Friday, 25 November 2011

Macro spacer rings for Four Thirds

There are a lot of accessories you can buy for your camera. Since I have a Four Thirds standard lens, the Olympus Zuiko Digital 50mm f/2 1:2 macro lens, I decided to buy some Four Thirds macro rings to extend the macro range of the lens even further. To use the lens on a Micro Four Thirds camera in the first place, and adapter is needed. The Panasonic DMW-MA1 or Olympus MMF1/MMF2 adapters should do. The macro spacer rings then go between the adapter and the Four Thirds lens.

The rings

These rings cost US$10, including shipment from China, which is very cheap. Upon arrival, I noticed that the quality did appear rather poor, in line with the price. The box is rather anonymous, with a "OM4/3" text and something in Chinese:


In the picture below, they are all screwed together, to give the longest possible extension:


And below, I have unscrewed them into individual components:


From left to right: The ring that goes into the adapter, or into a Four Thirds standard camera, and the first extension ring (1, 7mm), the second extension ring (2, 14mm), the third extension ring (3, 27mm), and finally the ring on which the lens is mounted.

By using these rings in different permutations, extensions of 17mm (just the front and rear ring), 24mm, 31mm, 38mm, 44mm, 58mm and 65mm (all the rings) are possible. The 24mm extension, using only the first extension ring marked with a 1, corresponds pretty much to the Olympus EX-25 Four Thirds extension ring at 25mm.

Operation

When using these rings, please note that they have are no electrical contacts at all. This means that the lens is "dead" when mounting it onto the macro extension rings, and you cannot operate the focus or the aperture.

I'm guessing that it is best to first extend the focus of the lens all the way, and then mount it on the extension rings. To do this, you must do a small trick, namely to first manually focus the lens to the minimum focus distance while it is mounted to the camera, and then unmount it without turning off the camera first. That way, you can mount the lens on the extension rings while the focus is already at the closest. Most likely, you'll want to use a smaller aperture than f/2, and again you must do the same trick: Change the aperture and unmount the lens without turning off the camera first. Of course, this process is rather awkward if you are going to experiment with different apertures.

The results

So how do these extension rings affect the close focusing possibility of the ZD50 1:2 macro lens?

First, let's see how close it can focus without any extra extension. Here the lens is mounted to the 4/3 to M4/3 adapter, on the Panasonic GH2 camera:


And the resulting image, at f/8, ISO 160:


24mm extension, 1:1 macro

Using the 24mm extension, corresponding roughly to using the Olympus EX-25 macro extension, the setup looks like this, note that the figure is closer to the front lens element:


With this resulting image, also at f/8 and ISO 160. This corresponds to around 1:1 magnification:


65mm extension, 2:1 macro

Finally, adding all the macro rings for a total of 65mm extension yields this setup:


Note that the figure is now very close to the front lens element. It is not easy to light the figure properly in this position, since the lens casts shadow over the subject. The resulting photo looks like this, at around 2:1 magnification, also written as 2x:


Conclusion

These macro extension rings were cheap, and not very good quality. Further, since they have no electronic contacts, they are very awkward to use. You must stop down the aperture before mounting the lens on the extension rings, which makes focusing harder. Normally, you focus at maximum aperture, and then stop down for taking the picture, which is handled automatically by the camera. But with no communication between the camera and lens, this is no longer possible.

The Olympus EX-25 extension rings allow for changing the aperture, and is probably much easier to use. However, it is also much more expensive.

At full extension, the macro rings allow for roughly 2:1 macro magnification, meaning that you can photograph an object with a diameter of half the diameter of the imaging sensor.

If you want to increase the magnification of a Four Thirds lens, but don't want to shell out the cash for the EX-25 extension ring, I would recommend that you simply crop the center of your images, rather than buy these cheap rings. The rings are not very fun to use, due to the lack of electronic contacts, and the poor quality. Keep in mind that since these rings are for the Four Thirds format, they cannot be used for Micro Four Thirds lenses. They can only be used for Four Thirds lenses.

Sunday, 20 November 2011

Olympus 45mm f/1.8 review

The Olympus M.Zuiko Digital 45mm f/1.8 is a much anticipated lens. When it arrived, it closed one of the major gaps in the Micro Four Thirds lens lineup: The portrait prime lens.

Appearance

The lens is fairly compact, with a 37mm front lens thread, and is significantly smaller than the other 45mm prime lens, the Panasonic-Leica 45mm f/2.8 1:1 macro lens. They are shown below:



LensPanasonic 45mm f/2.8 macroOlympus 45mm f/1.8
AnnouncedSept 2nd, 2009June 30th, 2011
Lens elements/groups14/109/8
Minimum focus0.15m0.50m
Weight225g116g
Diameter63mm56mm
Length63mm46mm
Filter thread46mm37mm
Hood includedYesNo
Optical Image StabilizationYesNo

Sadly, the lens does not come with a hood. You can buy a hood from Olympus, which is rather expensive, and fits into the bayonet threads under the silver front ring. I chose to buy a collapsible rubber hood with a 37mm screw thread. It cost around US$12 including shipment from China. In the picture below, I have removed the silver ring, revealing the black bayonet mount, and mounted the third party hood:




As far as I can tell, the lens itself is constructed out of plastic materials, has a metal mount, and has polished metal exterior. I know this is a subjective thing, but my opinion is that the appearance is very cheesy. I would have preferred a matte black plastic exterior, which I think is better. I'm looking into ways of making the lens less obtrusive, perhaps using black electrical tape to cover the metal surfaces is a good idea?

Focus

Just like most Micro Four Thirds lenses, the Olympus 45mm f/1.8 has internal focus. This means that there are no moving mechanisms on the outside, beyond the focus ring, and the lens feels solid. This is in contrary to the Lumix G 20mm f/1.7 pancake lens, which has a traditional focus mechanism which moves the entire lens assembly back and forth, making the focus relatively noisy and slow.

The focus ring moves smoothly, and feels like good quality. I could have wished for a rubberized focus ring, though, as the metal is not as ergonomic to use. But I don't see myself using the focus ring a lot anyway, as the autofocus works well.

The autofocus is very fast, and virtually noiseless. I have compared the focus speed with the Panasonic-Leica 45mm f/2.8 macro lens on a Panasonic GH2 camera, and found that in generous lightning, the Olympus lens focused a tad bit faster. In low light, though, the Panasonic lens focused faster, which surprised me.

The focus timings of the Olympus lens in good light are a little bit slower than the kit zoom lenses. See the comparison here for some reference numbers. However, keep in mind that the Olympus 45mm f/1.8 requires a lot more focus accuracy than a kit zoom lens at 42mm f/5.6, due to the much larger aperture. Considering this, I think the Olympus 45mm f/1.8 focus timings are very respectable.

When it comes to autofocus performance during video recording, I've found the lens to be comparable with the Panasonic-Leica 45mm f/2.8, which is to say, not very good. With a moving scene, it can take some seconds before the lens regains focus during video capture, which can be very annoying. But I suspect this is much due to the camera, and that future advances in CDAF and image processing will make continuous autofocus better in time.

The minimum focus distance is 0.5m. While this does not sound very impressive, when comparing with other portrait lenses, it is in fact rather good. The classic 85mm f/1.2-1.8 portrait lenses generally have a close focusing distance of 0.8-0.9m. If used for a headshot portrait, this makes sense, since around 1 meter is the distance needed to fill the head into the frame at this field of view. Nikon's newly released Nikkor 85mm f/1.8G portrait prime lens has a close focusing distance of 0.8m, which is not as good as the Olympus lens.

Image stabilization

The lens features no optical image stabilization at all, just like all other Olympus lenses. When used on an Olympus camera, you get the sensor shift image stabilization, which is effective for stills capture. During video capture, though, there is only digital image stabilization available, which I am told does not work too well.

On the other hand, the Olympus OM-D E-M5 camera, launched early 2012, does provide sensor shift image stabilization during video recording.  Using this technology, perhaps this lens can be useful for video on newer Olympus cameras.

On a Panasonic camera, there is no image stabilization at all. So for still images, you should try to use a shutter speed of 1/100s or faster to be fairly sure to avoid camera shake when handholding the camera. For video recording on Panasonic cameras, there is no image stabilization available, and it is quite simply difficult to handhold the camera stably during video capture.

In this example, I have recorded a video with the Panasonic GH2 and the Olympus 45mm f/1.8 lens. Believe it or not, but I am doing my best to hold the camera stably, holding the viewfinder towards my eye. To my defense, I can say that I had just gotten off my bicycle during my daily commute to work, which could explain my somewhat shaky hands:



Image Quality

I have made some image quality comparisons with the Panasonic-Leica 45mm f/2.8 (PL45) here. It must be said that all the comparisons are not optimal, since the focus point is not always exactly the same. However, I think this shows that the Olympus lens does not have any significant vignetting.

The Olympus lens does, however, have some Chromatic Aberration (CA) artifacts when the aperture is larger than f/2.8. I also think that the PL45 performs better at f/2.8 in terms of image quality, although the differences are small.

I have tried to do another image quality comparison. To avoid the problem of different focus distances, I chose a subject that was fairly flat, a car registration plate. I focused on the "P" in both cases. The focus distance is about 1 meter, which corresponds to a headshot portrait distance for this focal length. Here is the whole scene, the images are rescaled and sharpened:



PL45 @ f/2.8
Olympus 45 @ f/1.8

Looking at 100% crops to better evaluate the sharpness, I find this:

From the left middle part:


From the right hand lower corner:


In this comparison, it looks like the sharpness is comparable in the centre of the image, while the PL45 performs somewhat worse in the corner. I would like to add that this comparison is not as challenging for the lenses as my previous one was. The examples with trees rendered against a bright sky are much more challenging for the lenses, due to the high contrast.

All in all, I think the image quality is quite good. There is little vignetting, some CAs at apertures larger than f/2.8, and the sharpness is quite respectable for a large aperture lens.

Bokeh

My sharpness comparison also included some bokeh examples. As far as I can see, the lens does not have any problems with the bokeh. It renders the background nicely blurred when it is out of focus, at all apertures. And out of focus highlights are even and rounded.

One thing to look out for, though, is that the aperture diaphragm blades are not as rounded as on the Panasonic-Leica 45mm f/2.8 1:1 macro lens. This means that when stopped down, the out of focus highlights get a slightly more jagged edge.

Here is yet another bokeh study, compared with the Lumix G 20mm f/1.7 and Sigma 30mm f/2.8 lenses.

Example image

Here is an example image:


I used the Panasonic GH2, and the image parameters are: ISO 160, f/2, 1/10s. I focused on the front wheel. The camera was handhold, without any support. How come the image is sharp, with a shutter speed of 1/10s? Because I also used the onboard camera flash. The flash is very quick, and freezes all movement. However, it has a fairly short effective distance, so only the front part of the truck is lit by the flash. The rear part is lit by ambient light, and the tail lights from a passing car.

Since the rear part of the car is out of focus anyway, a bit of blurring due to camera shake during the 1/10s shutter time doesn't matter.

Compared with the Panasonic-Leica 45mm f/2.8 1:1 macro

So, which 45mm prime lens should you get? The Olympus M.Zuiko Digital 45mm f/1.8 (MZD45) or the Panasonic-Leica 45mm f/2.8 1:1 macro (PL45)? If you want to take macro images, there is only one choice, the PL45. However, if you are on a tighter budget for a macro lens, you could also consider the Olympus 35mm f/3.5 1:1 macro lens (Four Thirds standard, not Micro Four Thirds). For this lens, you will also need an adapter, e.g., the Panasonic DMW-MA1 or the Olympus MMF1/MMF2. This combination will have poor autofocus performance on Micro Four Thirds cameras, but some people prefer manual focus for macro use anyway.

If you are looking for a traditional portrait prime lens capable of selective focus and good bokeh qualities, I think the MZD45 makes the most sense, since it has the largest aperture. However, I personally think that the f/2.8 aperture of the PL45 lens is sufficient for a portrait, given that you can plan the background a bit. So either lens should get the job done most of the time, in my opinion.

For video use, the Optical Image Stabilization (OIS) of the PL45 comes handy. Holding a 45mm lens stably while recording video is not easy, and the OIS does give some help. So if you intend to use the lens for video as well, you may want to consider buying the most expensive of the two, the PL45.

Conclusion

This lens comes with a fairly reasonable price tag, especially in Europe, which makes it a must buy lens for people interested in portrait photography and selective focus.

The image quality is good, and the focus speed is fast. The lens is not so well suited for video recording, due to the lack of optical image stabilization. Also, when recording videos, it can be a good idea to pre-focus, and then turn off autofocus before starting the recording. The continuous autofocus performance during video recording is not so good, especially in poor lightning.

Alternative lenses

A low cost alternative to the Olympus 45mm f/1.8 is the Sigma 60mm f/2.8. It is considered a very sharp lens, and it has a nice, smooth bokeh. See my test of the lens here.

In the other end of the cost scale, you have the Olympus 75mm f/1.8, which is often considered one of the sharpest Micro Four Thirds lenses. For a portrait lens, it is quite long, meaning that you get a generous working distance of about 2 meters.

And if you want the very best, go for the Lumix-Leica 42.5mm f/1.2. It has an impressively large aperture of f/1.2, allowing for a very thin depth of focus (DoF), blurring the background effectively. Also, the lens features optical image stabilization, making it easier to hand hold, also while recording video.

Saturday, 19 November 2011

GH2, ETC mode for macro video

The Panasonic GH2 has a very interesting feature, the ETC, Extra Tele Conversion mode. This is like a digital tele zoom. However, when used with videos, you still get the full resolution, with the centre of the sensor being used. This drawing illustrates the concept:


With this feature, you can record full HD videos with an effective 2.6x tele effect, with 2.6 being the fraction 2800/1080. Using the ETC mode, the Lumix G 100-300mm f/4-5.6 tele zoom lens gets an effective 1560mm maximum tele reach, in 35mm film camera equivalents.

However, this effect can also be used for even more enlargements when using a macro lens. Using the Panasonic Leica Lumix DG Macro-Elmarit 45mm f/2.8 1:1 macro lens gives you an maximum enlargement of 1:1. Using the ETC mode gives you a maximum of 2.6:1, which is very impressive. Keep in mind, though, that this only makes sense with videos, not with still images.

I have illustrated this effect with a macro video recording of my own eye. The following footage shows the same scene without and with ETC:



It was recorded using the "Manual Movie Mode", 1080p24, f/5.6, 1/25s. To get a sufficient exposure, I used ISO 1600.

As you can see, the depth of focus (DOF) is very thin, and it is difficult to keep my iris in focus. Setting a smaller aperture, e.g., f/8, would help here, but that would require an even higher ISO. And in my experience, there is significantly more noise with ETC mode compared with the ordinary video mode, especially at high ISO.

Saturday, 5 November 2011

Focus speed, PL45 vs MZD45

There are two competing 45mm prime lenses in the Micro Four Thirds lineup. The Panasonic Leica 45mm f/2.8 macro lens and the newer Olympus M.Zuiko Digital 45mm f/1.8 portrait lens. While one is a macro lens, and the other could be categorized as a portrait prime lens, they can of course be used for a wide variety of other tasks.

I have previously compared the sharpness of the two lenses in various settings. While the comparisons are not always optimal, and could even be a tad bit misleading, I think it is clear that the Panasonic lens is a little bit better in terms of sharpness. This is not really surprising, since a large aperture lens contains more optical compromises, and usually cannot have the very best sharpness. As a general rule, one does not buy a large aperture lens for the optimal sharpness, but for using it wide open or near wide open, in which case sharpness is usually not the main concern.

People generally say that the Olympus M.Zuiko Digital 45mm f/1.8 features faster focusing. But is it true? The Olympus lens is rated as Movie-Still-Compatible (MSC), which means that the focus speed should be quite good.

I have compared them head-to-head in the same setup. The Panasonic GH2 camera was set up about 60cm from the subject, and I selected centre spot focus. The Olympus lens has a close focus distance of 50cm, and the Panasonic lens has a selectable focus limiter, which cuts off at around 50cm for better focus speed.

When powering on the camera, the lens is focused around infinity. Upon pressing the shutter release button, the camera focuses, and then takes the picture. I measure the time from the camera notes that the shutter release button is pressed, until the camera is ready to expose the image. The first event can be noted by the number of remaining frames being shown in the lower right part of the LCD display, and the latter by the green dot appearing in the upper right corner of the display.

Light background, daylight

Here is the comparison in daylight, the lightning was about EV7.



The focus speeds are rather similar:

PL45, focus delimiter off: 0.32s

PL45, focus delimiter on: 0.32s

MZD45: 0.26s

Dark background, dark room

And another test at EV2, which is very dark:



In this test, the Panasonic-Leica lens focuses faster:

PL45, focus delimiter off: 0.68s

PL45, focus delimiter on: 0.66s

MZD45: 1.12s and 1.08s (two tests)

Conclusion

lightdark
PL45, limiter off0.32s0.68s
PL45, limiter on0.32s0.66s
MZD450.26s1.08s, 1.12s

As people have been saying, the Olympus M.Zuiko Digital 45mm f/1.8 lens is indeed faster in terms of autofocus. But only by a small margin. And in dark conditions, to my surprise I found that the Panasonic-Leica 45mm f/2.8 lens focused faster.

This is just some few simple measurement, and in practical use, the experience might be different. During the time I have used both, I have generally found that the autofocus speed is comparable between them for practical, daily use.

Generally, the speed readings here are quite good. I have previously seen that the Panasonic kit zoom lenses achieve focus speeds of around 0.17s to 0.33s under similar conditions. But keep in mind that a much higher degree of focus accuracy is needed for a large aperture lens at f/1.8 than the kit zoom lens at 42mm f/5.6. With this in mind, a speed reading of 0.26s is in fact a very good achievement.

For video use on the Panasonic GH2, it is my opinion so far that the Olympus 45mm f/1.8 is better at keeping the autofocus correct during video capture. With the Panasonic 45mm f/2.8 lens, it generally takes more time before the focus is reached when there is movement in the image frame. But this is just my feeling so far, I haven't examined it in a scientific way.

The Olympus lens also appears to have a more silent autofocus operation.