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How close: Oly 75mm w/ 2x "digital zoom" vs. Oly 14-150mm at 150mm?

Discussion in 'Native Lenses' started by CarlB, Feb 20, 2013.

  1. CarlB

    CarlB Mu-43 Veteran

    Hi, I'm wondering about what my next m43 lens purchase might be. The answer will be in some part answered by the following:

    How close in image quality is the Oly 75mm with 2X crop (or 2X "digital zoom") to the Oly 14-150mm at 150mm?

    I'm guessing the 14-150mm can out-resolve the 75mm covering 150mm, but how close of a race is it?

    I know the f1.8 75mm has some incredible sharpness and bokeh opportunity at 75mm, which is definitely in favor of that lens.
  2. psu_13

    psu_13 Mu-43 Rookie

    Jan 24, 2013
    Digital zoom is just cropping. So you are giving up a ton of your pixels.
  3. CarlB

    CarlB Mu-43 Veteran

    Yes, but the OMD EM5 has a ton to spare ... There's a lot going into a trade-off such as this, so I'd like to know this one bit to add into my "weighted pros vs. cons" decision list.
  4. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    Just get the 75mm and when you need to get in closer, walk in a little closer. That's how primes are meant to be used.
    • Like Like x 2
  5. CarlB

    CarlB Mu-43 Veteran

    But at the edge of the fast river, and that yellow-throated titwillow is on the other side? :) 

    Seriously, I do sneaker-zoom if possible. There are also times when I just can't get closer yet still get the shot. Some animals spook easily, and sometimes I'm at the edge of a rail or such.

    Again, for me it's about the trade-offs, and I'd like to know this one piece of the decision before making the decision.

    I suspect the answer will be "Oly 75mm," but believe it or not it's close enough that this could make the difference.
  6. Talanis

    Talanis Mu-43 Top Veteran

    Oct 15, 2012
    Sherbrooke, Canada
    Eric Cote
    I don't know for the 14-150mm but here are 2 images taken with the O75mm

    This one Zoomed 2x in Lightroom
    E-M5    ---    75mm    f/2.5    1/2500s    ISO 200

    And this one a 100% crop (not sure what the magnification factor is)
    E-M5    ---    75mm    f/4.0    1/500s    ISO 200
  7. Talanis

    Talanis Mu-43 Top Veteran

    Oct 15, 2012
    Sherbrooke, Canada
    Eric Cote
    But this focal length is really short for birds/animals. Might want to check the 75-300mm.
  8. CarlB

    CarlB Mu-43 Veteran

    OK, let's see if I can answer my own question. (I do like getting opinions too, why I've posted this question, really.)

    Oly 14-150mm at 150mm at f5.6

    Center: 1125 lines per inch
    Sides: 600 lines per inch

    Oly 75mm cropped to 150mm at f5.6 (as best toward "apples to apples"):

    Center: 2,683 lines per inch / 2 = 1341 lines per inch.
    (Didn't see any sides figures, but very likely worse).

    Holy crud! Unless I'm wrong on how to compare the 75mm's resolution at 150mm to the 150mm optical resolution, It looks like the 75mm wins.

    Anyone know if I'm missing anything on comparing their resolving power for 150mm?
  9. CarlB

    CarlB Mu-43 Veteran

    Yes, it's a bit short for birds and animals, but it's also quite "carry-able," so that's a trade for what I'm likely to run into during any given photo-walk. I'm not 100% a "birds" shooter, I'm more of an "opportunistic realist" shooter. :) 
  10. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    I suspect you are right. However, that really means that the 75mm would out-resolve while using a teleconverter. When using digital cropping on the other hand, you are cropping out sensor capture rather than magnifying optical resolution.

    If only we had native teleconverters for our system already...
  11. kwalsh

    kwalsh Mu-43 Top Veteran Subscribing Member

    Mar 3, 2012
    Baltimore, MD
    Where are you getting those resolution numbers from? They seem suspicious - as if they've come from two different sites that use totally different testing methods and report different numbers with completely different meanings.

    In answer to your question, the 150 will easily out resolve the 75 cropped by 2x. Of course a 2x cropped photo from an E-M5 with a nice lens like the 75 will still look quite good at reasonable print and display sizes.

    Besides the resolution difference also keep in mind that as far as noise goes cropping is like upping the ISO (or equivalently using a smaller sensor camera). So shooting a cropped 75 will be like shooting the 150 at 4x ISO. Or shooting with an LX7 instead of an E-M5.
  12. Talanis

    Talanis Mu-43 Top Veteran

    Oct 15, 2012
    Sherbrooke, Canada
    Eric Cote
    I agree
  13. kwalsh

    kwalsh Mu-43 Top Veteran Subscribing Member

    Mar 3, 2012
    Baltimore, MD

    A good 1.4x is really needed for the system.
  14. CarlB

    CarlB Mu-43 Veteran

    Anyone with both the 75mm and the 14-150mm?

    DPReview for the 14-150mm numbers, PCMagazine for the 75mm. That could be an issue, for sure.

    Would anyone with both lenses be willing to do a direct A/B comparison between the two lenses on the same subject with the same camera with same conditions? Would need to be a subject in the distance, with a bit of contrast.
  15. kwalsh

    kwalsh Mu-43 Top Veteran Subscribing Member

    Mar 3, 2012
    Baltimore, MD
    Ah, yeah that is the problem. In general the lens "tests" that all the various online sources do are not comparable at all. In fact, even for the same site tests are not comparable between lenses shot on different bodies. None of these sites are really testing the lens, they are testing the lens-body-software system of their choice. The last two items in the system can introduce surprisingly large differences between sites.

    I don't own both of those lenses, but you can get a rough idea of the concept from analogous lens pairs:

    photozone.de - 40-150@5.6: 2399/2226 60/2.8@5.6: 2889/2567
    dpreview - 14-150@5.6: 1125/750 45/2.8@5.6: 1500/1100

    The centers of the 60 and 45 at 5.6 are going to be very comparable to the 75. It looks from the DPR test that the 14-150 is weak at the center at 150.

    Finally, keep in mind the "tests" done by these sites are particularly suspect for very high resolving numbers at the center of a lens. That is the case in which the camera body and software start to play a very large role and can create false peaks in resolution often seen in the test results.

    Comparing two images (as you have requested) is really the best option.

    Personally, I'll be curious to see the results if someone posts them!
  16. Savas K

    Savas K Mu-43 Top Veteran

    Jan 10, 2013
    Native teleconverters seem to be something that lens makers will create once they have built and sold any and all manner of prime and zoom lenses, otherwise the teleconverter would cannibalize sales.
  17. WT21

    WT21 Mu-43 Legend Subscribing Member

    Feb 19, 2010
    You could be right, but selling a TC both gets money for a (relatively) simple TC and doubles the reasons to get the 75. I know for me, I keep thinking about the lens, but it's a lot of money for the single FL. A 2X (or even 1.4) TC would make it vastly more flexible, and an easier purchase decision, at least for me.
    • Like Like x 1
  18. sin77

    sin77 Mu-43 Veteran

    Dec 9, 2011
    I prefer 75mm with digital teleconverter. Great dof and speed.
  19. MAubrey

    MAubrey Photographer

    Jul 9, 2012
    Bellingham, WA
    Mike Aubrey
    Well, just so you know, I've up-scaled 75mm images from 16MP to 32MP that still look absolutely incredible even when pixel peeping. I would have absolutely no qualms with using the 75mm and cropping. Whether its better than the 40-150mm at 150mm, I don't know. I don't have that lens. But if I want some reach and don't feel like lugging out my 50-200mm, the 75mm is very useable.
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