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Old May 28th, 2008, 03:50 PM   #1
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HPX500 Chromatic Abberation

Just doing some tests with an HPX500, especially with long stills lenses (Canon 300 and 150-600). Varying amounts of CA (blue fringing), but this is lessened greatly by knocking the exposure down. I suppose this is to be expected as it's reducing some of the contrast between black and white areas, but not something I'd seen on Sony HDW750 with the same lenses. Any thoughts? If underexposing, keeping the whites well down below maybe 90 IRE greatly reduces CA that could be useful to a lot of shooters, just bring exposure back up in post?
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Old May 28th, 2008, 05:42 PM   #2
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Canon and Fujinon have specific lenses for the HPX500 to correct for the CA found in the HPX500's. Does your testing include any of the HPX500-specific, CAC (Chromatic Aberration Compensation) lenses?
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Old May 29th, 2008, 02:51 AM   #3
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No, just long telephoto stills lenses. It's a sign of the times that there even has to be a CAC function!
I wonder if any camera is more prone to it than another, as I said, I've not seen this on the HDW750 (well, very little anyway) with the same tele lenses, yet we're talking about a camera with over 3x as many pixels on the chips - could that be an issue, the pixel-shifting increasing the visible CA?
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Old May 29th, 2008, 08:04 AM   #4
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Quote:
Originally Posted by Steve Phillipps View Post
could that be an issue, the pixel-shifting increasing the visible CA?
Steve
I don't know. Looking at some clips from the JVC-100/200 series with the stock lens, there is a lot of CA and that camera has 720p imagers.

I think CA is optically based.
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Old May 29th, 2008, 08:23 AM   #5
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CAC isn't new technology it's been in use on ENG-type cams like the 500 for years.

How in the world did you mount that old FD monster, the FD 150-600mm f/5.6L to your rig? What a beast. Although that lens is an "L" series it was known for tons of CA (I owned one when my primary camera was the F1-N) so that would be one of the major reasons for your troubles.

I don't know which 300mm you're using but if it's not one of the ultra-bright f/2.8 models (they only made one f/2.8 in the SSC lineup before introducing the "new" FD ultra teles that had the white body) that too is going to be troublesome.

Unfortunately since you're using still lenses the CAC circuitry can't talk to the lenses and help make corrections, you'll have to deal with it in post. Assuming you're using one of the lens adapters to connect to the 500 my recommendation would be to use a different lens mount, either Canon EOS, Nikon F or Zeiss and get better glass to start off with.

Although not a forum sponsor contact RPLens http://www.rplens.com about getting some pristine, re-purposed FD glass for your rig. What you're using now isn't ever going to give you what you want.
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Old May 29th, 2008, 01:00 PM   #6
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Robert, all my Canons (300mm f2.8, 150-600 and 800 f5.6) are in Universal mount so I can use them on B4, PL, Aaton, Nikon etc.
Never heard of the 150-600 having CA problems (at least not colour fringing, I have seen flare problems), and I and many others have used them on Super 16 and 35mm film for years, plus I've used it on Digibeta and HDCam and looks pretty CA free - especially when compared to HD video lenses!
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Old May 29th, 2008, 02:32 PM   #7
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I do remember the 150-600mm zoom had fringing issues; I didn't notice it much until I started shooting chrome (we're talking mid-'80's) and after that the darkest lens I owned was the 1200mm f/5.6. (When I got into the EOS system the 50mm f/1.0 had bad CA too).

The 500 will have more CA to deal with than a native HD chipset; one way to show this is to shoot in SD (the 500 is in fact using the SDX900 PAL imaging blocks); in SD mode the 500 is unbelievably crisp and has such low-noise characteristics it's scary. But, when it's doing the spatial-offset to achieve HD it will definitely exacerbate any CA characteristics of any lens attached.

Although I've never used a still lens as a direct-mount to any video camera I've shot extensively with the Pro35 and various 35mm glass (Nikkors, Zeiss and even EOS Canon) and I would not use any lens that is darker than f/4 on the 500 so again I feel that a brighter, more recent lens will do better on that camera.
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