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Andy Webb
05-17-2017, 04:33 AM
I've been sent a photograph which I need to match the LW camera with.

Now the photo was taken on a Samsung S7, which according to Photoshop has a 35mm : 26mm lens?

The focal length used for the picture was 4.20mm, the question is what focal length is that for a 35mm camera?

I have set the scene up using LWs camera matching and with a bit of adjusting have a good match, this has given me 66mm focal length,
but is this correct? :)

Cheers

Ztreem
05-17-2017, 06:39 AM
I have no answer to your question, but I assume you have uses the match perspective tool to match the camera. Have you tried to use the real lens camera and use from image? this camera uses the meta information from the image and sets all the settings of the camera according to this info. I don't know if this helps or will get you any better result...

I would say if it looks good then it is good whatever focal length you got. :)

Andy Webb
05-17-2017, 07:57 AM
Ztreem thanks for your reply, I tried that but the settings were all greyed out :(

Ztreem
05-17-2017, 08:15 AM
I haven't tested this myself but maybe you can edit the metadata of an image yourself with the data you have and use that image as a setup for real lens camera.

http://www.colorpilot.com/exif.html

MonroePoteet
05-17-2017, 11:18 AM
You might look on the web for a similar image which does have metadata, for example here:

http://www.techradar.com/reviews/phones/mobile-phones/samsung-galaxy-s7-1315188/review/5

I was able to take the high-res photo of the columned building and use the "from image" in the Real Camera's Zoom Factor pulldown to load what looks like good data, then use the Render=>Match Perspective to line up vertical (green), horizontal (red) and depth (blue) lines to the building's lines and it appears to set up the camera very well for that image.

mTp

Thomas Leitner
05-18-2017, 03:47 AM
...The focal length used for the picture was 4.20mm, the question is what focal length is that for a 35mm camera?

I have set the scene up using LWs camera matching and with a bit of adjusting have a good match, this has given me 66mm focal length,
but is this correct? :)

Hi,
to convert the focal length you must know the size of the sensor.
What I found is that the S7 has a 1/2,5" sensor. Unfortunately this "sensor size" is not the real size of the sensor. Apparently, the real size is 6,69 mm x 5,55 mm. If this is true, 4,2 mm should be 14,2 mm for 35 mm Full Frame (this is more plausible than your findings: 4,2mm is more likely a wide-angle lens and 66mm is a little bit of tele).

To convert your focal length in Lightwave you have to use the real sensor height in your Camera properties "Frame" input (e.g. 5,55 mm for the S7). Than input the the known focal length to "Lens Focal Length" input (e.g. 4,2 mm). Change "Lens Focal Length" to "Zoom Factor". Than you can change the "Frame" value (Sensor/Image height) to your new Format (e.g. 35 mm Full Frame). Because "Zoom Factor" prescribe the field of view the focal length changes automatically.

ciao
Thomas

Andy Webb
05-18-2017, 09:03 AM
Thanks for the info.

I seem to have stop receiving email notifications so wasn't aware of these answers :(