Different sensor aspect ratios are simply different rectangular crops of that circle. The view angle of this lens is the angle of the cone that corresponds to the image circle.
Think of it this way: the lens projects an image circle on the sensor plane. You're getting confused over view angles and aspect ratios. IMO, in order to know the angle of view linked to the diagonal, you have to divide the 4x3 diagonal angle of view by 1.09 that is the meaning of the computations made by the second poster in this thread. This is easy to understand : if you keep the same sensor and the same lense, the angle of view can't increase however, since you are cropping something at the bottom and the top, the angle of view linked to the height will diminish and the angle of view offered by the diagonal will diminish too, although less dramatically than that of the height. Since the 16x9 ratio is only a crop of the 4x3 ratio, this angle of view (aka the width of the landscape caught by the lense) would remain the same, for the two aspect ratios. IMO, the most important angle of view (the one by which you judge whether you have a wide angle view or not) is the one going from the left side to the right side (aka the picture width). I think it is not as great as you think (a preceeding post already explained why). So I just don't see how you can somehow all of the sudden start talking like this somehow relates to the full-frame 135 format. Remember your original post's question posited was comparing the 4:3 and 16:9 aspect ratios of the u4/3 sensor. I think you're reading into this calculation some sort of hopefulness that wasn't intended. This conversion is intended to compare the 4:3 and 16:9 aspect ratio of the u4:3 sensor's angle of view, AND NOT intended to compare either u4:3 aspect ratio with the 135 (so-called "full-frame") format. I think the 1.09 multiplier needs to be applied to the original 4:3 aspect ratio angle of view, such that (from your original post) 57 degrees time 1.09 equals 62.13 degrees. can that be right? that by using the 16:9 aspect ration you have the field of view of a 24mm lens on a 35mm camera? if so, that would be simply outstanding, 24mm is one of my favorite focal lengths. Most notably about halfway down the page at: "Angular Field of View Calculator"īut if i understand your conclusion correctly, instead of using the 2x focal length multiplier for 4/3rds, i.e., 20mm x 2 = 40mm, you use 1.09x which would mean 20mm x 1.09 = 21.8mm.
I'm not embarrassed to say that most of your math went over my head! but in following search results based on your equations i did find some very useful calculators at: Of as compared to 40mm where the angle of view is given at >ĥ7degrees. If you are using a 40mm lens on the gf1 at 16:9 aspect ratio, what is the >Įquivalent angle of view? or, in other words, what is the equivalent focal length > Since 16*9 crops 4/3rds, it has a smaller diagonal with a focal length multiplier of 1.09, although a focal length multiplier doesn't really work when comparing different aspect ratios. Make sure that your calculator is in degree mode if you are calculating in degrees. SideToSideAngle = 2 * ArcTan( tan( CornerToCornerAngle / 2 ) * 4 / 5 )Ģ * ArcTan( tan( 57 degrees / 2 ) * 4 / 5 ) = 46.96 degrees
I think the side to side angle would be calculated as: The 4/3rds sensor's 2 side lengths and diagonal form a convenient 3, 4, 5 integer side ratio right angle triangle. To convert the corner to corner angle to left to right angle requires a bit of trigonometry. Most lens angles are given from corner to corner. That means that the angle from left side to right side remains the same as on standard 4/3rds. According to DPreview, the Gf1 has the same 4/3 " (18.00 x 13.50 mm, 2.43 cm²) sensor size of the standard 4/3rds cameras, so to get 16*9, the top and bottom of the image are cut off. You probably care more about the angle from left side to right side than the diagonal from corner to corner. If you are using a 40mm lens on the gf1 at 16:9 aspect ratio, what is the equivalent angle of view? or, in other words, what is the equivalent focal length of as compared to 40mm where the angle of view is given at 57degrees.