Sunday, 19 October 2014

Improving the ergonomics of the 12-32mm lens

The Lumix G 12-32mm f/3.5-5.6 (my review) is representative of a trend I dislike: That every consumer electronic item must be clad in a smooth metal surface. This makes the items harder to handle, as I see it.

Here is the Lumix 12-32mm lens (on the top), compared with the Nikon 10mm f/2.8 (bottom):


The Nikon lens has the glossy tab on it, which makes it easy to feel with your fingers which way to mount the lens to the camera. It also has the ribbed ring on the front, which provides a good grip.

The Lumix lens, on the other hand, only has the thin, smooth ring with the white dot and the "12-32" text on it to hold on to when mounting it. And there is no physical mark to feel to know which way it goes on the camera. None of the two lenses have a focus ring.

If you are like me, annoyed by this trend, here is a tip to make the lens more ergonomic. What I did, was to attach a cable tie around the inner ring, with the tab on top of the white dot symbol. This provides a physical reference, so that you can easily feel which way the lens goes on the camera.

Here is the lens, a rubber band, and a cable tie:


First, I put the rubber band around the lens, so that the cable tie will not slip off later.


The cable tie needs to be at least 20 cm long.


Cut off the excess cable tie:


To make the lens easier to handle still, I roughed up the cable tie surface with a sanding paper, to make it less slippery.


Here is the Lumix GM1 camera with the slightly modified lens:


The black ring in the front lens threads is not a filter. It is a cheap 37mm filter which I removed the glass from, to create a simple hood. It helps me avoid getting finger prints on the front lens element, and does not create any vignetting at 12mm.

While I use the Lumix G 12-32mm f/3.5-5.6, with updated ergonomics, I hope that the trends will change, and that the manufacturers again dare to put ergonomic details on lenses and cameras. Currently, there is a perception in the market that a smooth metal surface is always the best, which I think is counter productive.

Friday, 10 October 2014

Normal lens shootout

Some decades ago, when film SLR cameras became popular, the 50mm lens was abundant. Due to the long register distance of SLR cameras, the 50mm lens was the shortest which could be designed cheaply with a large aperture, which is why it became so popular. It became the standard lens people bought with an SLR camera, the normal lens.

Nowadays, the kit zoom lens has become the normal lens, but the field of view corresponding to a traditional 50mm lens is still popular. So most manufacturers release a fast "normal lens" when they invest into a new lens mount. In this article, I will compare two normal lenses for two different systems, the Nikon 18.5mm f/1.8 for Nikon 1, and the Leica 25mm f/1.4 for Micro Four Thirds:

LensNikon 18.5mm f/1.8Leica 25mm f/1.4
AnnouncedSep 13th, 2012Jun 13th, 2011
System crop factor2.72
Equivalent focal length50mm50mm
Maximum aperturef/1.8f/1.4
Equivalent max aperture, in terms of DoFf/4.8f/2.8
Weight70g200g
Diameter56mm63mm
Length36mm55mm
Filter thread40.5mm46mm
Minimum focus0.20m0.30m
Lens elements/groups8/69/7
Hood includedNo, HB-N104Yes
Focus ringNoYes

Both correspond to 50mm field of view on a 135 film camera, and both are quite fast, with large maximum apertures:


Physical


Both lenses feature the now fashionable finish: A smooth and glossy barrel. However, the Nikon lens has a ribbed pattern on the front of the lens, which is not, as one could expect, the focus ring. Rather, the ribbed ring does not rotate, and makes it easy to get a good grip on the lens when mounting it.

The Lumix 25mm lens has a nice, rubberized focus ring, which rotates smoothly and is a joy to use. Both lenses feature internal focus, and appear very solid and sturdy.

From the rear side, we see that both lenses have an exit pupil recessed into the lens, which is covered by a matte, ribbed surface, as one would expect.


Both lenses have relatively large exit pupils relative to their formats. However, the exit pupil of the Nikon lens is of course smaller, since it covers a smaller sensor area, and it has a smaller maximum aperture.

The Nikkor 1 18.5mm does not come with a hood supplied, but you can buy the optional HB-N104 hood, pictured to the left below:


I think this Nikon hood is very nicely designed: It does not add any extra diameter, it offers a real protection against stray light, and it protects the front lens element against finger prints. Further, you can still use same front lens cap on the hood, as it has the same 40.5mm opening diameter. I would highly recommend getting the HB-N104 hood.

The Leica 25mm f/1.4 does come with a hood in the box, but I don't like it much. It is too wide for a normal lens, but not wide enough to be reversed around the lens barrel. I think the hood is designed to look retro, not to be functional, which I think is sad.

Autofocus


For still image photography, both lenses focus very quickly.

Here is a comparison of the continuous autofocus performance during video recording. I used 1080p 60FPS on both cameras, the Nikon 1 V3 and the Lumix GH4. I set the ISO to 200 on both cameras:



We see here that the Nikon system performs vastly better. I think this is not so much because of differences in the lenses, but rather because of differences in the cameras.

Nikon have successfully implemented on-sensor PDAF right from the start in the Nikon 1 cameras. This works very well both for AF-C with moving subjects, and for continuous AF during video recording, at least as long as the light is reasonably bright.

Panasonic have implemented the DFD (depth from defocus) technology on the Lumix GH4, which does improve the continuous autofocus compared with previous generations. But it still lags significantly behind the Nikon mirrorless technology in this aspect.

Image quality


To test the image quality, I have taken a number of pictures with both lenses. I used a tripod, and a 2 second shutter delay to avoid camera shake. I also set the base ISO, for the best quality. As for the cameras, I used the Nikon 1 V3 and the Lumix GH4 (my review):


Here is a test at near infinity focus distance (click for larger images):

Nikon 18.5mm @ f/1.8
Leica 25mm @ f/1.4

Here are 100% crops from the centre of the image, at various apertures:


And from the lower left corner:


Here we see that the Leica lens is remarkably sharp already wide open in the centre. The Nikon lens is not as sharp wide open, but sharpens up when stopped down to f/2.8

In the lower corner, which tends to be more challenging for all lenses, the Leica 25mm lens again does much better in terms of sharpness. Even if the Leica lens improves when stopping down, it is still very adequate wide open in the corner.

And here is a test at near portrait distance (click for larger images):

Nikon 18.5mm @ f/1.8
Leica 25mm @ f/1.4

In this collection of 100% crops from the centre area, we see that, again, the Leica lens is the most sharp:


But the big problem in this example is not the sharpness, the problem is the flare handling. The strong light source inside the image frame is handled well with the Leica 25mm lens, which still retains a good contrast level.

With the Nikon 18.5mm lens, though, the strong light source flares inside the lens, causing a loss of contrast, as well as a ghost image of the light source mirrored around the optical axis. Using the hood is not going to help here, as the strong light source is inside the image frame. This problem does not go away when stopping down the lens.

Finally, here is another test at a fairly distant focus. The focus was set on the digger in the foreground:

Nikon 18.5mm @ f/1.8
Leica 25mm @ f/1.4

These 100% crops from the top of the image tell the same story again: The Leica lens is the most sharp out of the two.


Bokeh


The nature of the out of focus rendering is called bokeh. For a large aperture lens, the bokeh is very important. If out of focus objects are rendered in a distracting way, then you cannot use the largest apertures anyway, which makes the lens less useful.

Here, I have focused on the metal tube, and we can compare the out of focus highlights in the background, click for larger images:



Leica 25mm @ f/1.4
Nikon 18.5mm @ f/1.8
Leica 25mm @ f/1.8
Nikon 18.5mm @ f/2.8
Leica 25mm @ f/2.8

As you see, the bokeh of both lenses is perfectly fine. I would say that the Nikon lens has the most round out of focus highlights when stopped down.

See another bokeh comparison here, featuring a number of large aperture lenses.

Geometric distortion correction


Most mirrorless lenses feature some in camera distortion correction. To examine the geometric distortion characteristics, I have photographed a square tiled wall, and then overlaid the out of camera JPEG (in black) with the uncorrected image (in red). I used the third party RAW converter software UFraw to assess the uncorrected image.


The percentage in brackets is the relative distortion correction applied in The Gimp image processing software to get a rectilinear image. This is a way to compare the relative distortion between the lenses.

Contrary to what many would have guessed, the Leica lens is the one which requires the most distortion correction in post processing. I don't see this as a problem, though. I think that designing lenses to require some geometric distortion correction is a sensible choice, and allows the lenses to be more compact, and give better end results.

Portrait lens?


These lenses have a large maximum aperture, typical also for portrait lenses. So, can you use them as portrait lenses?

Sort of.

With a 50mm equivalent focal length, you must go quite close to fill the face into the whole image frame. Typically, you need a distance of around 0.5m. At this close distance, you will get distortions to the facial features, i.e., the chine and nose looking very large.

To avoid this, use a longer lens for portraits, which allows you to take the same images from a distance of about 1m, safe from these distortions. Example lenses can be the Nikon 1 Nikkor 32mm f/1.2 for Nikon 1 cameras, or the Olympus 45mm f/1.8 (my review) or Leica 42.5mm f/1.2 for Micro Four Thirds cameras.

Read more about the subject here, including example images.

Example images


Nikon 18.5mm @ f/1.8
Leica 25mm @ f/1.4

Here are 100% crops from both images:


Conclusion


The simple conclusion here is: You get what you pay for. The Leica 25mm f/1.4 is the most expensive, but it is also by far the best lens.

The main advantage of the Nikon lens, is the size and weight: It is truly portable. Given the price, I would say it performs well. It is plenty sharp enough for most use, and the flare issue is not a problem with normal, low contrast, daytime use.

Pros: Compact, light, inexpensive, good bokeh.
Pros: Consistently good image quality, very good handling of high contrast, making it perfect for night images.
Cons: Not super sharp, poor flare performance.
Cons: Expensive, not very compact.

Alternative lenses, Nikon 1


Within the Nikon 1 ecosystem, there are not really any alternative lenses. While Nikon released the 18.5mm fast normal lens fairly soon, to the joy of enthusiasts, they have not since made any more lenses of this category, and it is not very likely that they will at this point.

The closest thing to an alternative is the Nikon 32mm f/1.2 portrait lens. While it is much longer, it shares the aspect of being fast, with a large maximum aperture.

Alternative lenses, Micro Four Thirds


The Micro Four Thirds system is more mature, and has an impressive lineup of lenses.

From Olympus, there is the Olympus 25mm f/1.8. Not as fast as the Leica 25mm f/1.4, but more compact, and cheaper. It is not a whole lot cheaper, though, so personally, I would rather spend a bit more and get the Leica 25mm f/1.4.

For those who like using manual focus lenses, there are the Cosina Voigtlander Nokton 25mm f/0.95 and the SLR Magic 25mm T/0.95. These are fairly large and expensive, though.

Further reading


A further test of the Leica 25mm lens, as well as some example night photos.

About the concept portrait lens.

Thursday, 2 October 2014

GH4: 2.0 firmware, 4K photo mode

Recently, the 2.0 firmware was released for the Lumix GH4, use this direct download link. One of the big new features is the "4K Photo" mode. See the official documentation here.

Basically, the mode makes it easier to grab photos from a 4K video stream, even at 4:3 and 3:2 aspect ratios. However, there are three drawbacks which are good to know about:

1. Using the 30p mode, you can use this mode to continuously take 30 frames per second, and then later browse through them to see which you would like to save. There is one big disadvantage, though: You only get the JPEG file, no RAW file.

This is in contrast to the Nikon 1 cameras, which can take 60FPS continuously, and save the RAW files. I've used the Nikon 1 V3 to take pictures of birds in flight at 20FPS, and it can do fast and accurate AF-C at the same time. This feature makes the Nikon 1 cameras well suited for sports, action and wildlife photos.

2. Contrary to the normal picture mode, the 4K Photo mode does not use the whole sensor. Just like the 4K video mode, it only uses a part of the sensor, as illustrated below:


Essentially, you have an extra crop factor of 1.3 when using the 4K Photo mode. So a 14mm lens becomes equivalent to 18mm on Four Thirds, or 36mm on a traditional film format.

The good news in this respect is that you can choose other aspect ratios than 16:9. With the previous firmware, you were of course free to record 4K video and then grab still images from it, but you were limited to the 3860x2160 pixel crop (16:9). Now, you can also use a number of other aspect ratios.

3. When using the 4K Photo mode, you use the electronic shutter, not the mechanical shutter. This can lead to rolling shutter effects, since the images are read out sequentially, row for row, rather slowly. So avoid panning, or photographing objects that move horizontally, when using the 4K Photo mode. Here is an example pair of images showing the rolling shutter side effects, with both images taken at 1/320s shutter speed.

Mechanical shutter
4K Photo mode

Using the 4K Photo mode, the car is skewed due to the rolling shutter effect. If you keep the camera steady, and you don't photograph fast moving objects, this should not be a big issue.

Just how fast is the electronic shutter in 4K Photo mode, anyway? An easy way to evaluate that, is to take a picture with a fast shutter speed in artificial light. The light at my home flickers at 100Hz, since there is a 50Hz power source. Here is what this looks like in 1/250s shutter speed:

Electronic shutter
4K Photo mode

I count about 3.3 stripes in electronic shutter mode, and 2.5 stripes in 4K Photo mode. This corresponds to an electronic scan of 1/30s and 1/40s, respectively. So the 4K Photo scan is the fastest, which is natural, as it does not use the whole sensor area. Notice that the crop is tighter, for the same reason.

1/40s 4K Photo scan time is faster, but still slower than the competing Nikon 1 system, which has an electronic shutter readout of 1/80s, fast enough that it is rarely a problem in real life use.

Conclusion


As you could extract still images from the 4K videos previously as well, I don't see this new mode as a big improvement. It does add the extra aspect ratios like 4:3, though, which is useful.

Wednesday, 1 October 2014

New Bolex prime lenses

Recently, a set of three prime lenses were announced by Bolex, with C-mounts:


The lenses are quite small, with a filter thread of 43mm. Pancake lenses like the Lumix 20mm f/1.7 and Lumix 14mm f/2.5 have a filter thread of 46mm. These Bolex lenses cost around US$350 per lens.

So how is this relevant for Micro Four Thirds?

Even if the C-mount is one of the few mounts which has a shorter register distance than Micro Four Thirds, there still exists adapters. Here is just one out of many examples:


Using an adapter like this, you can use c-mount lenses on Micro Four Thirds cameras. However, most c-mount lenses have a smaller image circle than the Four Thirds sensor, so you will frequently get vignetting problems.

Bolex claims, though, that these three lenses have an image circle which includes also the Four Thirds sensor, so it should be safe to use them on Micro Four Thirds cameras.

This illustration shows the difference between the standard Super 16mm image format, which most C-mount lenses conform to, and the Four Thirds sensor size. As you see, Four Thirds is much larger, which is why many C-mount lenses vignette on Micro Four Thirds cameras.


There are more oddities to these lenses. Of course, they are all manual focus only. Further, they have the special "cine gears" on the focus rings.

These are used to mount a remote controlled servo motor to the focus ring. The purpose is to be able to control the focus in a very smooth manner. Servo motors for cine use tend to be very expensive, and are not seen used by amateur enthusiasts very often.

Finally, the lenses do not have any aperture diaphragm mechanism at all. You only have one aperture available, f/4.

For indoor use, I would say that is no problem. You can set the camera to a suitable shutter speed, and then select the ISO which gives you the proper exposure. The Lumix GH4 camera (my review) now even has auto ISO in manual exposure mode, which makes this easy.

For outdoor use, this is going to be a problem. Using the "sunny 16" rule, you need a shutter speed of 1/2000s at ISO 200 on a bright, sunny day. This is much faster than desirable for video use.

For movie use, it is often preferred to have a shutter speed which is twice that of the frame rate. So if you have a frame rate of 30FPS, set the shutter speed to 1/60s. This is called a "180 degree shutter", and the purpose is to get some motion blur on moving objects. Read more about this here, and see some examples illustrating how using a 180 degree shutter is different from a faster shutter.

To achieve a slower shutter speed outdoors, you need a neutral density filter (ND filter). Preferably a variable ND filter, like this.

An ND filter stops a large portion of the light coming into the lens, and lets you use a slower shutter speed.

Another typical use of ND filters, is to combine fill flash with a large aperture during daytime. Let's say you are taking a portrait photo during daytime, with the sun behind the subject. To avoid shadows in the face, you use a flash. At the same time, you want to use a big aperture, to blur the background.

The camera will need a very fast shutter speed, to avoid over exposing the background. The ND filter comes in here, allowing you to use a slower shutter speed, slow enough to fit inside the flash sync range of the camera. With the Lumix GH4, the flash sync speed is 1/250s, meaning that you must keep the shutter speed below 1/250s while using the flash. On the Lumix GM1, the flash sync speed is much slower, 1/50s, so you need an even stronger ND filter.

Conclusion


Given all this, are these lenses still interesting for use on Micro Four Thirds cameras?

I think the shortest lens is. It has a focal length of 10mm, which is a quite wide lens. There are no other very wide lenses like this, which are also very compact. And I think the f/4 aperture is quite adequate for most uses.

The other lenses, I don't see much use for. I would rather go for the Sigma 19mm f/2.8 lens, rather than the Bolex 18mm f/4. The Sigma lens is cheaper, and faster.

And rather than the Bolex 38mm f/4, why not get a lens like the Sigma 30mm f/2.8 or the Olympus 45mm f/1.8? I think those would be better choices for most uses.

Beyond these three lenses, there are heaps of cheap c-mount lenses available. However, most of them are poor quality, and will cause vignetting on the Four Thirds sensor.

Saturday, 27 September 2014

Lumix X 35-100mm f/2.8: Expensive, but fantastic

The long f/2.8 zoom is a standard part in a pro photographer's lineup. Back in the time of the film SLRs, these lenses were typically around 70-200mm f/2.8. With the 2x crop factor of the Micro Four Thirds format, the corresponding focal length range becomes 35-100mm, and Panasonic have conformed to the tradition here.

Here is the Lumix X 35-100mm f/2.8 (left) seen together with the Pentax version of the same lens type, the Pentax DA* 50-135mm f/2.8 (right):


As you can see, the Lumix lens is much smaller, due to the larger crop factor of the Four Thirds sensor, compared with the APS-C sensor size the Pentax lens is designed for. The Lumix lens is also remarkably light for a lens of this type.

Specifications


Here are the specifications, compared with some similar lenses:

LensSigma 60mm f/2.8 DNLumix X 35-100mm f/2.8Lumix X 12-35mm f/2.8Olympus 40-150mm f/2.8 Pro
AnnouncedJan 19th, 2013Sep 17th, 2012
Mar 21st, 2012
Sep 15th, 2014
Lens elements/groups8/618/1314/916/10
Aperture diaphragm blades7779
Minimum focus0.5m0.85m0.25m0.70m
Diameter61mm67mm68mm79mm
Length56mm100mm74mm160mm
Filter thread46mm58mm58mm72mm
Weight190g360g305g880g
Hood includedYes, but wide and pretty uselessYes, well designedYes, well designedYes, well designed
Optical image stabilisationNoYesYesNo
Price$220$1250$1000


Physical


Below I have placed the Lumix X 12-35mm f/2.8 (my review) together with the Lumix X 35-100mm f/2.8 below. The 12-35mm lens is the little cousin of the 35-100mm lens, and as you can see, they are designed very similarly, both with hoods mounted:


Both lenses have a metallic like barrel at the base, with a somewhat cheesey, glosse purple finish. I would have preferred to see a more matte and grip friendly surface being used here.

On the positive side, both lenses have a generously rubberized zoom ring, which is well dampened and easy to handle. I really like the zoom rings of these lenses. Besides, the 35-100mm lens does not extend when zooming, which makes it feel very solid.

The focus rings are made of some plastic material, and are not as well dampened as the zoom ring. They operate quite ok.

Focus speed


I have compared the focus speed head to head with the Sigma 60mm f/2.8 DN here. The test was done by placing a figure about 1m from the camera, and seeing how long time it takes from pressing the shutter until the picture is snapped. The light was quite dim, around EV7 (corresponding to a city night scene).



The shutter delay is 0.25s at 60mm and 0.33s at 100mm, which is very good. The autofocus speed is not likely to be a problem with this lens.

Here is a test of the autofocus speed during video recording, using the GH3 and GH4 cameras. With the GH4, the lens performs quite well.

Image quality


With tele zoom lenses, the image quality is often the most problematic in the long end. That is why I start by testing the lens at 100mm.

@ 100mm


I tested the lens by mounting it to the Lumix GH4 camera (my review) set on a tripod, at base ISO, and with OIS turned off. I used 10s shutter delay to avoid camera shake. For reference, I tested the lens against the Lumix G 100-300mm f/4-5.6 (my review). I focused on the blue sign in the centre:


To better compare the sharpness, here are 100% crops from the centre at various apertures (click for a larger image):


Looking at how well defined the blue sign is, I would say that the Lumix X 35-100mm lens is the sharpest at f/4.

Another test at 100mm:


And here are 100% crops from the lower centre area:


From the extreme lower right corner:


In this example, we see one weakness of the lens. While it is very sharp in the centre at 100mm, it is not so good wide open outside of the centre. The performance becomes better when stopped down, though. We shall see later in the tests that the lens does better even in the corners at shorter focal lengths.

@ 60mm


At 60mm, I use the Sigma 60mm f/2.8 DN as a reference lens. With both lenses being very well regarded, it is interesting to do a comparison of them. Here is a photo of some trees quite far away:

Sigma 60mm @ f/2.8Lumix 35-100mm @ f/2.8

To better compare the image quality, here are some 100% crops from the centre of the images (click for larger images):


And from the lower right corner:


Here is another comparison, also taken from a fair distance:

Sigma 60mm @ f/2.8Lumix 35-100mm @ f/2.8

It is easier to see the differences by enlarging the images from the centre:


And from the left frame:


Both lenses are performing very well here, and it is difficult to compare them. In the centre, they are pretty much flawless already wide open at f/2.8. Perhaps the Sigma 60mm lens looks a bit better at f/2.8, but the difference is very minor.

In the corners, the Sigma 60mm lens appears to be somewhat duller, and does not sharpen up even when stopping down to f/5.6. The Lumix 35-100mm, on the other hand, is quite impressively sharp already from f/2.8, and becomes even better when stopping down to f/5.6.

Still, it is fair to say that both lenses do very well, and would satisfy most conceivable needs in terms of sharpness.

@ 45mm


Here is a collection of M4/3 lenses covering 45mm, both primes and zoom lenses:

From left to right: Lumix X PZ 45-175mm f/4-5.6, Olympus 45mm f/1.8, Lumix X 35-100mm f/2.8, Panasonic-Leica 45mm f/2.8 1:1 macro (custom hood solution)

The Lumix X PZ 45-175mm f/4-5.6 is a compact tele zoom lens with power zoom. The zooming can only be operated electronically, which is good when you want to zoom while recording videos. It also works well for stills, as you can use the zoom ring much like a normal mechanical zoom ring. The lens is very good optically, and is a good choice for those who would like a compact tele zoom lens, at a somewhat steeper price. There are also more moderately priced alternatives.

From Olympus, the first dedicated portrait lens for Micro Four Thirds, the Olympus 45mm f/1.8. It is reasonably priced, quite good in terms of sharpness and bokeh.

Launched with the GH3 in 2012, the Lumix X 35-100mm f/2.8 is Panasonic's interpretation of the classic pro tele zoom lens. Sporting a constant f/2.8 max aperture across the focal length, it is generally regarded as a very good lens. It is also one of the most expensive Micro Four Thirds lenses available.

Finally, the Panasonic-Leica 45mm f/2.8 1:1 macro is responsible for a lot of firsts in the Micro Four Thirds lens lineup: The first Leica co-branded lens, the first macro lens, the first prime lens with OIS, the first portrait focal length prime. It is fairly expensive, and Olympus users are probably better off getting the Olympus 60mm f/2.8 for macro capabilities.

In my previous comparison, I tested the lenses at pretty close focus distance. This time, I chose to use a longer distance. The focus distance is about 20m, practically infinity. I had the camera, the GH3 on a tripod, and used the 2s shutter delay to avoid camera shake. I set ISO 200.

Here are the test pictures taken:

Lumix 45-175mm @ 45mm f/4 Olympus 45mm f/1.8
Lumix 35-100mm @ 45mm f/2.8 Leica 45mm f/2.8

To better compare the image quality, I have collected 100% crops from the images at different apertures. These are from the centre:



Based on the centre crops, we see that all lenses do very well. The Olympus 45mm f/1.8 is a bit soft wide open at f/1.8, and further improves at f/2.8 and f/4. This is quite normal for a fast prime lens. Even the best lenses cannot be expected to be very sharp wide open. For a reasonably priced fast portrait lens, it is doing very well.

The Lumix 45-175mm is quite sharp at f/4, and improves marginally at f/5.6. When testing lenses at 100mm, I was disappointed with the Lumix X 35-100mm f/2.8. This time, however, I am happy to see that it performs well.

Finally, the Leica 45mm f/2.8 1:1 macro is sharp already wide open, as I think most would have expected.

And from the lower right corner:



The corner performance is usually much more challenging for lenses, and this is where we are more easily able to separate the good from the less good. We can also see which lens has vignetting issues: They will have darker corner crops.

Is is no surprise that the Olympus 45mm f/1.8 needs to stop down to f/4 for the best performance. But considering that it is a fast prime, I don't think the f/1.8 image is that bad. Considering the price, I think it is doing well.

The Lumix 45-175mm vignettes a bit at f/4, but doesn't really get much sharper at f/5.6. For a compact tele zoom, I think the corner performance is quite adequate wide open.

It is a bit disappointing to see the vignetting at f/2.8 from the Lumix X 35-100mm f/2.8. However, the sharpness wide open is very good, even in the corners.

One would perhaps have expected the Leica 45mm f/2.8 1:1 macro to perform the best in this test, given that it is the most expensive of the prime lenses. However, it appears to need to be stopped down to f/4 for the best corner performance. That also takes care of the vignetting issue.

Bokeh


The Lumix X 35-100mm f/2.8 one would typically use wide open for the selective focus look. Hence, it is important that it are sharp wide open, which I tested in the previous section.

It is also important that the out of focus rendering (bokeh) is pleasant. To test this, I took these photos using the 35-100mm lens and the Sigma 60mm lens. I focused on the power outlet to the right. The focus distance is about two meters, a suitable distance for a people portrait with these lenses. Here are the full images:

Sigma 60mm @ f/2.8Lumix 35-100mm @ f/2.8

And some closeups on the out of focus rendering:


Both lenses do quite well here in terms of bokeh. The Sigma 60mm f/2.8 DN probably has the upper hand here, though, as the out of focus highlights are more round. But the differences are fairly small. Both lenses do very well.

Like many Panasonic lenses, this one also has non-round out of focus highlights outside of the centre. You can see this in the examples below, click for larger images:

Lumix 35-100mm @ 35mm f/2.8Lumix 35-100mm @ 100mm f/2.8

As you see, the corner out of focus highlights are elliptical-like in shape. So is this a problem? Probably not, it depends on how you plan to use the lens. If you use it outside at daytime, with less contrast, this is not an issue at all.

Alternative lenses


If you are looking for long, fast lenses, there are not that many to choose from. Olympus has a 40-150mm f/2.8 pro zoom lens coming, but it will be quite large, and very expensive.

In the mean time, you could go for the Olympus 75mm f/1.8, which is generally regarded as a very good lens: Sharp, and with a nice bokeh. If you are prepared to pay the fairly expensive price, you can hardly go wrong with this lens.

A lower cost alternative is the Olympus 45mm f/1.8, which is a reasonably priced and well performing portrait lens.

Olympus also have a macro lens specified at 60mm f/2.8. It is generally well regarded, and could be a good choice if you also have an interest in macro imaging.

And as seen previously in this article, the Sigma 60mm f/2.8 DN is a good and cheap alternative.

However, all the lenses mentioned here has one thing in common: They lack optical image stabilization. So if you intend to record video handheld, the Lumix X 35-100mm f/2.8 is going to be your best choice anyway.

Conclusion


The Lumix X 35-100mm f/2.8 is a very good lens. It performs well in comparison with all the lenses I have put to the test here. It is compact and light, and easy to handle. With the constant length (non-extending zoom design), it feels very solid.

The only negative factor I can see, is the price. The Lumix X 35-100mm f/2.8 is not cheap, but I think it is worth the price tag.



Example images


This picture was taken at 100mm, f/7.1, 1/200s, ISO 1250:


This picture was taken at 60mm, f/4, 1/125s, ISO 800: