normal lens for GH3

Discussion in 'Native Lenses' started by mangomonster, Apr 29, 2013.

  1. mangomonster

    mangomonster Mu-43 Regular

    Jun 10, 2012
    I'm just curious what you guys would recommend:

    I know 50mm prime is the normal lens for full frame cameras.

    I believe that corresponds to about a 22-25mm lens depending on which m43 camera you're using.

    I'm curious if there is more edge distortion on these lenses with a shorter focal length. I.E. if you compared a 50mm on a full frame with a 20mm or 25mm on an m43 camera, what are the differences? I really just want a fast, sharp portrait lens.

    I have the Panny 20mm 1.7 but I have nothing to compare it to and I wouldn't mind having something a bit faster and it feels just a tad wide when I use it for portraits and get close... almost like there is a bit of distortion. Am I just seeing things and is this lens about as normal as they come?

    I'm considering the:

    Panny 25mm Leica f1.4 summilux
    Nokton 25mm f.95

    Any recommendations?
  2. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    The m43 equivalent of 50mm on a full frame is 25mm. The crop factor for m43 is 2 so divide the full frame focal length by 2 in order to get the m43 equivalent or multiply native m43 lens focal length by 2 in order to get the full frame equivalent.

    Field of view is roughly identical between a full frame lens and its m43 equivalent. If by 'edge distortion' you mean the exaggeration of perspective at the edges of the frame when using a wide angle lens, things are about equal when comparing a full frame lens to the equivalent m43 focal length. That distortion is due to the field of view, not the focal length itself. Lenses with equivalent fields of view should show equivalent distortion of that sort.

    The term "portrait lens" normally refers to a short telephoto, not a standard lens. With full frame cameras, the focal length of portrait lenses is usually around the 85-105mm focal length. If you're after a fast prime portrait lens for m43 the only choice is really the Olympus 45mm F/1.8 which is a very nice lens.

    20mm is actually just slightly shorter than the focal length for a standard lens so it is starting to verge on being a wide angle lens. It's not surprising that it feels a little wide for you when you get close for portraits. On the other hand it can be a good lens for what is called "environmental portraits", portraits taken from a bit further away in order to include the surroundings with the subject. A standard lens can also be used for environmental portraits but you'd need to be a little further away if you want to include the same area as you get with the 20, and you could expect the results to show less of a hint of the edge effects you get with the 20.

    If you're considering a 25mm standard lens the only lens I have experience of is the PL 25mm F/1.4. While both are native m43 lenses, the Nokton is manual focus only whereas the PL has autofocus. I think the Nokton is also slightly larger physically and heavier. If you want autofocus you need to pick the Panasonic. If you want the fastest lens and/or the shallowest depth of field, pick the Nokton. Otherwise I think it comes down to personal preference.

    There are image threads here for both 25mm lenses and also for the 20mm and 45mm. You can take a look at them and find lots of examples of portraiture with each lens.

    There's also a Panasonic Leica 45mm F/2.8 macro lens. It's slower than the Olympus 45mm and corrected for a flatter plane of focus as you would expect for a macro lens. It could be used for portrait work as well but the general feeling is that the Olympus is definitely the better choice for portrait work.
  3. spatulaboy

    spatulaboy I'm not really here Subscribing Member

    Jul 13, 2011
    North Carolina
    You mention portraits several times in your post. If portraiture is your primary concern, I would consider going with a 45mm.
  4. mangomonster

    mangomonster Mu-43 Regular

    Jun 10, 2012
    Thanks David, you answered my question very well. Some good thoughts.
  5. CaptZoom

    CaptZoom Mu-43 Regular

    Apr 11, 2013
    The diagonal of m4/3 sensors is 21.6mm, so a normal lens for the m4/3 format is a lens with that focal length. Your Panny is as close as m4/3 gets. The "distortion" you see is because 20mm is a wide angle lens and follows that geometry. It's a rectilinear lens (most lenses are) and is designed to preserve straight features (walls, lines, etc), however on the edges of the frame things start looking stretched and enlarged. This effect becomes more apparent the wider the focal length.

    As an aside, the diagonal of the typical full frame sensor is 43.3mm. A normal lens for it is one with a focal length closest to 43.3mm, which is usually 50mm. There just aren't very many 40mm lens made for FF format.
  6. jloden

    jloden Mu-43 Hall of Famer

    May 15, 2012
    Hunterdon County, NJ
    I don't think you're seeing things... it's the difference between a 40mm and a 50mm full frame lens, so there's certainly a noticeable difference between the two focal lengths.

    I own both 25mm lenses and like both of them a lot, but they're very different lenses. If you know from experience you like a 50mm equivalent for environmental portraiture, then either one will be right up your alley. The specs tell you most of the story on the two IMO; if you want AF then the Voigtlander is out of the running right off the bat, for instance. That's the reason I own both and also the reason the PL 25mm gets so much more use than my Voigtlander even though I absolutely love shooting with it when I can take my time.

    Both are sharp lenses with excellent contrast, but I'll note the Voigtlander is noticeably softer at it's widest apertures. That glowly soft-edged look is sometimes a plus so may or may not be a drawback for you. I find that from f/1.4 and beyond it sharpens up considerably and I most often shoot with it at f/1.4 or smaller unless I need the light gathering or shallow DoF. The rendering characteristics differ, but I like them both very much. I find the Voigtlander to be extremely crisp looking and for whatever the reason it tends to remind me of a cinematic look. The PL 25mm tends to stand out for me in terms of great micro-contrast especially. It could be my imagination but I feel it responds really well to B&W processing also.

    Lastly I'll mention build. The CV 25mm feels every inch the fine optics it is. It's heavy, solid... nothing but metal and glass and the focus ring is beautifully damped. For pure tactile enjoyment and quality the Voigtlander is special. The aperture ring gives good feedback and I find it very natural to control exposure through aperture and the scroll wheel for shutter speed. None of that matters as far as the all-important optical performance, but for certain you at least get the feeling your money went somewhere tangible :wink:
  7. mangomonster

    mangomonster Mu-43 Regular

    Jun 10, 2012
    Wow... thanks guys. I know I need to just get out there and shoot more but I just came back from a month long trip in Asia where I had to take about 200+ portraits and my main lenses were the 12-35 and 35-100 f2.8 from Panny as well as a Canon FDn 50mm 1.4...

    I loved them all but feel they aren't exactly what I'm looking for as my go-to portraiture lens. The 50mm, while amazing, was too tight for me often. I really have no complaints with the 35-100. The 12-35 however often had lens flare and I don't feel that it handles it particularly well. The 20mm pancake is gorgeous with flare... but like I posted earlier, a bit too wide. So now, I want to experiment with another lens and I'm definitely feeling the 25mm focal length. I think my 35-100 is probably my nicest lens and getting a 45mm really is in the same focal range. So 25mm is probably where I should go.

    Since I'm primarily filming with my GH2/3, the Nokton probably makes the most sense out of the 2 lenses we've talked about.