"Apparent" focal length of 4:3 vs. 3:2 formats?

Discussion in 'Native Lenses' started by cptobvious, Dec 19, 2013.

  1. cptobvious

    cptobvious Mu-43 Veteran

    239
    Jan 8, 2013
    I remember reading somewhere that some author's preferred wide focal length was 28mm (on 35mm format), but he said that the Olympus 12mm was suitable because the more square-ish format of 4:3 compared to 3:2 made the 24mm seem more like a 28mm. As someone who's used to shooting in 3:2 and jumping into 4:3, I am curious have any of you found this to be the case? I've ordered the Olympus 12, 17, and 45 lenses and often use the 24/35/85 lengths on FF and am curious how the lenses will 'frame'. Thanks.
     
  2. AceAceBaby

    AceAceBaby Mu-43 Veteran

    249
    Jan 21, 2013
    The lenses you've listed, may all frame "tighter" horizontally than you might expect, for good or bad.

    Actually, I decided to do the maths on it: The diagonal for a 35mm slide is 43.27mm. The diagonal (different angle/ratio) for mu43 (based on the active sensor size of 17.3mmx13mm) is 21.64, which is almost exactly 0.50

    Horizontal ratio is 0.48
    Vertical ratio is 0.54

    So if you typically frame for how much you can see horizontally, then everything is a bit tighter, conversely, there's a fair bit more "head room" than you'd expect, vertically.

    I have an adapted(35mm SLR) 45mm lens. By my reckoning, this probably doesn't give the same angle of view as a native Olympus 45mm.
     
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  3. rbelyell

    rbelyell Mu-43 Veteran

    356
    Sep 15, 2013
    Mountains of NY
    3x2 for landscapes, street scenes etc; 3x4 for portraits. best of both worlds.
     
  4. Ray Sachs

    Ray Sachs Super Moderator

    Apr 17, 2010
    Near Philadephila
    I think I'm the guy quoted in the OP. I'd urge anyone to spend a bit of time with a Panasonic LX5 or LX7, which has a multi-aspect sensor (so you're not just cropping off the sides or top and bottom - you're actually enlarging one while shrinking the other when you switch aspect ratios) and a step zoom function. It's a great way to get a feel for different focal lengths at different aspect ratios. So any given focal length on a 4:3 native sensor will give you less width but more height than a 3:2 and a 16:9 will give you more width and less height yet. One caution, the 1:1 ratio with those cameras is just a cropped 4:3, so the lessons are mostly between 4:3, 3:2, and 16:9, all of which the sensor does natively.

    I agree with Tony - 3:2 for most landscape format shooting and 4:3 (or 3:4 as he more accurately puts it) for most portrait format shooting. Ironically, for street shooting I prefer 4:3 because I often crop down to 1:1 anyway, but my street camera is a 3:2 Nikon Coolpix A because I like the functional parts of the camera so much for street shooting, and the sensor is just a bit better for low light zone focussing.

    -Ray
     
  5. Ray Sachs

    Ray Sachs Super Moderator

    Apr 17, 2010
    Near Philadephila
    I was with you up to the last statement. Either lens will look the same if you're using both on an m43 body, but either will look different on an m43 body than the adapted 45 would on an SLR with a native 3:2 sensor (or film). So it's not about the lens - it's about the shape of the sensor the light falls on.

    -Ray
     
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  6. fredlong

    fredlong Just this guy...

    Apr 18, 2011
    Massachusetts USA
    Fred
    An adapted 45mm and a native 45mm are both 45mm and will have the same angle of view. That is if they are both actually 45mm. Many lenses, especially older ones, are rounded up or down to a nice even sounding number.

    A 45mm lens on a u43 body will have a different feel than a 90mm on a 35mm body because of the different aspect ratio.

    My thoughts on this subject are: get used to u43 and get over comparing to another format. Just shoot the lenses you have and add linger or shorter focal lengths as needed. Longer is always always longer, shorter is always shorter. Or shoot a different format.

    Fred
     
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  7. dwig

    dwig Mu-43 Top Veteran

    624
    Jun 26, 2010
    Key West FL
    True, but only approximately. Lens FLs are not all that accurately marked. Generally there is a up to a 5% difference between actual and marked FL on fixed FL lenses and sometimes as much as 10% on legacy zooms, with the zooms' minimum FL almost always being 5-10% longer than marked and the maximium FL being 5-10% shorter.. Two different "45mm" lenses could easily differ by up to 10% if one was a bit shorter of the marked FL and the other a bit longer.
     
  8. rbelyell

    rbelyell Mu-43 Veteran

    356
    Sep 15, 2013
    Mountains of NY
    imo, whether or not a 45/90 has a different 'feel' on different formats depends in large degree on how one shoots. besides the obvious, and objective, DOF differences, when i shoot a 45/90 i'm less concerned with a 'scene' and more concerned with the 'player(s)'. therefore framewide fov is not particularly relevant, therefore i kinda prefer 3:4.

    so for me, that fl will feel the same on any format most of the time. again for me, that 'feel' changes with the format when i concerned about the framewide scene, which is usually with 35 on down.
     
  9. Consider the Panasonic GH1 which has a true "multi-aspect" sensor. It has the following maximum resolutions in 4:3, 3:2, and 16:9

    4000x3000 (4:3)
    4128x2752 (3:2)
    4352x2448 (16:9)

    These numbers show that the height of the frame varies much more than the width. In terms of pure width, a 3:2 frame is only 3.2% wider than a 4:3 frame. Different yes, but not massively so. Going to 16:9 is more significant with a 5.4% increase in width over 3:2, and 8.8% wider than 4:3.

    Follow the numbers on the metal ruler below.

    4:3 Aspect

    P111054943Aspect_zps8bd14107.



    3:2 Apsect

    P111055032Aspect_zpsc12b55a0.



    16:9 Aspect

    P1110551169Aspect_zps83898991.



    I think that a lot of the difference that we think exists in width between a 4:3 and a 3:2 aspect sensor is perceptual rather than actual. This is why cropping an image to a different aspect ratio has such a powerful effect on the look of the image even though the actual width doesn't change.
     
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  10. greenarcher02

    greenarcher02 Mu-43 Veteran

    330
    Feb 13, 2012
    Manila, Philippines
    Interesting, but I have a question. Is it recommended to use 3:2 or 16:9 (for landscapes for example) on non multi-aspect sensors? Like, say, a GX7? Or will it be similar to cropping and I should just shoot 4:3 and crop it myself in post? I currently do the latter. And if I crop, I rarely change aspect ratios. I have it locked to 4:3 (I find the ratio pleasant to my eye).
     
  11. fredlong

    fredlong Just this guy...

    Apr 18, 2011
    Massachusetts USA
    Fred
    On any body except the GH1 and GH2 changing aspect ratio is just a crop. So shoot the full frame and crop later or crop in the camera, whichever is more comfortable to you.

    Fred
     
  12. RoadTraveler

    RoadTraveler Mu-43 All-Pro

    Nov 23, 2012

    I do agree that changing the aspect ratio can affect the feel and framing of images, just not necessarily as much as making a 12 feel/look like a 14 on m4/3. Though, there is not a huge gap between these two angles-of-view, so maybe it's more akin to the pronunciation of tomato? If both lenses are shot on the same aspect ratio, 4/3 or 3/2, I think the differences will apparent.

    I was very accustomed to shooting 3/2 aspect ratio cameras (decades, mostly film, then digital) but the 4/3 ratio has grown on me, I think I even prefer it most of the time. For me it's not so much that I think a 12 is very similar or very different to a 14 in m4/3, but that I prefer a bigger split between my primes, similar to the three you have chosen.

    In addition to the several native zoom m4/3 lenses I own, I recently purchased a few manual focus primes, essential the same angles of view that you have chosen, 12, 17.5, and 42.5mm. If my 'normal' was a 25mm instead of 17.5, then I might gravitate to a 14mm as my wide prime lens. However, since I like the angle-of-view provided by a 17 (or a 35mm on 35mm frame) as my wide-ish normal, I chose and prefer the wider 12 for my wide prime. I'd probably even like something wider if available in a fast, wide prime in m4/3.
     
  13. I always believe in setting the aspect ratio to suit the image over maintaining the full resolution of the native aspect ratio of the sensor, although I always shoot at the native ratio with the intention of cropping later. Using the GH1 however requires a decision at the point of capture over whether I want to "unlock" the extra pixels in width at the expense of not being able to retrieve the loss of height if I changed my mind.
     
  14. meyerweb

    meyerweb Mu-43 Hall of Famer

    Sep 5, 2011
    True, but that has nothing to do with whether the lens was designed for 35mm or 4/3 frame sizes.
     
  15. RoadTraveler

    RoadTraveler Mu-43 All-Pro

    Nov 23, 2012
    I agree with Mr. Sachs here. With previous compact cameras I'd owned (Canon G, S100, etc.) I never really played with their aspect ratio crop features. However, with both the excellent LX7 that I own and use as my 'compact', and my favorite and everyday tool, the Panasonic GX1, I do change the aspect ratio at times depending on the lens and subject. I prefer 4:3 most of the time, but I've found I really like 16:9 for my fisheye 7.5mm, and even with less extreme lenses sometimes 3:2 just works/looks better.

    Playing with the different ratios in the camera as Ray suggests can really help you ‘see’ and appreciate the differences before you take with shot, while your subject is in front of you. Of course, I’m also a big fan of doing everything I can ‘in camera’ to limit post processing adjustment time when possible.
     
  16. An illustration of the effect of the claimed focal length of a lens vs resulting angle-of-view.

    Panasonic Lumix G 14-45mm f3.5-5.6 @ 14mm

    P111055314-45mm_zps7f5d786d.



    Panasonic Lumix G 14mm f2.5

    P111055414mm_zps29e56ed8.



    This is the difference between the two lenses at a distance-to-subject of approximately 40cm from the sensor plane, and represents a 6.6% difference in width between two lenses that claim the same focal length which is twice that which occurs just going from 4:3 to 3:2 aspect. I note that the angle-of-view between the two lenses might start to equalise at longer focusing distances, since lenses DO change their angle-of-view as distance to the focal point changes.
     
  17. Cruzan80

    Cruzan80 Mu-43 All-Pro

    Aug 23, 2012
    Denver, Co
    Sean Rastsmith
    The other thing to realize is that m43 lenses have built in distortion correction, so depending on how much or little distortion, it may crop the resulting image accordingly.
     
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  18. AceAceBaby

    AceAceBaby Mu-43 Veteran

    249
    Jan 21, 2013
    OK, thanks for the explanation. On a side note, I think the normal for mu43 will be +/1 21mm (21.5 for 4:3, 20.7 for cropped 3:2)
     
  19. dwig

    dwig Mu-43 Top Veteran

    624
    Jun 26, 2010
    Key West FL
    True, but also note that:

    1. Humans tend to brag which results it longer than normal focal lengths to more often be rounded up and wider than normal to be rounded down. If designed for m43, a "35mm" lens is long and more likely rounded up while one designed for 35mmFF would be "wide" and more likely rounded down.
    2. The "cropping" that Cruzan80 mentions will also come into play unless you shoot m43 RAW and use software that will ignore the build-in distortion correction info.

    Bottom line: my point is that one should not look for too much precision when doing these comparisons.
     
  20. RoadTraveler

    RoadTraveler Mu-43 All-Pro

    Nov 23, 2012
    Interesting graphic comparison.