depth of field or lack of...

Discussion in 'Beyond the Basics' started by guitarkid, Oct 18, 2006.

  1. guitarkid

    guitarkid TPF Noob!

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    if you are using 58mm 1.8 or any prime for that matter, and you need lots of light, and you don't want massive depth of field, are there lenses out there that can stay at 1.8 while keeping everything in focus.....i have heard of these. i know that everything is a sacrifice, but there were times where i needed 1.8 to allow more light in but was just too much depth of field.
     
  2. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    That does not make sense... :scratch:

    When shooting at F1.8...you have very little DOF (at most distances).

    Do you want everything if focus? That would be a large DOF...which you seemingly don't want.

    Do you want more things in focus or less things in focus?
     
  3. guitarkid

    guitarkid TPF Noob!

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    sorry for the confusion. i want more things in focus at 1.8

    i heard there may be expensive lenses out there with some kind of ring on the lense that allows you to set the DOF regardless of the Fstop. you can keep it at 1.8 and have more DOF or less. so basically, DOF is not affected by the Fstop, if you so desire. i have never heard of this. so yes, set it at 1.8 with large depth of field. sounds too good to be true.
     
  4. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    Yes, too good to be true.

    The lenses with 'aperture rings' are just a manual way of setting the aperture. DOF is the physical result of a few factors. Aperture is the main one, focal length plays a factor, distance to subject, size of medium/projected image...which has to do with the distance of the lens to the 'film plane'.

    Google 'circle of confusion' and you can learn more.

    Basically, no you can't get more DOF while shooting at F1.8. You could back up, so that the lens is at infinity focus...then anything past the focus point will be in focus...but that's not always practical.

    Most digicams would do a good job of this for you....because their sensors are so small...they have a deep DOF.

    You could probably find a DOF chart for your lens/camera combination...again, Google is your friend.

    Also, look up hyperfocal distance. The DOF will always (I think) extend 1/3 back toward the camera and 2/3 forward from the focus point. So get the most efficient use of your DOF...you will want to focus 1/3 of the distance...from your closest subject to your farthest.
     
  5. fmw

    fmw No longer a newbie, moving up!

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    Depth of field involves aperture, focal length and distance. If you want more depth of field you use a smaller aperture, shorter focal length lens or photograph things that are further away. There is no getting around that. A 58mm lens at f1.8 will only have everything in focus if the subject is at infinity.

    There are tilt and shift lenses that can help with focusing more of a subject, but only if parts of the subject are out of focus due to the lens being out of parallel with the subject. There is no way to truly add depth of field without dealing with one of the issues in the first paragraph.
     
  6. guitarkid

    guitarkid TPF Noob!

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    thanks guys for clearing that up
     
  7. Torus34

    Torus34 No longer a newbie, moving up!

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    There just ain't no free lunch, Man.
     
  8. cosmonaut

    cosmonaut No longer a newbie, moving up!

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  9. DepthAfield

    DepthAfield TPF Noob!

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    Agggghhhh!!! This is the best utility-based photo site I’ve seen in quite some time.

    Thank you!
     
  10. gizmo2071

    gizmo2071 TPF Noob!

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    Probably not the best option.
    You could try multiple exposures and layering afterwards?
    A fronted focus picture and one focused further back, should help with a better depth of field.
     
  11. rt45

    rt45 TPF Noob!

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    I think you may be thinking of a Tilt Shift lens? You can get your DOF to run perpenducular to the camera instead of parallel to it. More info can be found here: http://photo.net/equipment/canon/tilt-shift However, I've never used one myself so i could be losing my mind...
     
  12. danalec99

    danalec99 TPF Noob!

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