Perspective Distortion and Focal Lengths

Discussion in 'This or That? (MFT only)' started by DynaSport, Sep 27, 2013.

  1. DynaSport

    DynaSport Mu-43 Hall of Famer

    Jan 5, 2013
    I have recently switched from using my kit zoom to a P14 and O45. I bought these lenses based on an analysis of the most used focal lengths I used on the kit zoom. I have discovered, however, that I need something between the two extremes. I just got back from a visit with family I don't get to see very often and took several photos of small groups of people inside. The 45 was too long for this and the 14 resulted in very unflattering perspective distortion. So, it looks like I need a new lens.

    I have been considering the O17, the P20 and P25 and both Sigmas (19 and 30). Each has there strengths and weaknesses. Cost is a factor, which hurts the 17 1.8 and the P25 (otherwise I think my preference would be the P25). I had hoped for a faster lens than 2.8 which goes against the Sigmas and the O17 2.8. That leaves the P20. My concern is that it is not enough different from the P14 and I will still end up with perspective distortion. I am also concerned about focus speed as my daughter is pregnant and I am going to want to take photos of a moving toddler at some point. Although that time my be far enough in the future that a new lens would be possible if the 20 turns out to focus too slow.

    So, what recommendations do you guys have? Is the 20 long enough to avoid perspective distortion and wide enough to take small group photos inside? And how bad is focus speed? I'll be using it mainly on a G5 if that matters, but I also have an E-PM1.

  2. AceAceBaby

    AceAceBaby Mu-43 Veteran Subscribing Member

    Jan 21, 2013
    If you still have your kit lens, you could see how it looks. I think personally that 20mm is a lot different to 14mm (1.4x the focal length). I have the Sigma 19mm, and I think it's a good length for anything indoors. I understand that you may feel it's not bright enough, but I don't know if you'd typically get a group of people all in focus at much wider apertures? I've had good results with that lens indoors in relatively dim light.

    I'd also suggest checking out flickr photos done with each lens, you can get a good idea of what's possible that way, too.
    • Like Like x 1
  3. Wisertime

    Wisertime Mu-43 Hall of Famer

    Aug 6, 2013
    I can't offer an experience w/the P20, but I'd look for a used P25. It's an amazing lens, does what you need and you already implied you want it. It's worth the cost. You might even find it becomes your main lens. And if not, you can easily sell it for break even, as they are always in high demand. The Sigma might be a decent/cheaper alternative though, but I have not used any Sigmas either.
  4. Wisertime

    Wisertime Mu-43 Hall of Famer

    Aug 6, 2013
  5. WasOM3user

    WasOM3user Mu-43 Veteran

    Oct 20, 2012
    Lancashire, UK
    Yes 20mm is very different to the 14mm (you could try this if you still have the kit lens and someone who will sit still so you can take a few snaps).

    No the 20mm (or even 25mm) will not completely eliminate the impact on faces you see with the 14. This is why people normally use 45, 60 and 75mm for portraits. As you have found out though you also need the space to use them.

    Yes they will be an improvement over the 14 for portraiture but again you need to decide if it's enough of an improvement - again if you still have the kit lens and a somebody try it at 14, 17, 20, 25, 30 and 42mm.

    The 20 or 25 would be a nice "fit" between the 14 and 45 for a trio of primes for allround use but given you have already stated most of your shots are not in this "middle" range between 14 and 45 it's hard to recommend the higher cost 25mm (although this is the lens I am saving for to fit between my own 14 and 45). But try to do the test shots before you spend anything
  6. CiaranCReilly

    CiaranCReilly Mu-43 Veteran

    Oct 18, 2012
    Ciaran Reilly
    I've had the 14mm, 20mm and 30mm. I've just sold the 30mm as I found I wasn't using it enough since I picked up the 20mm, which was the last of the three I got.

    The difference in distortion between 14mm and 20mm is big, but I did some blind tests between the 20mm and 30mm and they were very similar, distortion wise. I'd go for the 20mm because of the focal length, fast aperture and size. I had a very soft spot for the 30mm in terms of rendering, handling and speed of AF, which was as fast as the 14mm, and I was sad to see it go but happy that the 20mm would do the same job, but smaller and with an added 1.5 stops. Hope that helps!
  7. b_rubenstein

    b_rubenstein Mu-43 All-Pro

    Mar 20, 2012
    Melbourne, FL
    Perspective Distortion is due to the camera to subject distance only. What happens with a wide angle lens is that you get closer to the subject to fill the frame. What you need is a focal length that fills the frame with your subject without distorting the look of the subject. Typically, small groups will look ok with a 35mm FOV lens, so the 20/1.7 will be good. Just keep in mind that in a small room, you may not have enough room to back up far enough to get every one in the picture. What you do in a case like that is to shoot with the 14, but stand as far back as possible (increase the subject to camera distance) and crop later.
    • Like Like x 2
  8. DynaSport

    DynaSport Mu-43 Hall of Famer

    Jan 5, 2013
    Yes, of course you are correct.
  9. cmpatti

    cmpatti Mu-43 Veteran

    May 8, 2011
    Berkeley, CA
    I have the 14mm, 20mm, and Olympus 45mm. I've found the 45mm can work with groups shots up to 4 people abreast if you've got some room to step back. I tend to go with the 20mm for larger groups (or if there's no room to back up). With the 20mm you can get a shot of 5 people abreast filling 85% of the frame side-to-side with no noticeable perspective distortion. Using the 20mm at a recent family gathering I got a nice shot of 25 people (in rows) and a dog. Had the group been any larger, I probably would have had to switch to the 14mm.
  10. flash

    flash Mu-43 Hall of Famer

    Apr 29, 2010
    1 hour from Sydney Australia.
    The "normal" focal length is estimated to have about the same perspective you see with the human eye because It sort of sees the way you do. On m43 that's about 23mm. Anything wider will stretch and longer will compress a scene. It's also why 1/2 prefer a 35mm lens and 1/2 prefer a 50mm lens on 35mm film/sensor. One's a slightly wide normal and one's a slightly compressed normal.

    Most people prefer to see themselves with a slight telephoto edge (a bit of compression), so your 45mm is a nice lens for portraits.

    If it were me (it's not obviously) I'd get the 25mm. Slight compression. The Sigma 30mm is too close to your 45 for my tastes.

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