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Panasonic 20mm F1.7 II low-light AF performance on E-M1

Discussion in 'Native Lenses' started by barry13, Apr 24, 2014.

  1. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Hi,

    I've seen lots of complaints about the low-light AutoFocus performance of the Pana 20mm F1.7 (original and/or II), but I haven't seen anyone with an E-M1 post.

    Anyone have one of these on an E-M1, and if so, how is the AF?

    Do the dual focus modes (Contrast and Phase, iirc) on the E-M1 make a difference with this lens?

    Thanks!
    Barry
     
  2. napilopez

    napilopez Contributing Editor

    826
    Feb 21, 2012
    NYC Area
    Napier Lopez
    I can only comment on my experience with the older E-M5, where the 20mm was slow, but not too terrible. It really depends on how "low" low light is. Regular indoor lighting? Pretty fine. Dark bar? Super slow.

    Personally, I just preferred to use MF in low light, although I know that's not favorable to anyone. Still, I found it faster and more reliable than the AF system once things got really dark.

    In any case, I really doubt the phase detect points would be any help for this lens at night, and I also believe the E-M1 doesn't even use phase detect unless you're shooting continuous focus specifically; the contrast detect system is simply better for other situations.
     
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  3. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Thanks Napier.

    Anyone have one on an E-M1?

    I'm debating the following:
    17mm F1.7 Oly
    20mm F1.7 Pana (I or II, probably a used I)
    25mm F1.7 Oly

    I don't currently have any native primes.
    I'm leaning towards the 20mm based on price, sharpness, and AOF/FOV (vs the 25mm) but I'm still a bit worried about the AF.

    Barry
     
  4. EarthQuake

    EarthQuake Mu-43 Top Veteran

    832
    Sep 30, 2013
    Get the 17, or the 25 (either the Pana 1.4 or Oly 1.8) if focusing speed is a concern. The 20/1.7 AF speed is fine in good light, but hunts incessantly in poor light, the other lenses mentioned here do not, or at least not to anywhere near the same degree. Focusing speed of the 20/1.7 on EM1 is about the same as on EM5.
     
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  5. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Ok, thanks!

    Barry

    Sent from my SM-N900T using Mu-43 mobile app
     
  6. penfan2010

    penfan2010 Mu-43 All-Pro

    Nov 12, 2010
    NJ, USA
    Barry - if size of the lens and the angle of view of a 20mm (40mm Full frame equiv) is not as critical, I agree that the 25mm Oly 1.8 is great choice. It works very well on my GM-1, as does on the E-M5 and GX-7. That said, the 25mm is a bit big for the GM-1.

    I can let you know how the old 20mm F1.7 does on the GM-1 when I get my copy in a few days (it's the third time I've bought one over the last 3 years). I suspect that it will continue to hunt a bit in lower light, as I experienced when I used it with my E-M5 (sold off the last one before I could use it on the GX-7 or GM-1). BTW, I never found the hunting very bad; as with any piece of kit, you adjust to its specific quirks. The reason I am getting a 20mm again is that it is a good compromise FOV between my preferred 25mm and 17mm, has a fast max aperture, and is very compact, which is key for keeping the GM-1 pocketable. I am getting a lot of really good use of the GM-1, I try to have it with me always, and while I have gotten very good results with the kit zoom, there are times when I do prefer a faster aperture lens.

    Good luck.

    Ed
     
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  7. Bif

    Bif Mu-43 Veteran

    380
    May 28, 2012
    San Angelo TX
    Bruce Foreman
    The Lumix 20mm is a nice sharp lens you might want to have for "traveling light". Slow focus and "hunting" in low light is easily addressed by programming the AEL/AFL button to autofocus and lock, set shutter button AF to OFF, and set focus mode to SAF + MF with MF ASSIST to ON.

    This gives you both autofocus and manual focus with magnified assist on one button. First press of AEL/AFL button does single autofocus and locks focus. You can take that and press the shutter button to take the picture. Or...

    ...start turning the focus ring on the lens (especially if you don't trust the autofocus result), the magnified assist will "kick in" and you can "nail" focus quickly with a little practice. The focus remains in MF with ASSIST ON and you can grab the focus ring and "touch it up" anytime. A light touch on the shutter button returns the viewfinder to normal mode. Second press of the AEL/AFL button clears the mode lock and you're back to square one.

    Only "fly in the ointment" is that the buttons on the OMD E-M5 are so TINY. It does take some practice to find the AEL/AFL button by feel.

    I use the same settings on my GH3s and GX7. Once you get used to it it is fast and sure.
     
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