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Does a 50mm distort in crop frame mode?

Discussion in 'Sony Alpha E-Mount Lenses' started by adwb, Aug 2, 2016.

  1. adwb

    adwb TalkEmount Regular

    127
    Sep 30, 2015
    Bristol UK
    Alistair
    if we accept the general premise that a 55-50mm lens will distort a person's face if used to close, then does it follow that by using the crop mode on a FF body and therefore being further away from the subject for the same image size in the viewfinder this distortion can avoided?
     
  2. dbmiller

    dbmiller TalkEmount Top Veteran

    777
    Mar 2, 2012
    New England
    Right - Crop mode to the APS-C area would be the equivalent of shooting with the lens on an APS-C camera. So 50->75 or 55->82.5

    The 75mm equivalent will be better than 50, but will it be enough?

    l46Cxn3DvFngmYzba.

    Edit: Thanks bdbit - Source for the above animation is Amazing how focal length affect shape of the face
     
    Last edited: Aug 3, 2016
    • Informative Informative x 4
  3. addieleman

    addieleman Passionate amateur

    Nov 13, 2012
    Netherlands
    Ad Dieleman
    That's an interesting experiment. I prefer the 105mm shot, incidentally the classical focal length for portraits.
     
  4. AlwaysOnAuto

    AlwaysOnAuto TalkEmount Top Veteran

    712
    Feb 17, 2015
    Hey db, can you slow that down just a tad? It's hard to see each focal length when it changes that fast.

    I'd actually like to do something like that where one camera morphs into another.
     
    • Agree Agree x 1
  5. bdbits

    bdbits TalkEmount Veteran

    400
    Sep 10, 2015
    Bob
    • Appreciate Appreciate x 1
  6. Noor

    Noor TalkEmount Regular

    116
    Jan 25, 2016
    Noor Arnaout
    I have the Sony 50mm OSS ordered , so I guess ill be fine.

    75-105 seems like the sweet spot , I guess this animation is on FF
     
  7. adwb

    adwb TalkEmount Regular

    127
    Sep 30, 2015
    Bristol UK
    Alistair
    Thanks for the answers and comments but I don't think anything actually answers my question.
    The gif demonstrates different lenses on a FF not the same lens on a ff and a crop frame which is my question.
     
  8. Noor

    Noor TalkEmount Regular

    116
    Jan 25, 2016
    Noor Arnaout
    It should be like 75mm on Full frame , I'd say it will be OK
     
  9. addieleman

    addieleman Passionate amateur

    Nov 13, 2012
    Netherlands
    Ad Dieleman
    Simply divide the focal length in the demo by 1.5 to get to the equivalent focal length for Sony APS-C format. So 75mm in the demo is what a Sony E 1.8/50 would do for you on APS-C.
     
  10. Noor

    Noor TalkEmount Regular

    116
    Jan 25, 2016
    Noor Arnaout
    Yes it will be like 75mm , my subjective view is that 75mm is acceptable for environmental porteights
     
  11. JMM

    JMM TalkEmount Regular

    43
    Jul 29, 2016
    John
    Since i got only Zenit FF so i cant make real-life comparision, but according to my physics knowledge, crop affect effective T stop, F stop and FOV (field of view) BUT IT DOESNT affect amount of perspective distortion (so called tellephoto compression and wideangle spread).
    So in summary: 50mm lens is a 50mm lens. No matter if FF or APS-C. Its a 50mm with slower aperture and smaller FOV, but same amount of distortion, if the working distance is maintained.
    Can someone with FF and APS-C body test this?
     
    • Agree Agree x 1
  12. Noor

    Noor TalkEmount Regular

    116
    Jan 25, 2016
    Noor Arnaout
    Not true , perspective is linked with your distance from the subject. So if you are going to compose a shot with a 50mm on APS-C like 50mm on a full frame camera you will have to take a few steps back , hence changing your perspective
     
    • Agree Agree x 2
  13. JMM

    JMM TalkEmount Regular

    43
    Jul 29, 2016
    John
    With same logic about WD i can take two steps back with 50mm FF, crop in PP and call it a 70mm lens.
     
  14. chalkdust

    chalkdust TalkEmount Veteran

    279
    Sep 25, 2015
    Bert Cheney
    I find this demonstration to be simply adding confusion. It is poorly labelled. In order to produce that set of images, TWO things changed. Primarily the distance from the camera to the subject changed. Secondarily, in order to keep the face size about the same within the image, either the focal length of the lens was changed - OR - the image was cropped and resized. But the only thing that affected the distortion was the the distance from the camera to the subject. You can do this without a camera. Use your eye. Close one eye then look at a person's face from a few inches away and compare it to looking at the person from a few meters away. The demonstration should have been labelled with both lens focal length and with distance to subject.
     
  15. Noor

    Noor TalkEmount Regular

    116
    Jan 25, 2016
    Noor Arnaout
    Saw this on the page :

    Screen Shot 2016-08-03 at 4.52.17 PM.
     
  16. adwb

    adwb TalkEmount Regular

    127
    Sep 30, 2015
    Bristol UK
    Alistair
    I found this which I saved from somewhere; do you agree with the 15 foot? it seems a bit far to me? thats the length of my small studio and I shoot head and shoulder with a 50mm a lot closer than that, with out any one complaining about distortion.
    quote
    "Our brains recall people's facial features as they appear to be from about 15 feet (5 meters) away.
    Ask a human visual system researcher for the details, but our eyes don't actually see anything by themselves. All our eyes do is send signals to our brains which are then interpreted in ways about which we're still learning.
    In the case of facial recognition, when our eyes see a familiar face, it triggers our brain to reconstruct an image of those features as they appear from about 15 feet.
    If we see someone from only inches away, we don't see them distorted as a camera would; our brain perceives and reconstructs their features in proportions similar to a distant view.
    Therefore we want to be at least about 15 feet away when photographing people in order to achieve realistic proportions.
    " end quote
    and
    What's the optimum portrait lens?
    quote

    "It depends on how much of a person you're showing.
    If you want the whole person standing, you can use a 50-70mm lens. If they sit down, a 70-105mm works great.
    If you want just head and shoulders, you'll want a 200mm to 300mm lens, at least, since you want to stay at least fifteen feet away." end quote

    Alistair
     
  17. adwb

    adwb TalkEmount Regular

    127
    Sep 30, 2015
    Bristol UK
    Alistair
    my original question is because I have a A7r2 and as a pensioner really can't afford to splash out on a 55mm and a 85mm or a 55mm and a 90mm macro from Sony or Zeiss.
    So I thought that the 55mm1.8 might, when used in crop mode, give me a fast 75 as a solution even if was short to medium term.

    quote "There are two lenses that every portrait photographer should own at least one of – the 85mm and 50mm prime lenses.
    • If you have a full-frame camera, then the 85mm lens is generally best for head and shoulder shots. The 50mm lens works well for half or three-quarter length portraits, or for a more intimate feel with a head and shoulders portrait." end quote
     
  18. bdbits

    bdbits TalkEmount Veteran

    400
    Sep 10, 2015
    Bob
    I do not do portraits myself but over the years have sat for a few professional shots. As I recall, I do not think they were ever 15 feet away, more like 10 feet or less, even in a studio. These were head-and-shoulders type shots, as obviously whether you want head-and-shoulders or full-body portraits plays into this also.

    Out of curiosity, I did a search and found your quote comes from Ken Rockwell. Personally not a fan, so I was not surprised I disagreed with him.
    Portrait Lenses
     
  19. WestOkid

    WestOkid TalkEmount All-Pro

    Jan 25, 2014
    New Jersey, USA
    Gary
    I think I understand your question. The problem is that it implies that focal lengths are dictating what can be captured regardless of environment. The only reason people speak in general about focal lengths in terms of 50mm for 3/4, 85mm for shoulder shots, WA for landscapes etc. is because there is always an assumption of general working distance. You are likely to shoot portraits in a room or studio or even a crowded street. In addition to distortion, each of those environments may limit how far you can move back without bring other factors into play like an obstruction or unintended objects into the scene. So those focal lengths suggestions generally work.

    As has been noted Noor, perspective changes because the distance to subject has to change in order to achieve the same framing. The example posted with the guys face changing fails to point out that as the focal length is changing to higher focal lengths, the camera is moving away from the subject to achieve the same framing of the face. If it wasn't, then by 200mm you would only be looking at an eye not a face. So with this in mind you can imagine your example were you enable crop on your A7RII and change the effective focal length from 55mm to 82mm. You would need to move back to achieve the same frame as you had when you were at 55mm. This movement would change the perspective to one that yields a more flattering portrait and achieve your goal.

    Also - I'm sure you know this, but for the record. By switching to APSC mode, you are losing resolution, total light and other equivalency factors, so it's not really like you have replaced FF 75mm.

    Hope this helps
     
  20. dbmiller

    dbmiller TalkEmount Top Veteran

    777
    Mar 2, 2012
    New England
    Thanks for finding it. I got it from a Facebook post by my daughter's photography teacher which did not give the source. The link from bdbits has the separate images, the whole blog post, comments and such.