Timing & Performance

Overall impressions are pretty positive; the GX100 is no speed demon, but it's by no means sluggish and feels highly responsive in most shooting situations. Our biggest complaint is focus speed, and even then only in low light or (more specifically) at short distances or in macro mode, when it can be infuriatingly slow (taking up to two seconds to find its mark).

If you're out snapping wideangle scenes in good weather on the other hand, it's actually very fast (and the 'snap focus' setting, which fixes the focus to the hyperfocal distance, makes for a 'press to capture' speed that's as fast as any compact we've used). Unusually the GX100 doesn't appear to require you to half press to pre-focus; you can just press the shutter and the picture is taken as soon as the camera has focused. Doing it this way causes the screen to blank out but - as long as your subject is more than a few feet away - is incredibly fast, as close to instantaneous as you'll ever experience with a compact camera.

As usual with non SLR digicams the raw performance is pretty poor (roughly 5.5 seconds between shots), but it's a lot better than the GR-D. I'd also like to see a slightly better shutter lag (0.1 seconds is hardly a problem, but it's also far from class-leading). It's worth reiterating that the very fast full press lag (as little as 0.3 seconds in good conditions) means the shutter lag won't worry anyone unless they're trying to capture sports action... and this is not the kind of camera you use for sports action...

Timing notes

All times calculated as an average of three operations. Unless otherwise stated all timings were made on a 10MP Fine JPEG image (approx. 3,600 KB per image). The media used for these tests was a 1.0GB SanDisk Extreme III SD card.

Action Details
Time, secs
Power: Off to Record   1.7
Power: Off to Play Image displayed 3.3 
Power: Record to Off All activity ceased 2.1
Power: Play to Off When buffer is empty, lens extended 1.9
Power: Play to Off When buffer is empty, lens already retracted 1.9
Record Review Image displayed ~0.5
Mode: Record to Play   0.4 *1
Mode: Play to Record Lens already extended ~0.2
Play: Magnify To full magnification (16x) ~2.5 
Play: Image to Image Time to display each saved image ~0.2*1
Play: Thumbnail view 4 x 3 thumbnails 2.0

Action Details
Time, seconds
Zoom: wide to tele 24-72mm (3x) 1.5
Half-press Lag (0->S1) Wideangle: Multi AF ~0.5-1.5*2
Half-press Lag (0->S1) Telephoto: Multi AF ~0.5-1.5*2
Half-press Lag (0->S1) Wideangle: Snap AF ~0.0 *3
Half to Full-press Lag (S1->S2) LCD live view ~0.1
Half to Full-press Lag (S1->S2) Using electronic viewfinder ~0.1
Full-press Lag (0->S2) Multi AF ~0.3 *4
Off to Shot Taken LCD live view ~1.9 *4
Shot to Shot Flash off 0.9 
Shot to Shot Flash on (red eye off) 2.4 *5
Shot to Shot Flash on (red eye on) 3.0 *5
*1 The GR-D uses low resolution proxies when first displaying images in playback mode, meaning you can scroll through images quickly. A full image takes around 1.3 seconds to load (allowing you to magnify)
*2 In good light the GX100 focuses fairly quickly, but in lower light or at short distances (and in macro mode) it gets a lot slower. No significant difference between multi AF and spot AF
*3 Snap mode uses fixed focus, and therefore doesn't have to wait for the AF to work before a picture is taken.
*4 By pressing the button firmly (without using the half-press to pre-focus) it's possible to take a picture in around 0.3 seconds (though it takes longer at the tele end of the zoom or in poor light). The camera does focus but doesn't always get it right (at the short end of the zoom at distances over about 4 feet this simply isn't an issue thanks to the extensive depth of field).
*5 Flash recycle time depends on shooting distance and battery charge. This figure is for a short shooting distance and a fully charged Li-Ion battery.

Continuous mode

The tables below show the results of our continuous shooting test, indicating the actual frame rate along with maximum number of frames and how long you would have to wait after taking the maximum number of frames before you could take another shot. Media used for these tests was a 1.0GB SanDisk Extreme III SD card. Shutter speed was kept above 1/200 sec during these tests.

Continuous drive mode

The GX100 has three continuous shooting modes, though only one that records at full resolution (the other two combine 16 shots into a single 10MP frame at around 7.5 frames per second). The standard continuous mode doesn't show a preview but you do get a brief review image after each shot during the burst. The shooting rate, which we measured at between 1.6 and 2.4 frames per second (depending on the file size chosen) is more than enough for a camera of this type and you can keep shooting until the card, or battery, runs out.

Image Type
Avg. frames
per sec
Frames in a burst *1
10MP JPEG Fine Continuous 1.6 No limit n/a 
10MP JPEG Normal Continuous 1.7 No limit n/a 
8MP JPEG Normal Continuous 1.9 No limit n/a 
5MP / 3MP JPEG Normal Continuous 2.2 No limit n/a 
1MP / VGA JPEG Normal Continuous 2.4 No limit n/a 

*1 In a single "burst" (finger held down on shutter release).

It's unlikely that many people will ever use the GX100's continuous shooting mode for any serious sports action; the 24-72mm lens is hardly designed for that type of photography. That said, 1.6 frames per second at full resolution - for an unlimited number of frames - is a respectable performance.

File Write / Display and Sizes

Timings shown below are the time taken for the camera to process and "flush" the image out to the storage card, the timer was started as soon as the shutter release was pressed and stopped when activity indicator went out. This means the timings also include the camera's processing time and as such are more representative of the actual time to "complete the task". The media used for these tests was a 1.0GB SanDisk Extreme III SD card.

Image Type
Time to store

Time to display

File size *1
Images on a *2
1.0GB Card
10MP Raw ~5.5 0.2 *4 14,792 KB  53
10MP JPEG Fine ~1.4 ~1.1 *3 3,600 KB 250
10MP JPEG Normal ~1.2 ~1.0 *3 2,100 KB 436
8MP JPEG Normal ~1.2 ~0.8 *3 1,650 KB 543
3MP JPEG Normal ~0.9 ~0.4 *3 650 KB 1,346

*1 All file sizes are an average of three files. As is the case with JPEG it's difficult to predict the size of an image because it will vary a fair amount depending on the content of the image (detail and noise).
*2 Camera estimation.
*3 The GX100 uses low resolution proxies when first displaying images in playback mode, meaning you can scroll through images quickly. These take only 0.2 seconds to display, but you can't edit or magnify images until the full resolution version has loaded. The time to load the full res image is the figure shown here.
*4 You cannot view a 'full res' raw image

With write times averaging around 5.5 seconds for a 15 MB raw file, the GX100 is a lot faster than the GR-D, and better than many compacts (though still a world away from DSLR performance).