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Thread: Lenses FF/APSC

  1. #1

    Default Lenses FF/APSC

    A good article in the latest magazine....I think a whole series of articles could be written about this subject. It was good to be reminded of the effect of the circle of confusion especially as this could affect APSC images that have to be enlarged more to produce an image of a given size.

    in trying to dispel the belief that DoF is greater on an APSC sensor, I tell people to take an picture on full frame, print it and note the dof......and then trim off the edges of the print with scissors and see if the DoF changes.
    Canon EOS 5D MKIII, 17-40 f4L, 24-105 f4L, 100-400 f4.5-5.6L, 24mm f1.4L II, 50mm f1.2L, 100mm f2.8L macro, 85mm f1.8 USM
    Canon EOS 100D , Canon EOS 200D
    EF-S 10-18mm STM, EF-S 18-55mm STM, EF-S18-55mm IS II, EF-S 55-250mm IS STM, EF-S 24mm f2.8 STM, EF 50mm f1.8 STM

    brianvickersphotography.com

  2. #2

    Default Re: Lenses FF/APSC

    Same for apsc gives you more reach....the times I've had to explain that!

    Sent from my SM-N910F using Tapatalk

  3. #3

    Default Re: Lenses FF/APSC

    Quote Originally Posted by supergeeman View Post
    Same for apsc gives you more reach....the times I've had to explain that!

    Sent from my SM-N910F using Tapatalk
    Ditto

  4. #4

    Default Re: Lenses FF/APSC

    Quote Originally Posted by brianvickers View Post
    in trying to dispel the belief that DoF is greater on an APSC sensor, I tell people to take an picture on full frame, print it and note the dof......and then trim off the edges of the print with scissors and see if the DoF changes.
    The size of the print and the viewing distance does have an effect on our perception of DOF. If you printed the same image at 6x4 and then compared both at the same viewing distance, eg arms length, then the 6x4 will look to have greater depth of field since at that size it's not technically possible to reproduce the same gradation from sharp to soft as you can see in the large print. However if you then move back from the large print until it subtends the same angle of view as the enprint does at arms length the apparent DOF will then be similar to the small print at arms length.
    Nigel

    You may know me from Another Place....

    The new ElSid Photogallery...

    Equipment: Far too much to list - including lots of Nikon...

  5. #5
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    Default Re: Lenses FF/APSC

    In terms of the alleged more "reach" with APS-C
    Suppose we take the same image with the same lens on FF and APS-C bodies with the same number of pixels, e.g. the 70D and 6D, both of which have 20.2 megapixels, but on different size sensors. Yes, we can crop in on the 6D image to make the subject the same size as that from the 70D, but only by throwing away a lot of the pixels. The subject may be the same size on each, but the one taken with the 70D will be made up of many more pixels than the one from the 6D. Surely that should mean that we can get better resolution from the 70D image? If we crop in both images even further, then the image from the 6D will lose resolution and detail before the one from the 70D.

    So although we may not actually get more reach with the smaller sensor, isn't the practical effect as if we did? So if we want to take a photo of a small bird from a long distance and need to crop in quite a lot, are we not better off using the smaller sensor, all other things being equal?

    I also find discussion about focal length pretty irrelevant. While 50 mm may still be 50 mm on any body, on the APS-C it gives the same field of view as an 80 mm lens on FF. It's field of view that is relevant to the uses of a lens, not actual focal length. There's little point in putting a 24 mm lens on an APS-C body for wide angle as the field of view will be equivalent to 38 mm and more like a standard lens than wide angle. As I have both type of bodies, I tend to think of everything in terms of FF equivalent rather than actual focal length, it's much more useful and after 30+ years of 35 mm film use, I can look at a subject and think "That looks about right for 24 mm (which means a 15 mm on APS-C)".
    EOS 6D, 5D Mk II, 80D, 70D, 100D, 200D, 50D. Canon 10-18, 18 - 55, 55 - 250 IS STM lenses, Canon 50 mm F1.8 STM, 60 mm EF-S macro, MPE-65 macro, 85 mm F1.8, 200 mm F2.8 L II, Sigma 24 - 35 F2 Art, 17 - 50 F2.8 DC, 105 mm DG OS macro, 100 - 400 C, 150 - 600 C, Kenko 1.4x TC

  6. #6

    Default Re: Lenses FF/APSC

    I totally agree Nigel.
    Richard.....I think that is correct too, the point in the article for crop not being quite as good as the FF is that the crop image has to be enlarged more to print it the same and thus the circle of confusion is enlarged that bit more too....the extra pixel density won't help....though its also logical that the extra resolution of the APSC should improve things.
    Canon EOS 5D MKIII, 17-40 f4L, 24-105 f4L, 100-400 f4.5-5.6L, 24mm f1.4L II, 50mm f1.2L, 100mm f2.8L macro, 85mm f1.8 USM
    Canon EOS 100D , Canon EOS 200D
    EF-S 10-18mm STM, EF-S 18-55mm STM, EF-S18-55mm IS II, EF-S 55-250mm IS STM, EF-S 24mm f2.8 STM, EF 50mm f1.8 STM

    brianvickersphotography.com

  7. #7

    Default Re: Lenses FF/APSC

    AFAIK there are three factors controlling DOF. These are the focal length of the lens, the aperture and distance the subject is in front of the lens. There are some "out there" who say DoF is not dependent on the focal length of the lens. Those folks tend to "prove" this by taking images with different F.L lenses and if you compare the results they do seem to show the same DoF. What they usually did is to move the position of the camera to keep the same image size, which is cheating because that is changing two of the three factors at once.
    That said, it means that the DoF on an APS-C body is likely to be worse not better than on FF because you generally use the 1.6 crop factor in choosing a lens. So if you use a shorter lens (e.g. 50 for a portrait) the DoF is greater than for the 85 on FF for the same aperture. Perception is that DoF is different. But like for like the same FL lens on either camera body will give the same DoF. But if you want to match the FF image on an APSC exactly using a 1.6 ratio lens (to keep the same field-of-view image size at the same working distance) you will need a 1.6 greater aperture ... a more expensive lens, if there is one!
    Last edited by neonlamp; 08-10-2017 at 20:40.

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