Sponsor Message:
Aviation Photography Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Help! Depth Of Field  
User currently offlineILUV767 From United States of America, joined May 2000, 3141 posts, RR: 8
Posted (12 years 9 months 2 weeks 1 day 1 hour ago) and read 1786 times:

Hi everyone,

I am in a begining photo class at my school, and I was wondering if one of you could give me a solid definition for depth of field? What factors affect it? I have very little understanding of it, and I have a test on it tomorrow.

Your help is greatly apreaciated.

I L U V 7 6 7

4 replies: All unread, jump to last
 
User currently offlinePUnmuth@VIE From Austria, joined Aug 2000, 4163 posts, RR: 54
Reply 1, posted (12 years 9 months 2 weeks 1 day 1 hour ago) and read 1769 times:

Depth of field is mainly influenced by the aperture you are using. The higher the number the more depth of field the lower the number the less you get.
Depth of filed describes which parts of the picture are in focus. Low depth of field: The main subject you are focussing on is sharp and the fore and background are unsharp. Higher depth main object you are focusing on and parts of the fore- and background are sharp.
Peter



-
User currently offlineJan Mogren From Sweden, joined Dec 2000, 2043 posts, RR: 51
Reply 2, posted (12 years 9 months 2 weeks 1 day ago) and read 1758 times:

Factors affecting depth of field are:
1. Aperture (Peter described this)
2. Focal length (The longer the lens, the shorter depth of field)
3. Focusing distance (The closer the object, the shorter the depth of field)

/JM



AeroPresentation - Airline DVD's filmed in High Definition
User currently offlineCkw From UK - England, joined Aug 2010, 730 posts, RR: 16
Reply 3, posted (12 years 9 months 2 weeks 22 hours ago) and read 1747 times:

One final detail - depth of field extends further beyond the point of critical focus than it does ahead of it.

Cheers,

Colin



Colin K. Work, Pixstel
User currently offlineCfalk From , joined Dec 1969, posts, RR:
Reply 4, posted (12 years 9 months 2 weeks 16 hours ago) and read 1737 times:

Depth of field (or DOF) is, as stated above, a measure of how much of your picture will be in focus.

No lens will have everything in focus, from a section of chain-link fence touching the lens right out to infinity. when you focus on an object, say 10 feet away, you may have, for example, everything between 8 and 15 feet away in focus, but the horizon and stuff in the forground less than 8 feet away is blurry. In this case, you depth of focus is 8 to 15 feet. Most old SLRs and some new ones have a function which will actually let you "preview" the depth of field.

Depth of field depends on 2 things: 1) the design of the lens, and 2) the aperture that you use. (Shutter speed has in itself no relation at all to depth of field.) The first one, you can't do anything about (other than buy another lens). But the second you have control over. The larger the aperture (which is equal to low f/stop numbers, like f/2.8), the smaller the depth of field will be. Portrait photographers often use lenses with very wide apertures, as it allows them to have the subject in focus, and all the backgroud be totally blurred, which prevents background feature from distracting attention from the subject.

A small aperture (equal to a high f/stop number like f/16) will give you a much larger depth of field.

If you focused on a specific object at 10 feet away, at f/2.8 your depth of field may be in the range of 9 feet (inner-limit DOF) to 12 feet (outer limit DOF). At f/22, your depth of field maybe from 2 feet to 60 feet.

Note when you look at the focusing distances on your lens (any lens) are not linear, but logorithmic. This results in that as your depth of field changes by changing the focusing point (keeping the f/stop constant) the distance in absolute terms of your outer limit DOF changes faster than your inner-limit DOF. Theoretically, the inner and outer limit DOF will intersect right in front of the lens, 0 inches away.

One concept that very few people use because of the popularity of rotating ring-type zoom lenses is hyperfocal distance, which is immensely useful, as it eliminates any calculation or trial and error needed to get the correct depth of field. Tell me if you want a description of that. But you won't be using that if you use most zoom or AF lenses.

Cheers,

Charles


Top Of Page
Forum Index

This topic is archived and can not be replied to any more.

Printer friendly format

Similar topics:More similar topics...
Help! Depth Of Field posted Tue Oct 2 2001 06:49:26 by ILUV767
Suggestion To Help Quality Of Categories posted Fri Apr 25 2003 20:17:43 by TZ
Amazing Wing Drop/Depth Of View? posted Sat Aug 17 2002 10:15:57 by Luftaom
Is Copying Of Files In The Field Possible posted Sun Nov 12 2006 20:03:58 by THVGJP
Tad Bit Of Help Please! posted Mon Jun 12 2006 21:48:59 by BmiBaby737
Help! 1st Shots Of New Airline Go! Rejected. posted Tue May 9 2006 06:24:10 by Phxplanes
Help/criticism Required On One Of My First Uploads posted Fri Apr 14 2006 01:47:24 by Aviamil
A Little Of Help Please - Preupload posted Thu Mar 9 2006 09:22:06 by Glapira
A New Idea, But Need The Help Of Everybody posted Sun Mar 5 2006 17:17:51 by Glapira
Help - Snow In Front Of Wheel = Rejection? posted Sat Feb 18 2006 08:56:05 by Frippe