DOF and Cropping take 2

Started 10 months ago | Discussions thread
Ian Stuart Forsyth
Senior MemberPosts: 1,878Gear list
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Re: DOF and Cropping take 2
In reply to moving_comfort, 10 months ago

moving_comfort wrote:

Ian Stuart Forsyth wrote:

http://www.dpreview.com/forums/post/53084843

continued from the post above

Just a highlight key points I would like to address

red is Ian

Green is GossCTP

and Black awaldram

But I see it as equivalent please see below

Do you really believe this website above , I mean really ?

How accurate is the information they provide ?

.

That Cambridge Tutorials page is not very accurate, and that site has been debunked in the Nikon fora before.

Some folks are just not careful with their googling, and they still try to source it, adding to their confusion

.

As you can see that it calculates the same equivalent of lens and F stop as I had calc’d

Here is a quote from the site

“As sensor size increases, the depth of field will decrease for a given aperture (when filling the frame with a subject of the same size and distance). This is because larger sensors require one to get closer to their subject, or to use a longer focal length in order to fill the frame with that subject. This means that one has to use progressively smaller aperture sizes in order to maintain the same depth of field on larger sensors. The following calculator predicts the required aperture and focal length in order to achieve the same depth of field (while maintaining perspective).

As an example calculation, if one wanted to reproduce the same perspective and depth of field on a full frame sensor as that attained using a 10 mm lens at f/11 on a camera with a 1.6X crop factor, one would need to use a 16 mm lens and an aperture of roughly f/18. Alternatively, if one used a 50 mm f/1.4 lens on a full frame sensor, this would produce a depth of field so shallow it would require an aperture of 0.9 on a camera with a 1.6X crop factor — not possible with consumer lenses!”

And a reminder that whether you crop an image in the camera or in post with PS you are altering the size of the format, just as many do with a D7100 or a D800 in camera or during post

Now which site do I believe yours or mine?

Yours is of course correct.

http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm

Its kind of funny as Cambridge Tutorials has got this right and even their calculator is correct as this is what I used who would have thunk EH

& it looks like I am late to the party

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