Comparison between Oly trinity, plus 12-40 PRO.

Discussion in 'Native Lenses' started by Johbremat, Jan 9, 2014.

  1. Johbremat

    Johbremat Mu-43 Regular

    130
    Dec 5, 2013
    As I understand it, a prime has a different FOV/POV to a zoom lense at the same focal length.

    Anyone lucky enough to have the O12, O17, O75 and 12-40 PRO (or zoom across a similar range) in there possession?

    Using a tripod and the same composition, would love to see a shot in each of the primes, and the zoom at comparative measures.
     
  2. nuclearboy

    nuclearboy Mu-43 Top Veteran

    851
    Jan 28, 2011
    USA
    I don't have the 12-40 but do have the 12-35 pan...

    There is no FOV/POV difference if you are at the same FL. If you are at 17mm on the zoom, you get the same FOV/POV as the 17mm prime. The only lens I have seen a slight difference on is the 20mm prime. It seems to be approximately 19mm IMO from some informal comparisons on a tripod squared up to a photo resolution chart on a wall. This is not a general issue but more likely just a round off issue on the labeling of this particular lens.

    In general, 17mm = 17mm, 25mm = 25mm, etc...
     
  3. e_kjellgren

    e_kjellgren Mu-43 Regular

    173
    Oct 17, 2011
    Sweden
    It will be a hard task to compare the O75 :)
     
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  4. fredlong

    fredlong Just this guy...

    Apr 18, 2011
    Massachusetts USA
    Fred
    Any two lenses of the same focal length will have the same field of view and perspective. I've never seen anything to suggest otherwise.

    I've never heard ( or read ) anything to suggest otherwise, but the internet is a big place filled with inaccurate information.

    Fred
     
  5. phl0wtography

    phl0wtography Mu-43 Veteran

    227
    Apr 15, 2011
    IF the focal lenghts are actually the same. And there's the rub. Not only can primes have a slightly different focal length than indicated, but especially with zoom lenses marked focal lengths on the barrell are quite inaccurate.

    However, what Johbremat might refer to is a phenomenon with internally focusing zooms that has come to known as "focus breathing", which can be quite pronounced with long telephoto zooms. I don't really pay attention to it though. First of all I only shoot primes, second of all, if noone points it out to you, or you have a prime of the same focal length to compare with, your noticing it is highly unlikely.
     
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  6. Johbremat

    Johbremat Mu-43 Regular

    130
    Dec 5, 2013
    Cheers for the education.

    THAT now clarified, any hope of seeing the same comp on tripod with the primes?

    Still interested in seeing what the different lenses offer against the same view.
     
  7. Superstriker#8

    Superstriker#8 Mu-43 Regular

    194
    Jun 24, 2013
    What is focus breathing?
     
  8. alex66

    alex66 Mu-43 Top Veteran

    715
    Jul 23, 2010
    It is where some lenses due to their design change focal length or angle of view as they move from close focus to infinity. I think some of the Sigma super zooms displayed this in spades, one of the 18-200 I think it was, something to do with internal focusing with a sub set of elements moving. However this is from memory so could be wrong.
     
  9. BigTam

    BigTam Mu-43 Top Veteran

    773
    Mar 19, 2012
    Dortmund, Germany
    Ron
  10. Superstriker#8

    Superstriker#8 Mu-43 Regular

    194
    Jun 24, 2013
    My 60mm macro does this a lot, I have yet to get used to it, as its very weird, this being the first time I've encountered it.
     
  11. nuclearboy

    nuclearboy Mu-43 Top Veteran

    851
    Jan 28, 2011
    USA
    I don't have the images with me now but I will state again that there is no significant difference. 17mm is 17mm is 17mm for all practical purposes.

    I carefully setup a test target, squared the sensor to the center of the target, and took comparison photos will all of my primes and zoom lenses at various times. The tripod was set at a distance for each FL such that the black fringe around my target pattern poster just sat at the edge of the image. differences between lenses of the same focal length are within the size of the black band around my poster.

    I do this for the purposes of looking at image resolution, vignetting, and distortion. While doing it, I can also observe that for all practical purposes, the lenses have the same field of view and point of view when using the same Focal length. i.e 17mm = 17mm. 25mm = 25mm. In other words, I could setup my tripod and put a zoom on and carefully adjust to 25mm. I take my range of photos. Then I swap out the lens for a 25mm prime and I can take the same photos with the same field of view without moving my tripod forward or backward.

    There are minor differences that crop up which have been discussed here but none of these are significant enough to make any practical difference in a real photograph.

    I relied on the FL indicator on the screen in my E-P5. Clearly this reading is probably only accurate to +/- 1 given how I can watch it change/not change with small adjustments to the lens barrel. In addition, the primes may not be 100% accurate to their stated FL. There may be some rounding issues and there may be some cropping done by the camera that changes the FOV slightly. I compared Jpgs in my work. In addition, there is the focus breathing that was mentioned. There are probably 5 other issues that affect the actual FOV of the lens if you want to get technical. There seems to be no point.

    Bottom line, in my experience with looking at about 10 m4/3 lenses (and some legacy glass), there is no practical difference in the field of view between a zoom and a prime. Any measured differences would be small and unique to the particular lens and not a factor in a real photograph. Any attempt to compare photos to see these differences would require very careful setup in order to observe very slight differences. Unless you are doing scientific research on the images, this seems pointless.
     
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  12. Your Funny Uncle

    Your Funny Uncle Mu-43 Regular

    38
    Dec 12, 2013
    York, UK.
    Rob
    I wonder if the OP meant DOF (Depth of field)? The larger apertures in prime lenses mean that you can get a shallower depth of field (the part of the image that is in focus) at the same focal length. Sometimes it's desirable to have a narrow depth of field such as in a portrait when you're trying to isolate the subject from the background.

    The effect is reduced in MFT due to the smaller sensor size and is more obvious the longer the focal length and the closer is the subject upon which you're focusing, but you should see a difference in some images. For example with a head-shot taken with the Panasonic 25/1.4 wide open and the Oly 12-50 at 25mm wide open, you should see a more blurred background with the prime lens.
     
  13. phl0wtography

    phl0wtography Mu-43 Veteran

    227
    Apr 15, 2011
    This.

    The most prominent contender would be the Nikon 70-200/2.8, that does this at pretty much any FL, and it gets worse the longer the FL gets, as much as 200mm actually being between 135-165mm reportedly at CFD.

    I'm pretty sure he didn't mean something that obvious. :wink:
     
  14. Your Funny Uncle

    Your Funny Uncle Mu-43 Regular

    38
    Dec 12, 2013
    York, UK.
    Rob
    Looking at the OP's other posts, it seems that the E-M1 is their first interchangeable lens camera, so maybe not so obvious to them. It's easy to get confused when you're starting out!
     
  15. zensu

    zensu An Old Fool

    Aug 8, 2012
    Southeastern USA
    Bobby
    In my case it's just easy to get confused.
     
  16. Jonathan F/2

    Jonathan F/2 Mu-43 Hall of Famer

    Aug 10, 2011
    Los Angeles, CA
    I though the Olympus prime trinity is the 12, 17 & 45? :wink: The 75 is in a class by itself. :biggrin:
     
  17. Johbremat

    Johbremat Mu-43 Regular

    130
    Dec 5, 2013
    I think I've botched this.

    New tact. Can you show me the differences in PERSPECTIVE?

    Such that, if you were taking a shot of a statue and wanted it to take 100% of the vertical of the frame, surely in each instance the statue may look the same but the surrounding material is going to differ, no?
     
  18. Your Funny Uncle

    Your Funny Uncle Mu-43 Regular

    38
    Dec 12, 2013
    York, UK.
    Rob
    If you take the same shot at the same aperture then the shots will look virtually identical and the only differences will be down to the quality of the lens. There may be a difference in the feel of the out-of-focus areas, or in the detail captured in the in-focus areas but it will be minimal. The key difference is that with the prime lenses you can open the aperture wider (the lower the f number given on the lens, the wider the maximum aperture) which will narrow down the in-focus area. This will throw the areas that are not in focus ( the stuff behind the statue) further out of focus to make for a smoother background that will make the statue stand out more in the shot.

    As I said, you'll notice this effect more strongly at more telephoto focal lengths or if the object upon which you're focusing is closer to the camera.
     
  19. phl0wtography

    phl0wtography Mu-43 Veteran

    227
    Apr 15, 2011
    Now I know what you meant, right.
    No, it wouldn't look the same. It would only look the same if your object was two dimensional, like a painting. Focal length does NOT determine perspective, but the scale (magnification) of an object on the film plane/ sensor. Perspective is only determined by the distance of a given object to the camera.
    If you take 3 pictures of a statue with 3 different focal lengths from the SAME point, then the difference will only show in angle of view, not in perspective. The statu would appear smaller and larger, but would be in fact the same in all three. Cropping, and enlarging the 2 wider angled shots from the statue to the one from the longest FL would easily show, that all 3 crops of the statue would be congruent.
    If OTOH you - like you asked - take a picture of a statue with 3 different focal lengths as such that the statue always takes 100% vertical space (you have to change your distance to the statue to make that happen), the 3 pictures will show quite different perspectives. The longer FL will compress depth considerably more than a wider FL, thus altering the relation of space and size between objects in your frames. No amount of cropping, enlarging and whatnot (apart from deconvolution of course) would result in the same image scale as in the first example.

    - Focal lengths determines magnification of an object.
    - Distance from object to camera determines perspective.

    I recommend Feininger, Andreas: The Complete Photographer. Revised Edition as an in-depth read on anything photography related.
     
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  20. fredlong

    fredlong Just this guy...

    Apr 18, 2011
    Massachusetts USA
    Fred
    If you use a prime lens and a zoom lens at the same focal length from the same position the field of view and perspective will be the same.

    Fred