Page 6 of 6 FirstFirst ... 456
Results 101 to 109 of 109

Thread: one lens for all

  1. #101
    Member fmeeran's Avatar
    Join Date
    Nov 2010
    Location
    Clementi, Singapore
    Posts
    834

    Default

    Quote Originally Posted by BTBFM2

    sensor size stated as 1/2.33" (6.08 x 4.56 mm).
    goodness, this is really small.

    However, i think your way of calculation may not be exactly right. My opinion, don't flame me.
    Your calculation assume that the only variable is the sensor size. That is you are assuming the lens physical characteristics [actual aperture diameter and actual focal length etc] remain unchanged. The lens used in the FZ has a different set of actual physical focal length and actual aperture diameter that give the same f-number of f2.8. Remember that the f-number is just a dimensionless number indicating the ratio of focal length to aperture diameter. So, a totally different set of lens [physically] would give the same f-number if the ratio of the actual physical focal to the actual aperture diameter fits that number.

    don't get confused. The 25-600mm zoom spec that they give is the "equivalent" of a 35mm sensor. The actual physical focal length is different.

    As i said, there is, however, a physical limit to the sensor size reduction before other optical problems kicks in.
    Think if it this way. For the same framing of apparent focal length, the smaller sensor camera is going to have a smaller light collection area (reflected as smaller front element). So whatever be the improvement in technology, the camera with the larger sensor is going to be better at signal-to-noise assuming similar technology.
    Dxxxx | 35/1.8 | 50/1.8 | Tokina 28-70 | Panny G1 | 14-45 | 25/1.7
    My Flickr

  2. #102
    Deregistered
    Join Date
    Jun 2012
    Location
    singapore
    Posts
    136

    Default Re: one lens for all

    ".....assuming similar technology" True if based on similar technology. agree.
    but as you can see, technology is moving rather fast.
    On the other hand, however, there is still physical limits.

  3. #103
    Moderator daredevil123's Avatar
    Join Date
    Oct 2005
    Location
    lil red dot
    Posts
    21,627
    Blog Entries
    1

    Default Re: one lens for all

    Quote Originally Posted by BTBFM2 View Post
    sensor size stated as 1/2.33" (6.08 x 4.56 mm).
    goodness, this is really small.

    However, i think your way of calculation may not be exactly right. My opinion, don't flame me.
    Your calculation assume that the only variable is the sensor size. That is you are assuming the lens physical characteristics [actual aperture diameter and actual focal length etc] remain unchanged. The lens used in the FZ has a different set of actual physical focal length and actual aperture diameter that give the same f-number of f2.8. Remember that the f-number is just a dimensionless number indicating the ratio of focal length to aperture diameter. So, a totally different set of lens [physically] would give the same f-number if the ratio of the actual physical focal to the actual aperture diameter fits that number.

    don't get confused. The 25-600mm zoom spec that they give is the "equivalent" of a 35mm sensor. The actual physical focal length is different.

    As i said, there is, however, a physical limit to the sensor size reduction before other optical problems kicks in.
    well, what is F stop? F stop = focal length / aperture diameter. Panasonic FZ200 focal length is 4.5-108mm. It is not hard to calculate aperture sizes from that. These are definites, not some unknown and "secret" numbers.

    http://en.wikipedia.org/wiki/F-number

    My calculation is based on the same FOV, and the same subject distance. It is correct, because it is math. Don't believe, just plug the numbers into a dof calculator... It is not about opinion. Either you know it or you don't. At least learn about the science and math behind the terms before sprouting nonsense like what you did.
    Last edited by daredevil123; 20th August 2012 at 02:19 PM.

  4. #104
    Moderator daredevil123's Avatar
    Join Date
    Oct 2005
    Location
    lil red dot
    Posts
    21,627
    Blog Entries
    1

    Default Re: one lens for all

    Quote Originally Posted by BTBFM2 View Post
    seems that for the 2nd pic, you are much further away from the subject as compared to the first. [or if you were to zoom in further to make the subject appears as close to the first pic, then you FOV would be much different]. Also, the choice of the background may not be a good comparison.
    Yes subject distance is slightly further away. but still, i already told you what the difference is.. the DOF is like the difference between a F2.8 to a F4 aperture.

  5. #105
    Deregistered
    Join Date
    Jun 2012
    Location
    singapore
    Posts
    136

    Default Re: one lens for all

    Quote Originally Posted by daredevil123 View Post
    Yes subject distance is slightly further away. but still, i already told you what the difference is.. the DOF is like the difference between a F2.8 to a F4 aperture.
    seem to contradict what you hv said in yr previous post.

    Anyway lets not delve too much on this technical detail.
    lets test it out when the FZ is out.

  6. #106
    Moderator daredevil123's Avatar
    Join Date
    Oct 2005
    Location
    lil red dot
    Posts
    21,627
    Blog Entries
    1

    Default Re: one lens for all

    Quote Originally Posted by BTBFM2 View Post
    seem to contradict what you hv said in yr previous post.

    Anyway lets not delve too much on this technical detail.
    lets test it out when the FZ is out.
    how did I contradict?

  7. #107
    Senior Member edutilos-'s Avatar
    Join Date
    Dec 2010
    Location
    The Universe
    Posts
    5,991

    Default Re: one lens for all

    Quote Originally Posted by BTBFM2 View Post

    However, i think your way of calculation may not be exactly right. My opinion, don't flame me.
    Your calculation assume that the only variable is the sensor size. That is you are assuming the lens physical characteristics [actual aperture diameter and actual focal length etc] remain unchanged. The lens used in the FZ has a different set of actual physical focal length and actual aperture diameter that give the same f-number of f2.8. Remember that the f-number is just a dimensionless number indicating the ratio of focal length to aperture diameter. So, a totally different set of lens [physically] would give the same f-number if the ratio of the actual physical focal to the actual aperture diameter fits that number.
    Hi,

    While it is a fact that crop frame sensors have less control over the DOF and will not have the same DOF as a FF sensor, all other things being equal (i.e. subject-to-camera distance, focus point, background-to-camera distance, equivalent field of view, etc), I must say that the two examples provided by daredevil123 earlier are not the best way to prove the point. Due to the varying conditions in the two photographs, the statement he intends to prove will not be immediately apparent, since it's debatable as to whether the background is comparable, is the subject-to-camera distance the same... Is the focus on the same distance from the camera... And so on so forth.

    You are right that the f-stop number will be the same. So given the same ISO used on a FF camera and the FZ camera (small sensor), and the same F-stop, the same shutter speed will be needed.

    However, what daredevil123 is trying to say is that, if you shoot with the same field of view compared to the FF camera, using the same aperture you will have much deeper DOF compared to the FF camera. To achieve the same amount of DOF on the FF camera you would have to stop down to F/15 or so on the FF camera. That is what he's trying to say. And he would not be wrong.

    I tried to find good examples and comparisons on the Internet, but it is such a well-known fact that no one really bothers making extensive comparisons done properly. My suggestion is that you try shooting shallow DOF with your handphone camera and do the same with your DSLR or larger sensor camera if you have one. Even if you use the same equivalent focal length I think you'd find what he says to be true. Cheers.

  8. #108
    Deregistered
    Join Date
    Jun 2012
    Location
    singapore
    Posts
    136

    Default Re: one lens for all

    Quote Originally Posted by edutilos- View Post
    Hi,

    While it is a fact that crop frame sensors have less control over the DOF and will not have the same DOF as a FF sensor, all other things being equal (i.e. subject-to-camera distance, focus point, background-to-camera distance, equivalent field of view, etc), I must say that the two examples provided by daredevil123 earlier are not the best way to prove the point. Due to the varying conditions in the two photographs, the statement he intends to prove will not be immediately apparent, since it's debatable as to whether the background is comparable, is the subject-to-camera distance the same... Is the focus on the same distance from the camera... And so on so forth.

    You are right that the f-stop number will be the same. So given the same ISO used on a FF camera and the FZ camera (small sensor), and the same F-stop, the same shutter speed will be needed.

    However, what daredevil123 is trying to say is that, if you shoot with the same field of view compared to the FF camera, using the same aperture you will have much deeper DOF compared to the FF camera. To achieve the same amount of DOF on the FF camera you would have to stop down to F/15 or so on the FF camera. That is what he's trying to say. And he would not be wrong.

    I tried to find good examples and comparisons on the Internet, but it is such a well-known fact that no one really bothers making extensive comparisons done properly. My suggestion is that you try shooting shallow DOF with your handphone camera and do the same with your DSLR or larger sensor camera if you have one. Even if you use the same equivalent focal length I think you'd find what he says to be true. Cheers.
    I hv a 80-200mm f2.8 nikkor can try on my d70, say at 150. Also hv a fujifilm HS20, but at 150mm equiv, the f-number would higher than 2.8.
    would i be able to see any difference if i were to set my f2.8 nikkor lens at a higher f-number similar to that on the hs20? Or should i compare the result obtain from d70 to a P&S nikon L22 [would it be able to zoom to an equiv of 150?] both at f-number higher than 2.8?

  9. #109
    Senior Member edutilos-'s Avatar
    Join Date
    Dec 2010
    Location
    The Universe
    Posts
    5,991

    Default Re: one lens for all

    Think you can compare D70 with 80-200mm f/2.8 and HS20 and stop down. Just focus as close as possible.

    Do note that at 150mm equivalent, you will need to set the 80-200 f/2.8 lens at 100mm (d70 has 1.5x crop factor)

Page 6 of 6 FirstFirst ... 456

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
  •