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Transitioning to Sony A7 ii

Discussion in 'Back Room' started by zulfur666, Mar 17, 2015.

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  1. eteless

    eteless Mu-43 All-Pro

    Jun 20, 2014
    If you buy me an A7 I'll have a go at cropping its files, however for now I'm happy with the lowly 16mp output of my E-M1s :)  .
     
  2. budeny

    budeny Mu-43 All-Pro

    Mar 4, 2014
    Boulder, CO
    This is what really matters.
     
  3. pellicle

    pellicle Mu-43 Hall of Famer Subscribing Member

    Feb 10, 2010
    Killarney, OzTrailEYa
    pellicle
    oops, I was meaning to direct that at the other poster.

    sorry

    I too am happy with the m43 and even if I was to buy a Sony A7 would still use the m43 in telephoto as I think it shines when looking for the reach.
     
  4. ijm5012

    ijm5012 Mu-43 Legend Subscribing Member

    Oct 2, 2013
    Pittsburgh, PA
    Ian
    Like @robbie36@robbie36 said, it's based on the square root.

    Take the 2x ETC on a Panasonic camera. The sensor is 16MP, but when using the 2x ETC the resultant image is only 4MP. Applying this to the A7II, a 2x crop of the 24MP sensor would result in an image with a resolution of 5MP, while a 1.5x crop on the 24MP sensor would result in an image with a resolution half of the native resolution, so cropping your 200mm shot to 300mm should result in an image that is 12MP, not 16MP.
     
    • Informative Informative x 1
  5. Turbofrog

    Turbofrog Mu-43 Legend

    Mar 21, 2014
    Yes, precisely. On a 24MP sensor, it's actually 1.5*1.5 = 2.25 that is your divisor, so you end up with even less; 10.7MP. When zulfur was talking about cropping to 16MP, I had assumed he had an A7R, since 36/2.25 = 16MP, so that example makes sense. Assuming you have a lens that can perfectly resolve 36MP on FF, that is! (there aren't many - the Nikon 200mm/f2 and 400/f2.8 primes are among the few, probably)

    As an another example that may be more intuitive to others around here, take a look at how the LX100's modest sensor crop (from 2 down to 2.2) reduced the MP count from 16 down to 12.8! The power of squares...
     
  6. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    Doesn't stand up actually. The 24-70 is mediocre-goodish. For the price and the name on the front, it measures disappointingly. The 12-40 is top-drawer. You can make a $100 lens that is sharp as blazes in the centre, sorry.
     
    • Agree Agree x 1
  7. WT21

    WT21 Super Moderator Subscribing Member

    Feb 19, 2010
    Boston
    Not directed at Turbofrog, but just in general.

    The a7, when in APS-C crop mode, produces a 10.something MP file. I don't know the math, but I read the specs, and took test shots. The a7 has in-camera APS-C cropping, and that's what it produces, which would be the same as cropping the 70-200 at 200mm to a 300mm FOV, AFAIK.
     
  8. ijm5012

    ijm5012 Mu-43 Legend Subscribing Member

    Oct 2, 2013
    Pittsburgh, PA
    Ian
    Hmm... How did you come to this conclusion? Comparing the 24-70 (http://www.photozone.de/sonyalphaff/867-zeiss2470f4oss?start=1) to the 12-40 (http://www.photozone.de/m43/862_oly1240?start=1), the 24-70 actually looks to be a very good lens.

    Comparing barrel distortion, the Sony has FAR less uncorrected barrel distortion than the Olympus (-3.84% vs -8.53%). Vignetting is also pretty similar between the two, with slightly more vignetting present on the Olympus lens. Looking at MTF values at the widest setting, the Sony obliterates the Olympus in the center from wide open (4281 for the Sony vs. 2954 for the Olympus), beating it yet again at the border (2992 vs. 2597). Only at the extreme does the Olympus lens equal the Sony (~2400). Both lenses progressively get worse at longer focal lengths, but the Sony still surpasses the Olympus from wide-open. Chromatic Aberrations are a bit worse on the Sony lens, but this is something that can be automatically corrected during import in a program like Lightroom.

    Looking at the numbers, the Sony lens appears to out perform the Olympus lens, even wide open (something that has been a strength of m43 lenses in the past). If the Sony lens is "mediocre-goodish", then what does that make the Olympus?
     
    • Agree Agree x 1
  9. ijm5012

    ijm5012 Mu-43 Legend Subscribing Member

    Oct 2, 2013
    Pittsburgh, PA
    Ian
    Yep, like what Turbofrog said, the 1.5x crop will result in a 10.7 MP file. So if you want an equivalent 300mm FoV, you're better off shooting m43 with 150mm or APS-C with 200mm compared to using the A7II in APS-C crop-mode at 200mm.
     
  10. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    Top drawer, like I said. Good old photozone, measuring only half the corrections a lens is designed to utilise is truly blundering along. No one interested in MFT should look at photozone if you want the right idea of what the lenses are like. Also you are making a mistake if you compare lw/ph numbers from different sensors - even photozone explain this on their site, at least they got that little bit right.

    Try slrgear. Then you will get the idea. The 12-40 "is a powerhouse of a lens with excellent optical performance: sharp images, great CA control, hardly any distortion and low vignetting." The 24-70 f/4 "we had high hopes that the Zeiss-branded 24-70 ƒ/4 lens would be another excellent piece of glass. ... When it comes to RAW-file image quality, however, we found ourselves a little disappointed. With soft corners at essentially all focal lengths (and even stopped down), plus strong vignetting and distortion, the Sony FE 24-70mm ƒ/4 ZA OSS Carl Zeiss Vario-Tessar T* didn't meet our expectations. ".

    Personally I doubt that the OP is going to get as much resolution from his FF camera with that lens as he would get from MFT with the 12-40.
     
  11. ijm5012

    ijm5012 Mu-43 Legend Subscribing Member

    Oct 2, 2013
    Pittsburgh, PA
    Ian
    Hmmm... So can you tell me how to compare the lw/ph numbers for both lenses on the same sensor? Otherwise, we're kinda stuck using the lenses with the sensors they're meant to be used with, which by your theory, would make MTF comparisons useless between different cameras, let alone different systems.
     
  12. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    Not my theory! Please check the blue information bar near the top of this page (link)

    Put the same lens on different sensors and you get completely different LW/PH numbers. photozone used to put a legend on the MFT test charts, to help confused readers, showing what number of LW/PH constitutes poor/good/excellent for this particular lens test.

    They don't seem to do it so much now if at all, so now they are really confusing readers. Somewhere on their site they say they are going to stop using LW/PH on their resolution tests and revert to grades like poor, good, etc. But they didn't.

    I'm not a big fan of photozone for numerous reasons. Try another source, maybe. For this particular comparison, I suggested slrgear.
     
    Last edited: Apr 2, 2015
  13. Wolfeye

    Wolfeye Mu-43 Regular

    64
    Mar 20, 2015
    Iowa
    It should all come down to "do you like your images?" no matter what the camera is. Apparently the OP did not, or was bored and had money to burn, which is another reason to get a new camera system. A reason I'll never have, but I digress. :)  Some people too, believe that a new camera or system will make them better photographers. It won't, but hey, it's their money. It simply isn't a rational decision when the urge for something new and shiny outweighs using what you already have. You can rationalize it any way you want to convince yourself that lens X or system Z will make your photographs better.

    Sony makes fine cameras. So does Olympus. Use what you want; there's no need to explain it nor defend it.
     
    • Agree Agree x 2
  14. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    No need to post anything on the web about one's decisions, actually. ;) 
     
  15. ijm5012

    ijm5012 Mu-43 Legend Subscribing Member

    Oct 2, 2013
    Pittsburgh, PA
    Ian
    But like you said, if you put the same lens on a different sensor, you get different LW/PH values. So then what's the point of try to compare sharpness of one lens to another if those lenses can't be mounted on the same camera?
     
  16. Turbofrog

    Turbofrog Mu-43 Legend

    Mar 21, 2014
    It's...troublesome.

    LW/PH is somewhat comparable between systems. In fact, LW/PH is in fact an evolution of the older standard LP/mm, (with the PH standing for picture height to normalize those values). The trouble comes in, however, because the testers will standardize their testing using a particular camera in each system in order to make them as extensible as possible, so that they don't need to retest all the lenses on all the cameras! So for instance, Photozone tests their M4/3 lenses on a GX1 - a 4-year old sensor - whereas they test their FE lenses on a A7r - the best sensor currently available for Sony. The overall measurement is the sum of a variety of factors along the chain - pixel density, AA filter, image processor, etc... - very little of which will be visible to us, and none of which can be easily compensated for to extend that comparison.

    So assuming you've got a GX1 and an A7r, you could reasonably expect that the 24-70mm would outresolve the 12-40mm based on those measurements.

    But if you've got an E-M5 II or an E-M1 (without its AA filter), and an A7 II with it's significantly worse sensor...well, who knows? You might find that in the real world, the 12-40mm actually gives better results.

    That's why they say that you can only compare the LW/PH within the system. Because it's not extensible unless you are literally matching all the different parameters in the image chain that affect ultimate resolution.
     
  17. zulfur666

    zulfur666 Mu-43 Veteran

    254
    Jan 30, 2014
    what really matters is your human eye, not some bogus tests..... just saying...
     
  18. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    Because you can compare sharpness, just not the way you did it in post #88 using LW/PH numbers. slrgear (third recommendation -- have you looked? If you had, I don't think we would be having this to-and-fro) have a system that presents lens sharpness in units that allow comparisons between lenses.
     
  19. ijm5012

    ijm5012 Mu-43 Legend Subscribing Member

    Oct 2, 2013
    Pittsburgh, PA
    Ian
    Why would I got to slrgear? I don't own an slr. Hell, I don't even own a dslr. I own a mirrorless camera (two actually, a GH3 and GH4). Is there a dedicated website for mirrorless cameras?
     
  20. WT21

    WT21 Super Moderator Subscribing Member

    Feb 19, 2010
    Boston
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