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Sony HVR-A1 and HDR-HC Series
Sony's latest single-CMOS additions to their HDV camcorder line.


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Old August 31st, 2005, 10:15 PM   #1
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work around with 2 polarizing filter to shoot at f1.8 only

Hi,
I try to set the camera at f1.8 and no gain to shot under the bright sun light, that is u set the exposure to far right and 6 notch back.
under the broght sun light.
then use 2 polarizing filter to cut light until the exposure is right.
i use zebra to set the exposure, which i find it very OK.
it's faster than change ND filters, and shutter speed is last thing i want to change.

the draw back is cheap polariser change the colour, so be aware and use white balance to correct it.

other things if the light is cut too much, the unevenness on the 4 corners.
1/3 CMOS works very ok, but never as good as mini 35.


enjoy
JY
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Old September 1st, 2005, 04:12 AM   #2
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hi john
I'm supprised you are getting a good result with that set up as i can't see how you are stopping the gain from kicking in on the HC1 as there is no way of controling when the enhanced processing on the CMOS will go into gain mode apart from AE 'sunset mode' which seems to hold the gain back.
In my experence a polarizing filter on the HC1 is not a good idea in general as the CMOS chip sees that lovely dark sky as a 'shade area' and knocks up the gain even in bright light to introduce a grain to the picture in the sky while knocking down instead of up the contrast in the overall picture. I wonder if the reason why you can't use filters with the hood is Sonys way of telling us that fiters and clever CMOS processing don't really work!
Paul
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Old September 1st, 2005, 05:05 PM   #3
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Quote:
Originally Posted by Paul Rickford
hi john
I'm supprised you are getting a good result with that set up as i can't see how you are stopping the gain from kicking in on the HC1 as there is no way of controling when the enhanced processing on the CMOS will go into gain mode apart from AE 'sunset mode' which seems to hold the gain back.
In my experence a polarizing filter on the HC1 is not a good idea in general as the CMOS chip sees that lovely dark sky as a 'shade area' and knocks up the gain even in bright light to introduce a grain to the picture in the sky while knocking down instead of up the contrast in the overall picture. I wonder if the reason why you can't use filters with the hood is Sonys way of telling us that fiters and clever CMOS processing don't really work!
Paul
I gotta love your cynicism with your last comment !! you could well be right there...

John - it sounds like one of the problems you're getting is vignetting. (darkening of corners). Am i right in assuming that you're using the polariser WITH the lens hood ? i'd leave the lens hood off and that might well fix the darkening at the corners issue.

Secondly, do try using the Program AE mode 'Sunset'. Certainly on the HC1000 is simply refuses to let the gain go above 9dB but otherwise doesn't affect the exposure. SO that mode could help you in your situation.
Otherwise rotate the polariser to give maybe *some* polarisation amount but not the full effect. Paul is right in that the HC1, from all that i read, does seem to interpret dark-ish heavily-polarised skies as a shadow area and it thinks "Ah i have to increase shadow detail there" and so applies some image processing. THe Sunset mode tells the camera that parts of the image are GOING to be shade/dark and that this is FINE as whats important is the pretty sunset colours. Since the HC1 appears to heavily process the image, i am fairly confident that the SOny engineers have programmed 'Sunset&Moon' mode not to mess so much with shadow areas.

So - i am curious - please can you try to shoot the same type of shot next time, but leave the lens hood off competely, and have the camera in PROGRAM AE mode "Sunset&Moon". Don't attempt to mess with the exposure manually.

Let me know the results compared to your previous method.

best regards
Stu Holmes is offline   Reply With Quote
Old September 6th, 2005, 10:47 PM   #4
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i work in manual mode only

my apology,
i work only in manual mode, it's set at manual1/50sec and exposure is set manual.white balance also set at daylight/tungsten/preset. i have no interest to use any automode in this camera, so i am afraid cannot tell the result with 2 polarisers.as i try and confirm that setting the exposure back 6 notch is at f1.8 no gain. so i stick to it for DOF issue.

vignetting , yes, could be a problem.i use 52mm filters so in a sense they are larger than 37mm size.

cheers
JYM
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Old September 7th, 2005, 02:19 AM   #5
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The only problem with using 2 polarisers is that when they are set at 90degrees to each other, the picture will go completely BLACK. that's the way polarisers work.

Try it by holding them off camera and holding one steady and rotate the other. At a certain angle you'll be cutting almost 100% of light. it'll be quite dramatic !
Honestly i think if you are trying to cut light then one or more ND filters is a better option.

Even though you are carefully setting the manual exposure to eliminate any gain, the HC1 will, selectively increase gain (via EIP image processing) in any area of the image which it perceives as being a'shadow'. With 2 polarisers, i think you may be making the gain/grain problem worse rather than better IMHO.

I have established on the HC1000 that Sunset&Moon Program AE mode will automatically restrict gain to 9db and, while i haven't checked that the HC1 does a similar thing, i think it's likely. Just try it and see if it helps you - no harm done if you don't like the result !

rgds
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