Why are compact cameras not affected by moire to the same extent as DSLR's?

[Dave2ic]

I understand the issue of moire/aliasing in DSLR's is a common one resulting from the video being generated by the camera skipping lines rather than downsampling the entire image. But why doesn't it seem to be as much of a problem with compact cameras? Do compact cameras not skip lines?

The reason I'm asking is that with the moire/aliasing issues I'm having with my NEX-6 I'm just wondering if I'd be happier with a premium compact camera - even as a backup camera that I use for video. So I was trying to gauge how much difference the effective sensor sizes would be - an APS-C NEX and a 1/1.7" premium compact like the Nikon P7700.

The NEX has a sensor 366 mm sqr, the P7700 only 42mm sqr - the NEX is nearly 9x larger. But if the NEX is only reading every 3rd line, does that effectively mean we treat the sensor size as 1/3 in terms of its light-gathering capability? Which would mean the NEX has an effective sensor size advantage of 3x - but only if the P7700 is also not line skipping. Then of course the P7700 lens is at least 1 stop better than my NEX with kit lens, which makes the difference not much.

Or am I completely wrong here? (I'm happy to be corrected!).

[2Bdecided]

I've only owned compact cameras that did 320x240 and 640x480 video, but they've had bucketloads of aliasing and moire. Terrible stuttering/strobing too, as in bright light the auto shutter speed was VERY fast, while the frame rate was only 30p (or 60p, which was fine).


For video, use a decent camcorder silent smooth zoom, wonderful image stabiliser, no aliasing or moire, 60i or 60p (or 50i or 50p!), reasonable sound, etc etc.

Cheers,
David.

[smrpix]

Dave2ic,

Different manufacturers will use different debayering and other image processing techniques to arrive at the final image, so it's more multidimensional that what you've described. Even different compression levels within the same camera can affect moire and aliasing. It also makes it hard to do an apples to apples comparison.

[Dave2ic]

Dave2ic,

Different manufacturers will use different debayering and other image processing techniques to arrive at the final image, so it's more multidimensional that what you've described. Even different compression levels within the same camera can affect moire and aliasing. It also makes it hard to do an apples to apples comparison.

Is there any way then to tell how well a particular camcorder will perform in low light compared to my NEX-6 for video? It's easy to compare a still cameras with other still cameras and camcorders with camcorders, but not still cameras with camcorders.

I like the low light performance of my NEX-6, but if I get a camcorder will I need to go as far as a Canon HF-G10/G20 to get comparable low light sensitivity? Or will something a little more modest like the Panasonic HC-V720 be enough? The Canon HF-M52 looks a good performer in low light but starting at 43mm (equivalent) that lens is just not wide enough.

The Panasonic V2720 actually looked like an option I could realistically afford and seemed to have some very good reviews, but I was rather discouraged by the following review:

http://www.techradar.com/reviews/cameras-and-camcorders/camcorders/panasonic-hc-v720-1142041/review

They have issues with the image quality so I'm not sure who to believe:

"While all of the Panasonic HC-V720's features make a compelling case for upgrading to a dedicated camcorder, the image quality is what really counts. And we have to say that we're a little disappointed by the Panasonic HC-V720, as we were by its predecessor."

[2Bdecided]

You need a proper review like this...
http://www.camcorderinfo.co.uk/content/Panasonic-HDC-TM700-Camcorder-Review-37681/Low-...erformance.htm
...if its comparable to the low light tests at dpreview?

Unfortunately I can't find one for the 720.

Cheers,
David.

[racer-x]

As a general rule, when I shoot video with my DSLR, I try to keep a shallow dept of field to help combat the moire/aliasing issues. Try shooting with the aperture wide open and adjust exposure via shutter speed. Obviously it's best to keep the camera in manual mode. You'll also have to keep adjusting focus for moving subjects, but it all works......

Here's a short simple example: