Thursday, 6 November 2014

One concert, two cameras

I had the chance to bring two different cameras to a concert, to see how they compare. I brought the Lumix GH4 with the Leica 25mm f/1.4, and the Nikon 1 V3 with the Nikon 18.5mm f/1.8. Both systems are shown below:


Even if the lenses have different focal lengths, they still have the same field of view, because of the different crop factors of the cameras systems. Both are what we usually call "normal lenses", with the classic 50mm equivalent field of view.

Also, both lenses are quite fast, in the sense that they have a large maximum aperture. This makes them well suited for use in dark venues. And the concert venue was very dark indeed, also having oddly coloured artificial stage lights which makes the exposure very tricky.

Lumix GH4


The exposure parameters used were: f/1.4, 1/120s, ISO 3200. The exposure was set by using the A-mode without any exposure compensation. The video was recorded in 1080p, 60FPS:



I left autofocus on during the video recording. Most of the time, the camera highlighted the face of the artist, making sure it was in focus. And the focus was kept pretty well during the recording. When the face was obscured too much, e.g., by the microphone, the focus was lost for some short while.

It would probably have been better to prefocus, and then switch to manual focus during the recording, but this was a nice test.

Nikon 1 V3


The Nikon lens has a smaller maximum aperture. However, using the A-mode, it exposed somewhat less, still using similar exposure parameters as the Lumix system: f/1.8, 1/100s, ISO 3200. It was also recorded in 1080p, 60FPS



Even if the Nikon systems uses on sensor PDAF for the best autofocus during video, I doubt that it can utilize this in the dark concert venue. So it probably has to resort to using CDAF, just like the Lumix camera. And just like the Lumix system, it was able to identify the face of the artist most of the time, and kept the focus on him.

The Nikon 1 V3 appears to find the better colour balance, in this very challenging lightning. I left both cameras on auto white balance.

Sound


I used the built in microphone on both cameras. They are a bit different: The sound of the Nikon system is a bit thinner, with less base. With a bit of mixing, though, one could probably eliminate most of the difference.

Friday, 31 October 2014

Basic tele lenses compared

All camera systems have a cheap tele zoom lens available. Here are two such lenses, the Lumix G 45-200mm f/4-5.6 for Micro Four Thirds, and the Nikon 1 30-110mm f/3.8-5.6 for the Nikon 1 system:


The Nikon lens is seen here in a glossy orange finish. I guess it could have been worse, it could have been pink. Yes, this lens also exists in pink!

Both lenses cover a fairly wide range of tele focal lengths, useful for daily use. The range of the lenses is illustrated in the diagram below, in 135 film equivalent terms. You can also compare the maximum aperture as a function of the field of view:

Even when extended, the Nikon lens is impressively small:


Both lenses have rubberized zoom rings, which are nice to handle. The Nikon lens does not have a focus ring at all. I don't see this as a problem. The autofocus works well anyway, and I rarely see the need to focus manually.

Specifiations


Lens
AnnouncedSept 12th, 2008Sept 21st, 2011
Equivalent focal length90-400mm81-300mm
Lens elements/groups16/1318/12
Minimum focus1m1m
Weight380g180g
Diameter70mm60mm
Length100mm61mm
Filter thread52mm40.5mm
Focus ringYesNo
Image stabilizationOpticalOptical

Image quality


To compare the image quality, I have taken the same pictures with both lenses. The images were taken with the Lumix GH4 (my review), and Nikon 1 V3, respectively. The images were taken with the cameras safely mounted on a tripod, with the self timer to avoid camera shake, and at base ISO.

Lumix 45-200mm @ 45mm f/4
Nikon 30-110mm @ 30mm f/3.8

Here are some 100% crops from the centre:


From the right side:


And finally 100% crops from the top left corner:


In the centre, both lenses perform very well. However, in the corner, the Nikon lens is clearly a lot better. It renders the corners more sharply, and also handles the high contrast between the sky and the leaves better. This situation is quite challenging to render for most lenses.

Here is another comparison at the long end of the lenses:

Lumix 45-200mm @ 200mm f/5.6
Nikon 30-110mm @ 110mm f/5.6

Now, the Lumix lens has some advantage here, as it is used at a longer reach. True, on the other hand, this is how people use these lenses: They are often used in the most extreme setting. So that is why I test them like this.

Here are 100% crops from the centre:


And from the top left corner:


In this setting, the Lumix lens appears to show more details. However, it also has slightly more magnification. The Nikon system suffers from somewhat more diffraction effects when stopped down, that is why you see more dullness at f/9.

Bokeh


At long focal lengths, the depth of focus is thinner, and you tend to get the foreground and/or the background out of focus. Hence, the nature of the out of focus rendering, the bokeh. Therefore, it is important that the bokeh does look nice, and effectively blurs the out of focus areas.

To illustrate the bokeh, here are a couple of pictures taken wide open, at the short end of the lenses. I focused on the bicycle light in the top left part of the image:

Lumix 45-200mm @ 45mm f/4
Nikon 30-110mm @ 30mm f/3.8

Here is a magnification from both lenses:


Both lenses have perfectly fine bokeh in this example. The Lumix lens does feature slightly "dirty" out of focus highlights, but it is hardly a problem.

Autofocus during video


Panasonic and Nikon are taking different approaches to autofocus. Panasonic relies entirely on contrast detection (CDAF), and the most recent model Lumix GH4 adding DFD (depth from defocus), which attempts to find out in what way the image is out of focus by analysing the bokeh.

Nikon, on the other hand, has relied on phase detection sensors on the imaging chip (PDAF). This approach leads to very fast AF performance, even with moving subjects, and while recording video. However, the performance can be sub-par in darkness.

To test the autofocus performance during video recording, I recorded two sequences with the Lumix GH4 and the Nikon 1 V3. The first sequence was recorded inside an artificially lit shopping centre while riding an escalator, to get the same movement speed in both sequences.

The second sequence was recorded in darkness while watching an approaching bus:



All of it was recorded in 1080p, 60FPS. The settings were 150mm f/5.6 for the Lumix lens, and 110mm f/5.6 for the Nikon lens.

In the first sequence, the Nikon system certainly keeps the focus up better. Even in darkness, it does retain a good focus.

Conclusion


Generally, I am more convinced by the image quality of the Nikon 30-110mm lens. It is not as long, and, hence does not provide as much details in the tele end as the Lumix 45-200mm.

With the Nikon lens, I feel more confident using it wide open at all focal lengths, and I think it handles challenging contrasts better. While, with the Lumix lens, I more often feel the need to stop it down for better image quality.

The Nikon system also keeps the focus better up while recording video, and with moving subjects. However, as the image processing improves, future Micro Four Thirds cameras may very well be able to perform as good.


Alternative lenses


For Micro Four Thirds, there are a lot of alternative lenses. If you have an Olympus camera, with built in image stabilization, you could go for the affordable and great Olympus 40-150mm f/4-5.6.

For use on Panasonic cameras, you could go for the very compact and reasonably priced Lumix G 45-150mm f/4-5.6. Another alternative is the more expensive and very good Lumix X PZ 45-175mm f/4-5.6 (my review).

From Nikon, there are not any alternative lenses in the same price range. For a bit more money, you can get the Nikon 1 10-100mm f/4-5.6. It is not as long, but with the added wide angle range, it is very flexible, and covers most focal range needs in one lens.

Tuesday, 28 October 2014

Third party grip for the GM1, LB-GM1

The Lumix GM1 is a fascinating camera: Very small, nicely designed, has good external controls despite the size, and offers top image and video quality.


The only problem I have with it, is the lack of a proper grip. It is awkward to hold.

There is the official grip, which I reviewed here. However, it is quite expensive, and it blocks the tripod mount, and the battery and SD card compartment. Which makes it less than optimal, to say the least.

However, there is an interesting third party alternative grip, which fixes these issues. Both the grips are laid out below (the official grip behind on the left):


The black third party grip comes with two hex keys, and in addition to the grip, it also adds an Arca-Swiss mounting plate on the right side, for setting the camera up in portrait layout.

Mounted to the camera, it looks like this:


The side Arca-Swiss grip can be disassembled using the hex key:


As you see, there are two tabs in the side mount, which makes sure it is aligned correctly. It fits tightly, and there is no wobbling when attached. Using the side mount, the camera can be put on an Arca Swiss compatible tripod head in either landscape or portrait position:


In the pictures above, I used an Induro BHD1 ball head with an Arca-Swiss compatible clamp. But there are many, many ball heads available which are Arca-Swiss compatible.

With the grip mounted, you can still access the battery and SD card. Behind the open battery door, you can see the extra tripod attachment:


Here is what it looks like in the hand. The grip part is a bit glossy and slippery, compared with the original grip. Also, the grip is wider, which leaves less space for your finger between it and the lens:


The whole front grip can also be removed, in case you want to use only the tripod attachment functionality of the grip.

Conclusion


I like the third party grip better. It adds a lot of functionality, at a lower price.

It is unclear to me if you can also use the grip with the Lumix GM5 camera. Based on the pictures I have seen, both cameras appear to have the same footprint, so it may be possible. But I have not tested them physically.

Pros:Light, very nicely finished, good finger grip.Pros: Adds two Arca-Swiss compatible tripod mounts, a second tripod screw hole, access to battery and SD card possible.
Cons:Expensive, blocks battery, SD card door and tripod hole.Cons:Heavy, grip is glossy, with little grip texture. Not much space between grip and lens.


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.