# Depth of Field?



## dubnut71 (Jul 25, 2006)

Guys - Took this today









And the exif data shows it as F3.5 (as low as my lens will go) the cam was on aperture priority mode (D80) Strangely enough the exif data doesnt show the shutter speed.

My question is this, I am keen to get this type of effect (eg foreground in focus only) but dont really understand the option for depth of field and the DOF preview button just darkens the viewfinder, not sure what that is meant to show me.....

Again these 2 are at (low??) depth of field and this is the type of effect I am going for, any comments??

Semme like getting the a/f to latch onto the foreground is the same effect but I am sure I am confusing the 2 key principles of photography here.

I have read a heap of posts on DOF but still dont get it truly, I must be a bit thick.....


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## dino (Oct 26, 2005)

I only just understand it myself so I'll be a simple as i can.

The lower the F number is means it's a high F number (stupid!!) so therefore the higher the F number is the less of the background is in focus. if you set the F number lower the majority of the picture will be in focus.

does that help at all?


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## dino (Oct 26, 2005)

The pictures with the F number on these sites helped me understand it better than all the jargon i've read;

http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/950/depth-of-field.html
http://www.cambridgeincolour.com/tutorials/depth-of-field.htm


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## dubnut71 (Jul 25, 2006)

Dino,

Thanks for that it does help a bit (although I think I am definately in the circle of confusion...!!)

So the lower the number the higher the aperture.......

The lower the number the less of the background / foreground is in focus around the point of focus???

Se I told ya I was thick., cant get the 2nd link to work but possibly my connection.


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## giarc (Feb 8, 2006)

my understanding is that if you increased the zoom, (effectively the number of stops (f's)) then the DOP would increase.


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## john1.2pearl (Jan 12, 2007)

just starting out with DSLR photography myself so as i understand for a limited depth of field you need to use a large aperture and a short telephoto focal range, so anything from 50mm upwards and use the largest aperture at that focal range and remember DOF reduces the longer the focal length get
:thumb:


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## nzgunnie (Feb 3, 2007)

John got it right. F2.8 will give you less depth of field than f8. This effect is enhanced with e telephoto lense. Also this effect is enhanced if you are close to what you are photographing, If you are working nearer infinity on your lens, most of the image will be in focus.

As for depth of field preview button, what this does is forces the aperture to close to what you have it set to, so you can actually see what the depth of field will be.

Lenses by default are held wide open until you take the photo, then they close down to the apperture selected, the shutter opens and closes, then the apperture open up again. All rather quickly of course.

This is to let lots of light into the view finder for composition and focusing.

All that depth of field preview does is let you see what the image will look like stopped down. Generally this will be darker, because most photos wont be taken at the widest apperture, so less light gets through. You can see, if you look carefully, what is and what is not in focus.


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## dubnut71 (Jul 25, 2006)

John / NZgunnie and all, thanks for the help I am slowly getting it!!!!!
After taking a range of shots at 2.8 all the way to 22.

I hadn't factored for the fact when I zoomed in the focal area also moved (simple huh?).

Am trying to use the cam mainly on aperture priority or full manual and not rely on the point and shoot settings no matter how excellent they are!!!


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## parish (Jun 29, 2006)

This is a good guide/explanation of DoF - http://www.wrotniak.net/photo/tech/dof.html - it gets quite technical so you may need to read through it a couple of times to grasp it all - I did. One thing to note is that digital cameras have a greater DoF than 35mm film cameras.

You can always fake the effect - or "enhance" it if the effect isn't as pronounced as you'd like - in Photoshop using the technique described in this thread - http://www.detailingworld.co.uk/forum/showthread.php?t=20487 - but blurring the background rather than making ti b&w.


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## ResB (Feb 16, 2007)

http://www.dpreview.com/learn/?/Glossary/Optical/Depth_of_Field_01.htm


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