Focal lenght

[kris]

I need to make photomontage and when I open photo in Photoshop I can see in preferences focal lenght is 5,7 mm.

 

What lens of camera in 3dsmax I have to use and how to calculate that becouse its not the same in digital camera and 3dsmax camera.

[Crazy Homeless Guy]

in my experience the best way to line up a photomontage is to set the image as a background in max, then move and adjust the focal length, position, and rotation of the camera as needed. it will save you a lot of time and headache.

[kris]

Yes I do that all the time but it would be much easier if I dont have to think on focal lenght.

I think there must be the way to calculate that.

[klaas]

the focal length in digital cameras is quite different than analog ones, I thought. The focal length in Max corresponds with analog focal length.

 

You should find out the focal range of the camera the picture was taken with and find some documentation. Most of the time these cameras say the have a range from 35 to 80 mm (for example). This means they correspond with the analog focal length of 35 to 80 mm. Their actual focal length is much smaller. So your 5.7mm might be 28mm in max?

 

klaas

[kris]

So thats aproximatelly 5 times more. Is there a way to calculate it corectly becouse i think its more 35mm than 28mm in my photomontage.

[random]

what camera model was used for taking the photos?, google for the camera specs if you don't have the documentation, you should be able to find the equivalent focal length to a 35mm camera.

 

if the photo was taken using the minimum or the maximum focal length for that camera then you just replace the focal length value with the corresponding equivalent focal length value, but if an in-between value was used, then you have to find the lmf(lens multiplier factor), which is just dividing the equivalent focal length by the actual focal length, and then multiplying that number by the actual focal length used to take the picture;

here's an article explaining that and also other methods in case you can't find the focal length specs for that particular camera

 

http://www.outsight.com/hyperfocal.html#digital