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Canon G1 X Dynamic Range (JPEG)

Our Dynamic Range measurement system involves shooting a calibrated Stouffer Step Wedge (13 stops total range) which is backlit using a daylight balanced lamp (98 CRI). A single shot of this produces a gray scale wedge from the camera's clipped white point down to black (example below). Each step of the scale is equivalent to 1/3 EV (a third of a stop), we select one step as 'middle gray' (defined as 50% luminance) and measure outwards to define the dynamic range. Hence there are 'two sides' to our results, the amount of shadow range (below middle gray) and the amount of highlight range (above middle gray).

To most people highlight range is the first thing they think about when talking about dynamic range, that is the amount of highlight detail above middle gray the camera can capture before it clips to white. Shadow range is more complicated; in our test the line on the graph stops as soon as the luminance value drops below our defined 'black point' (about 2% luminance) or the signal-to-noise ratio drops below a predefined value (where shadow detail would be swamped by noise), whichever comes first.

Note: this page features our interactive dynamic range comparison widget. The wedges below the graph are created by our measurement system from the values read from the step wedge, the red lines indicate approximate shadow and highlight range (the dotted line indicating middle gray).

With no DR enhancement features switched on the G1 X's default tone curve is a little steeper in the highlights, with about half a stop less highlight range than some cameras in the same class. This steeper tone curve means there can be a rather abrupt transition from near-white pixels to clipped data, for example in clouds or an overcast sky.

The G1 X offers two Dynamic Range enhancement options - DR Correction and Shadow Correction. 200% DR Correction is the same as Highlight Tone Priority (HTP) on Canon DSLRs and is designed to retain highlight detail in high contrast scenes. However, in addition to the 200% DR option (equivalent to HTP) it also offers a 400% DR mode for even more highlight range. It does this by applying less amplification to the signal coming from the sensor, then compensating for it by using a different tone curve to ensure the correct brightness in the final image.

At the 200% setting ISO 200 becomes the minimum sensitivity and ISO 400 at the 400% setting respectively. In our test the 200% option gives you one additional stop of highlight range, the 400% option two stops, making it a good option for high-contrast scenes. When using the system the effect is the same as underexposing an ISO 100 shot by one stop for the 200% setting (two stops for 400%), then pulling up the mid tones and shadows to compensate. On the downside you loose some low contrast detail in the shadow areas due to increased noise reduction.

Shadow Correction is the same as the Auto Lighting Optimizer (ALO) on Canon DSLRs and is designed to slightly lift the shadows and increase shadow detail. You can choose between 'Off' and 'Auto' settings for the feature. Unfortunately our dynamic range test scene doesn't trigger the system but you can see real-life samples which were taken with both DR Correction and Shadow Correction on the 'Photographic Tests' page of this review.

The G1 X used Canon PoweShot series tone curves which are a little different to what we've seen from Canon DSLRs. The Neutral setting is unusually steep in the highlights and while the tone curves of most other settings variy a little bit in the mid-tone range they all clip around the same point as the neutral setting, thus not offering any additional highlight range. Sepia is the only setting that offers a tone curve with a noticeably smoother roll-off and about half a stop additional highlight range.

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Canon PowerShot G1 X

Comments

Total comments: 9
rugosa
By rugosa (2 months ago)

I bought a G1X 2 weeks ago from a person that bought it for his wife for Christmas. She found it too much camera for her needs and so I bought it with about 10 shots total for $400. I usually shoot with a Nikon D300 and the Nikon higher priced lenses. For underwater and a light carry around I had a G10 for 5 years. After 2 weeks of shooting I must say that I'm amazed by the IQ of the photos this camera puts out. Low light shots up to ISO 1600 are allot better than my D300. It's not a perfect camera but then non of them are. Ordered a Canon 500D close up lens for it after seeing how well that worked on Marco Nero's photos with the G1X on www.pbase.com . This camera also shoots some very good underwater photos from examples I have seen on the internet so I picked up Canon's case on sale for my trips south. All told I think that although this camera is not for everyone most owners give it at least an 8/10. www.witnesstobeauty.com has another good review, great landscape photos

Comment edited 51 seconds after posting
0 upvotes
Gunzorro
By Gunzorro (2 months ago)

I've been wanting this camera since it was announced. I'm primarily a DSLR shooter, and FF at that. I also have owned a G6 and currently G10 and S110. So, I'm pretty familiar with where this camera fits in and what a step it is for Canon to take.
I just bought a used version at a very nice price so will be trying it out in the near future.
I would have rated the camera a little higher, based on my past experience with Canon and reports I've read from reviews and owners. Particularly, Optics and Performance would have got a couple ticks up in my estimation. I think a 79 or 80 would have been appropriate -- being practically in a category of its own: attached zoom, large sensor, compact camera.
It won't be a camera for everyone, true. But if you want better IQ than P&S and use it as a second camera to your DSLR for quick grab shots and take-anywhere convenience, you should be well served! :)

0 upvotes
jan snks
By jan snks (5 months ago)

Image quality G1X, dpreview reports "excellent image quality across the ISO range without nasty surprises".
I would like to refer to the www.imaging-resourcing.com review of this camera. They reported a nasty Light Leakage phenomenon at higher ISO settings and short shutter times. This defect seems to be confirmed by Canon.
Would anybody comment on this ?

0 upvotes
millhoud
By millhoud (6 months ago)

I've noticed that the g1x took this studio shot at f7.1 , while other "enthusiast" compacts (g15 or p7700...) at f4.5. Could somebody explain me why's that? It would be nice to know the shutter speed too. Thanks

0 upvotes
Richard Butler
By Richard Butler (6 months ago)

It's to offer enough depth-of-field (it's a 3D target).

This has a sensor much bigger than the others, so needs to be stopped-down further in order to provide enough depth-of-field.

0 upvotes
millhoud
By millhoud (6 months ago)

Please sorry my ignorance, but to achieve this it has to use a slower shutter speed too or, thanks to the higher light-catching capabilities of the bigger sensor the g1x uses comparable shutter speeds as, say, the g15 or p7700 , with a smaller aperture?

0 upvotes
lem12
By lem12 (7 months ago)

If Canon increases DR able to at least match T2i and updates its Panorama mode (similar to the Sony's would be great), this would be true compact I'm looking for. I'll buy it no doubts!

0 upvotes
Wildbegonia
By Wildbegonia (7 months ago)

Almost but not there yet.

3 upvotes
Ponderer
By Ponderer (8 months ago)

G1x Cannons almost camera
Almost an APS-C sensor, Almost a good EVF, Almost enough lens magnification, Almost small enough. A good first try for a company that just started designing cameras.

9 upvotes
Total comments: 9