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neilp
06-01-2005, 03:09 PM
If I shot a digital photo with setting F8, how do I add this focal length correctly into the camera properties interface?

Lottmedia
06-01-2005, 03:36 PM
Need more information. I'm supposing that you're talking about the F-stop being 8, still, that's not enough information, it's only one small part. Most of the information I think that you're looking for in in the camera properties pannel. The F-stop isn't really signifigant, but again, I'm not sure what you're trying to do, so maby it is.
Give us some more information to work with and lets see....


J-Rod

hairy_llama
06-01-2005, 03:38 PM
f8? I am assuming this was your iris setting... just enter that into the DOF field in LW.
You also need to know your film back size or CCD/CMOS size for the DOF to work correctly. You also need to know the focal length of your lens and the focus point.

So to match up footage you need:
Camera coordinates. position and rotation.
Lens focal length(mm).
focus point.
film back size.
Iris setting.

lardbros
06-01-2005, 06:19 PM
It's not the easiest thing matching background plates to lightwave camera properties, but with all the info it can be done.

You probably know this anyway, but check out the advanced properties of the photo taken with your digital camera... lots of photo and camera statistics to get your head around.

Cheers,
Tim

badllarma
06-02-2005, 01:07 AM
I'm afraid to say this but there is NOTHING that in Lightwave will match your settings and apart from following the above advice from others the old trial and error approach is your best bet.

This has been a major querk of mine for some time that the setting in Lightwave are WA................................................ ......Y.out if you compaire them to say a 35 mm stills camera to get anything looking like F2.8 for instance you have to use negative numbers in the camera setting in Lightwave which is VERY poor.

Coming from a photographic back ground I know what F2.8, F11, F22 look like and lightwaves camera setting don't even come any where near. :rolleyes:

hairy_llama
06-02-2005, 10:30 AM
badllarma, did you set your film back size correctly?
It directly relates to the amount of DOF blur you are going to get.

neilp
06-02-2005, 10:39 AM
how do you set the film back size when using a digital SLR?

hairy_llama
06-02-2005, 10:56 AM
Get the CCD/CMOS size from your camera manual. Lightwave calls it
"aperture height".

neilp
06-02-2005, 11:34 AM
my cmos is 3088x2056 (pixels dimensions I guess)
question:
what is the correct way to enter this value into the aperture height numeric panel?

Exception
06-02-2005, 11:55 AM
my cmos is 3088x2056 (pixels dimensions I guess)
question:
what is the correct way to enter this value into the aperture height numeric panel?

that is not the film back size/cmos size. It's the cmos resolution.
Check out the technical specifications on your digital camera. The specs can either state the cmos size directly (as in, so and so mm or so and so inches) or it can say: 3/4th of 34mm.
I think only the Canon D1 MkII has a full size (35mm) image sensor.

wacom
06-02-2005, 12:08 PM
It's a fairly lame way to do it...but if all else fails I've seen it done this way.

you MUST messure the hieght of your camera from the floor/ground. Pray that you have a fairly flat surface.

Next, try and messure the angle your camera is at, many tripods will have degree markings etc.

Before you take your shot, put a box in the frame, on the ground where you can see it well (like dead center) with it turned 3/4. Messure the distance from the camera to the box. This shot will be your referece shot. Take a picture.

In LW model a "floor" and the box to exact dimensions.

In layout move your camera to the correct hieght, distance from the box and angle.

put your shot in the background in LW- make sure to get the aspect ratio correct in your camera settings so that they match your real camera.

Now you'll need to adjust the camera settings until you get close enough. After pulling all you hair out you'll then need to buy Worley's plug-in and/or the realeyes one so you don't die from an early death.

http://www.worley.com/taft/taft_cameramatch.html#topcameramatch

badllarma
06-02-2005, 12:11 PM
badllarma, did you set your film back size correctly?
It directly relates to the amount of DOF blur you are going to get.


Do you mean Aperture Height??? in the camera setting pannel? (Drop down menu of different camera set ups.

Never heard of the film back size? And by DOF Blur I take it we are all talking about DOF setting of AA of medium and above (in the camera setting pannel) and not the DOF Image filter.

Exception
06-02-2005, 12:25 PM
I don;t know of ANY camera manufacturer who doesn't put the cmos sensor size in their technical specifications.

Cmos sensor size / film back size: Aperture height in Lightwave.
This is a diagonal....
I think...

Lottmedia
06-02-2005, 04:09 PM
OK, so I don't mean to be rude or anything, but we seem to be spending a lot of time on something that just dosen't matter. The aperture setting dosen't matter one lick to LW. Once the picture is taken that's it, it's a still image. None of the settings really matter after the picture is taken (except maby for lighting information. If you're trying to do a camera match or set the image as a background plate then ok, but everyone needs to be on the same page and I feel like everyone is getting drawn off on their own things.
neilp, what exactly are you trying to do and lets work from there.

J-Rod

neilp
06-03-2005, 02:18 AM
I am trying to position a modeled building into an existing site photograph, yes I can tweak and change and use a little trial and error and get a convincing result, thing is I was exploring the more technical approach i.e. inpputing known physical camera data into the lightwave camera fields and analysing the results. The previous posts are valid in the respect that they illustrate the methods to convert the info required.
Below is a trial and error match for cc

neilp
06-03-2005, 02:19 AM
sorry here it is

neilp
06-03-2005, 02:46 AM
that is not the film back size/cmos size. It's the cmos resolution.

ok, I think I may have found my cmos: 22.7mm x 15.1mm.
how would I convert this into LW aperture height though?

Exception
06-03-2005, 06:39 AM
Ok, well, let's see.
Let's take a 60x45 rollfilm camera. The film back size of these camera's is either 60x45 or 45x60. LW's Aperture height setting for this is 1.7717". STUPID INCHES
Ok so 1.7717" = 45 mm

So for a 60x45 filmback, LW's aperture height = 45mm

Let's check this again...

90x60 mm filmback = 2.3622" = 59.99988

So apparently the aperture height is measured in the short side of the film...

So in that case, 35mm should not be an aperture height of 35mm...
35mm -> 1.0512" = 26.7

Checks out fine...

So, it seems this thing of Lightwave does NOT make sense. Why?
Well, a 60x60 mm camera can have a 60x45 mm film back. Same lens. No changes to the actual zoom or amount of mm focal point. Pretty nasty.

But so, taken as a rule you need the short side of your image sensor, or film back plane, and convert it to inches (1 inch = 25.4 mm, 1 mm = 0.03937 inch), then put that in your aperture height setting. Then take the amount of focal length that you took your picture at (non-zoom lenses: what is on the lens barrel, zoom lensen you will have to write it down, or check the EXIF information if it is a digital camera (rightclick the picture in explorer, choose properties, then summery, then Advanced, see attached picture)), and put that in the input field above Aperture Height while choosing 'Lens Focal Length' as its property.

So your image sensor is 22.7mm x 15.1mm. That means 15.1mm = 0.5945".
It would more or less compare to the 35mm motion film camera setting of 0.5906", if you can't remember the actual setting : )

then you're getting pretty close already. God hope you are not using a real technical camera with yaw control, because you can forget camera matching then.

neilp
06-03-2005, 07:46 AM
Exception, your support has been superb on this matter. I hope one day I may return the favour and help you out.
thanks a lot
neil