Jump to content

Dalsa Origin


Landon D. Parks

Recommended Posts

I have a few questions about the Dalsa:

 

#1: Is there any test's available on DVD yet? Or maybe even just a DVD about the camera in general?

 

#2: Is there a way to leave the 4k data 4k all the way through editing and then output to 35mm film @ 4k?

 

#3: How would the Dalsa store 4k data while on the set? What kind of recorder does it use, and is it huge?

 

#4: Is it renting yet? and from where? there website said it should have been available Nov 2004, but I still have not found it at any rental places.

 

thanks for any and all answer's you may have!

Edited by Landon D. Parks
Link to comment
Share on other sites

Why would you ever need or want to EDIT at 4K??? You'd just edit using lower-rez proxies or downconversions off of the 4K originals, then create a conformed 4K edited master using your EDL as a guide.

Ok, My bad. Well then offline it @ a lower resolution. But still, There should be a way to online edit @ 4k from your EDL.

 

Although trying to run 4k material through a computer would be fun at very least! Is there even a computer that could handle Online Editing / Color Correction in 4k?

 

Is your fridge moveable?

:o Holly Cow.... It certtainly Isn't the size of a fridge?

 

#6 What would happen if the magazine fell on operators feet?

:D :blink: :lol: :lol: :rolleyes: ;) :huh: :D :lol:

Edited by Landon D. Parks
Link to comment
Share on other sites

  • Premium Member
Is there even a computer that could handle Online Editing / Color Correction in 4k

 

There's no need. The way it works is that you work with a reference of the image at a perfectly viewable resolution (there's no point in working with 4K material when your computer monitor only does 1600 :D ) You don't need to see all the 4K pixels to color grade. So you work with a lower resolution at higher speed to create your settings, then have the computer(s) apply them to the original 4K material at a later stage - like overnight while the operator is in the bar.

 

So the indirect answer to your original question #2 is yes - you can start with 4K and end with edited / color graded / effected 4K. This is already the case for stuff shot on 35mm, scanned at 4K and with a 4K DI and film-out.

 

This works perfectly for 95% of work. Anything directly pixel based though will need to be seen at 4K to know if it is working properly. But this only relates generally to special effects, such as particle animation where the actual number or size of pixels drives an effect.

 

As for recording on the set, you just need a set of disks that can do something like 1.8Gb per second (assuming 16bit linear at 4K / 1.31 full height aspect ratio / 24FPS). We have something being put together for our post production storage that will do that, but you wouldn't want to carry it (or drop it, or shake it, or get it wet, or freeze it, or heat it, or get sand in it).

 

So for digital 4K recording, thats the main stumbling block - a practical disk that is capabale of that sustained speed in a sensible size and a sensible cost. Then you would need enough of them so you could film on one one day, then have it sent off to your post house for "emptying" (copying to thier big system) and then returned to the set. If this turnaround is 2 days, you need three of them. If 5 days, 6 of them etc.

 

Its just a matter of time. It was hard with 2K just a year ago, now it is perfectly practical - if you do it right.

 

David Cox

Baraka Post Production

www.baraka.co.uk

Link to comment
Share on other sites

Guest Jim Murdoch
#2: Is there a way to leave the 4k data 4k all the way through editing and then output to 35mm film @ 4k?

 

#4: Is it renting yet? and from where? there website said it should have been available Nov 2004, but I still have not found it at any rental places.

 

thanks for any and all answer's you may have!

Don't hold your breath. Seeing as the Dalsa has a 4:3 sensor with only six megapixels, I can't see how it could possibly produce a "4K" image, even in monochrome, and I'm certainly not alone in this! Attempts at getting clarification from Dalsa yield either dead silence or a lot of double talk. Or outright hostility. If that's some B.S. "up-res" figure, surely that would be better done in post, anyway. If nothing else, you'd get longer recording time!

 

Panavision's Genesis was also supposed to have been available in November last year and there's no sign of that either! I can tell you, it's really frustrating being retained as a technical consultant on new technologies when nobody will tell you anything that makes sense!

 

Frankly I don't know what they hell they're up to and neither does anybody else :(

Link to comment
Share on other sites

Actually, the dalsa has a 4k x 2k sensor, in what I think is almost 2:1 Aspect ratio. (Something like 1.98:1 or something.) Correct me if I'm wrong. And they actually advertise it as 8.2 Mega Pixels, not 4.

 

As for if its renting or not, it has to be. Because on the dvxuser forum someone posted a topic with pictures about a friend who shoot a short on the Dalsa. I wonder if the Dalsa Digital cinema center in woodland hills is open yet? That was suppose to have opend in January.

 

I must admit, the camera is pretty ugly and kinda, how do you say, BIG? And the recorder is not a big as I though, maybee about 4.8' high and 3' wide from the photos I'v seen.

 

dalsa0278.jpg

I think this is the recorder... I hope the person who took this photo dont mind me using it, If I knew who took It, I'd ask. But, I don't. So thanks to whoever took it!

Edited by Landon D. Parks
Link to comment
Share on other sites

That's not real 4Kx2K of image information, allthough if it is state of the art technology, it might just look like it is actual 4Kx2K resolution.

You need at least 24 megapixels to make a real 4K image.

 

The thing is that in this 4Kx2K field of sensors, you have mixed pixels of green blue and red information

 

The highest in resolution is the green chanel, and it records about 2K of resolution, blue and red record something like 1K resolution.

 

When you interpolate everything you probably do get actual scene information worth around 2K-3K resolution, while the result might look like a genuine 4K image.

 

Genesis does the real think of recording TRUE resolution of 2K wihout any interpolation.

Link to comment
Share on other sites

You need at least 24 megapixels to make a real 4K image.

 

Genesis does the real think of recording TRUE resolution of 2K wihout any interpolation.

 

 

Is that 24 megapixels for a full 35mm frame?

 

Genesis was billed as a 4K sensor at 12.4 megapixles.

 

I understood a Super 35mm frame 4096x3112 as 12.74 megapixels

Link to comment
Share on other sites

  • Premium Member

Hi,

 

I spoke to the Dalsa people at their NAB launch a couple of years ago, and we discussed it in terms of being a 4K sensor before Bayer. With every mathematical get-out in the world it's no more than a 3K real RGB image.

 

But hey, that's pretty respectable!

 

Phil

Link to comment
Share on other sites

Is that 24 megapixels for a full 35mm frame?

 

Genesis was billed as a 4K sensor at 12.4 megapixles.

 

I understood a Super 35mm frame 4096x3112 as 12.74 megapixels

 

 

4096x3112 pixels IS 12.74 megapixels BUT the story is a bit more complicated with Bayer pattern CCD devices.

 

8 megapixel camera has 8 million sensors. Now if you would want 8 million

color pixels out of that, each "sensor" would have to have 3 subsensors, but that is not how these cameras work

 

There are no subsensors for RGB colors. Instead out of thses 8 million sensors (4Kx2K) some capture green color, some red, and some blue.

 

Here is the pattern:

 

G R G R G R G

B G B G B G B

G R G R G R G

 

each letter is one "pixel"

 

So in a 4Kx2K sensor CCD, green is the luckiest channel as you can see,

it gets

 

2Kx2K pixels

 

blue gets: 2Kx1K

red gets 2Kx1K pixels

 

The actual optically captured resolution is 2Kx2K at maximum even thought the sensor has 4Kx2K sensors. Beyond 2Kx2K its just guessing for the missing holes in resolution and interpolating up to 4Kx2K

 

If you wanted a true 4Kx2K image, you would need 4Kx2K sensors for green, 4Kx2K sensors for red and 4Kx2K sensors for blue.

that is alltogether 24 millions of sensors, or what manufacturers call it 24 megapixels.

 

That is how genesis works, only it's for 2K resolution

 

Bayer pattern sensors at their less-than-perfect edition give artefacts.

 

You can see those in areas such as telephone wires wich don't appear solid black but have red green or blue outlines, usually all three like rainbow

 

The artefacts are similar to misregistration in YCM printing, only it appears on some critical areas only.

 

But I'm sure such an expensive peace of equipment could compleatly eliminate such artefacts. Of course you can never compeleatly get rid of that Bayer "look" at 100% magnification, but you can reduce it to the point where it acceptable, or even pleasant enough to view at 100%

 

On the other hand, when you scan a piece of film, the sensors are linear (tri-linear) and all 3 of them scan the exact same spot with some delay between one another, so there is no need for interpolation, only aligning of the 3 lines of pixels into one line.

 

So the bottom line is:

you need 24 millions of "pixels" because in the end they would combine to form 8 million pixels (4Kx2K)

Edited by Filip Plesha
Link to comment
Share on other sites

Ahhh ok.

 

On a tri-linear film scanner each color would have 4Kx2K sensor.

 

Or in the case of the Arriscanner which has one monochrome sensor that takes a picture of the frame three times in each color.

 

Either way you end up with the equivalent of 24 megapixels.

Link to comment
Share on other sites

Ahhh ok.

 

On a tri-linear film scanner each color would have 4Kx2K sensor.

 

Or in the case of the Arriscanner which has one monochrome sensor that takes a picture of the frame three times in each color.

 

Either way you end up with the equivalent of 24 megapixels.

 

 

Not really...

 

a trilinear sensor only has 3 lines of filtered monochrome linear CCDs

For 4K scanning, each line would have 4K active pixels, so that's only

around 12000 active photodiodes (0.12 megapixels)

These 3 lines combine into one after 3 steps of the head movement, or film movement, because each line has to pass over the same spot to make a full color line of pixels.

So then roughly, for 2000 lines (4Kx2K) you need to make 2000+2 motor steps to have full color color image of 4Kx2K

 

I think you have mistakened trilinear sensors for full resolution area sensors.

 

As for arriscan..

that trick has been used in medium format digital photography for some time.

The photographer uses 3 filters in front of the lens with 3 exposures to expose the monochrome CCD.

That is the only way to get a color image of the same number of pixels as the number of sensors on the device. For all the other options you either have to

have 3 times more sensors, or you have to "cheat" (Bayer pattern)

 

the only difference is that in the arriscan, the lightsource color changes, and in

photography, you change the filters on the lens.

 

Such procedure is used for still life or product photography, allthought I do think that it is less used todays as the Bayer sensors get better and better.

 

Some modern digital backs support up to 16 exposures for only one image, which produces high quality images.

 

So then these are the theorethical choices (and their "megapixel" counts) for capturing REAL 4Kx2K images:

 

-area sensors with 3 sets of filtered diodes, side by side (3x4Kx2K=24 "megapixels")

-trilinear sensor with 3 lines of 4K of diodes (12000 active diodes) and a motor that moves the head (or film)

-3 separate CCD devices, each for one color, again 24 megapixels total,

light is split by prism

-one area monochrome CCD used with 3 exposures (8 megapixels)

 

and one more option:

 

foveon X3 technology.

 

The sensor chip is covered with silicone. One of the natural characteristics of silicone is that different colors of light penetrate different dephs of siilicone.

So they take advantage of that and place 3 diodes one below each other at different dephs of silicone.

 

So then, for a 4Kx2K image, you would have 8 millions of "stations", and each

station would have 3 diodes at different dephs

Edited by Filip Plesha
Link to comment
Share on other sites

  • Premium Member
Holly Cow.... It certtainly Isn't the size of a fridge?

The drive rack that it records to is about the size of a 17 cubic foot fridge. The actual camera is only about the size and shape of the front third to half of a BNCR.

 

The chip has 4096 x 2048 photosites, but a column 50 wide on one side is metallized over as a black reference, leaving 4046 x 2048 active sites.

 

The width of the active area on the chip is about equal to the whole width of 35mm film, edge to edge, including the perfs. Typical lenses for 35mm motion picture cameras will vignette severely on that chip, 3000 or so wide is the most you could use with them. To use the whole chip, they might consider re-packaging still camera lenses.

 

 

 

-- J.S.

Link to comment
Share on other sites

  • 4 weeks later...

I know the guy in the picture (quite well I might say ;-)). I have also seen the new recorder (half the size).

 

It is true it is heavy but you don't need to move it because the optical cable connecting the camera to it it's about 200 m long (can be up to 1km).

Link to comment
Share on other sites

It is true it is heavy but you don't need to move it because the optical cable connecting the camera to it it's about 200 m long (can be up to 1km).

 

Sounds like you've had some experience with the camera. Can you elaborate on both working with it physically as well as the results?

Link to comment
Share on other sites

Is there something in particular that you would like to know?

 

Okay - yes. It has a reputation of being huge. Is that really a problem in actual use? Would one ever remotely consider taking it to a location?

 

What was your personal impression of the image quality? Have you seen the Genesis? How would you campare the lattitude. If not, how would you compare it to what you have seen?

 

thanks.

Link to comment
Share on other sites

Okay - yes.  It has a reputation of being huge.  Is that really a problem in actual use?  Would one ever remotely consider taking it to a location? 

 

What was your personal impression of the image quality?  Have you seen the Genesis?  How would you campare the lattitude.  If not, how would you compare it to what you have seen?

 

thanks.

 

Well, it's not small. But it wasn't a (big) problem; it might be difficult to fit the whole system (camera + recorder) inside a small car; but that's because of the recorder + UPS to power the recorder. I have seem footage shot from a minivan.

 

I have not seem Genesis footage yet. But Genesis is able to output only 10 bit compared to 14 bit of Dalsa. Dalsa is probably getting closer to film quality in terms of lattitude.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...