35mm SLR lenses ona Digital SLR?

[cameron_inness]

I have a Canon EOS"50" SLR with a 28-80mm lense & a 75-300mm "IS"

lense and am wanting to upgrade the body to a Canon 30D Digital SLR

and would like to know what the effects on the lense "length' will

be effectively on my old lenses. I am hearing all kinds of

information and am fairly confused about it all, I am hearing there

is no effect on lense length to it will be factored up by 1.6 ie: my

300mm lense will effectively become a 480mm lense. Is this true and

if I buy what appears to be a standard digital lense 18-55 mm for

the Canon 30D will my other lenses be compatible? Will there be any

image quality differences between this lense and my existing lenses?

[Ken Katz]

The effect in your viewfinder will be a lenthing of the focal lenth of each lens by 1.6x. If the 28-80 is a Canon lens, there should not be any issues with compatibility.

[tommyinca]

IMHO, you should get the EFS 18-55 along with the 30D too. This way you have a wide angle while you decide the lens up-grade path should you want to. The 18-55 is a lot better then what you read in internet. Just use it at f5.6 and above (f8,f11 and etc). The 30D Field of view of the 28-80 will be 40-125mm compared to film camera. The 18-55 is more like (FOV) 28-85mm.

[peter_white2]

The 30D's digital sensor is smaller than your 35mm frame. So it's like cropping. It's not that your lenses somehow magically change their focal lengths. Focal length stays the same. Field of view shrinks because the sensor is smaller than the film, that's all.

[nolefan32]

The sensor in most of DSLRs on the market, including the 30D, is about 3/4 the size of a frame of 35mm film, so when it records an image, it effectively crops out the outer quarter of what most 35mm photographers are used to seeing. Hence the 1.6x multiplication factor that you've heard about -- because of the smaller sensor size, your 300mm lens will capture the information that a 480mm lens would when shooting film.

 

Canon has so far released two bodies with full-frame sensors, though, the 5D and the 1Ds Mark II. Neither is cheap, though the 5D is the bargain of the two (relatively speaking). With these cameras, there's no multiplication factor; your 300mm lens would still behave just like a 300mm lens, because the sensor is big enough to capture the entire image. A third camera, the 1D Mark II N, isn't full frame, but its sensor is still bigger than most, with only a 1.3x multiplication factor.

[oceanphysics]

This chip is not three quarters, but significantly less than two-thirds the size of a 35mm frame. 62.5% to be exact. So you lose 37.5% of the image linearly, and 61% in terms of area.

[andrew_certain]

I'm sure all your confusion is cleared up now.... :)

 

Imagine three images of a person's face, standing from the same distance away:

 

Image 1 was taken on your film camera with a 100mm lens.

 

Image 2 was taken on your film camera with a 160mm lens.

 

Image 3 was taken on a 30D with a 100mm lens.

 

If you print all of these images at the same size, say 4x6, so that the entire negative/

digital image is visible on the print (i.e. no cropping) then you will observe the following

things:

 

1) The face will fill roughly the same area of the print for images 2 and 3 (hence the

observation that there is a 1.6 lens-length multiplication factor).

 

2) The face's features will appear roughly the same (e.g. the size of the nose relative to the

size of the ears) for images 1 and 3 (hence the observation that it's only cropping).

 

2) If you were to blow up image 1 so that it were 1.6 times bigger (e.g. 4x6 -> 6.4x9.6)

and then crop it back so you only see the center 4x6 image, it would look exactly the

same as image 3.

 

For most people, they think mostly about how big an object will be in the frame, so it's

convenient to just think about the 1.6 multiplication factor.

 

Andrew