# some theory question...help thanks!

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#### Blankies

##### New Member
question is...

photo quality wise...when you dig zoom using software

6x opt zoom @2 meg == 3x opt zoom @4meg

or

6x opt zoom @2 meg > 3x opt zoom @4meg

or

6x opt zoom @2 meg < 3x opt zoom @4meg

or it is like orange to apple ???

#### mpenza

##### Senior Member
The accurate one:
3x opt zoom @4meg ~ 4.2x opt zoom @ 2MP

resolution ~ area, while optical zoom ~ length.

you need to take the square root, that is square root of (4/2).

#### Lennier

##### New Member
But you're assuming one thing, that the lens resolution doesn't change... which isn't true.

If you optical zoom, you're using the full power of your lens resolution to record the 'zoomed' in the picture.

When you digital zoom, lens resolution has to be proportionately reduced as well.

#### mpenza

##### Senior Member
yup, when you "digitally zoom a 4MP ~1.4x, you end up with 2MP left of image data/resolution.

#### Blankies

##### New Member
Originally posted by mpenza
yup, when you "digitally zoom a 4MP ~1.4x, you end up with 2MP left of image data/resolution.

so that is 4.4x @2 mega == 3x @ 4 mega ?

getting confused ???:bwhat:

#### mpenza

##### Senior Member
Originally posted by Blankies

so that is 4.4x @2 mega == 3x @ 4 mega ?

getting confused ???:bwhat:
just wondering what do you mean by your initial "equation"? guess the confusion starts from there.....

what I meant was that if you want to crop 2MP out of a 4MP pic (thereby achieving a zoom effect), the degree of zoom is 1.4x. So, if you took a 4MP using 3x optical zoom, and then you crop the middle 2MP out, the equivalent zoom is 1.4x3 = 4.2x. So, it's something like a 2MP camera with 4.2x optical zoom.

#### Blankies

##### New Member
Originally posted by mpenza

just wondering what do you mean by your initial "equation"? guess the confusion starts from there.....

what I meant was that if you want to crop 2MP out of a 4MP pic (thereby achieving a zoom effect), the degree of zoom is 1.4x. So, if you took a 4MP using 3x optical zoom, and then you crop the middle 2MP out, the equivalent zoom is 1.4x3 = 4.2x. So, it's something like a 2MP camera with 4.2x optical zoom.

oohhhhh that ar....yuan lai ru chi...

thanks man ! think i will hold my purchase till photokina over...till exams over...

PRAYING FOR PRICE TO DROP

:cry:

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