Page 2 of 2 FirstFirst 12
Results 21 to 32 of 32

Thread: 100mm + 1.6x Crop factor not = 160mm

  1. #21

    Default

    If the distance is the same, the perspective is the same, field of view notwithstanding.

  2. #22
    Senior Member
    Join Date
    Apr 2004
    Location
    London, UK
    Posts
    2,358

    Default

    So do we shoot according to the crop factor or not?
    The equipment can only bring you so far - the rest of the photographic journey is done by you.

  3. #23
    Member
    Join Date
    Dec 2003
    Location
    CCK
    Posts
    1,051

    Default

    Quote Originally Posted by EiRiK
    OT abit...

    i assume perspective does not change on a x1.6 right?

    eg.we all know that a 100mm used on a film slr is just nice for portraits.
    but on a dslr, if i use a 60mm (x1.6=96mm) will i get the same nice portrait, perspective wise?
    or must i still use the 100mm but stand way back to shoot the portrait?

    thanks.
    Here's my understanding. If you want to keep your subject the same size in the final print (w/o cropping), and are using the same focal length lens on the camera, your shooting position will change depending on whether you are using a FF or 1.6x camera. If your shooting position changes ---> perspective also changes. Obviously, you can overcome this by shooting from the same position, and cropping the FF image by 1.6x to get the same image from the 1.6x sensor, in which case, your perspective will not change.

    Any comments from the experts?

    Here is a somewhat related article -->

    http://www.luminous-landscape.com/tutorials/dof2.shtml

    Cheers,

  4. #24

    Default

    Multiplying the focal length by 1.6x is just a gauge for what view you'll see if you've used a FF sensor/film before.

    not to be confused with DOF. DOF is not the same.

  5. #25
    Senior Member
    Join Date
    Jan 2002
    Location
    UK
    Posts
    3,911

    Default

    Another point to add. I think when you use a smaller sensor you should forget all about whether you are getting 35mm DOF, or 35mm perspective, or 35mm focal length. When you raise the camera to the eye you see what you see, and you shoot based on that.

  6. #26

    Default

    Quote Originally Posted by Belle&Sebastain
    i dun think its right, if your theroy of 'enlarging the cropped area' is true, than lots of ppl are going to complaint abt DSLR with smaller than 35mm field of view sensors makes all lenses slower by a few stops.


    OT a bit....i was fooling around with my F801 and D70 a few days ago. I noticed that at the same ISO and aperture, the F801 almost always indicates a shutter speed 1 or 0.7 stops faster than the D70.....

  7. #27
    Senior Member
    Join Date
    Jan 2002
    Location
    Singapore
    Posts
    12,938

    Default

    it might be the ISO sensitivity on the D70 is overstated.

  8. #28

    Default

    Quote Originally Posted by BurgaFlippinMan
    OT a bit....i was fooling around with my F801 and D70 a few days ago. I noticed that at the same ISO and aperture, the F801 almost always indicates a shutter speed 1 or 0.7 stops faster than the D70.....
    Were you using matrix metering? If so, its just difference in the matrix algorithm. When u spot meter, there shouldn't be any difference unless one of the meters is off.

  9. #29

    Default

    I tried Matrix and Centerweighted (F801 has no spot), and while it does occur in both modes, it happens more in Matrix than centerweighted, in which they are usually 1/3 of a stop within each other. But even if it was a difference in the algorithm, one stop is a lot don't u think?

  10. #30

    Default

    Quote Originally Posted by BurgaFlippinMan
    I tried Matrix and Centerweighted (F801 has no spot), and while it does occur in both modes, it happens more in Matrix than centerweighted, in which they are usually 1/3 of a stop within each other. But even if it was a difference in the algorithm, one stop is a lot don't u think?
    Their centerweighted weightages may not be identical either so 1/3EV variance is insignificant.

    A 1stop difference in the output of the matrix algorithm is hardly surprising given that there is abt 8yr difference in the metering tech in the f801 and the 1005RGB meter. Matrix algorithms are basically camera guesswork.

    Try metering a scene with a large patch of sky or an open patch of water, I believe the F801 should underexpose more than the D70 in those situations.

  11. #31

    Default

    I havent had the time to do as u suggested, (its early morning now), but last night i was playing with something else. I was digging through dad's old books and stuff and discovered a card sized chart with exposure settings for various low light situations. Since my bedroom is lighted by one red ceiling lamp, I guessed that my room according to the chart is a "averagely lit hotel lounge" for which the chart suggested an exposure of 1/8s @ f/3.5. Sure enough, that exposure was indicated as spot on by the F801 meter, but it was 1 stop underexposed on the D70.

  12. #32

    Default

    Quote Originally Posted by nickmak
    So do we shoot according to the crop factor or not?
    Yes, we do shoot according to crop factor. Because with the crop, u are effectively getting a longer lens. Here is something to illustrate.

    Picture A


    This was shot at 70mm on the 18-70mm DX lens

    Picture B


    This was shot at 18mm on the same lens from the SAME SUBJECT TO LENS DISTANCE and then cropped later to achieve the same FOV as the 70mm shot.

    There is no difference in perspective between the two.

Page 2 of 2 FirstFirst 12

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
  •