Panasonic 20mm f/1.7 ASPH LUMIX G

Lens Reviews / Panasonic Lenses i Lab tested

Lab Test Results

  • Blur
  • Chromatic Aberration
  • Vignetting
  • Geometric Distortion
20mm $349
average price
image of Panasonic 20mm f/1.7 ASPH LUMIX G

SLRgear Review
September 30, 2009
by Andrew Alexander

The Panasonic 20mm ƒ/1.7 was introduced alongside the GF-1, to provide an extremely compact shooting solution. The lens is very small, owing to its efficient optical layout (seven elements in five groups) and micro-four thirds lens mount.

The lens is only compatible with micro-four thirds camera bodies, and mounted on such a camera it will produce an effective field of view of 40mm. The lens takes 46mm filters, and will be available in October 2009 for approximately $400.

We tested the Panasonic 20mm ƒ/1.7 on the Olympus E-P1, as we had that camera body standardized for lab testing. In our initial handling we had the impression the lens was quite sharp, and our full range of tests bear this out.

The lens is at its sharpest at ƒ/2, but the difference between ƒ/2 and ƒ/8 can only be measured in tenths-of-blur units. Between ƒ/2 and ƒ/8, we note sharpness between 1 and 1.5 blur units. With the lens set wide open to ƒ/1.7, there is some light corner softness, with a generous sweet spot of sharpness and corner softness only presenting itself in the extreme edges of the frame. In the corners, we note about 2 blur units of sharpness.

Diffraction limiting technically starts in at ƒ/8, but isn't statistically noteworthy until ƒ/11. In practical usage, you won't see a difference unless you use the lens fully stopped-down at ƒ/16, where we note about 2 blur units of sharpness across the frame.

Chromatic Aberration
The lens is quite resistant to chromatic aberration, showing only slight magenta fringing in areas of high contrast in the corners of the image.

Shading (''Vignetting'')
If there's a weakness in the lens, it would be significant corner shading when used at larger apertures. This is especially noticeable when used wide open, where we note corners which are a full stop darker than the center of the image. This light falloff reduces as the lens is stopped down, becoming 3/4 of a stop at ƒ/2, and 1/2 a stop at ƒ/2.8. At ƒ/4 it remains more or less constant at a third-of-a-stop of light falloff.

We've confirmed that the Olympus E-P1 performs some image post-processing in camera, reducing the effect of distortion. Our testing shows that for the 20mm ƒ/1.7, distortion is almost non-existent, at just +0.1% barrel distortion in the corners.

Autofocus Operation
The Panasonic 20mm ƒ/1.7 takes about one second to focus from infinity to closest focus. It focuses with a slight whirring noise and vibration which can be felt while holding the camera; nothing disconcerting, just noticeable, owing to the small size of the camera. Short focus throws happen very quickly. Interesting, we felt that the lens focused faster on the Panasonic GF-1 than on the Olympus E-P1, though this was totally anecdotal.

Macro performance is nothing to write home about here: just 0.13x magnification, with a minimum close-focusing distance of 20cm (about 8 inches).

Build Quality and Handling
It's almost hard to get used to the diminutive size of micro-four thirds products, and this isn't made any easier by the especially small size of the Panasonic 20mm ƒ/1.7. (Years from now, we'll be starting sentences with, "Back in my day, lenses weighed over a pound and were this long...) The lens weighs only 100 grams, just three and a half ounces. As our technician Rob says, this lens could easily fit in a pocket... even a shirt pocket. Mounted on either the GF-1 or the E-P1, the combination is extremely handy and easily transportable. The lens mount is metal, the 46mm filter threads are plastic, and it doesn't seem to ship with a lens hood (we're not sure if one is even available).

The lens is devoid of any switches or control surfaces other than the manual focus ring; there isn't much room for anything and in the micro-four thirds cameras it can attach to, lens functions are controlled at the camera level.

The focusing ring is plastic with deep ribs, about a half-inch wide. The lens uses a fly-by-wire design for the focusing ring, so there is no direct mechanical connection between the ring and the focusing lens element. The result of this is that the focusing ring has no stops at either the infinity or close-focusing end. Consequently we can't report on things like focusing range, or whether the lens focuses past infinity. Manual focusing is quite responsive with a high degree of sensitivity: rotate the ring slowly, and you get a lot of fidelity while focusing, for very slight adjustments. Rotate it quickly, you go through the range very quickly. While focusing, there is a very slight amount of lens extension, but the front element does not rotate.


Olympus 17mm ƒ/2.8 M.Zuiko Digital ~$300
The only other prime designed specifically for micro-four thirds at the time of writing, the Olympus 17mm is a slower lens (ƒ/2.8 instead of ƒ/1.7) but offers a slightly wider field of view. The lens is slightly smaller than the Panasonic 20mm and the Panasonic easily bests it in terms of sharpness, resistance to chromatic aberration, and distortion. To its favor, the Olympus shows less corner shading than the Panasonic.

Panasonic 25mm ƒ/1.4 ASPH Leica D SUMMILUX ~$900
We haven't yet tested this lens, but with an adapter it should mount on a micro-four thirds camera body. The result would be effectively a 50mm ƒ/1.4, though with the adapter it could be a fairly bulky combination, especially compared to the 20mm ƒ/1.7.

Olympus 25mm ƒ/2.8 Zuiko Digital ~$240
With an adapter, the Olympus 25mm ƒ/2.8 should mount on micro-four thirds bodies. While a slower and longer lens (ƒ/2.8 vs ƒ/1.7, and 25mm vs 20mm) the lens is slightly less expensive. At ƒ/2.8, the Panasonic is easily sharper, but stopped down to ƒ/4 and beyond the two lenses are comparably sharp. The Panasonic is also more resistant to chromatic aberration and produces less distortion, though the Olympus shows less corner shading.

Sigma 30mm ƒ/1.4 EX DC HSM ~$400
It would take an adapter, but in theory you should be able to mount the 4/3ds version of the 30mm ƒ/1.4 on a micro-four thirds body. The result would be an effective 60mm ƒ/1.4, though the combination might look a little ungainly (the 30mm ƒ/1.4 is a large lens when compared to the small size of the m4/3 bodies). That said, the 20mm offers a wider field of view, and looks to be sharper than the 30mm.

With excellent results for sharpness, resistance to chromatic aberration and essentially no distortion, Panasonic has done well with the 20mm ƒ/1.7, and we've been having fun shooting with it. For a really compact shooting package, the lens is a worthwhile investment.

Sample Photos

The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.

As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.

Panasonic 20mm f/1.7 ASPH LUMIX G User Reviews

9.2/10 average of 21 reviews Build Quality 8.8/10 Image Quality 9.3/10
  • 10 out of 10 points and recommended by (2 reviews)
    Great size! Bright! Beautiful images!
    Slow to focus, and some compatibility issues w/ newer cameras.

    This lens was my introduction to micro four-thirds. I still carry it everywhere I go.

    It is quite slow to focus by modern standards, but is still my favorite carry-everywhere companion.

    reviewed October 2nd, 2015
  • 5 out of 10 points and not recommended by (3 reviews)
    Perhaps the size
    Focus speed and fluidity of the focus ring when used in manual

    After 25 mm Oly that I recommend to all I was looking for something more wide and I took the Oly 12 mm, but it is too wide.
    Having sold 25 and 12 I try the Pana 20 f 1.7.
    Sharpness and boken seem in line with the Oly 25 but focus speed and fluidity of the focus ring are not acceptable when used in manual.
    I would not recommend it, better 25 mm Oly.
    I think selling it soon.
    Anyway here some photos taken with the Pana 20
    Greetings to all

    reviewed June 9th, 2015 (purchased for $350)
  • 9 out of 10 points and recommended by (6 reviews)
    IQ, aperature
    noisy a/f sounds like a pepper grinder, price

    great lens, way too noisy for video. noise always worried me. a little pricey but you get your $ worth IQ wise

    reviewed October 1st, 2014 (purchased for $275)
  • 9 out of 10 points and recommended by (4 reviews)
    small and portable, wide aperture, good sharpness
    a bit slow focusing, it hunts in very low light

    It is probably one of the lenses that made the Micro-Four-Thirds system be what it promised to be: small and high quality. It is my lens of choice when I need a to make my Olympus EP3 fit in my coat's pocket.

    Pros: its focal length (40mm equiv. - a bit wider than the standard 50 mm equiv.) makes it good for an ultra-compact all-rounder

    Cons: in low light it hunts for focus, making it difficult to use on badly-lit events etc. when you still need to catch the instant action.

    reviewed September 8th, 2014 (purchased for $250)
  • 10 out of 10 points and recommended by (3 reviews)
    Small, sharp, great IQ, makes a discrete package with an Olympus E-P2

    It does what it says on the box! Turns my Oly E-P2 into a Leica basher! Put it on an E-P5 or E-M5 and it gets even better. Sharp and lovely tonal quality even shot direct into the sun over water.... Can't fault it.

    reviewed December 7th, 2013 (purchased for $335)
  • 9 out of 10 points and recommended by (2 reviews)
    light, tiny, optically superb
    corner shading up till f4 not great but easily adjusted out. bad CA under certain conditions too (but dxo nukes them)

    if 40mm field of view is your thing, you've got nowhere else to go in the M4/3 system.

    optically, i had to just 'get over' the whole distortion and CA auto correction issue. so i did :) good god this thing is sharp. have had all manner of top shelf lenses over the years, but the micro contrast on this thing is truly stellar.

    colour and contrast are just as good.

    only real weakness (provided you've got decent CA removal software or dxo), is focus speed because it's good but not brilliant.

    other than that, it's a no brainer and actually feels like it will be with me for many years to come.

    reviewed May 11th, 2012
  • 9 out of 10 points and recommended by (40 reviews)
    Lightweight, small, fast aperture, sharp, good contrast
    AF a little slow, moving front element

    For the small pancake that it is, this lens is an excellent performer. Apart from the somewhat slow autofocus and the loose, moving front element, there's nothing I don't like about this lens. Images are sharp and crispy and they have good contrast. The autofocus is slowish but accurate.

    The front element moves in and out during focussing and it seems a little fragile to me. The 14mm f/2.5 for instance, has no external moving parts. Maybe Pansonic will build a new 20mm f/1.7 someday with a design like this 14mm.

    Images taken at f/1.7 are usable, but I think images taken at f/2 have better contrast and sharpness. It's a small lens and this helps to keep your micro 4/3 camera (and lens set) more 'micro'.

    Although I think the Panasonic 25mm f/1.4 Summilux is a better lens, this 20mm pancake probably is good enough for most uses. It has the advantage of being smaller, lighter and less expensive. So, great image quality in a small package.

    Update 23/9/2013
    The new version (II) is optically and mechanically identical, but the lens now has a black metal barrel. I think it’s a nice touch. The front element is a little more recessed. That’s a good thing too. Unfortunately, being mechanically identical, the autofocus speed is still a little slower than the focus system in newer lenses. A missed opportunity? I don’t know, because the lens does deliver excellent results and it’s a micro 4/3 classic for a reason.

    The new kid on the block is the Olympus 17mm f/1.8. It focusses fast and silent, but I don’t find the image quality convincing. Sharpness and contrast are just not on par with the Panasonic. If you need focus speed or a slightly wider field of view, the Olympus 17mm might be good for you, but image quality wise it’s a step backwards.

    Update 24/4/2015
    Even after using almost every available alternative, I keep coming back to this little lens. It's the combination of the (to me) very versatile focal length, excellent image quality and the small size. An excellent lens, really (old and new version).

    reviewed March 16th, 2012 (purchased for $400)
  • 10 out of 10 points and recommended by (2 reviews)
    Image Quality, Size, Build Quality, f/1.7

    I've put this lens through some heavy use for the past two years with a GF1 and more recently a GX1. It is my most used M4/3 lens. My experience has shown it to be a rugged reliable lens. Image quality overall is excellent. It is a primary player in my street photography projects. 40mm equivalent is the sweet spot for what I do. Highly recommend this lens for overall balance of size, speed, and IQ.

    reviewed February 16th, 2012 (purchased for $350)
  • 10 out of 10 points and recommended by (5 reviews)
    Sharp, low CA, small, fast, price, bright, build
    loud, VA

    Considering this is the focal length am using most out of 14-42 mm range, this lens is very practical for me. I gave my kit lens on this one and am keeping this lens since it was released and used it extensively. Many times only this lens in my camera bag.

    Well as already listed its pros the only major cons is: I wish if it would be sielent like other M43 Pany/ Oly are making recently.

    For vigg as the review already suggested, stopping down will help, as for small primes of this size its more or less understandable.

    I recently added a photo-set that contains only photos taken through this glass, for some real world performance:

    reviewed December 8th, 2011 (purchased for $420)
  • 10 out of 10 points and recommended by (12 reviews)
    Fast, small and sharp lens.

    A real lens for MFT: good image quality, small, fast and not expensive.

    reviewed October 16th, 2011 (purchased for $340)
  • 10 out of 10 points and recommended by (10 reviews)
    sharp even wide open, works with Olympus Micro 4/3, very affordable
    none yet

    We got this for my Olympus EP1, and were blown away. This is a major improvement over the 14-42mm kit lens, and way better than the Olympus 17mm lens the PEN launched with. It is just brilliant. To explain how good it is, I went into my camera store looking to purchase the Canon 28mm 1.8 which is an outstanding lens. After using this lens, I saved nearly $200 and felt I walked out of the store with the better product for cheaper. The color is great, sharpness is incredible, and IQ is pretty good. There is a touch of CA problems, but that is expected out of a lens like this, and its nothing that can't be fixed in post. Everyone who has seen the images this little lens has produced so far has been blown away. Highly recommended!!

    reviewed December 28th, 2010 (purchased for $329)
  • 10 out of 10 points and recommended by (25 reviews)
    Small, sharp and really nice!

    Another of these lenses that offers so much in a small, fairly cheap, package. My experience is with it attached to an Olympus E-PL1, and it is just as good as my DA21 on my Pentax!

    reviewed September 5th, 2010
  • 9 out of 10 points and recommended by (1 reviews)
    Size, sharpness wide open, bokeh, focal length
    Noisy, plasticky, focus-by-wire, exposed front element, price

    Optically, this lens is like Mary Poppins: Practically perfect in every way. It's razor-sharp wide open (sharpenss is almost always limited by focus accuracy and camera handling) and has nice, smooth bokeh. The 40 mm focal length is just about perfect for a day-to-day lens, especially indoors. It shows little to no signs of flare or glare (with an aftermarket hood). I've shot straight into lights 5+ stops past being blown out, and never observed a flare. Fundamentally, I love the lens because I never need to worry that the lens will let me down optically.

    It's also tiny, which makes it exceedingly easy to carry.

    The focus isn't all that brisk, and it's not exactly silent. The focus-by-wire system (common to all mFT lenses) makes manual focus less pleasant than it might be.

    Build quality is adequate, no more.

    Without a hood, the front element is very exposed, and given is propensity to be pocket-carried, this is a little unnerving.

    This is not a cheap lens by any stretch of the imagination. However, twice its purchase price would be insufficient to part it from me.

    reviewed August 17th, 2010 (purchased for $400)
  • 7 out of 10 points and not recommended by (21 reviews)
    light, seems solid, no CA
    Overpriced!, no good AF-Performance, Noise, no OIS, Flare, Vignetting, plastic, to thin

    farly overpriced, should cost around 180 !
    Good in low light, but the AF is far to slow!
    I hope for better mFT primes!!!!

    reviewed July 31st, 2010
  • 10 out of 10 points and recommended by (3 reviews)
    Light, small, very good performance, very good build quality
    vignetting wide open

    I have it mounted on a GF1 and it makes a perfect light and small package.

    Image quality is almost flawless. Shoot at f/2.8 for sharpest images and also at f/4 for eliminating the vignetting. I may have said that the lens is sharper at f/2.8 but you'll be surprised at the image quality at f/1.7!

    Its focal length (40mm equivalent) makes it a perfect lens for general purpose. It is good for landscape, for street photography and its f/1.7 makes it very very good (but not perfect) for portraiture and some interior shots.

    Autofocus is excellent. Very fast. And with the genial red AF assist lamp on the GF1 autofocusing in low light is easy.

    Manual focusing ring feels great. It is addictive using it.

    As I said the only flaw is the vignetting wide open at f/1.7 to around f/2. You can eliminate vignetting at f/4 or you can just correct it later in post processing (something very easy and 100% efficient with a good software).

    Falling in love with this lens is inevitable. Highly recommended when looking for something like this!

    reviewed June 15th, 2010 (purchased for $490)
  • 8 out of 10 points and recommended by (5 reviews)
    Good image quality, compact, about right for a 'standard' lens for Micro Four Thirds
    Overpriced, suffers from flare, noisy aperture and AF

    The lens is very compact, reasonably fast and focuses well. This makes a great little all-round 'standard' lens.

    The image quality is generally very good. As an everyday lens that can be left on the camera and cope most day-to-day candid photography, hard to beat.

    The lens does suffer from more flare than it should for a modern lens of a fairly simple design and few lens elements.

    The aperture and AF are quite noisy.

    reviewed May 19th, 2010 (purchased for $450)
  • 10 out of 10 points and recommended by (3 reviews)
    small light sharp and very good in low light.
    Expensive for compared to comparable full frame lenses e.g. canon 50mm 1.4

    Excellent lens that can be used in really low light. e.g. in a darkened theater, picture still comes out sharp where a P&S would simply give up.

    reviewed April 17th, 2010
  • 10 out of 10 points and recommended by (4 reviews)
    incredibly sharp and compact lens
    AF noise audible on video sound track

    Tested on my GF-1, this lens can match or beat the sharpness of any Nikon or Sigma lens I've ever tested on my Nikon D90, at comparable apertures. This lens is simply superlative.

    reviewed March 11th, 2010
  • 10 out of 10 points and recommended by (20 reviews)
    Lightweight, sharp, fast

    No doubts it's good lesson for all competitors. "That's what I call the lens" =) Small, sharp and fast. Very good, contrast images ! BTW colors from my G1 + 20mm much better than for my D700 and 5D, I mean without processing. And in spite of 2x crop I like it's pictures more than from Canon and Nikon 1,5 crops.
    Amazing little jewel !

    You can see some of my shots here:

    reviewed January 27th, 2010 (purchased for $500)
  • 9 out of 10 points and recommended by (12 reviews)
    small, sharp, great fun
    lack of stabilisation

    it's small, it's sharp and it's fast. Coupled with a compact m4/3 camera this makes for a nice unobtrusive little set up.

    it's a tadge expensive and so makes most sense as part of the GF-1 kit. I guess you are paying for size (compare to Nikon 35 f1.8).

    build quality is ok.

    I must admit to being a bit of a m4/3 sceptic at first but this really changed my opinion!

    Now if panasonic would only be so kind as to make 12mm pancake!

    reviewed January 27th, 2010
  • 9 out of 10 points and recommended by (1 reviews)
    Small, Fast, Sharp

    It works as advertised... small, unobtrusive and it's speed opens a whole new world of low light photography and video.

    It has the typical panasonic plastic construction but it's really very solid feeling. Much better than Canon and Nikon consumer lenses.

    Some would fault it for not being stabilized, but its speed makes up for it.

    reviewed December 7th, 2009 (purchased for $400)