Sunday, 30 June 2013

Tokina 300mm f/6.3 mirror reflex tele lens review

The Tokina 300mm f/6.3 is the first mirror reflex tele lens made specifically for the Micro Four Thirds format. Also marketed as Kenko, this lens revives a segment of tele lenses which was popular some decades ago.

They appear to cheat on the laws of physics, by designing tele lenses much shorter than usual. This is achieved by employing a catadioptric optical system, which uses both reflection and refraction to focus the light onto the sensor. Normal lenses only use refraction.

This illustration of a typical reflex lens was made by Paul Chin, with the film plane (sensor) to the right:


Wednesday, 26 June 2013

Camera bag review: Kata 3N1-20 DL

For years, I have been a fan of the Tamrac Velocity 6x sling bag. It is a fairly small camera bag which carries one body and two-three lenses, depending on their sizes. Normally, you wear the sling strap over the left shoulder, and when you want to move it from the back carrying position to the front, you slide it under your right arm. The lip opens towards you in the front position. In both positions, the bag stays fairly level, so you don't need to keep the lid closed when standing still.

However, I often need to carry more stuff as well, say, some clothes, books, a water bottle, and so on. In those cases, I often bring another backpack as well. Handling both a backpack and a sling bag at the same time is of course not very elegant. So I was looking into a bag which replaces both, when carrying more stuff.

I found the Kata 3N1-20 DL, which is like a backpack, but it can be worn both as a sling bag, and as a regular bag. Below it is shown in the sling configuration. When worn on the back, it appears like a normal backpack:



Just like the Tamrac Velocity 6x, it can be slung under the right arm, and then ends up horizontal, with the lid opening towards you:



The bag is symmetrical, so if you prefer to wear it the other way, both sides open, by the zipper which goes all the way around the bottom of the bag.

There are two straps, and by default, they are both connected diagonally. They are colour coded, so that you'll know which to connect where (white-to-white and black-to-black):



With the straps connected diagonally, you can wear them both on your shoulders like a backpack. This is good for transportation, when you don't need easy access to the camera. You can also undo the straps and connect them non-diagonally, if you prefer, like a normal backpack.

when you need easy access to the bag contents, you only wear one of the diagonal straps over the shoulder. This puts more strain on one shoulder, and is not good for carrying over a long period.

Just like all the Kata bags, the inside is bright yellow, which is a nice effect:



The inside is divided into two compartments. The lower is accessible through the zippers which cover both sides, and the very bottom of the bag. This is the largest space inside, and can be configured as you want by using velcro dividers. It may take a bit of experimenting to find the layout that suits you the best. This space can easily contain, say, two camera bodies and four to five lenses, depending on their sizes.

There is another room inside, which is available through the top lid. This room cannot be divided with the velcro sections, and is good for carrying, e.g., books, clothes and other stuff you might need. You can also merge both the two rooms by opening a zipper, to create one single room inside, accessible through both the sides and the top. Further, there are two smaller pockets, one on each top side. Neither of the rooms fit a normal size laptop.

Unlike the Tamrac 6x sling bag, this bag changes configuration from horizontal to vertical when slung on the back. So you must always take care to close the side room when slinging it to your back to get it out of the way. I find this to be a bit clumsy, compared with the Tamrac 6x.

Considering that this is a rather large bag, it does not have much in the way of smaller pockets for keeping memory cards and other stuff you don't want to get mixed in with bigger items. Also, there are no outside mesh pockets for carrying water bottles and the like. This keeps the bag looking sleek and stylish, but is not as utilitarian as some might have desired.

On the outside, there are some straps for connecting, e.g., a tripod, but you can realistically only attach a fairly small tripod to this bag. It does come with two extra straps for this purpose, which is probably adequate.

There is a yellow rain coat for the bag included. You can put it outside the bag when needed, and it is kept in place with a flexible string around the edges. I have stress tested the rain coat in heavy rain, and it did keep the bag dry. But when using the rain coat, you cannot access any of the pockets.

Here, the bag is shows with the lower, largest compartment, open. The zipper which allows the side rooms to open traverse the whole front bottom of the bag, and it is opened all the way below:



Below, I am showing the bag with an example configuration of the velcro dividers. I have packed the bag with some of my favourite equipment. When opening up the side pocket, the Panasonic GH3 is revealed, with the Lumix X 45-175mm tele zoom lens mounted:



Removing the camera and opening the lower flat, I have, clockwise from the bottom left, Lumix-Leica 45mm f/2.8 macro, Lumix G 20mm f/1.7 pancake, Samyang 7.5mm f/3.5 fisheye, and Sigma 30mm f/2.8 EX DN.



Finally, under the upper flap, I have the Lumix X 12-35mm f/2.8 premium zoom lens:



Conclusion


This bag looks stylish and sleek, and the functionality is quite good. It combines both the sling and backpack carrying styles in a good way. Unlike the Tamrac 6x, you must always make sure to close the lids before swinging it back to get it out of the way. In terms of ergonomics and flexibility, it could have scored a bit higher, and appears to have dropped some outside mesh pockets and smaller bags to achieve a more clean look. Not a bad choice, but it might not suit everybody.

Tuesday, 18 June 2013

Using Micro Four Thirds lenses on Sony NEX cameras

When the first Micro Four Thirds cameras were launched, they became instantly popular for using old, legacy lenses with adapters. Since the register distance is smaller than most other mounts, it is possible to create adapters for mounting lenses from many other systems to Micro Four Thirds cameras. This makes the most sense with lenses that feature a manual, mechanical focus ring and aperture. Even if there exist adapters for mounting Canon EF lenses on Micro Four Thirds, they do not allow for changing the aperture, hence, they are not very useful. This is because the Canon EF mount is an electro-optical system (EOS), which means that there are no manual rings to control the aperture setting.

As the Sony E mount has an even shorter register distance, though, this is one of the few formats that can not be adapted to the Micro Four Thirds system. Sony NEX lenses have a register distance of 18mm, hence, even if a thin adapter was made for using them on M4/3 cameras, you would not be able to focus to infinity with them. This is because the Micro Four Thirds cameras have a register distance of 20mm, too long for the optical formula of the Sony NEX lenses.

But, the other way around is possible: There are adapters for mounting Micro Four Thirds lenses on Sony NEX cameras. As the difference in the register distance is only 2mm, these adapters are very thin. Note that most Micro Four Thirds lenses are electro-optical, just like the Canon EF lenses, so you will not be able to control the focus or aperture from the camera, rendering most M4/3 lenses useless for this purpose.

The most useful M4/3 lenses for adapting on Sony NEX are those that are fully manual, e.g., the Samyang 7.5mm f/3.5 fisheye, the Olympus 15mm f/8 body cap lens, the Cosina Noktor 17.5mm f/0.95, and so on.

Here is what my adapter looks like:



It does not appear to be the best quality, but works ok. You use it as you would expect: The adapter goes on the Sony NEX camera, and then you can mount a Micro Four Thirds lens to it. Note that the adapter has no electrical contacts: Electronic focus operation and aperture operation is impossible, as is the use of the optical image stabilization (OIS), if the lens has this feature.

Using the Wanderlust Pinwide


Here's the Sony NEX-3N with the Micro Four Thirds to Sony NEX adapter, and the Wanderlust Pinwide:



The Wanderlust Pinwide is not a lens, but a pinhole camera body cap. It is recessed into the camera, for a better wide effect. It corresponds to 11mm focal length, hence, behaves like a 22mm lens on a traditional film camera. Which is very wide indeed.

But when used on the 1.5x crop sensor in the Sony NEX-3N, it becomes like a 17mm lens, i.e., extremely wide. See the difference below:

Used on the GH3Used on the Sony NEX-3N

The problem is the light falloff outside the centre of the image frame. The extra wideness does not help much, as there is a very significant vignetting. The vignetting is caused mostly by the sensor's sensitivity to the angle of the light hitting it: Light coming from a steep angle does not work well, ideally the light should come perpendicular to the sensor. This appears to affect the green channel the most, giving a purple tint outside the image centre.

Using the Samyang 7.5mm f/3.5 fisheye


The Samyang 7.5mm f/3.5 fisheye is a manual focus lens with a manual aperture ring, hence, very well suited for adapting on a non-Micro Four Thirds camera. See the lens mounted below:



One problem with this setup, though, is that the adapter appears to be too thick, placing the lens too far from the sensor surface. This gives problems focusing to infinity. This is still not a fatal problem: You can still stop down the lens to achieve infinity in focus. I had to set around f/8 to get infinity reasonably in focus.

Here are some example images taken on both a Micro Four Thirds camera, and the Sony NEX-3N:

Used on the GH3Used on the Sony NEX-3N

In the right image, above, you can see that the left and right sides are black. This is due to the built in lens hood: It keeps out light which would fall outside of the Four Thirds sensor surface, hence, giving black sides. Notice also that the black areas are a bit skewed, because the lens adapter mounts the lenses slightly rotated.

In the corners, you can see parts of the image circle ending. The image circle spans 180° field of view, and where this ends, you can see the black bits in the corners. So one advantage of using the fisheye lens on the Sony NEX camera, is that you can crop the image to several different aspect ratios, and still achieve a 180° diagonal field of view. Using a native Four Thirds sensor, you can only achieve this in the 4:3 aspect ratio. Due to the multi aspect sensor, the Panasonic GH1 and GH2 cameras could achieve this also in 3:2 and 16:9 aspect ratios.

Another comparison example:

Used on the GH3Used on the Sony NEX-3N

Using the Lumix G 14-42mm f/3.5-5.6 kit zoom lens at 14mm


So, the kit zoom lens is of course an electro-optical lens, and you can only adjust the focus and aperture while having the lens mounted to a native Micro Four Thirds camera. However, there is a small trick. You can mount the lens to a Micro Four Thirds camera, turn on the camera, set the focus and aperture you want, take a long exposure, and then remove the lens during the exposure. The lens then has your desired focus and aperture set.

Using this trick, I used the kit zoom lens at 14mm, infinity focus, f/8 aperture:

Used on the GH3Used on the Sony NEX-3N

Again, we see the vignetting due to the lens hood. This time, though, I could have removed the hood, but I left it on to illustrate that the lens is mounted slightly rotated when using this adapter. We can also see that the image has a bit of barrel-distortion. This is because the lens needs in camera geometric distortion correction to give rectilinear images. And when using the lens this way, there is no such distortion correction done.

Finally, even when pre-focusing at infinity and setting the aperture to f/8, infinity is not really in focus here. Again, this is due to the adapter being slightly too thick, making it impossible to focus on infinity with most lenses.

Conclusion


Using an adapter, it is possible to mount Micro Four Thirds lenses on Sony NEX cameras. However, my adapter was a bit thick, making infinity focus impossible. Also, most electronic lenses cannot be used at all, since there is no way to operate the focus or change the aperture.

This could be a way to reuse your manual focus Micro Four Thirds lenses on Sony NEX, though, like the Cosina Noktor 17.5mm f/0.95, especially if you don't care about infinity focus. That way, you can use the Sony NEX focus peaking as a manual focus assistance.




Saturday, 15 June 2013

Sony NEX focus peaking demonstration

Some of the more recent Sony NEX mirrorless cameras include the "focus peaking" feature. This is a mode which adds highlights to the display where the image is in focus, for use when focusing manually. The camera finds which parts of the image is in focus by using a simple edge detection algorithm: Where there is a hard edge, the image can be assumed to be in focus.

This mode is quite useful when using a legacy manual focus lens on an adapter. To demonstrate how this mode works on the Sony NEX-3N, I mounted an old Nikkor 24mm f/2 AIS lens to the camera, using a Nikon AI to Sony NEX adapter. Using the lens on a 1.5x crop camera, it becomes like a 36mm lens in terms of field of view.

I placed some lenses on a table, to demonstrate how the focus peaking highlights the borders when a part of the image is in focus. I set the lens to f/2, f/5.6 and then f/11. At f/2, only a thin part of the image is in focus. At f/11, you can see that much more is in focus. The camera can be set to display the peaking highlights in white, red and yellow. I selected yellow in this demonstration.



This feature works the best when there are strong contrasts in the subject. With soft, organic shapes, it tends to  not work as well, as there are fewer edges to be highlighted by the algorithm.

The focus peaking feature works when using legacy manual focus lenses, but also when using native Sony NEX E-mount lenses. What's more, it also works fine during video recording, which is very useful. I get the feeling that the algorithm is somewhat optimistic, meaning that it can categorize areas as being in focus, even if they are not in perfect focus. Then again, for critical inspection, you can still easily bring up the magnified view by clicking the upper control button.

Within the Micro Four Thirds system, the focus peaking feature is sadly not as commonly implemented. The most recent Panasonic model, the G6 has the feature, and so does the Olympus PEN E-P5, but no other models, at this time.

When the premium Panasonic GH3 was released in December 2012, a Panasonic engineer was quoted saying that no future firmware upgrade could add the focus peaking feature to it. However, a later interview stated that this might be possible, after all.

On one hand, it does not make sense for Panasonic to continue enhancing an older model: Spending the effort on new models make much more sense. On the other hand, if they make the GH3 even more attractive, they can sell a bigger volume of them. It does have at least one more year as a premium camera in the Panasonic lineup.



Thursday, 6 June 2013

Sony NEX-3N vs Lumix GF3

The Sony NEX-3N and the Panasonic Lumix GF3 are similar camera models. They are both made to be as small as possible, and come with a collapsible power zoom kit lens:



Comparing them is not entirely fair, though, as there is some age difference. The Sony NEX 3N was released in February 2013, while the GF3 was launched in June 2011. The GF3 has been replaced by the Lumix GF5 in April 2012, and then later by the Lumix GF6 in April 2013.

The GF5 is basically the same camera as the GF3, except that it adds a rubber grip surface on the front, which is actually a big difference. The GF6 is a big improvement, though, with a newer sensor, better ergonomics, and a tiltable rear LCD.

In this article, I compare the video output of the two cameras. Both were set to the base ISO, 1080p, 25fps. I used the Lumix X PZ 14-42mm f/3.5-5.6 at 14mm f/3.5, while the Sony NEX also had the kit zoom lens Sony 16-50mm PZ lens was set to 20mm, to match the field of view of the Lumix lens.

Here is the comparison:



Here are also some still images for comparison:

Sony NEX 3NLumix GF3
Sony NEX 3NLumix GF3

Test results


Even if the Sony NEX 3N is two years newer than the Lumix GF3, I still find that the GF3 outperforms the 3N in terms of video performance. It focuses faster, it generally exposes better, and has better colours. The startup delay is also significantly shorter with the GF3. The Sony NEX appears to have the upper hand by a small margin when it comes to handling of rolling shutter, but that is hardly a problem with either of them.

I find the same conclusion with the still images: The Lumix GF3 generally exposes better, and I like the out of camera colours better. If I had spent some time editing the images with a RAW converter, I think I would get better images from the Sony NEX 3N, though.

Autofocus


Overall, it is fair to say the Lumix GF3, the oldest model, focuses the fastest by a good margin. This applies during video recording, as shown in the video above, and also for still image use. I found this to be true especially when using the long end of the zoom lens.

Both cameras use CDAF technology for focusing. The speed of CDAF during video largely comes down to image processing power. Hence, it is not unexpected that the premium camera Panasonic GH3 outperforms them both in this aspect. I have tested the AF during video here, and the GH3 performance is very impressive.

Some newer and more expensive Sony NEX cameras feature on-sensor PDAF. This will probably give better autofocus performance. For example, the Sony NEX 5R has this feature. However, the real life benefits of on-sensor PDAF is somewhat uncertain.

Operation


The power zoom lever is longer on the Sony NEX lens, spanning a larger part of the lens diameter, so that it can be easily operated both in landscape and portrait mode. That is not as easy with the Lumix X PZ 14-42mm, having only a small lever.

On the other hand, though, the Lumix lens has two zoom speeds, while the Sony lens only operates at one zoom speed. This makes a huge difference, and it is much more pleasant to use the Lumix lens when zooming. Especially when taking still images, it is very awkward and annoying to try to get the desired field of view with the Sony camera, by pushing the zoom lever briefly to get the change you need. On the Lumix camera, just pushing the zoom lever slightly operates the motor at the slowest speed, in which case small and accurate adjustments are very easy to make.

When it comes to video recording, the Sony camera has one clear advantage over the Panasonic cameras: It displays the exposure settings in the display while recording. A very annoying feature of the Panasonic Micro Four Thirds cameras, even the "video optimized" GH3, do not display the aperture, shutter speed, and ISO settings while recording videos. Unless you set these manually, that is. Seeing the exposure settings while recording makes it easier to use the Sony NEX 3N for video, in my opinion.

In general, the Sony camera feels a bit less responsive, perhaps this feeling is magnified by the somewhat slower autofocus, especially with the lens in the longer end of the focal range.

The Sony camera adds a tilting LCD display, which I find very useful. When having the camera in a neck strap, one can keep it at waist level, while looking down into the tilted display. This way, it is easy to achieve stable video recording. With the GF3, one must keep the camera at arm's length in front of the face, where it is quite hard to hold steadily. The newer Lumix GF6 also adds a tilting LCD display, so Panasonic is aware of this problem.

Conclusion


The Sony NEX-3N is an interesting camera, with a large APS-C sensor in a very small body, and a compact and light power zoom lens. I find that it does not operate as smoothly as the older GF3, though, and it does not perform as well when it comes to video colours and autofocus. The camera feels solid, but the lens wobbles a bit when extended. This is in contrast with the Lumix X PZ 14-42mm lens, which is rock solid even when extended.

In terms of pricing, the Sony NEX-3N with the power zoom kit lens is very competitively priced. The lens extends to 16mm in the wide end, corresponding to 24mm equivalent, which is more interesting than the focal length range of the Lumix lens. All in all, the Sony camera kit is quite interesting for people who want to get started with mirrorless cameras at a reasonable cost.




Saturday, 1 June 2013

Wanderlust Pinwide review

From Wanderlust Cameras comes the "Pinwide" for Micro Four Thirds:



The tin case it comes in The pinhole "lens" itself

Background


Pinholes are nothing new. Far from it. The first cameras were pinhole based. The principle is easy. If you mask the windows of a room, and make a very small hole in the curtain, you can see an upside down picture of the outside on the opposite wall. So why do we need glass lenses, anyway? The answer is that to achieve sharpness, the pinhole must be very small, only letting through a very small amount of light, far too little to make a decent exposure. Also, glass lenses can be made to have better vignetting properties.

DIY fans have made pinholes for their cameras for years. The principle is simple: Drill a hole in a spare body cap, put some tin foil over the hole, and carefully make a tiny, round hole with a needle in it. And there you are!

The downside with this method on traditional SLR cameras, is the long register distance: This means that the pinhole has a focal length of around 50mm, corresponding to a normal lens. With Micro Four Thirds, this is a bit better. The register distance is 20mm, meaning that the pinhole becomes a short normal lens, but still not very wide.

The Wanderlust Pinwide fixes this by recessing the hole into the camera lens mount. This gives it a focal length of about 11mm, i.e., an ultra wide angle lens. Much more fun to use! This corresponds to 22mm on a traditional film camera, and gives you a massive 80° field of view.

Physical


The pinhole comes in a nice, retro looking tin case. The pinhole itself is made out of what appears to be good quality plastic. However, don't let that fool you into thinking that this is just a molded plastic piece. The hole itself is in fact made in a piece of metal glued to the centre of the plastic item. Also, the hole is recessed from both sides, meaning that the hole itself is well protected. Here is the hole as seen from the rear side, photographed with the Leica 45mm 1:1 macro lens at maximum enlargement:



Looking at a 100% crop, it does look like the hole has a nice circular shape to it:



The picture was taken with a Panasonic GH3, which has 4608 pixels horizontally. The hole itself is 30 pixels wide, hence, we can conclude that the hole is about 0.11mm in diameter (17.3mm * 30 / 4608). This corresponds to an aperture of around f/96. (Focal length divided by the hole diameter.)

f/96 is a bit abstract for most people, since it is so far from what we are used to. It is nine stops slower than f/4, which is what you would normally find on a similarly wide lens, e.g., the Lumix G 7-14mm f/4.

You should take care not to touch the hole with anything, e.g., a needle or other sharp objects. That will ruin the roundness of the hole, and make the images look bad.

Compatibility


The Pinwide can be used on any Micro Four Thirds camera, except if the camera has some built in ND filters, like the Panasonic AF-AG100. The ND filter mechanism sits between the sensor and the lens mount. Since the Pinwide has a deeply recessed end pointing into the camera, it can interfere with the ND filter, potentially damaging the mechanism. So don't use the Pinwide on that camera!

In use


Since the Pinwide does not have any electrical contacts, you must select "shoot without lens" in the camera menu:



Other than that, it is just a matter of mounting it to the camera and go!

There is no optics, and, hence, no focus adjustment. Everything is in focus. On the other hand, the sharpness is rather limited, so I might be tempted to rephrase that to everything is in "focus".

At ISO 200 (the base ISO for most newer Micro Four Thirds cameras), you can use a shutter speed of about 1/2 second on a bright, sunny day. If you set the ISO to 3200, you can use a shutter speed of about 1/30s, which should be possible to handhold.

This is also useful for video: Set the shutter speed to 1/30s and the ISO to 3200, and use 25fps (PAL version) or 30fps (NTSC version). If the light is dimmer, set a higher ISO.

Here is how to mount and use the pinhole, as well as an example video. The video at the end was done in sunlight, with ISO 3200 and 1/25s on a Panasonic GH3:



Example images


Here is the same image taken with the pinhole and with the Olympus 9-18mm f/4-5.6 @ 9mm:



Pinwide, ISO 200, 1.6s Olympus 9-18mm f/4-5.6 @ 9mm, ISO 200, 1/100s

Note that the perspective is a bit different in the two images, even if the camera is at exactly the same position during both photos. This is because the Olympus 9-18mm f/4-5.6 extends around 10cm further from the camera than the pinhole does. This creates a different perspective, especially for near objects.

Here is another example image:



In this example image, I use the fact that the even near objects are in "focus":



Vignetting


As you see in the images above, there is a significant amount of vignetting. This is very easy to explain. The light simply travels further from the hole to reach the corner of the sensor, compared with the centre of the sensor. And the further the light travels, the larger area it spreads out to, i.e., losing intensity. The formula is simple: The light intensity is inversely proportional to the squared distance. Hence, the light intensity is significantly smaller in the corner. See this illustration:



Based on this insight, we see that the centre of the vertical borders should have 0.7 stop less light than the centre, and the corners should have 1 stop less. But the pictures clearly show that there is much more vignetting.

What's going on here, is that the angle of the light hitting the corner is too steep. Generally, digital imaging sensors require that the light hits them fairly straight on, ideally at a 90°. That is why the original Four Thirds lenses were designed to be tele-centric, with the light from the rear lens pupil coming straight to the sensor.

Since the Four Thirds system was conceived, sensors have evolved to handle a greater angle, and hence, Micro Four Thirds lenses are no longer entirely tele-centric.

But the pinhole still gives far too steep angles for the sensor to handle, and that is the main reason for the severe vignetting.

Also, we can see that the colour is wrong in outside the centre of the frame. The colour becomes magenta in the corners, indicating that the green is missing. Hence, it is reasonable to think that the sensor green photosites handle steep angles the worst.

A pinhole with a more narrow field of view does not have this problem to the same degree. If the focal length is longer, there is a more similar distance travelled for the light hitting the centre and the corners of the sensor, and what's more, the angle also becomes more similar. But a pinhole tele lens is not as interesting, in my opinion. So I like the choice done by Wanderlust here, to make the pinhole as wide as possible.

By the way, this is the same challenge that Leica have had when designing their full frame digital camera. Most Leica lenses are far from tele-centric, especially wide angle lenses. This works well for film, which handles light coming from steep angles well. Digital sensors, on the other hand, do not. Hence, it was not until quite late that they did launch a full frame digital camera, the Leica M9. And the sensor was made especially to handle the Leica lenses, with microlenses on top of each photosite offset outside the centre of sensor, to better handle the steep angles.

Conclusion


The Wanderlust Pinwide is an interesting pinhole. With the recessed design, it achieves an impressive wide angle effect. On the other hand, the wide angle effect is the reason for one of the disadvantages: The very strong vignetting. There is simply a much larger distance from the pinhole to the sensor corner than the sensor centre, giving this very pronounced vignetting effect.

It is fairly inexpensive, small and light. The tin case takes about the same space as the Lumix G 20mm f/1.7 lens:



But keep in mind that if you bring the pinhole, it is likely that you also want to bring an extra rear lens cap. This is to put on the lens that you remove from the camera when mounting the pinhole. You cannot mount a rear lens cap to the pinhole, due to the recessed design.

So why buy this pinhole? If you spend a bit more money, you can get the Olympus 15mm f/8mm compact lens. It is a proper lens, with some focus mechanism. It gives you significantly better images, and is just as compact. On the other hand, it doesn't have the same wide angle effect. And: The focal length is most likely already covered by the kit zoom lens that most people have. So why get the 15mm lens? Perhaps for the novelty effect.

And the novelty effect is probably the main reason for getting a pinhole lens, as well.