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12 f2 or 15 f1.7

Discussion in 'Native Lenses' started by Cederic, Oct 17, 2014.

  1. Cederic

    Cederic Mu-43 Veteran

    212
    Nov 14, 2012
    Nottingham
    Just back from a trip where I really suffered from having nothing wider than the Panny 20mm.

    So looking at wide angle lenses, and because I'll use them for indoor dance photography, I want nice and fast.

    How do the 12mm f2 and the 15mm f1.7 compare? If there was a 12mm f1.7 I'd just click 'buy' immediately, but since I'm going to have to compromise somewhere I'd be grateful to hear peoples thoughts on the best direction to take.
     
  2. OzRay

    OzRay Mu-43 Legend

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    It depends on how wide you need, the difference in f stop is marginal, so it's angle of view that you need to consider. The 12mm will give a greater depth of field, if getting more of the scene into focus is of concern.
     
  3. Johbremat

    Johbremat Mu-43 Regular

    130
    Dec 5, 2013
    Interesting statement, as you could stop down the P15 to obtain the deeper plane of focus.

    The O12 is a joy to handle and the manual focus clutch works a treat. Figure the benefit of a wider field of view would be more useful for your purposes.
     
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  4. OzRay

    OzRay Mu-43 Legend

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    A 12mm lens will inherently have more depth of field than a 15mm. If the OP intends to shoot in an indoor dance environment, then being able to use a faster aperture, but at the same time obtain greater depth of field would be an inherent advantage.
     
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  5. biza48

    biza48 Mu-43 Regular

    42
    Jul 31, 2014
    Portugal
    Only you can know if you need 12 or 15mm focal length. In practical terms, the difference between f1.7 and f2 is a wash.
     
  6. edmsnap

    edmsnap Mu-43 Veteran

    430
    Dec 20, 2011
    Edmonton, Alberta
    There would be no practical, reasonable way to tell the difference between an f/2 and an f/1.7 version of the same lens, so clicking "buy" seems like your next step.
     
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  7. eteless

    eteless Mu-43 All-Pro

    Jun 20, 2014
    I suspect that there is an easy test if the lenses existed - check the buy it now price on a few random ebay auctions. The F/1.7 will be two or so times the price... 17% faster, so worth it!
     
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  8. tjdean01

    tjdean01 Mu-43 Top Veteran

    842
    Feb 20, 2013
    If you have the 20 and want wider I would really think that the 12 would be your best choice because what if you buy the 15 and still want wider? If you buy the 12 and want longer all you have to do is a) crop or b) put on the 20. Problem solved! :)
     
  9. kwalsh

    kwalsh Mu-43 Top Veteran

    775
    Mar 3, 2012
    Baltimore, MD
    That's only true in the most trivial sense. He will get deeper DoF only if he accepts the smaller subject size of the dancers in the 12mm shot compared to a 15mm shot from the same distance. If he either crops his 12mm image to get the dancers to better fill the frame or he shoots closer to the dancers with the 12mm to fill the frame then there is no DoF difference between 12/2 and 15/2. Stated another way DoF depends only on numerical aperture and does not depend at all on focal length for identical subject magnification. This is important to realize when shooting people as we often either reposition or crop to a particular subject magnification (e.g. head only, head and shoulders, full body, group).

    For the OP it really comes down to how wide you want to go as others said. You can of course crop 12mm down a bit in the cases in which it is too wide but if the 15mm isn't wide enough you are sort of out of luck. If you find yourself always cropping the 12mm then you might have been better of with the 15mm. Also as others said the difference between 2.0 and 1.7 is just half a stop and so probably not the deciding factor.
     
  10. eteless

    eteless Mu-43 All-Pro

    Jun 20, 2014
    If he crops the 12mm there will be absolutely no difference in DoF between the uncropped and cropped, all that's happened is he's taken the middle part and used it. A 50mm lens on a 135 camera (FF) will have exactly the same depth of field for a given fstop if you were to put it on a half frame (APS-C..ish) or 110 format camera(4/3).

    The problem with the second is we don't use numerical aperture, we use fstops which are based on focal length.
    12.5mm at f/1.0 = 12.5mm aperture
    25mm at f/2.0 = 12.5mm aperture
    35mm at f/2.8 = 12.5mm aperture
    50mm at f/4.0 = 12.5mm aperture

    In theory the depth of field won't change for any of the above, just the field of view (Assuming the same format, naturally the tstops change).

    The difference between f/2.0 and f/2.5 on a 15mm lens (12mm @ f/2.0 = 15mm @ f2.5 for DoF) is pretty small, so much that if the difference in depth of field between them came down as the deciding factor when making a shot then I would have to say you're doing it wrong. Go with what's available at a good price, they're both fantastic lenses.
     
  11. oldracer

    oldracer Mu-43 All-Pro

    Oct 1, 2010
    USA
    Cederic, as others have said, there is no practical difference between f2 and f1.7.

    But I'm assuming from your question that you are not an experienced user of WA lenses. I read in it the idea that there is not a huge amount of difference between 12mm and 15mm, so aperture is the main consideration. Actually there is quite a difference between 12 and 15.

    For travel photography and really any shooting of interiors where you want to have a sense of space my experience is that 24mm (35mm equivalent) is the longest lens that really works. I carry a 12/f2 for when light is low, but I prefer using my 9-18 wherever possible because it gets me quite a bit more space. When you say you "suffered" from lack of a WA on your trip, I'm guessing that it is the interior shots you're dissatisfied with. For scenery, lack of a WA just means you shoot in-camera or stitched panoramas.

    There are many kinds of dance, but I think you will find that to use a 12mm will mean that you will be intrusively close to your subjects -- probably meaning that you'll have to shoot during rehearsals rather than during public performances. The perspective distortion you'll get is a two-edged sword. On one hand it offers some spectacular effects, on the other it can produce some really ugly results. If you're not familiar with perspective distortion, study here: http://en.wikipedia.org/wiki/Perspective_distortion_(photography)

    So IMO, bottom line from reading the somewhat limited information in your post is that the 12 is probably what you want for travel and the 15 (or longer) may be what you want for dance. For one-size-fits-all, the 12-40 f2.8 or something like it might be worth a look, even at the penalty of shooting higher ISOs.
     
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  12. kwalsh

    kwalsh Mu-43 Top Veteran

    775
    Mar 3, 2012
    Baltimore, MD
    Sorry that's flat out wrong. DoF is dependent on the CoC for the final image. So when cropping you use a smaller CoC just as you use a smaller CoC when using a smaller format precisely because you magnify more to get to the same output print size. Try a DoF calculator or just read and understand the equations here:

    http://en.wikipedia.org/wiki/Depth_of_field
     
  13. EarthQuake

    EarthQuake Mu-43 Top Veteran

    832
    Sep 30, 2013
    Right, for a given output size (for instance, a print) two prints from an identical shot, the cropped one with show narrower DOF. This is because the background is enlarged/the magnification is changed and the out of focus elements will appear larger/more out of focus.

    The same happens with prints of varying sizes. With two prints (viewed from the same distance) at different sizes, the larger print will appear to have narrow dof as well. If I know I'm going to print large, I will generally stop down a stop or two extra, as what may appear to be wide enough DOF in a web sized image or 6x4, may look out of focus in a 18x12 or whatever.

    The content of the image at the pixel level doesn't change of course, but DOF is hugely dependent on output size and viewing distance. These variables are often fixed with DOF calculators, but some will allow you to change them, at which point you can see the impact.
     
  14. OzRay

    OzRay Mu-43 Legend

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    The point I was making is that if needs a wider angle lens (how wide?) for his dance shots, then clearly he isn't going to be cropping out individuals, but wanting more people in his shots to show the entire scene. To that end, the greater depth of field of the 12mm will be to his advantage. If he's going to be seriously cropping from the 12mm, then it's pointless getting it in the first place.
     
  15. oldracer

    oldracer Mu-43 All-Pro

    Oct 1, 2010
    USA
    OK, my eyes are glazing over with all this DOF minutiae. Yes/no questions: Do any of you guys think that differences in DOF should be a significant selection criterion for the OP? Or is it just a small factor to be considered?
     
  16. OzRay

    OzRay Mu-43 Legend

    Jan 29, 2010
    South Gippsland, Australia
    Ray, not Oz
    It's 'one' factor to consider. In 35mm film terms, we're comparing a 24mm lens with a 30mm lens, the DoF will be more with the 24mm lens. It all depends on what the OP is really after that matters.
     
  17. BSH

    BSH Mu-43 Veteran

    208
    Jan 18, 2012
    WI
    Dance photography? I done some of that, and wished I had the 45mm 1.8. Otherwise, I use 14mm all the time, and often wished I had the 12mm.
     
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  18. edmsnap

    edmsnap Mu-43 Veteran

    430
    Dec 20, 2011
    Edmonton, Alberta
    F-stops aren't linear (contemplate that the difference between f/22 and f/32 is a 100% difference in brightness, not 45% as with your math). Then understand that in a good-ISO-performance world with image stabilization, differences need to be much greater before it actually changes how you're shooting. The half-stop difference between f/1.7 and f/2 makes no difference to what you can shoot and what results you'll get.
     
  19. agentlossing

    agentlossing Mu-43 Hall of Famer

    Jun 26, 2013
    Andrew Lossing
    Wait, what's with all this crop determining dof stuff? Granted magnification has a little bit to do with it (vis a vis you can't tell camera shake as easily in a wide lens as a telephoto) but you can't tell me I'd get similar dof from an adapted 50mm f1.8 and a cropped image from, say, the 17mm at f1.8. Obviously there are both factors at work here,but surely the 12mm has greater dof than the 15mm cropped, at some level (whether we could actually see it in practice or not).
    GX1•EP1•GF3•17/2.8•30/2.8
     
  20. Nam-in-Sonoma

    Nam-in-Sonoma Mu-43 Veteran

    436
    Aug 23, 2012
    Penngrove, CA
    Nam
    Exactly...when you shoot event such Dance or any sports, the primary constraint is how close can you get to the scene to take picture...once you determine that then you can decide on which focal lens to use.

    I do a lot of Mauy Thai boxing by the ring side for that the 12mm F2 is perfect. I don't know which camera you have but from my experience all my Lumix lens (20mm F1.7 and 25mm F1.4) don't focus as fast as the M.Zuiko on my E-M5, son in a fast action shoot I have a lot of out of focus with the Lumix lens, while the 12mm or 45mm do a great job.

    14323184035_bc3bb390f4_o.
    KO by Nam Ing, on Flickr

    12799893315_e1a9d01cc7_o.
    Million Dollar Baby by Nam Ing, on Flickr

    12776973143_03385728b8_o.
    Battle of the Sexes by Nam Ing, on Flickr
     
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