minolta 7d question

[backalley photo]

my buddy has a minolta 7d and i'm wondering if there is a chart anywhere that gives the 'digital' focal length for 'film' lenses.

he has a few zooms from his minolta film camera and was a bit surprised when i told him that they would be a different focal length because of the sensor size.

joe

[backalley photo]

thanks g'man!!

[Doug]

The focal length of the lens doesn't change due to its application on a different camera; it's the angle of view that changes because of the different size of the sensor/film. While it's handy in some ways to think of some different "equivalent" focal length, it adds a lot of misunderstanding at the same time.

[backalley photo]

it doesn't take much for me to misunderstand...;)

joe

[harbourlight]

Yup, "appear". I prefer the phrase "crop factor" because that's what's actually going on. The lens is focusing light the same way, but the sensor is not large enough to capture it all, so it "pre-crops" the image, fairly significantly. You'd maybe expect less quality this way, but it's also cropping into the sweet part of the lens. I find many classic lenses perform really well on a DSLR with a crop factor.

Gene

[dll927]

For many of us who tend to be mathematically challenged, this is still pretty simple arithmetic. As long as the 'factors' stay at 1.5 or 1.6, we should be OK.
It's just a matter of remembering it. Needless to say, the camera will do so without help!!

The whole thing works to advantage on the telephoto side of the spectrum. It's wide-angle that gets the short shrift. My 17mm lens that I bought for my (film) Maxxum 7 becomes about 26mm on my 7D. So you need a pretty miniscule focal length to really be ultra-wide on a DSLR.