The Panasonic AG-AC90 will be available next month and I got a demo to try out for a day. As there is little information and no footage online about the AC90 I wanted to do a video test comparison. Because of the DSLR / DSLM / large sensor hype and trends and the GH3 just released, I wanted to compare the small sensor AC90 with the micro 4/3 sensor of the hacked GH2. (I don't expect the image of the GH3 to be better as the hacked Gh2 anyway.)

It was not my intention to make good shots, but to put both cameras in 'hard' circumstances, such as high contrast, backlight, movement, moire, rolling shutter effects etc. I did different tests and tried to keep equal settings, same shooting moments and movements, tripod / handheld, slow motion, rack focus / auto focus, daylight / lowlight / dark, menu / settings. I only had the camera for a day (without a manual), so I don't know it that well. Most images in standard settings were a bit too bright (but this can be adjusted in the camera).

Working with a 'normal' camcorder is definitely more easy for run and gun shooting.
The AC90 has a smaller sensor so less DOF, but the Depth Of Field can be achieved with a ND filter. I didn't have one during testing (but I did use a ND in some shots with the GH2, so that is not a fair comparison). I expected the AC90 to do worse in lowlight but I am actually quite surprised!

GH2 standard 14-140 mm lens (not the best low light)

Some AG- AC90 specs

• 1080/60p, 60i, 30p, 24p, 480/60i. [50 Hz model]: 1080/50p, 50i, 25p, 576/50i.
• High sensitive BSI 3MOS sensor
• F1.5
• 29.8 mm wide angle / high powered zoom lens (12x)
• built in 5 axis hybrid OIS
• 3.5 inch lcd (touch) 1.150.000 dot resolution
• Dual SD Card Slots (support SDXC/SDHC/SD Memory Cards).
• 2 channel XLR audio inputs (MIC/LINE/+48V selectable).

• Audio CH1/CH2 with individual level controls and input selection.

• 4:2:2 HDMI output, AV Multi output (D-connector, composite video and audio 2 channel), USB connector.

• Remote terminals enable remote operation of iris, focus, zoom, Rec Start/ Stop functions
• LCD: 8.8 cm ( 3.5 inches) wide LCD monitor (Approx. 1152 K dots)
• Viewfinder: 0.61 cm (0.24 inches) wide EVF (Approx. 263 K dots)
• AVCHD 2.0
• Dimensions (W X H X D): 160 mm x 195 mm x 350 mm excluding protruding parts (6-5/16 inches x 7-11/16 inches x 13-1/16 inches)
• In build ND (automatic) exact same as HMC40 / 80 Seamless.
Barry Green writes about this The system uses zero ND filtration when the iris is set between f/1.5 to f/2.8. If you "stop down" the lens past f/2.8, the iris doesn't actually change at all. The system adds a little bit of ND filter to make the same exposure as if you'd actually stopped down the iris. It brings in more and more ND until you hit f/6.4 when the iris display reads out f/6.4, it's actually f/2.8 plus all the ND filter the camera can deliver. If you stop the iris down any further, it actually starts closing the iris again.

This has two massive benefits: 1) It delivers seamless exposure changes 2) It keeps the iris in the "sweet spot" for as long as possible, avoiding the crippling issues of diffraction. If they'd gone with true iris changes, diffraction would start mushing up the image as early as f/4 (and, in the red channel, as early as f/2.8!) By the time you got to f/11, the image would be a total mush of soft, fuzzy, out-of-focus nothingness. But by doing it this way, they avoid diffraction entirely down to about f/10. F/8 is pretty much diffraction-free. It's really clever engineering to avoid the serious side effects that could occur, from using such a small chip.

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