Olympus G.Zuiko Auto-S PEN F 40mm f/1.4 OM on NEX 3

Olympus G.Zuiko Auto-S PEN F 40mm f/1.4 OM on NEX 3

This is the middle of three compact standards from the PEN F system, how does this compact large aperture perform?

The Olympus PEN F series lenses are compact lenses designed for a half-frame (135 format 35mm) film SLR, which conveniently enough is basically the same size as an APS-C digital sensor. The PEN F shot a vertical picture on a 35mm frame. The longer dimension was up and down on the film, this meant you had to shoot with the camera held vertically to get a landscape orientation shot.

Being a half-frame lens, it was designed with a much shorter flange distance than a traditional SLR lens, so the adapter on the NEX is only about 10mm thick, and an overall length is only 47 mm with the adapter and lens. The adapter also tapers down and the lens is only about 46mm in diameter. This appears to be in the same barrel as the 20 mm f/3.5 lens, which is about 5 mm longer than the 38 mm f/1.8 and 25 mm f/4 lenses, but still nice and compact. Build quality is superb, with all metal construction, nice smooth focus and aperture ring. I find the front aperture ring easier to use than some of those next to the body.

Same as with other PEN F lenses, you can pull out (towards the objective element) on the aperture ring and spin it around so you can control in specific aperture numbers (f/1.4, 2, 2.8, 4, 5.6, 8, 11, and 16) or you can use f/stops relative from wide open (0, 1, 2, 3, 4, 5, and 6)

The lens has 7 elements in 6 groups, with a 5 slightly curved bladed diaphragm. The minimum focus distance is good at 0.35 m (1.1 ft), which is the same as the rest of the standards, and the weight is not heavy at 165 g (5.8 oz). It uses rangefinder standard filters of 43 mm.

Optical Performance

Please click on the tab you want to view. Only 1 tab may be active at a time. MTF, Distortion, and Lat CA data acquired using Imatest

Comments on the Results

The lens has good to excellent performance in terms of resolution and sharpness in the center, and corners don’t reach very good levels until f/4 or f/5.6.

The lens has noticeable barrel distortion, but is typical for an f/1.4 standard at about -1% barrel.

Lateral CA is noticeable, and high for this class of lens. Longitudinal CA is visible, and I see some purple fringing to the bokeh light shots. I have gotten more consistant on white balance on these, now setting it to the same thing for all lenses, so some of my older lens tests might be off in white balance on these. Lightroom 4.1 allows for correction of longitudinal CA and it does a good job, as long as you don’t overdo it and there aren’t strong colors behind the fringes that will desaturate.

Coma and astigmatism are fairly minor, but as with the others the bokeh is cut off due to mechanical vignetting (the bokeh circles are not circular in the corners at large apertures).

Resistance to iris reflections is low, and veiling glare is high. Not resistant to flare.

Measured focal length is 42mm at 1:53 magnification.

Pros and Cons

Bottom Line

The Olympus Pen F 38 mm f/1.8, 40 mm f/1.4, and 42 mm f/1.8 are all nice lenses. Buy based on what aperture you need. The 38 and 40 are probably most similar in performance and size, and the 42 is much larger. The 42 also performs the best at f/2.8. Buy this lens if you need f/1.2 or superb performance at f/2.8.

If you shoot mostly at f/5.6 or 8 the 40 or 38 are probably just as good and better value. The 38 a little better across the field with less distortion and the 40 offering a little larger aperture. The 38 is the best wide open, but is also the smallest aperture wide open. Measured focal length on all of them at 1:53 are about 2 mm low, I measured them at 40, 42, and 44 respectively.

I don’t have a lot of extra to say about this lens, I would personally only get 1 of the 3 unless you are a collector, any of the 3 are good. All can have crazy bokeh in forested settings, so you just need to be careful and step down in those situations so the bokeh smooths up.

Links to the other two Pen F standard tests:
38 mm f/1.8
42 mm f/1.2


The gallery images are © 2012 Eric Tastad, and may only be used for personal evaluation of the lenses. Click the play button and click “visit gallery” in the upper right to download full size images.


  1. Joe says:

    I am just curious to know how do you work with such a lens on nex.. For example would it work on different modes such as aperture mode? So if I manually change the aperture on the lens would the nex give me an automatic shuter speed? And can I see the light meter changing if I set it on manual and again changing the aperture from the lens?

    I am also curious about focusing .. What kind of focus assistance do you get on the LCD once you manually focus? And is it easy to get a good focus through the LCD ?


  2. admin says:

    Set the option in the camera menu Shutter Release without lens – enabled (similar option to that, don’t know exact wording). Then you can use the lens in A or M (maybe S too, don’t recall offhand) and in A mode the camera picks the ISO and shutter speed based on how much light it detects (if you step down the aperture the shutter speed gets longer or the ISO goes higher automatically). In S mode only the ISO would adjust as you change aperture on the lens. On the newer cameras you can use auto ISO in M, so you would probably use it instead of S.

    Focusing works a couple ways, you can zoom in and see a magnified view, and/or you can use focus peaking, which is an edge detect that highlights sharper edges with a line overlaid on the display (like white, red, or yellow edges highlight sharper points).

    On my A7 the EVF is good enough that I don’t need focus peaking or magnified view to focus, just turn until the image snaps into focus like you would with an old manual focus SLR camera with just a focusing matte).

  3. Joe says:

    Thanks !

    I have few pen ft lenses and I have just ordered nex 3n and the adapter.

    I usually use Canon 7D and Fuji X100s do you think the nex 3n pen ft combination would be a pleasant experience? How can you compare that to what I am getting from the 7D and the X100s? My pen FT lenses are
    38mm f1.8
    42mm f1.2
    25mm f4
    And I also have the 50-90mm f3.5

    And thank you in advance 🙂

  4. admin says:

    The 3n is okay for manual focus, but I actually prefer the NEX 5 series (5, 5N, 5R, or 5T) or NEX 6, since they can take viewfinders and have higher resolution rear displays. The 3n is nice if you want small, but the lower resolution display makes focus a bit harder. The Fuji X series cameras are nice (X-A1, X-M1, X-E1 or 2, X Pro1) with Pen F lenses.

    I have used the first 3 lenses you list and they work well on the NEX. A few of the Pen F adapters are not great for NEX, so I had to try a couple until I found ones that fit my lenses best. I also have a Fuji X to pen adapter which seems to work a little better.

    As far as quality, the Pen F lenses will be fun to use. Since your X100s is 23mm f/2, I imagine the 25mm f/4 won’t see a lot of use unless you just have fun using older lenses. The 42mm is a great lens, especially if you shoot f/2 to 2.8 with it. I think these old Pen F lenses are a lot of fun to shoot with and still offer good image quality.

  5. Joe says:

    Hi again,

    What’s the name of your preferred nex and fuji pen ft adapters please.

    Would be greater if you have an amazon or ebay link too.


  6. admin says:

    Sure, I generally buy from RainbowImaging in the US from eBay since I don’t have to wait for shipping times from China. I think they also have a lot of adapters on Amazon.
    Fotasy AFPF Olympus Pen-F Lens to Fujifilm FX Mount Camera Adapter and RainbowImaging Olympus Pen Pen-F lens to Sony E-Mount NEX-3 NEX-5 Camera Mount Adapter, (RainbowImaging Adapter)

    I haven’t tried this one yet, but might be worth a look for the NEX. Fotodiox 10LA-Pen-F-NEX Lens Mount Adapter, Olympus Pen-F Lens to Sony Alpha NEX E-Mount Camera Fits Sony