User coments on Panasonic AG-HPX500 pls?

[John Fishback]

I’m not knocking the camera. I own it. It’s one of those rare purchases where you are 100% satisfied. All I’m saying is before you spend more than the cost of this camera on an HD lens, check out what you can see through it. It might only be incremental. You might need that megapixel block to take advantage of the high-end HD lens.

John

Dual 2.5 G5 4 gigs RAM OS 10.4.8 QT7.1.3
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[Barry Green]

[Bob Cole] “I thought that the “cheap” glass, which has CAC, was to correct an imaging weakness in the 500 itself.”

No, it’s quite the other way around. The CAC function is designed to overcome the low-cost nature of the lens. It’s a high-end function, which is why Panasonic is putting it on their top-of-the-line HPX3000 too.

HD glass is designed to resolve at least 85lp/mm, but if the chromatic aberrations aren’t corrected out you’ll get a lot of green & purple fringing. Top-end glass undergoes an extensive, slow, and expensive multicoating process to optically correct all those aberrations, to get the lens to focus the red and blue wavelengths at the same point in space. The CAC lenses forego that expensive multicoating process, instead feeding the lens position/focal length/iris setting info to the DSP in the camera body. The camera body then references the internal “lens file” which has all the properties of the lens mapped out, and it then knows that based on the focus/iris/focal length combination that certain aberrations will have been introduced by the lens. It digitally compensates for those aberrations.

As such, you can get great aberration-free performance from lenses that haven’t undergone the extensive coating process to optically correct for the aberrations. According to a Fujinon rep I talked to, the glass is the same. The sharpness and MTF are the same. The difference is in aberration performance. If they take the time and effort to correct the performance optically through coatings, that lens will work on every camera body and perform predictably and optimally, and it’ll cost a fortune. If they ignore that process and instead rely on the camera to correct it digitally, you’ll get great performance on a CAC-equipped camera body at a tremendous cost savings. But you won’t get great performance on a non-CAC body; on a non-CAC body you’ll get notable green/purple fringing.

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[G.a. Kokes]

John,

It is my experience that this camera does benefit from the use of HD over SD glass.

Cheers,
G

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