HDSLR and Waveforms - overview

HDSLR and Waveforms - overview

I have a much larger project related to this in the works but I just wanted to quickly show you a little tidbit. 

Using a HDMI to SDI Mini Converter from either Blackmagic Designs or AJA Video, you can send a quality video signal to your SDI based video engineering equipment such as Waveform / Vectorscope from Leader. I've used both and I think that they're pretty much the same. Abel's version that's powered with Canon batteries uses the Blackmagic version I believe. 

For these little tests, I used the AJA. From the 7D, using the proprietary mini HDMI to full size, I hit the mini converter, from there I sent 1080 60i video from the box to my scope via SDI. 

This is a frame capture from the live video raster. For ease of illustration, the scene is a simple Kodak Gray Card in my living room. The raster captures from the Leader are always a little darker and a little warmer than what you see on the actual video. 

As you well know, there's no way to output clean, display free video from Canon SLR cameras. Let's hope they fix this in the near future. 

This is the waveform of the scene. The semi-opaque 16:9 matting and the white center marker are outlined with in red below. That is not part of the raster that's being recorded to card so if you use this method, you need to know what to look for on the waveform so that you can disregard it. 

Here is the scene on the vectorscope. Though the screen captures always look a little warm, we know our white balance is set correctly because our picture information is centered on the scope. 

Now let's have a look at the actual raster that was recorded to the CF card. 

And the accompanying waveform:

And side by side:

Quite close but let's have a look when they're on top of each other. The blue waveform is from the field and the red waveform is from the CF card:

Interesting eh? The codec seems to be compressing it a bit compared to the live video. It's very close though and if anything, it's better that your files are a little clamped down from the monitor rather than expanded. These cameras pretty much shoot WYSIWYG and with their reduced latitude and thin codec, all the more reason to use the right tools in my opinion. That is if you have access to them. If not, I've found that if I depress the shutter a little bit while shooting vid and call up the camera's built in light meter, that setting it right in the middle like you're supposed to results in pretty nice looking video. Pretty convenient actually.. Less stuff to carry and the results are just as good. Nice when that works out. There are plenty of situations where you're going to want a proper monitoring setup but for the average run and gunner, I think the built in light meter gets the job done. 

Next time there will be some much prettier examples but that's all for now ;)

More Canon 7D Test Vids

More Canon 7D Test Vids

I am loving this camera! It's so handy for pre-production - working out camera moves, finding placement and lens choice, working out blocking, etc. Nevermind the fact that it also shoots incredibly high quality raw stills and acceptable quality video. 

I'm trying to figure out if we can use the 7D for a time lapse shot on an upcoming job. I did this first time lapse test in medium quality jpeg just to get a feel for the process. I shot it out of my bedroom window in Brooklyn, NY from 10PM to 10AM. 1 frame per minute, Aperture Priority, f/4, ISO 400. I kept the white balance in Auto and I think for the next test I'll set it around 5000k and shoot in the large Raw file. There is an enormous amount of color temperature difference in available light between nighttime and daytime. At night in the city, it's orange with hard green spikes as street lights have a very low CRI. It then gets very, very cool as daylight approaches but the sun has not yet risen. As the sun appears and sunlight hits the color temp is in the 2800-3400k zone and then cools back off to between 5000-6000k once the sun has fully risen. These numbers are obviously crude approximations but you get the idea. Obviously with Raw, you can control these color temps and find an ideal setting for each time period. Or you can just find one setting that looks great for them all. I'm going to try 5000 Kelvin for my next one. I'm having fun with this and can easily see how it could become an obsession.   

Canon 7D Time Lapse Test 1 from Ben Cain / Negative Spaces on Vimeo.

Electronic Evaluation of the HDSLR Image

Electronic Evaluation of the HDSLR Image

It can be done! There are actually a couple of ways of doing it that I've been exploring. I'm going to show you how to do it and how it can help you capture better exposed and more robust HD images in the field.

We'll be doing a little video on the topic soon that will be available on Jem Schofield's amazing video resource site, The C47.

Stay tuned!

(also.. HDSLR, HD-DLSR, VDSLR, Video SLR... which one will stick?? I've got my money on HDSLR so I'm sticking to my guns.)