Easy lens question

Discussion in 'Digital Photography' started by Mrbobb, Aug 2, 2017.

  1. Mrbobb macrumors 601

    Joined:
    Aug 27, 2012
    #1
    So my SE is measured to have a 60 degree angle, I need to take photo that covers 104 degrees, what rating wide angle lens do I need? I don't understand the advertise 0.0x rating. TIA.
     
  2. kenoh macrumors demi-god

    kenoh

    Joined:
    Jul 18, 2008
    Location:
    Glasgow, UK
    #2
    It isnt an easy question without camera details and what you are trying to do, but anquick google.search found this Nikon field of view table that should help.

    https://www.nikonians.org/reviews/fov-tables

    So 104 degrees is between 10mm to 15mmon a full frame camera. You need to go wider depending on the crop factor of your sensor.

    Or use what you have, take a left side and a right side picture and stitch them together??? I dont know whay you are taking a picture of so this may or may not work
     
  3. Mrbobb thread starter macrumors 601

    Joined:
    Aug 27, 2012
    #3
    Oh brother. As per post#1, the camera is iPhone SE (this is a Mac forum right?), everything is accounted for, when I said measure I literally took a picture, measured the field of view from jpg as captured and came up with 60, this is it, this is what my SE does, now there got to be a simple math relationship, the wide angle adapters sold for iPhones, advertises 0.4x for example. Am aware lens adapters for DSLR are also advertised this way.
     
  4. kenoh macrumors demi-god

    kenoh

    Joined:
    Jul 18, 2008
    Location:
    Glasgow, UK
    #4
    You are in a generic Digital Photography sub-forum so SE without context is not descriptive I am afraid.

    0.4x is zoom factor not field of view. The SE I believe has a focal length equivalent to roughly 24-28mm on a full frame camera.
     
  5. Alexander.Of.Oz macrumors 68000

    Alexander.Of.Oz

    Joined:
    Oct 29, 2013
    Location:
    Adelaide, Australia
    #5
    Granted, I'm in Australia, but this is the first product that came up when I searched for iPhone SE wide angle lens.

    It states that the fisheye has a 180 degree field of view with a magnification factor of 0.33X and that the wide angle lens has a field of view covering 130 degrees with a magnification factor of 0.67X.

    Whether these are suitable for the SE I'm unsure of, as at the top of the page it say so, but doesn't down the bottom of the page. o_O
     
  6. ChrisA macrumors G4

    Joined:
    Jan 5, 2006
    Location:
    Redondo Beach, California
    #6
    The number 0.0x is a multiplier of the focal length. But you don't need to know the focal length of your camera lens. Let's call it "f". So assume you bought an adaptor that claims to be 0.4x When you attach the adaptor the focal length will become 0.4 x f which is smaller than f.

    To avoid having to learn trigonometry you can make a crude approximation. If you have a 0.5x adapter the field of view will be 1/0.5 wider or twice as wide. Buy a 0.66 lens and the field is 1/0.66 or about a third wider a 0.33 would be about 2/3 wider.

    If you remember trigonometry you can compute the exact answer but I doubt the multipliers they give are 100% accurate.
     
  7. dwig macrumors 6502

    Joined:
    Jan 4, 2015
    Location:
    Key West FL
    #7
    The cheap-&-dirty afocal screw on lens adapters are marked this way, but 99% of what is sold for DSLRs are discrete lenses which are always marked in their focal length.

    The lens attachments for phones are the afocal type and marked with their magnification factor. Since with these, distortion is high and the dimension used for the magnification factor is never specified the advertised factor can't ever be used for any accurate calculation.

    You fail to specify whether your needed and measured angle of view are vertical, horizontal, or diagonal. The industry standard is diagonal and most attachment lenses are measured this way. The typical barrel distortion that these have means that the diagonal factor is wider than either the horizontal or vertical factors. While your needs imply that something around 0.6x should do the job, if you were measuring the long side angle of view you may find that you need a lens advertised as 0.45-0.5x to actually get what you need.
     
  8. simonsi macrumors 601

    simonsi

    Joined:
    Jan 3, 2014
    Location:
    Auckland
    #8
    Two other options:

    1. Take a pano photo and stop when you have covered enough to cover the 104deg (thats a very specific requirement ;-) ), requirement OR

    2. Take two shots and stitch together with/without some $$$/free software or app to smooth out the resulting image, should/could be a similar result to the pano but with more effort.

    HTH
     
  9. Mrbobb thread starter macrumors 601

    Joined:
    Aug 27, 2012
    #9
    This is it.

    It happens I have another adapter for my other point&shoot, and I measured the angle before and after applying the adapter and this "approximation" is close enough for my need.

    Thanks for the other suggestions but my project needs to be done in a single, time-exposure shot.
     

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