•• Locking Exposure Prior to Entering LIVEVIEW vs Locking Exposure during LIVEVIEW••

Coco Bermudez

Coco Bermudez

Well-known member
So I would like to know what everyone thinks the benefits are of locking the exposure prior to entering LIVEVIEW to locking it after entering LIVEVIEW.

I just covered a golf tournament and I was crazy enough to do it entirely on the d90. What a sunny/ cloudy gorgeous day it was to shoot. i was a little concerned with how it would look but I saw the footage and it blew me away. Usually I bring out my Sony DSR490 or DSR500's...but I just wanted to cover it differently.

While on the field, I had my d90 hooked to the IKAN 8000HDMI....sucked big time. The colors where not even close to the image I was getting from the Nikon screen. Plus within 35 minutes it heated up my camera so badly that it began to do the wicked evil countdown. As soon as I disconnected it, the camera went back to normal. In my opinion...a junky monitor I should have not bought at all.

I had to do my AE locks on the fly while using the LIVEVIEW...it was much quicker for me to do so as action was happening all over the place...I wonder if I did it correctly..the footage looks great but I am curious if I added unwanted noise.

The way I was doing it was to open the lens to a F5.6 and then set my exposure. This way if clouds rolled in, I would be able to open it to F 1.4 and still be able to get a decent picture...

Any thoughts?

These are untouched video still from some of the shots I took.
for some reason some of the closeups look soft in the picture stills...but they are sharp as can be on video....must be the compression or something.....

GOLF1.jpg

GOLF2.jpg

GOLF3.jpg

GOLF4.jpg

GOLF5.jpg
 
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in bright light you'll be struggling to get a long enough exposure time to prevent strobing, not to get a noise free image. i've never got a noisy image in daylight no matter what locking technique. the various tricks might work, i don't know i don't use them, but ultimately it's about exposure. a dark image requires a higher iso and a bright image requires a fast shutter. using the aperture wisely as well as adding nd's is the only way i've found of getting a consistent look.

/matt
 
My biggest problem in bright light is the chromatic sparkle effect, for lack of a better way of putting it. What is the correct name? Any idea what causes it?
 
Looking at those grabs, you can really see the compression artifacts on the shot of the grass much more than the other grabs. Note to self: Watch out for scenes with high complexity.

To the original post. I always lock exp during liveview, and find that if I don't, it changes the exp after entering liveview.
 
yeah the D90 struggles with nature, grass, leaves etc.

I was out shooting the kids in the park the other day with an ND8 filter locking exposure @ f/5.6 and opening up to f/2. I shot with the vivid curve and matt's custom curve and I found that the vivid curve was capturing about 20Mbps and Matt's only grabbed about 11-14Mbps. I still have to grade it to see which ultimately looks better.
 
Yeah it's very likely that the vivid curve gets a higher bitrate since it produces more high contrast edges. My curve is designed to preserve shadow detail, which helps a lot in grading. I've found the contrastier presets to cause a lot of noise and blockiness in the shadows should you choose to bring them up. It's always easier to add contrast than remove it. Let us know your results. /matt
 
Btw you can use my curve with the vivid preset too. I have created custom settings based on all the presets that i change between.
 
so what preset do you generally use with this curve with for say an outdoor shot? I was using portrait.
 
squig said:
yeah the D90 struggles with nature, grass, leaves etc.

I was out shooting the kids in the park the other day with an ND8 filter locking exposure @ f/5.6 and opening up to f/2. I shot with the vivid curve and matt's custom curve and I found that the vivid curve was capturing about 20Mbps and Matt's only grabbed about 11-14Mbps. I still have to grade it to see which ultimately looks better.
Click to expand...

I think that you are on to something here--as has been mentioned a few times in the discussions, if we can force the d90 to use a higher bit rate we hopefully can get a better final image. Perhaps combining the Vivid preset and decreasing the contrast of the image (via the contrast settings or a custom curve) will provide the best that the d90 is capable of.

I look forward to hearing what you think of your final graded shots.
 
Isn't the bitrate simply related to the complexity of the image?
If you have a shot of a white wall, you get a low bitrate, if you shoot grass with movement, you get a high bitrate. Maybe it's not that simple.

In your example squig, perhaps the higher bitrate was due to a larger color pallet being used in the vivid image?
 
Also, I suspect that the MJPEG codec First sets the quality, then the bitrate is determined by the material you shoot.
Just like making a still jpeg at quality 4, for example, it depends on the image complexity is to what the file size ultimately turns out to be.

I also suspect that the Quality setting that is used in the D90 is a compromise between overheating/ processing power and the image quality. Personally, I'd take more overheating if they cranked up the codec. Ice-packs here I come!
 
hehe more overheating.....ok for you in vermont......I'd need like 3 D90's to shoot anything here.

It's really hard to put your finger on what the mjpeg is doing. I've shot a lot of stuff in vivid and got low bitrates with complex scenes too. I'm looking forward to seeing what the AVCHD on the GH1 is like. mjpeg would look good at 50mbps but AVCHD at 17Mbps should look just as good if not better.

Nikon needs to go with 24Mbps AVCHD or better on the D400.
 
why would the sensor care if the jpeg quality changed? anyway, yes, it's constant quality, easily verifyable with a jpeg-inspector, with supposedly a slight compensation to avoid too high bitrates. too bad there's none to pump it up for low complexity scenes too. it's not always easy to judge yourself what a high or low complexity scene is, it's not just a lot of high frequency data, it's a lot of all frequencies.

i use portrait for most scenes unless they're very low contrast in which case i use normal or even vivid.

/matt
 
squig said:
yeah the D90 struggles with nature, grass, leaves etc.

I was out shooting the kids in the park the other day with an ND8 filter locking exposure @ f/5.6 and opening up to f/2. I shot with the vivid curve and matt's custom curve and I found that the vivid curve was capturing about 20Mbps and Matt's only grabbed about 11-14Mbps. I still have to grade it to see which ultimately looks better.
Click to expand...

So was this true that you were capturing @20Mbps? Or is Matt right and it is useless to try to fool the compression algorithm into using a higher bit rate?
 
I've captured up to 24Mbps but I can't say that it looks any better than other stuff I've captured at 12Mbps. I think the D90's codec falls down in really complex scenes like natural foliage. My worst looking footage was shot in the bush (forest) The volvo driving abba loving blonde muff diver is right most of the time.
 
Robert Altman said:
is Matt right and it is useless to try to fool the compression algorithm into using a higher bit rate?
Click to expand...
please don't quote me unless you're really quoting me. i never said such a thing, nor will i ever. quite the contrary. what i did say is that the trick doesn't necessarily make the video look better, for various reasons. i mean all those extra bits are used to encode the extra complexity, not for the "rest" of the image.

/matt
 
So Matt what do you think about 17Mbps AVCHD? Specifically converting to prores grading and transferring to 35mm.
 
i think most codecs and bitrates work fine, even for blowups. it's the grading that's problematic with some. avchd causes banding and removes noise and texture, not great, low bitrate mjpeg causes blocking, not great, agressive quantizing causes loss of visual information, not great either. i think mpeg-2 is the best compromise but requires a very high bitrate, hdv is the absolute minimum. hdv has some blocking problems and some slight loss of visual information, but even at 30 mbit as in xdcam it's usually fine. 50 mbit mpeg-2 would be perfect.

/matt
 
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