Implications of crop factor

[altair8800]

While it is true that the object size on the sensors is the same with the same lens, the view in the viewfinder of the 30D will be magnified by 1.6x compared to the 5D. Uncropped prints from the 30D will be magnified by 1.6x compared to uncropped prints from the 5D.

With the 200mm lens mentioned in your OP, the 5D would need a 320mm lens to match the 30D view. Or you could crop the 5D image, but you would end up with a 5 mp image.

Dan

Your logic in the paragraph below seems to make a lot of sense. Then
in that case when I use a 50 mm lens with a FF or crop frame camera,
the magnication of the object stays the same, just that with the FF,
I have more of the surroundings of the object. Very, very interesting
indeed - thanks!

Note below, he is talking about DoF staying the same, not maginification.

Well, the same rules above apply. If you take the FF shot, print at
8"x12", then crop off the sides down to 6"x9", you have the same
image as the APS-C camera. Now, if you blow that image up to 8"x12",
you can imagine how it will compare to the original FF shot. DoF will
apparently decrease (even though it didn't really decrease)
because you blew up the image. I say it apparently increased without
really increasing because, if you enlarge any photo, whether taken on
a FF camera, APS-C, medium format--whatever--you're not changing the
DoF. However, things that were out of the focal plane that seem sharp
on a small image will show as blurry on an enlargement. Many
photographers mistakenly conflate apparent decreases in DoF with real
decreases in DoF (even though they'd never make the same mistake when
simply making an enlargement).

 

[Ron_M]

http://doug.kerr.home.att.net/pumpkin/FOV_Crop.pdf

I've a question about the crop factor of 1.6 translating a 200 mm
lens into a 320 mm lens. Is this increased zoom seen in the
viewfinder or only by the sensor? The reason I ask is because in an
SLR, the image in the viewfinder does not have anything to do with
the sensor (correct?)

--
Ron_M

 

[Izzy5156567]

the 10D/20D/30D/40D all put more pixels in the same image area
compared to the 5D cropped to the 1.6x viewing area, so they are all
generally regarded to have 'more reach'. The original claim that the
image is the same in both cases, with the same number of pixels, is
wrong.

The 200mm lens mounted to a 1.6x body will provide the same field of
view as a 320mm lens mounted to a 1.0x body. If you try to use the
same 200mm lens on both bodies, then crop the 5D to the same 320mm
field of view as the 1.6x body, you will have less pixels in the 5D
crop.

Even an xTi (400D) puts more pixels in the same image area than the 5D does.

So unless you are pretty much filling the frame with the 5D, a 400D will put more pixels on a subject.