It’s often asked and actually a lot but people get very confused when it comes to focal lengths of lenses when used on different sensors.
This is getting more and more confusing when cameras like the Sony F3 come out with kit lenses including the 35, 50 and 85mm and when I say to people you need to take into account the equivalent field of view of these lenses won’t be what you are used to if you are using a full frame camera. If you have only ever shot super 35mm film you will know what a 50mm will give you on the F3 or any other S35 camera (although some digital camera sensors differ slightly in size)
The thing is a lens is a lens. No matter what it is sold for or even stuck on. It’s always going to be a piece of glass that projects an image onto a sensor. It’s the field of view that matters. If I stuck a 50mm lens on a Sony Ex3 my magnification (or crop if you want) would be about 5.2x giving me an equivalent focal length on a full frame camera of 258mm….anyway, I can try and explain as much as I can but it’s best if I leave it to much cleverer people than me. AbelCineTech have done a great video and Field of View comparator. Click on the video image to see the video by Mitch Gross and the field of view calculator to see that. There are also some great iphone apps that help you with this. So remember, if you buy the Sony F3K kit your widest lens is a 35mm, this is not a very wide lens so you will need to budget for a wider lens to go with it.
My friend Mike Collins has done a simple video below these to show the difference between a 5dmk2 and 7d for FOV.
This is a short test with the tripod in the same spot switching between prime lenses to show how the crop affects the 7D. The subject, ace stand in Chris Clement, was roughly five feet from the camera. This isn’t meant to be an aesthetic test to show the difference in image quality between the two cameras. It’s a down and dirty field guide for myself and the other shooters we work with so we can quickly figure what lens we want to use on each camera.
We go from 20mm all the way to 100mm with a Lensbaby composer thrown in at the very end.