Results 1 to 18 of 18

Thread: Max Aperture on Crop Sensor

  1. #1

    Default Max Aperture on Crop Sensor

    Pardon me for my potential silly question. Does a FF lens appear to be give a crop camera a larger aperture?

  2. #2
    Member HHenrYY's Avatar
    Join Date
    Mar 2009
    Location
    Singapore
    Posts
    235

    Default Re: Max Aperture on Crop Sensor

    maximum aperature depends on the lens.

    FF lens on dx body
    or
    dx lens on FF body
    maximum aperature is the same,
    it all depends on lens ..
    Always a pleasant smile when we look back at our own photos.

  3. #3

    Default Re: Max Aperture on Crop Sensor

    The FF lens will project an image circle too large for a cropped-sensor camera (hence the use of the term "crop" in the first place, as the smaller sensor uses the centre crop of the image circle).

    Aperture is a function of the lens and is independent of camera.

  4. #4
    Moderator Octarine's Avatar
    Join Date
    Jan 2008
    Location
    Pasir Ris
    Posts
    12,422

    Default Re: Max Aperture on Crop Sensor

    Quote Originally Posted by KY1977 View Post
    Pardon me for my potential silly question. Does a FF lens appear to be give a crop camera a larger aperture?
    You might want to read a bit about Aperture. You'll notice that the whole article doesn't even mention the camera body.
    EOS

  5. #5
    Member
    Join Date
    Oct 2008
    Location
    East
    Posts
    609

    Default Re: Max Aperture on Crop Sensor

    Would you like to share why you think that way? Could be interesting...

  6. #6

    Default Re: Max Aperture on Crop Sensor

    no. it does not. end of story.

  7. #7

    Default Re: Max Aperture on Crop Sensor

    I am also not sure if I understand the question by TS correctly.

    The aperture size is the same.

    However, the DOF of FX will be shallower than DX using lens of same focal length and subject of the same size. The reason is because for DX to have the subject of the same size as the FX using lens of same focal length, you have to move back. The increase of focus distance will increase the DOF.

    You can use this website to calculate the DOF that you will have. http://www.nikonians.org/html/resour...perfocal2.html

    Not sure if I am right. Can the experts please correct if I have misunderstooding on the Apertures.

  8. #8
    Member
    Join Date
    Feb 2009
    Location
    Singapore, East Sider
    Posts
    367

    Default Re: Max Aperture on Crop Sensor

    last heard, the bokeh of an F4 on FF is about the same as F2.8 on crop. Not sure how true it is, but I believe it. Anyone concurs on this?
    1 Camera Body and a couple lenses.

  9. #9
    Moderator Octarine's Avatar
    Join Date
    Jan 2008
    Location
    Pasir Ris
    Posts
    12,422

    Default Re: Max Aperture on Crop Sensor

    Quote Originally Posted by LukaviZ View Post
    last heard, the bokeh of an F4 on FF is about the same as F2.8 on crop. Not sure how true it is, but I believe it. Anyone concurs on this?
    How can you seriously believe something if you are not sure whether it is true? Photography is not a religion.
    Apart from that, a little bit of reading about bokeh and aperture (plenty of links available here in forum) will show you the factors that contribute to bokeh. Here is a recent thread discussing Out of Focus and Bokeh. The sensor size is never mentioned...
    Last edited by Octarine; 1st September 2009 at 12:52 PM.
    EOS

  10. #10

    Default Re: Max Aperture on Crop Sensor

    Quote Originally Posted by LukaviZ View Post
    Not sure how true it is, but I believe it. Anyone concurs on this?
    I definitely do not concur on this. Also, you should not believe things you do not know to be true. If you do, I would like to interest you in a deal, I have $60M hidden away from a dead warlord in Somalia, I just need some assistance from you to transfer it, my dear trusted friend...
    Alpha

  11. #11

    Default Re: Max Aperture on Crop Sensor

    In terms of exposure, the aperture is only dependent on the lens. This is because exposure is a factor of light intensity, it doesn't matter if you crop out the center part of the image circle, the intensity is still the same.

    Bokeh is a little more difficult to understand. It is related to the physical size of the aperture, lens-to-subject and lens-to-background distance, if my memory serves me correctly. Anyway, the image circle cast by your lens is fixed. Take for example a 135mm f/2 lens on a fullframe sensor, you get a certain image. On an APS-C sensor, you are just taking the center part of the image circle, equivalent to cropping the image from the fullframe sensor.

  12. #12
    Member
    Join Date
    Apr 2003
    Location
    Jurong
    Posts
    524

    Default Re: Max Aperture on Crop Sensor

    Quote Originally Posted by Rashkae View Post
    .......... Also, you should not believe things you do not know to be true. ...........
    100% agreed!. Unfortunately, some do, and a few even come out with own theories and experience to support it. Quite sad..
    Last edited by swhyge; 3rd September 2009 at 05:17 PM. Reason: choice of words correction

  13. #13
    Senior Member ZerocoolAstra's Avatar
    Join Date
    Mar 2008
    Location
    rainy Singapore
    Posts
    9,522

    Default Re: Max Aperture on Crop Sensor

    Quote Originally Posted by Richter
    I am also not sure if I understand the question by TS correctly.

    The aperture size is the same.

    However, the DOF of FX will be shallower than DX using lens of same focal length and subject of the same size. The reason is because for DX to have the subject of the same size as the FX using lens of same focal length, you have to move back. The increase of focus distance will increase the DOF.

    You can use this website to calculate the DOF that you will have. http://www.nikonians.org/html/resour...perfocal2.html

    Not sure if I am right. Can the experts please correct if I have misunderstooding on the Apertures.
    Yes you are right. SPOT ON!
    The depth of field is a function of:
    a) lens' focal length
    b) aperture
    c) focus distance
    Up to this point there's no mention about the camera body itself.

    The reason that 50mm f/1.8 can give a thinner depth of field on FF vs cropped is that with the FF camera, you can go closer (reduction in focusing distance) to get the same FOV as on the cropped camera. And vice versa, you have to step back with the cropped camera, causing an increase in focus distance, and consequently greater depth of field.

    ps. I don't know what is "misunderstooding" though
    Last edited by ZerocoolAstra; 3rd September 2009 at 05:25 PM.
    Exploring! :)

  14. #14
    Moderator catchlights's Avatar
    Join Date
    Sep 2004
    Location
    Punggol, Singapore
    Posts
    21,901

    Default Re: Max Aperture on Crop Sensor

    size of aperture is still the same, value is still the same
    however, the depth of field will change, larger the film format, narrower the depth of field.

    so on when on digital sensor, FX sensor will have narrower depth of field compare to a DX sensor using the SAME lens.
    Shoot to Live, Live to Shoot
    www.benjaminloo.com | iStock portfolio

  15. #15
    Member
    Join Date
    Apr 2003
    Location
    Jurong
    Posts
    524

    Default Re: Max Aperture on Crop Sensor

    Quote Originally Posted by catchlights View Post
    size of aperture is still the same, value is still the same
    however, the depth of field will change, larger the film format, narrower the depth of field.

    so on when on digital sensor, FX sensor will have narrower depth of field compare to a DX sensor using the SAME lens.
    You missed out an important parameter for this to be true.... cf Richter's post.

  16. #16
    Senior Member
    Join Date
    Feb 2003
    Location
    Outside the Dry Box.
    Posts
    16,268

    Default Re: Max Aperture on Crop Sensor

    Quote Originally Posted by catchlights View Post
    size of aperture is still the same, value is still the same
    however, the depth of field will change, larger the film format, narrower the depth of field.

    so on when on digital sensor, FX sensor will have narrower depth of field compare to a DX sensor using the SAME lens.
    simplest way to explain...

    if you have a full frame camera, shoot an image with say 50mm f1.4 with a subject in the middle. (pic A)

    then using that same image, draw a square box in the middle then cut it out. (pic B)

    Pic A is the full frame with more 'bokeh' than Pic B as Pic B is your Cropped Sensor.

    Image is the same, as aperture and shutter speed, etc is the same, standing at the same distance, hence same bokeh.

    Too tight for Pic B, take a step back.

    Take the image again with full frame. (pic C)

    then same crop on pic C (pic D)

    Pic C will have much more room than Pic D, but after cropping althou subject look the same. Bokeh of Pic B & D will not be the same. Distance change affect bokeh.
    Logging Off. "You have 2,631 messages stored, of a total 400 allowed." don't PM me.

  17. #17
    Senior Member ZerocoolAstra's Avatar
    Join Date
    Mar 2008
    Location
    rainy Singapore
    Posts
    9,522

    Default Re: Max Aperture on Crop Sensor

    Quote Originally Posted by Del_CtrlnoAlt View Post
    simplest way to explain...

    if you have a full frame camera, shoot an image with say 50mm f1.4 with a subject in the middle. (pic A)

    then using that same image, draw a square box in the middle then cut it out. (pic B)

    Pic A is the full frame with more 'bokeh' than Pic B as Pic B is your Cropped Sensor.


    Image is the same, as aperture and shutter speed, etc is the same, standing at the same distance, hence same bokeh.

    Too tight for Pic B, take a step back.

    Take the image again with full frame. (pic C)

    then same crop on pic C (pic D)

    Pic C will have much more room than Pic D, but after cropping althou subject look the same. Bokeh of Pic B & D will not be the same. Distance change affect bokeh.
    Sorry I don't quite understand what you mean by the sentence I highlighted in bold.
    Pic A and Pic B both have the same depth of field, as Pic B is just a crop of Pic A.
    What is "more bokeh"??
    Exploring! :)

  18. #18
    Moderator catchlights's Avatar
    Join Date
    Sep 2004
    Location
    Punggol, Singapore
    Posts
    21,901

    Default Re: Max Aperture on Crop Sensor

    thank you for highlighting missing out something in my last post, I just assuming that everyone will compare the same size of the subject relativity to the image frame.
    Shoot to Live, Live to Shoot
    www.benjaminloo.com | iStock portfolio

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •