Crop factor question

Flash80 said:

I should know this, but am I correct that crop factor has the same
effect as digital zoom?

What I mean is that a 1.6 crop factor is not making a 500mm lens
800mm, it is merely making the viewfinder appear that way.

Thus, if you have a FF camera and you took the same pictrue at
500mm as with a 1.6 crop factor, you would merely have more of the
surrounding area in the picture with the FF. If you cropped the FF
to 1.6, you would have the same picture at the same resolution
(assuming both cameras have the same # of MP)

Is this correct?

Click to expand...

SCOR said:

Thus, if you have a FF camera and you took the same pictrue at
500mm as with a 1.6 crop factor, you would merely have more of the
surrounding area in the picture with the FF. If you cropped the FF
to 1.6, you would have the same picture at the same resolution
(assuming both cameras have the same # of MP)

Click to expand...

Flash80 said:

I should know this, but am I correct that crop factor has the same
effect as digital zoom?

What I mean is that a 1.6 crop factor is not making a 500mm lens
800mm, it is merely making the viewfinder appear that way.

Thus, if you have a FF camera and you took the same pictrue at
500mm as with a 1.6 crop factor, you would merely have more of the
surrounding area in the picture with the FF. If you cropped the FF
to 1.6, you would have the same picture at the same resolution
(assuming both cameras have the same # of MP)

Is this correct?

Click to expand...

Flash80 said:

I should know this, but am I correct that crop factor has the same
effect as digital zoom?

What I mean is that a 1.6 crop factor is not making a 500mm lens
800mm, it is merely making the viewfinder appear that way.

Thus, if you have a FF camera and you took the same pictrue at
500mm as with a 1.6 crop factor, you would merely have more of the
surrounding area in the picture with the FF. If you cropped the FF
to 1.6, you would have the same picture at the same resolution
(assuming both cameras have the same # of MP)

Is this correct?

Click to expand...

Flash80 said:

I should know this, but am I correct that crop factor has the same
effect as digital zoom?

What I mean is that a 1.6 crop factor is not making a 500mm lens
800mm, it is merely making the viewfinder appear that way.

Thus, if you have a FF camera and you took the same pictrue at
500mm as with a 1.6 crop factor, you would merely have more of the
surrounding area in the picture with the FF. If you cropped the FF
to 1.6, you would have the same picture at the same resolution
(assuming both cameras have the same # of MP)

Is this correct?

Click to expand...

P. Kierstead said:

Flash80 said:

I should know this, but am I correct that crop factor has the same
effect as digital zoom?

What I mean is that a 1.6 crop factor is not making a 500mm lens
800mm, it is merely making the viewfinder appear that way.

Thus, if you have a FF camera and you took the same pictrue at
500mm as with a 1.6 crop factor, you would merely have more of the
surrounding area in the picture with the FF. If you cropped the FF
to 1.6, you would have the same picture at the same resolution
(assuming both cameras have the same # of MP)

Is this correct?

Click to expand...

Very close....since you are cropping the FF, it would have to have
more MP to start in order for the crop to be the same resolution.
Basically you can crop the h3ll out of a 1Ds picture and still end
up with a lotta MP....getting an effectively much longer lens if
the number of MP is still enough.

Click to expand...

Flash80 said:

Thanks for the explanation.

If I go from my D30 to a 1D, i will be loosing length on the long
end, correct?

Click to expand...

SCOR said:

Does this mean with the 1.3 of the 1D I will be loosing out on some
length with my 50-500mm?

Click to expand...

SCOR said:

I'm still alittle fuzzy on the fact that I can't crop the 1.3 to
1.6 and get the same quality picture.

Click to expand...

Ron Parr said:

Flash80 said:

Thanks for the explanation.

If I go from my D30 to a 1D, i will be loosing length on the long
end, correct?

Click to expand...

A tiny bit, but the 1D seems to get more detail per pixel than the
D30.

Member said:

Does this mean with the 1.3 of the 1D I will be loosing out on some
length with my 50-500mm?

Click to expand...

Going by the pixel count, a tiny bit.

Member said:

I'm still alittle fuzzy on the fact that I can't crop the 1.3 to
1.6 and get the same quality picture.

Click to expand...

Go to the reviews of each camera and the following:

Start with the 1D and consider only the width (calculations for
height will be similar):

Divide sensor size by no. of pixels to get the 1D pixel size.

Now multipy the 1D pixel size by the D30 sensor length to get the
number of pixels the 1D fits into the length of the D30's sensor.
Now do the same for the width and multiply the two numbers
together. This will tell you the number of pixels the 1D uses to
cover an area as large as the D30's sensor. Call this number X.

If you crop a 1D image down to D30 size, X will be number of pixes
you're using to cover that area. I think you'll find that X is
slightly lower than the D30's resolution.

This is why cropping isn't the same.

--
Ron Parr
FAQ: http://www.cs.duke.edu/~parr/photography/faq.html
Gallery: http://www.pbase.com/parr/

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