I'll have to closely re-read Ctein's argument which I just briefly
scanned. And I think I'm losing track of what's to be proven. I
thought the main point was that the distribution of the DOF changes
front to back with changing focal length. But I don't see in that any
argument for shooting from the same position. I shall have to actually
read deeply this time.
Chuck Norcutt
Jan Steinman wrote:
>> From: Chuck Norcutt <puhpxabephgg@xxxxxxxxxxxxxxxx>
>>
>> Very timely. Jan and Mike should find this interesting. Here's
>> more on
>> DOF and focal length (by Ctein) from The Online Photographer:
>> <http://theonlinephotographer.typepad.com/the_online_photographer/2009/06/depth-of-field-hellthe-sequel.html
>>
>
> I'm still willing to be convinced, but not by this article.
>
> Ctein writes: "I moved the camera to keep the on-film magnification
> [the same]..."
>
> He cheated. He clearly changed his position, and thus, the
> perspective. Sure, that changes DOF! But it would have changed it no
> matter the focal length.
>
> I will be convinced if he stands *at the same point* and shoots with
> the 25mm and 300mm lenses and a crop of the former to match target
> sizes shows DOF different than the latter. But I've actually done that
> to satisfy my own curiosity, and the DOF was identical.
>
> SUMMARY: if you move back and forth, it isn't the focal length that's
> changing DOF, it's the perspective.
>
> I'm still willing to be convinced, but you'll have to come up with
> something better than Ctein's article. :-)
>
> :::: There is no hope for any of us outside of a community. — Mike
> Ruppert ::::
> :::: Jan Steinman, EcoReality http://www.EcoReality.org ::::
>
>
>
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