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Depth Of Feild - Photography

Are the depth of field markers on a 35mm film lens correct when the lens is used on a DSLR with a 1.6x magnification factor? If I have a depth of field of three metres to infinity using a 50mm lens on a film SLR and I put it on a DSLR, does the DSLR still have a depth of field of three metres to infinity or does the magnification factor impact it?...

  1. #1

    Default Depth Of Feild

    Are the depth of field markers on a 35mm film lens correct when the lens is
    used on a DSLR with a 1.6x magnification factor?

    If I have a depth of field of three metres to infinity using a 50mm lens on
    a film SLR and I put it on a DSLR, does the DSLR still have a depth of field
    of three metres to infinity or does the magnification factor impact it?


    Edward Guest

  2. #2

    Default Re: Depth Of Feild


    "Edward Holt" <com> wrote in message
    news:4221949d$0$32605$zen.co.uk... 

    No. Look for various threads in this group eg RE: DSLR Depth fo field 10/2
    2005 . I learnt a lot from the group, in particuilar that the DOF scale is
    only correct for 10x8 print when using 35mm film !



    dylan Guest

  3. #3

    Default Re: Depth Of Feild

    "Edward Holt" <com> wrote in message
    news:4221949d$0$32605$zen.co.uk... 
    -----------
    As mentioned before, there are many tutorials and threads pertaining to
    your question. Depth of Field and Depth of Focus are commonly misunderstood
    terms and much has been written about it.
    An excellent (not too technical) source is:
    www.luminous-landscape.com

    Look under "Tutorials" and "Understanding Series". You will have a better
    understanding of what you are looking for.
    Regards,
    Don F


    Don Guest

  4. #4

    Default Re: Depth Of Feild

    "dylan" <com> wrote in news:cvs5h4$54b$svr.pol.co.uk:
     

    Hmmmm ... no ... not really. Look at this ...

    http://www.nikonlinks.com/unklbil/dof.htm

    It says the CoC is defined as 5 l/mm for a 10x8. This will
    result in CoC being d/1625, where d is the diagonal.

    But the value 1625 can be used for any size, so - the DOF
    scale on your lens is correct for any print size. It is
    just to change the viewing distance.

    OK - for smaller prints you need a magnifying glass and
    vary good photo paper - so there is a limit for smaller prints.


    /Roland
    Roland Guest

  5. #5

    Default Re: Depth Of Feild

     

    so the reply (below) I got to an early post is wrong then ?
     [/ref]
     

    Confused !!


    dylan Guest

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  8. #8

    Default Re: Depth Of Feild

    "Edward Holt" <com> wrote:
     

    You'll have less depth of field with the DSLR. People will give you all
    sorts of bull reasons why this isn't so but experimention bears this
    out. It has to do with the difference in sensor size requiring a smaller
    COC in order to maintain the same depth of field in indentically sized
    prints. You'll get the same DOF that you'd have if you cut the
    approprately sized piece out of the middle of one of your film camera
    prints and enlarged it to the original print's size. DOF is a nebulous
    term and requires that you standardize your print size and viewing
    distance before any sort of meaningful numbers for comparison can be
    generated.
    Bubbabob Guest

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  11. #11

    Default Re: Depth Of Feild

    "dylan" <com> wrote in news:cvsu2j$a89$svr.pol.co.uk:
     

    Yes - it is wrong IMHO. Read the web page I gave in my reply.
    There is it explained. And as far as I can see - the 10x8 is
    just an example. If you use 10x8 and look at it at 25 cm (called
    normal viewing distance), then the eye resolution is supposed to
    be 1/5 mm. Therefore - this is used as the definition of DOF.
    But - if you make a larger print at look at it further away you
    get the same figure 1625 - and thus the same DOF. If you make a smaller
    print - then it is problems though - and the DOF will in practice
    increase.


    /Roland
    Roland Guest

  12. #12

    Default Re: Depth Of Feild

    Crownfield <net> wrote in news:net:
     
    >
    > correction: you are wrong.
    >[/ref]

    You are both right :)

    The definition is that the CoC is 1/1625 of the diagonal.
    Then - it does not matter the slightest how large or
    small the print is. The DOF scale on the lens is the same
    for all print sizes. This is according to the defintion
    of DOF - so - if we are talking about DOF - it does not
    matter what print size you have.

    But - it does matter in practice what print size you have.
    In smaller prints you cannot see small details and when
    viewing larger prints you can go nearer. So - the actual
    sharpness needed usually change with print size. So - in
    practice the definition used for DOF might not be all that
    useful - and you could use another CoC. But - this is __NOT__
    according to the definition of DOF - it is another value,
    maybe more useful in some cirstances.


    /Roland
    Roland Guest

  13. #13

    Default Re: Depth Of Feild


    "Roland Karlsson" <com> wrote in message
    news:133.1.4... 
    >
    > Yes - it is wrong IMHO. Read the web page I gave in my reply.
    > There is it explained. And as far as I can see - the 10x8 is
    > just an example. If you use 10x8 and look at it at 25 cm (called
    > normal viewing distance), then the eye resolution is supposed to
    > be 1/5 mm. Therefore - this is used as the definition of DOF.
    > But - if you make a larger print at look at it further away you
    > get the same figure 1625 - and thus the same DOF. If you make a smaller
    > print - then it is problems though - and the DOF will in practice
    > increase.
    >
    >
    > /Roland[/ref]

    Thanks, makes sense now.


    dylan Guest

  14. #14

    Default Re: Depth Of Feild

    Roland Karlsson <com> wrote:
     
    >
    > Yes - it is wrong IMHO. Read the web page I gave in my reply.
    > There is it explained. And as far as I can see - the 10x8 is
    > just an example. If you use 10x8 and look at it at 25 cm (called
    > normal viewing distance), then the eye resolution is supposed to
    > be 1/5 mm. Therefore - this is used as the definition of DOF.
    > But - if you make a larger print at look at it further away you
    > get the same figure 1625 - and thus the same DOF. If you make a smaller
    > print - then it is problems though - and the DOF will in practice
    > increase.[/ref]

    You're saying that it's possible for the circle of confusion to be
    equivalent if you change the size of the paper *and* the viewing
    distance to maintain that relationship between them.

    And in that cirstance, yes, the DoF would be the same for the two
    prints. However, unless you somehow make it so that the larger image can
    only be viewed from a certain distance, the DoF will change as people
    get closer to it.
    Paul Guest

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  16. #16

    Default Re: Depth Of Feild

    Roland Karlsson <com> wrote:
     
    > >
    > > correction: you are wrong.[/ref]
    >
    > You are both right :)
    >
    > The definition is that the CoC is 1/1625 of the diagonal.[/ref]

    ....of an 8x10 print viewed at 25cm. :-)
     

    ....as long as it's an 8x10 print at 25cm. :-)
     

    ....that happen to be 8x10 viewed at 25cm. :-)
     

    I think that if you look for more definitions of DoF, you'll find more
    accurate information. '1/1625 of diagonal' is only part-way there. It's
    like saying that the theory of relativity is equal to 3, because you can
    solve e=mc^2 for e=3.
     

    The CoC doesn't change; your eyes' capacity to see detail is really only
    going to be affected by disease or old age. Relative to the constant
    CoC, the DoF changes as you alter print size and viewing distance.
    Paul Guest

  17. #17

    Default Re: Depth Of Feild

    Bubbabob <net> wrote:
     
    >
    > You'll have less depth of field with the DSLR. People will give you all
    > sorts of bull reasons why this isn't so but experimention bears this
    > out. It has to do with the difference in sensor size requiring a smaller
    > COC in order to maintain the same depth of field in indentically sized
    > prints. You'll get the same DOF that you'd have if you cut the
    > approprately sized piece out of the middle of one of your film camera
    > prints and enlarged it to the original print's size. DOF is a nebulous
    > term and requires that you standardize your print size and viewing
    > distance before any sort of meaningful numbers for comparison can be
    > generated.[/ref]

    I think you have confused 'Depth of Field' with 'Field of Vision.'
    Paul Guest

  18. #18

    Default Re: Depth Of Feild

    c0m (Paul Mitchum) wrote:

     

    In what way?
    Bubbabob Guest

  19. #19

    Default Re: Depth Of Feild

    Technically I agree with Bubbabob. Personally, I've always used the depth
    of field preview button and then close down one additional stop for
    insurance. It hasn't failed me yet regardless of format. I guess you might
    need to use the scale on the lens for really low light photography where
    the button is impracticle.

    --
    Message posted via http://www.photokb.com
    stephen Guest

  20. #20

    Default Re: Depth Of Feild

    "stephen zimic via PhotoKB.com" <com> wrote:
     

    I've experimentally determined the same thing. One additional stop seems to
    do it.
    Bubbabob Guest

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