Digital SLR, old 35mm film lenses and f stops

[johnymac]

Hi All, I was just wondering about the use of 35mm film lenses on digital SLR cameras. I understand that they have the effect of magnifying by about 50% but what about the aperature? Is f4 the same regardless or is there magifying effect on this also?
John

[Mr Will]

johnymac said:

Hi All, I was just wondering about the use of 35mm film lenses on digital SLR cameras. I understand that they have the effect of magnifying by about 50% but what about the aperature? Is f4 the same regardless or is there magifying effect on this also?
John

Focal lengths don't change between film and digital. A 50mm lens is a 50mm lens on either. Most digital cameras use a smaller sensor though, which effectively crops the image by a factor of 1.5 or 1.6 depending on brand. This means that f4 is still f4 for the purposes of shutter speed but the depth of field will be larger because of the requirement to be further away to achieve the same framing.

[nellyleelephant]

Aperture stays the same, as does focal length.

You just see less of the available field of view that the lens has when used on a crop body.....it pre crops it for you!

[johnymac]

Thank you guys.