"Cheating" a higher latitude... thoughts?

dory_breaux

dory_breaux

Todd Wannabe
Hey everyone.

I'm on a quest to find a way to get a larger range of latitude (or xposure range, whatever floats your boat) from the DVX. I guess the most obvious and easy way to do it for alot of shots is to drop a ND grad into my mattebox and adjust it accordigly. But what about shots that wont allow that? I was thinking polarizer but that mostly cuts down glare right?

Thoughts?

thanks,
dory
 
Seems like the ND grad would reduce the overall latitude, not increase it, as you stop down portions of the image. I personally don't know of any way to increase the dynamic range of a CCD except to use a better CCD (meaning a different camera.)
 
For the bright end, there's some post tricks that can allow you to recover detail in DV footage up to 110% IRE - but you ideally need to use a waveform monitor to make sure that you don't blow it out above 110% - and edit/online at above 8-bits per channel.

As far as "in camera" goes - maybe run with cine_like_D and adjusting master pedestal/knee according to where you want the bulk of your exposed image to lie.

Oh yeah - for landscapes etc - there's always the graduated ND filter :)
 
Hey Dory, two things- a polarizer and a Tiffen Ultra Contrast filter. I think a polarizer is a must have. It will not only significantly reduce glare on windows, but can also darken the sky independently from the fore ground. And the glare reduction they provide applies to any surface. Whether you're shooting foliage or a headshot, it's pretty impressive how much color there is when you can knock out the glare.

The Ultra Contrast Filters boost detail in the darker areas with surrounding light without any haziness or ghosting from highlights. I use an Ultra Contrast 3 filter which is the highest they make unless you start getting into 4x4 square filters (expensive). The polarizers are all pretty similar. Hope that helps!

Peace,
S-
 
semila58 said:
Hey Dory, two things- a polarizer and a Tiffen Ultra Contrast filter........Hope that helps!

Peace,
S-
Click to expand...

All good filter advice, I'm sure, but this has nothing to do with latitude and increasing effective latitude whatsoever.

The only thing I can suggest is to reduce contrast to a minimum in camera, aiming for what is sometimes called a digital negative, and apply contrast in post. This enables you to select whether you boost or reduce brightness, highs and lows. The last thing you want to do is increase contrast in camera.

A digital negative is nothing like a real negative in terms of latitude, but if you want the most post-production-correctable image, remove all sharpening, reduce contrast, reduce colour saturation, and you will produce a rather boring looking, soft in-camera image that you can make look wonderful in post production. That is the theory, and it is true, but the cost is that it takes a lot of time in post, and you don't watch nice rushes.

I hope that helps
Lucas
 
There's really no physical way to increase the 'latitude' of a CCD, unfortunately. Once the highlights hit that 100 IRE mark, you're losing detail almost immediately. I've seen it a hundred time on scopes. Like the others have said, you can try faking it with filters in camera and tweaking in post, but once the information is gone, there's no turning back. When you use the filters, already you've changed the overall image, so you might not get what you want.
 
Absolutely Lucas, all very good points. Whatever we do, we're still stuck with about 7 stops of latitude. The idea is to try and get everything in your scene to fall within those 7 stops so nothing is getting blown out and the blacks aren't falling into muddy grain. So the polarizer and Ultra Contrast filters really help in that respect.

And the Ultra Contrast filters reduce contrast (UC 3 reduces more contrast than a UC 1 yadda yadda...), sorry I didn't really make that clear. Similar to what raising the Master Pedestal does, but they bring out detail that the camera wouldn't normally see on it's own.

Peace,
S-
 
Also a good point. I'm sorry - I thought that contrast filters increased contrast - so I've learnt something there - thankyou, and sorry for being a know-it-all! You're absolutely right about decreasing the contrast in the scene with Polariser and contrast filters - we agree on the principals of what to do. What about Tiffens Low Contrast filter, as opposed to Ultra? It claims to take light from the bright areas and brighten the dark areas without darkenning the bright - how does that work??? They say it's the best contrast filter for achieving a film look with video...

Lucas

semila58 said:
Absolutely Lucas, all very good points. Whatever we do, we're still stuck with about 7 stops of latitude. The idea is to try and get everything in your scene to fall within those 7 stops so nothing is getting blown out and the blacks aren't falling into muddy grain. So the polarizer and Ultra Contrast filters really help in that respect.

And the Ultra Contrast filters reduce contrast (UC 3 reduces more contrast than a UC 1 yadda yadda...), sorry I didn't really make that clear. Similar to what raising the Master Pedestal does, but they bring out detail that the camera wouldn't normally see on it's own.

Peace,
S-
Click to expand...
 
Hey- no need for apologies, and I'm certainly no expert! I haven't used a Low Con filter before, but my understanding is that they create a slight amount of haziness around very bright areas, whereas the Ultra Cons do not. That haziness could really be a benefit too, because it should smooth out hard edges I'd think.

I had some free time this afternoon so I tried shooting some examples with and without the filters, but I should probably re-shoot them because I kept mangling the settings between shots (eh... the pictures should explain why I had problems...) and I wanted to try a 35mm adapter as well, which I didn't have enough light for as it turned out. Please keep in mind these were in no way scientific or well thought out tests. So...

I kept the polarizer on the camera for all of the clips to maintain a consistent exposure between images; it's just rotated to the point where it had the least effect in the "naked lens" and "ultra contrast" images. So "naked" is rather misleading. Sorry, I already flattened the images and it's 4am.

I had the Master Pedestal set very low at -11 where the blacks just started to clip on the waveform monitor. Again, this was set with the polarizer in a "neutral" position. The blacks are actually clipping in the top two images, even though it doesn't look like they're hitting zero on the waveform.

Full sized images here: http://www.flickr.com/photos/kmvlondon/



m
2923398305_8c9372b13f_b.jpg



2923395127_6d8b1fec46.jpg


Anyways, I was surprised that the Ultra Con brought down the highlights and smoothed them out as much as it did. I was also surprised that it didn't raise the black levels as much as I thought it would. But it seems like a good all around filter to just leave on the camera all the time.

Peace,
S-
m
 
Yeah, that is very helpful. The effect is a massive improvement. It effectively deals with one of the uglier aspects of video.

I may well get one of these, but my matte box is 4x4 and these things are unfathomably expensive - the two filters could cost me over £100 in resin and way more in the glass versions!
 
Lucas Adamson said:
I may well get one of these, but my matte box is 4x4 and these things are unfathomably expensive - the two filters could cost me over £100 in resin and way more in the glass versions!
Click to expand...

As far as the Ultra Cons go they're really not very expensive for the 72mm, I think it's under $100 USD, cheaper than my Heliopan UV filter. I just went with the 72 and never took it off the camera. I never realized how much good it was doing before I shot this.

There's really no cheap way around the polarizer though. I've got the same problem here- a new mattebox that I can't afford good filters for! But I may pick up a second Ultra Con and see what the results are with two of those. The pol is great for specific shots that require it and when you have time for setting them up, but you can pretty much set it and forget it with the Ultra Cons.

FYI- if you're using more than two 72mm filters on a DVX you'll start getting viginetting, so keep that in mind too.
 
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mounting a 72mm disc filter into in a piece of 4x4 plastic is an option too, I guess...There must be cheap adapters out there, no?
 
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