Trad Gang

Main Boards => Photography/Video Q&A Board => Topic started by: Chad Edgar on February 08, 2006, 07:31:00 AM

Title: Depth of field and lens size
Post by: Chad Edgar on February 08, 2006, 07:31:00 AM

I understand that use of f/ to limit the depth of field in an image.  My camera allows me to open it up to 2.8.  However I can't seem to "isolate" my subject, everything stays in focus.  Is there also some relationship to lens size in getting that creative exposure or am I missing something.  38-380 equivalent lens on the FZ740!  I could also buy a wide angle lens that would get me to 26.6mm if it will help.

Title: Re: Depth of field and lens size
Post by: Killdeer on February 08, 2006, 06:20:00 PM

Have you an example, Chad? You are on the right track, a wide open aperture leads to a shallow depth of field, allowing you to "posterize" the background. The further behind the subject that background is, the more pronounced the effect. The closer you are to your subject, the more pronounced the effect.

Killdeer

Title: Re: Depth of field and lens size
Post by: Killdeer on February 08, 2006, 06:24:00 PM

(http://img.photobucket.com/albums/v249/Killdeer/YCNH2cmp.jpg)

Title: Re: Depth of field and lens size
Post by: jcsnapshot on February 08, 2006, 06:24:00 PM

Chad, the shorter the focal length, the greater the DOF.  Here is a link to an   Online Depth of Field Calculator (http://www.dofmaster.com/dofjs.html)

Title: Re: Depth of field and lens size
Post by: Hutch on February 08, 2006, 10:30:00 PM

One other thing I've just come across is that the depth of field on a SLR/DSLR is different than what is in a point and shoot type digital. The point and shoot has a greater depth  than the SLR type cameras. " f2.8 is equivalant to f11 on an SLR." This comes from the auther of the book Understanding Exposure by Bryan Peterson. Published by Amphoto Books. ISBN 0-8174-6300-3

Just something to think about.


Hutch

Title: Re: Depth of field and lens size
Post by: Weasel on February 08, 2006, 10:57:00 PM

Bryan Peterson knows what he's talking about.  I'd be interested in an explanation of WHY they are the same.

Title: Re: Depth of field and lens size
Post by: Chad Edgar on February 09, 2006, 07:31:00 AM

Neat pic Killdeer!  I don't have any examples, since everything is in focus.  Interesting to note jcsnapshot.  So combining Killdeer's and your suggestions I would want to get as close as possible to my subject, keep as much "space between my subject and the background as possible, and increase my focal length.  I always assumed that the 38-380 is the focal length.  If so, do I want to be in telephoto or is that one of those quirky fractions like f/ and speed???  Hutch and Weasel, I read that book.  The only book I have ever read about photography!  I will have to go back and look up that chapter, can't recall that point he made.  I really liked the chapter on "creative correct" exposures.

Title: Re: Depth of field and lens size
Post by: Weasel on February 09, 2006, 10:03:00 AM

38-380 is the focal length range. The longer the focal length, the easier it is to isolate your subject.

This was taken with a 100-400 at about 300mm @ f5.6.  The background was about 60 yards away.

  (http://img.photobucket.com/albums/v323/jgowins/blueheronheadtradgangweb.jpg)

Title: Re: Depth of field and lens size
Post by: Chad Edgar on February 09, 2006, 01:36:00 PM

:thumbsup:

Title: Re: Depth of field and lens size
Post by: Hutch on February 09, 2006, 07:28:00 PM

Its on page 46. Jerry, once again awsome pic!!


Hutch

Title: Re: Depth of field and lens size
Post by: Killdeer on February 09, 2006, 08:28:00 PM

Wonderful frame of my hunting mentor there, Weasel! I can watch those guys all day.

Killdeer  :D

Title: Re: Depth of field and lens size
Post by: Weasel on February 09, 2006, 08:38:00 PM

Thanks!

Title: Re: Depth of field and lens size
Post by: Weasel on February 16, 2006, 03:16:00 PM

Depth of field explained:  http://www.outdoorphotographer.com/content/2006/mar/depthoffield.shtml

Title: Re: Depth of field and lens size
Post by: NEArcher on February 16, 2006, 09:46:00 PM

Jerry, wow. I guess thats a good example of what all us amatures are aspiring to!

Title: Re: Depth of field and lens size
Post by: Weasel on February 17, 2006, 01:21:00 AM

Thanks!  However, the heron was easy.  He even has a name, "Mooch".  When folks are fishing at the local park for hatchery trout (a.k.a. "pellet heads"), Mooch waits patiently nearby for handouts.  He will let you approach within 15'-20' if you stay close to the fishermen.

Title: Re: Depth of field and lens size
Post by: Steve Kendrot on February 21, 2006, 12:08:00 PM

(http://i33.photobucket.com/albums/d83/skendrot/GBHE_001copy.jpg)

Since Herons seem to be the theme...Here's one I captured in the everglades. Found the depth of field can be pretty finicky. Herons looking at you would have a bill out of focus if aperture was too wide. Having fun anyways!