W/A lens equivalent on different formats

[henry_kalen]

I use 35mm, 6x7 cm and 4x5 cameras. Is there a chart somewhere that

will tell me what lens on a 4x5 camera would be equivalent to a 14mm

lens on a 35mm camera? I know its got to do with angle of view, but

where can I find a list or method to determine the angles of view of

many focal lengths of lenses in the formats I use?

[al_kaplan1]

you really don't need to know the angles. You can just base your calculations on the size of the negative in relation to the focal length. The 35mm neg is 24mm across, most 120 cameras make an image 56mm across, and the short side of a 4x5 negative is perhaps 95mm. Assuming a crop of your 35mm to the same 4x5 ratio you have 24, 56 and 95mm lenses giving the same angle. the formula to figure the 4x5 equivalent of a 14mm lens on 35 would be 14 is to 24 as X is to 96. Since 24 goes into 96 4 times the answer is 56mm (4x14).

[m_.]

Al: With all the respect I have for how much you know about cameras and photography, I will have to disagree with your calculation. The seems-to-be-correct answer in calculating the focal length of a lens in different formats is to figure out the ratio of the diagonal lengths, not just the widths of the film. For instance, a 14mm lens in 35mm format will translate into a 35mm lens in 6x9 format. The reason is that a 35mm frame has dimensions of 24mm x 36mm that gives 43.3mm diagonal length, while 6x9 format has a frame size of 56mm x 86mm that gives a diagonal length of 102.6mm. So the ratio between the two is 2.37. But if you are to compare a 35mm frame to a 6x6 format (which by the way has a frame size of 56mm x 56mm that gives a diagonal length of 79.2mm), then the ratio is only 1.83. The equavelent lens of a 14mm lens in 35mm format on a 6x6 camera will then be 25mm.

[m_.]

By the way, the ratio between 35mm to 6x7 is 2.00, and the ratio bewteen a 35mm to a 4x5 is roughly 3.76. The 14mm equvelent lens is 28mm and 53mm, respectively.

[al_kaplan1]

The diagonal measurement only makes sense if we utilize the entire frame. If we print to standard paper sizes (8x10 for example) or magazine page size, all negative formats are going to be cropped to the same shape so it doesn't matter if you measure short side or diagonal OF THE AREA USED.

[m_.]

If we are going to talk about the cropping, then the angle of lens is irrelevant and cannot not be compared. A 35mm lens on 35mm camera can be crop to the same view (or similar anyway) to a 50mm lens on the same camera body. The only reason to figure the "equivelent" lens on different formats is the full frame comparison, IMO. But hey, photography is not about the science so who cares. Al, your website is impressive and the images are great. Would love to see more of them.