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ISO / Sensitivity accuracy

The actual sensitivity of each indicated ISO is measured 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 a calibrated Sekonic L-358), middle gray matched. We estimate the accuracy of these results to be +/- 1/6 EV (the margin of error given in the ISO specifications).

We found all these cameras produce images less bright than either our lightmeter or our reference camera. The test was made more complicated because the TL500 reports aperture in a slightly unpredictable way - it appears to have an aperture that can only operate in a series of steps, rather than having a stepless aperture that adjusts in tandem with the changing focal length. The result is that all the F number settings varies as you zoom (usually it's only the widest setting that changes, with the rest conforming to standard 1/3rd EV positions - F3.5, F4, F4.5, F5, F5.6, etc). However, in keeping with its peers, it actually appears a fraction less sensitive than the quoted figures would suggest. Since they are all doing the same thing, the other images on this page are directly comparable to one another.

Indicated
ISO value
Samsung TL500
measured value*
Canon S90
measured value*
Panasonic LX3
measured value*
Canon G11
measured value*
ISO 80
ISO 64
ISO 64
ISO 64
ISO 64
ISO 100
ISO 80
ISO 80
ISO 80
ISO 80
ISO 200
ISO 160
ISO 160
ISO 160
ISO 160
ISO 400
ISO 320
ISO 320
ISO 320
ISO 320
ISO 800
ISO 640
ISO 640
ISO 640
ISO 640
ISO 1600
ISO 1250
ISO 1250
ISO 1250
ISO 1250
ISO 3200
ISO 2500
ISO 2500
ISO 2500
ISO 2500

* Default settings.

ISO Sensitivity / Noise levels

ISO equivalence on a digital camera is the ability to increase the sensitivity of the sensor. This 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 ISOs. 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).

Samsung TL500/EX1 vs. Canon PowerShot S90 vs. Panasonic Lumix DMC-LX3 vs. Canon PowerShot G11

  Samsung TL500 Canon S90 Panasonic LX3 Canon G11
ISO 80 (64*) (64*) (64*)
ISO 100 (80*) (80*) (80*)
ISO 200 (160*) (160*) (160*)
ISO 400 (320*) (320*) (320*)
ISO 800 (640*) (640*) (640*)
ISO 1600 (1250*) (1250*) (1250*)
ISO 3200 (2500*) (2500*) (2500*)
*Measured ISO values

All four cameras produce great, detailed images at their lowest ISO settings but, understandably, this drops off as ISO rises. The EX1 does a great job as far as ISO 400 but all the cameras struggle beyond this point. And, while the Panasonic takes the approach of allowing more noise in an attempt to retain detail, the Samsung starts smudging both away.

That said, although it is rather heavy-handed with its noise reduction from ISO 800 upwards, it manages to produce a vaguely recognisable image at ISO 3200, which the Canons don't. It's a pretty good performance but the rather aggressive noise reduction is a pity, given that there are no options for toning it down.

RAW noise

  Samsung TL500/EX1 Canon S90 Panasonic LX3 Canon G11
ISO 100
ISO 100
ISO 200
ISO 400
ISO 1000
ISO 1600
ISO 3200

This test is a perculiar one in that three of the four cameras in this comparison almost certainly use the same sensor. As a result there's not a lot to call between them, with the exception of the LX3, which is visably noisier from ISO 400 upwards.

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Comments

Pantyhose Bandit
By Pantyhose Bandit (3 months ago)

But can the LCD swivel so that it can be viewed from the front?

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