Is it just me that has this exposure problem?
 

Hi All - I have mentioned in a few posts about my problem with the EA50 easily blowing highlights but here I can give a clear example - In the first shot the exposure is pretty good and balanced but as soon as the woman's face comes out from the shade of the umbrella I get what looks like (or actually is) banding or posterisation on her facial highlights!

It reminds me of them old 256 indexed colour graphics on old computers. BTW I'm using PP3 unmodified in this shot. Is it a consequence of 8bit video? When highlights popped a bit on my old Z1 it just seemed smoother somehow and more graduated.

Any thoughts or am I just pixel peeping!

Re: Is it just me that has this exposure problem?
 

you can reduce the "blown-out" effect using a better profile for smoother highlights, and you can use the exposure compensation to tweak auto-iris/auto iso, based on the scene.

as a lot of parts on the image are black/dark gray, its a correct behavior. she was on the shadow, then came to the light. the image should be set around to 1 stop less than that (easily done with the scroll control to adjust EV +/-)

Re: Is it just me that has this exposure problem?
 

Apparently the FS100 has the same issue

http://www.dvinfo.net/forum/sony-nxc...ighlights.html

Pete

Re: Is it just me that has this exposure problem?
 

Hi Pete

If you take the 2nd pic and blow it up 400% you can see that the posterisation on her face very clearly simply because PP3 profile does lift detail from shadows and you will get a bit of overexposure on bright light. Probably something like PP4 is a better bet as PP3 works for me indoors very well as well as in not so bright conditions. What you can do with PP3 is set an EV Value (negative just a tad) and assign that to button 2 (or any other) and that will autoset exposure to under-expose when selected.

That's why her face is "blown" a bit ... If you increase saturation however it exposes quite well.

Now, the posterisation is caused according to the experts is shooting in 50P ...It is said that 50P needs a bitrate of at least 50mbps not to do this on highlights and the EA-50 shoots at 28mbps at best. However if you expose correctly it won't happen and it tends to show up mainly on cheekbones and faces that are over exposed. It doesn't happen to me at all now cos I shoot in 50i not P ... I used to get terrible artifacts on closeups that were well lit on bridal party faces when shooting in 50P .... check the guys head..it's also a bit over the top BUT no posterisation on his bald bit at all. If you zoom the pic to 800% the lady's face is badly pixelated yet the guys bald patch is fine.

If you insist in shooting in progressive then watch your highlights carefully or change the PP3 profile or expose under a bit.

Personally the bride will never see it so yes, you are pixel peeping but the above is the reason why it does that. I wouldn't worry about it .... I cannot be bothered with progressive and trying to keep my shutter at 1/100th at 50P ...shooting interlaced I can rev the shutter to 1/600th without any issues and I really don't have time to micro-adjust stuff when I have bridesmaids tumbling out the limo!!

Chris

Re: Is it just me that has this exposure problem?
 

Chris that explains why I never had this issue with my Z1 as I shot interlaced!

Another example from the same shoot - well exposed but as soon as the tog's hand comes out of the shade (not even into the sunlight as it was overcast) - completely blown out! It is causing me an issue i need to address!

Re: Is it just me that has this exposure problem?
 

This can be easily fixed (the blown out area) in Adobe Premiere Pro using the Shadow/highlight filter.

Re: Is it just me that has this exposure problem?
 

Hi Pete

For purely the exposure issue I would copy the settings of PP3 into PP2 so you have two identical profiles (PP2 is for stills so I don't use it) ... Then lift the colour level on your new PP2 up two points. Finally set Knee to manual and set at 100% and leave the ramp at default. What this will do is compress any highlights in the image. You would have to try this before doing a wedding though as manual knee can be set from 75% to 105% and you have to decide where in the range suits you. If you push the knee level too much the image might look "plastic" ... which it will at 105% ... You might need to drop below 100% to avoid the artificial look so try shots at maybe 100%, 95% and 90% knee and see which looks best.

Set up a scene with something very bright white in the picture around duller objects ...maybe a white football in the garden so the camera will tend to over expose the light image and then shoot a bit on PP3 (as a reference) and then PP2 with the knee at 100, 95 and 90

Yeah I went back to 50i for weddings very quickly!!

Chris

Re: Is it just me that has this exposure problem?
 

Cheers Chris - It's a nice sunny day here so I'm going to spend an hour trying it out

Pete

Re: Is it just me that has this exposure problem?
 

Great Pete

Let us know the results ... according to Alastair Chapman (I think) if you set the knee manually too high the picture looks like it has been wrapped in clingwrap so I would suspect that setting the knee to 105% might give unwanted effects! Likewise 75% simply does nothing to compress the highlights.

Just for interest maybe shoot a few similar clips in 50i and see if the camera smooths highlights like your Z1??

Chris

Re: Is it just me that has this exposure problem?
 

Simple. Turn off your silly consumer orientated 'picture profiles'. (Audiophiles bypass tone controls on High Quality audio ampifiers - same thing) Set your 'Zebra' to 100% and NEVER see them!

PS: shooting 50i is a good idea. Conform to 25P with a professional transcoder, edit 25P and you'll be set.

Re: Is it just me that has this exposure problem?
 

Hi Craig

Exactly what I do but if you set the profiles to "off" the saturation goes crazy on indoor shots! Way too much saturation once you get indoors .... Most audiophiles prefer a flat response for audio right?? The flattest profile as far as I can see is the PP3 which conforms to a natural colour tone and ITU709 gamma and in audio terms it seems to me to be the flattest profile of all. I have no idea what "off" sets the camera to but skins tones under lights or indoors look very harsh whilst PP3 seems the most neutral and very easy and natural to boost in post.

I shoot 50i with 100% zebras and edit progressive and have no exposure issues. Even on auto exposure you have a good range of EV settings to compensate if the ceremony background is exceptionally dark or badly backlit and even pushing to EV 1.7+ is bad backlighting my correctly exposed foreground areas are dead even and accurate (of course the bright sky/water is blown out but in those cases you have little option!) It's like an adjustable (+ and -" ) "backlight button like the old camcorders used to have and is an essential tool when stupid brides insist on standing against very bright light!

Funny, a few years ago I was shooting on Panasonic AC-130's also in AVCHD and had the same pixellation issues on faces (especially cheek bones) when using 50P so it doesn't seem to be restricted to one brand so it must be a format restriction or a bitrate restriction. In 50i it never was an issue so I have been doing the edits as progressive and never had any major problem ... Doing it that way you are supposed to have only half the vertical resolution but my eyes have yet to see any difference between the formats despite videophiles (correct word?) insisting that 50P is the only format to shoot in.

Chris

Re: Is it just me that has this exposure problem?
 

Hi Chris,

Of course my 'reference' is for the Vg20 which (according to my extensive test chart analysis) shoots a 98% perfect colour balance at the tungsten or daylight presets (only 2% colour shift) so for the EA-50, you would be correct. I really urge users to get hold of some test charts, shoot at the various presets and look on their NLE's waveform and vectors to see what is actually going on.

PS: I'm flying to Kyoto, Japan on Sunday for a week's music video shoot and contrary to popular trends, I'll be shooting exclusively in 50i!

Re: Is it just me that has this exposure problem?
 

Nice Craig

Have a great time and I'm assuming the weather will also be a tad warmer in Japan than in the Blue Mountains in May.. snow must be pretty close to arriving now?

Safe trip

Chris

Re: Is it just me that has this exposure problem?
 

Well I had an interesting one yesterday - A wedding In the middle of a very dark forest with shafts of hot sunlight - what an exposure nightmare - I was shooting with PP3 (colour level up 2 points) but at 100% zebras It was hard to expose so they never showed - what happened was half the wedding party was in the darkness and the other half in bright sunlight - I kept it so the Zebras just creeped in on the highlights and it's sort of ok but I need to boost the mids in Premiere

I also find without using a profile indoors is way too contrasty and saturated.

Re: Is it just me that has this exposure problem?
 

Hi Pete

With zebras at 100% (I actually have mine at 90% as well) if you stop down to eliminate all zebras you will definitely be under-exposed. I almost always get zebras on bright sections like sky and it won't ruin the exposure at all. Just ignore those zebras and make sure that faces/skin tones have no zebras and you will be pretty much spot on. Just for interest, did you change the knee setting? My PP3 is currently just like yours with the colour level two points up. I find that it's almost correct for indoor shots but a bit under saturated for outdoor. Most of the time I tend to lift indoor shots just a tad and quite a lot more for outdoor. If you watch the facial skin tones and make sure they don't start turning orange but stay warm the saturation will be pretty close! I'm not sure how the graduations work in Sony Vegas but it goes from zero to 3 (positive and negative) and my indoors are set at 1.166 and outdoor at 1.333.

Did the exposure correction sort out the posterization problem as well??

Chris