Recent content by inspector-71

  1. I

    Calculate captured image area size on macro

    Thanks. i have fired a couple of test shots using a photography scale and compared to the ratio marks on the focus ring. The calculation is close enough to the image with the ruler for my needs 31cm to object 1:1 = 22.2 x 14.8mm 35cm to object 1:1.5 = 33.3 x 22.2 mm 39cm to object 1:2 =...
  2. I

    Calculate captured image area size on macro

    Is it as simple as... 1:1 is equal to the sensor size so 22.2 × 14.8 mm (thanks rapscallion) so at 1:2, double the area is captured by the sensor so 44.4 x 29.6 mm
  3. I

    Calculate captured image area size on macro

    Will try that, thanks.
  4. I

    Calculate captured image area size on macro

    yes. 31cm is the 1:1. Thanks for the info. How would I factor in increasing the distance up to 0.49 (1:3) and then get the size?
  5. I

    Calculate captured image area size on macro

    Using a cannon f2.8 100mm at 0.31m from the object on a 450d (crop), how can I calculate the area of the part of the object that is captured? Background: I am trying to photograph defect in a fabric using this set up and would like to use the image to count the number of physical defects and...
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    I think my marumi ring flash is faulty

    Cheers Tim. The problem with the marumi is that there is no manual mode so I can't compare with and without ETTL. I did try increasing flash compensation to +2 but there was no noticeable difference. I'll see if I can have anither go at 1:1 and post some above f22 Richard, I will try the lower...
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    I think my marumi ring flash is faulty

    You are correct. I forgot to add that I repeated the experiment Tim described and indeed lose 2 stops going from infinity to 1:1. So I guess we are saying the flash is working ok and it is my expectation of its performance that was wrong.
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    I think my marumi ring flash is faulty

    150 cm 1/160 iso 100 f9 f7.1 f5.6 f4.5 f3.5 f2.8
  9. I

    I think my marumi ring flash is faulty

    f5.6 f4.5 f3.6 f2.8
  10. I

    I think my marumi ring flash is faulty

    approx .45cm 1/160 iso 100 f22 f18 f14 f11 f9 f7.1
  11. I

    I think my marumi ring flash is faulty

    f5.6 f4.5 f3.6 f2.8
  12. I

    I think my marumi ring flash is faulty

    ok. Sorry for the image spamming that's coming next first up 1:1 approx .31m f22 f18 f14 f11 f9 f7.1
  13. I

    I think my marumi ring flash is faulty

    If that is the case it should still expose properly especially if I up to ISO 200. I will check out what happens on the actual lens and light meter as you suggested and also try exposure outside of the macro range. I'll post some shots this evening to put it into perspective. It is only a...
  14. I

    I think my marumi ring flash is faulty

    I have had my Marumi DRF14C Ring Flash for Canon for a few months now. I don't use it regularly but I always feel it is lacking in power and I have to drop the aperture and up the iso. I wan't to prove this by experiment or understand if I just have it wrong. So my understanding from the...
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