An old question?

[jamesferguson2]

I am using a 28-70 mm lens designed for film SLR on a DSLR camera. What is the focal length correction factor to allow for the difference in distances between a film and digital capture. i.e at what focal length should I set the'film' lens to be equivalent to a 50 mm digital lens

[ap4a]

It depends on which system you're using. For Nikon and most other DSLR manufacturers their APS-C cameras have a crop factor of 1.5, whereas Canon's have a crop factor of 1.6.

So, 50/1.5 (33.3mm) or 50/1.6 (31.25mm) will give you the focal length you need for the same field of view.

You won't, however, get the same perspective or degree of subject compression at that focal length as you would using a 50mm on a 35mm body, as that's a function of the actual focal length used and not the field of view.

[pburness]

Hi James,
If its an APS-C sensor, which most affordable DSLR's are it's approx. 1.5 - 1.6x, so about 33mm on the lens should give you about the equivelent of 50mm.

Phil

[jamesferguson2]

Thank you ap4a and phil for your prompt reply. Now I also know what a crop factor is.