvotes
canonaholic

No! This has no video capability whatsoever!
Doesn't even have live-view!!!

0 upvotes
Total comments: 5