Perspective vs. FOV

stevebrot · 09-28-2008, 06:50 PM

Just for the record, I warned against opening the DOF can of worms. If there is anything more confusing than explaining what determines perspective, it is explaining the intricacies of depth of field. Now the worms are loose...

Steve

BTW...Six months ago I was a firm believer that wide-angle lenses would give you exaggerated perspective and greater DOF as a property of the optics. Based on the challenge of some forum members, I set up the test images and proved myself wrong on both counts.

Last edited by stevebrot; 09-28-2008 at 06:58 PM.

Wheatfield · 09-28-2008, 07:06 PM

Originally posted by baw

I'm fine with a statement like: For a given FOV DOF is the same for different focal lengths. At least it seems to be so.
My point is that the article clearly implies that DOF is independant of focal length, which is nonsense.
I'm a bit surprised by this article. I had a high regard for Luminous Landscape....

Depth of field is a relationship between the size of the aperture and the reproduction ratio, nothing more.
Focal length is not part of the relationship.
And Steve, yer welcome...

stevebrot · 09-28-2008, 07:16 PM

In case anyone is interested, here is a link to the other thread where all of this stuff was discussed in detail a few months ago:

https://www.pentaxforums.com/forums/general-pentax-photography/30632-85mm-vs-...ification.html

Steve

baw · 09-29-2008, 01:51 AM

Originally posted by Wheatfield

Depth of field is a relationship between the size of the aperture and the reproduction ratio, nothing more.
Focal length is not part of the relationship.

Seems you have invented a whole new defintion of DOF. Perhaps you can explain what the relationship is. It's also unclear to me what you mean with reproduction ratio.

DOF is normally defined as a range of distances in front of the lens within which objects are reproduced ACCEPTABLY sharp in the resulting image.
See this page with a number of similar definitions and references.

wildman · 09-29-2008, 02:29 AM

One was taken with a Sigma 105mm macro at about 2 to 3 feet.

One was taken with a 560mm astro scope barlowed to an effective FL of 1100mm (about 30x magnification) with extensions to move focus closer. About 25 feet or so.

Can you tell which is which?

09-28-2008, 06:50 PM	#31
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	I told you so... Just for the record, I warned against opening the DOF can of worms. If there is anything more confusing than explaining what determines perspective, it is explaining the intricacies of depth of field. Now the worms are loose... Steve BTW...Six months ago I was a firm believer that wide-angle lenses would give you exaggerated perspective and greater DOF as a property of the optics. Based on the challenge of some forum members, I set up the test images and proved myself wrong on both counts. Last edited by stevebrot; 09-28-2008 at 06:58 PM.

09-28-2008, 07:16 PM	#33
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	In case anyone is interested, here is a link to the other thread where all of this stuff was discussed in detail a few months ago: https://www.pentaxforums.com/forums/general-pentax-photography/30632-85mm-vs-...ification.html Steve

09-29-2008, 01:51 AM	#34
baw Senior Member Join Date: Dec 2006 Location: Neterlands Posts: 189	DOF Originally posted by Wheatfield Depth of field is a relationship between the size of the aperture and the reproduction ratio, nothing more. Focal length is not part of the relationship. Seems you have invented a whole new defintion of DOF. Perhaps you can explain what the relationship is. It's also unclear to me what you mean with reproduction ratio. DOF is normally defined as a range of distances in front of the lens within which objects are reproduced ACCEPTABLY sharp in the resulting image. See this page with a number of similar definitions and references.

09-29-2008, 02:29 AM	#35
wildman Veteran Member Join Date: Jun 2008 Location: Flyover America Posts: 4,469	One was taken with a Sigma 105mm macro at about 2 to 3 feet. One was taken with a 560mm astro scope barlowed to an effective FL of 1100mm (about 30x magnification) with extensions to move focus closer. About 25 feet or so. Can you tell which is which? Last edited by wildman; 12-26-2008 at 01:00 PM.

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09-28-2008, 07:06 PM	#32
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,981	Originally posted by baw I'm fine with a statement like: For a given FOV DOF is the same for different focal lengths. At least it seems to be so. My point is that the article clearly implies that DOF is independant of focal length, which is nonsense. I'm a bit surprised by this article. I had a high regard for Luminous Landscape.... Depth of field is a relationship between the size of the aperture and the reproduction ratio, nothing more. Focal length is not part of the relationship. And Steve, yer welcome...