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Author: matze

Published on Leave a comment on So Google has their own DNS now

Google announces their own public DNS now. Some seem to think it's a good move and a fundamental threat to ISPs who are diluting the neutrality of the net. However, I tend to side with the conspirationalists who see it as an attempt of Google to gather even more information about what people do online.

Using the Google DNS you basically allow them insight into any connection your PC performs while it is online. Not about the data exchanged, but at least about what other computers you are connecting to, and not just during web browsing, but also email, instant messaging, chatting, peer-to-peer networking and so forth.

Of course my ISP provides their own DNS and uplink routers are normally configured to use the ISP DNS servers, but I bet Google's Chrome OS will by default use Googles DNS. Guess what I'm not going to use on my private machines.

Now, unfortunately ISPs are known to tamper with DNS queries of their users. If you ever tried to surf a non-existing site you probably found your browser displaying some "navigation aiding" by courtesy of your friendly Internet provider. While meant to be helpful towards their users it bears a threat as well. There you have an infrastructure which is specifically built to intercept connection attempts. While I can't say I actually appreciate this, the way Google harvests data is seriously creeping me out just as much.

Published on Leave a comment on Some photos from the summer

I only recently found time to process and upload some photos I took during our summer holiday this year. Instead of going abroad we decided to travel Germany, there are quite a few places we've never been. This year we went East, visiting Thuringia and Saxony. I've uploaded a selection to Flickr, with more to come. Enjoy today some impressions collected visiting Dresden, which marked the end point of our journey.

Published on Leave a comment on Control is an illusion?

In a recent interview with the Digital Photography Review web magazine a Nokia representative talks about convergence devices like the N86 mobile phone incorporating an 8MP digital still camera and aiming to replace digital compact cameras in many peoples' pockets. Read the story here.

Seemingly unrelated, The Register has an article about a provider in the United Arab Emirates pushing a trojan horse program as a software update to their customers Blackberry smart phones. The sting was only accidentally discovered and if anything can be learned from that, it is that stuff like that is not just overheated imagination of a few conspiracy theorists but happening right now under our very eyes.

This got me thinking. Do I really want all those features crammed into a connected device I have no control over? Each and every feature requires me to provide more, sensitive information. Phone books are no longer just phone books but store email and postal addresses of my contacts. browsers store web site credentials, Ebay, not to mention PayPal accounts. All my data under the reign of a software that can be changed at any time, without me even noticing.

I may want my camera be a camera, and my mobile phone be just that and nothing else.

Published on Leave a comment on Canon vs Tokina 135mm lens shoot out

A couple of days ago I acquired an old Canon A1 SLR camera. Someone was selling off old photo equipment on Ebay and so with the camera came a small collection of four lenses. One of them is a Tokina 135mm f2.8 telephoto. It's quite an impressive item, looking much sturdier mechanically than its Canon FD counterpart. It's made of all aluminium, even the aperture ring is made of metal. It feels quite heavy in your hand and appears to have been well treated since there is no apparent sign of wear. Since I also own the Canon lens, I started wondering which of the two to sell. Casual shooting with both lenses on the G1 didn't reveal major differences in image quality so I did a series of shots under more challenging conditions.

The following photos show performance of both lenses while taking images of a church in my home town against the bright sky before sunset. The sun is hidden behind a cloud layer just outside to the right of the frame on the G1, on a 35mm film camera it would still be inside the frame.

The photos taken with the Tokina are always on the left side. They start at f8 and go up to f2.8, the maximum aperture for both. The lenses feature a built-in hood, it was used while taking the photos but of course for a factor-two crop sensor it's not deep enough. The images were taken as RAW files and then developed without any sharpening or other corrections applied. They were downscaled for presentation and 100% crops of two interesting areas patched on.

Tokina f8 Canon f8

As you can see, at f8 there is not much difference between both lenses. If you look at the 100% crops, there is a slight advantage for the Canon, but it's not obvious. There is a difference in color tone, but I cannot say if its a difference of the lens or just subtle changes in the lighting conditions.

Tokina f5.6 Canon f5.6

At f5.6 the difference is more noticeable. While the Canon lens shows almost no degradation in sharpness and contrast, the photo taken with the Tokina is becoming a little soft with a very slight amount of CA, but it's still pretty good.

Tokina f4 Canon f4

The trend continues at f4, the gap between Tokina and Canon is getting wider. The Canon now starts to show a little softness and a bit of CA, but its overall still pretty good.

Tokina f2.8 Canon f2.8

At f2.8, the Tokina shows a significant loss of contrast and increased softness. Color seams appear around back-lit areas. The Canon has also lost some of the sharpness and contrast it displays at smaller apertures, but its a lot better than its Tokina counterpart.

Summing up, I found the Tokina lens to be performing quite well under most conditions. A challenging environment like strong light sources just outside of the frame requires stopping down to f4 or f5.6 for good image quality. The Canon 135mm however proves to be an excellent lens with good results even wide open.

Published on Leave a comment on Digikam hacking

Since a few days I'm officially a contributor to digikam! I even got my old KDE SVN account reactivated and updated and so I can directly contribute code to the project. It started with a bug in the lens correction plug-in I fixed that turned into developing a method to access sub-pixel image data. Currently I'm working on an additional tool for digikam's batch queue manager. This nice feature is particularly helpful for people who need to apply a series of operations to a large number of images at a time.

I'm developing a batch tool to sharpen images, for example after resizing them for print. I found that these two operations, resizing and then sharpening, are a somewhat common constant in my work flow. Usually, I shoot RAW images, import them into digikam directly, then apply white balance, tone curve corrections and sometimes input sharpening. There is little to be automatized there because each image needs different treatment. After this first step I save the post processed images as TIFF. Then, depending on what I do with them, I resize them differently, e.g. 1024x768 for Flickr, 1600x1200 for small prints, etc, and convert to JPEG. Downsampling tends to soften the images, so the final processing step is always a slight sharpen filter.

To demonstrate the effect, take a look at the following two images. The first one was just resized to 1600x1200 pixels, the second one was treated with an Unsharp Mask filter after resizing. It looks more crisp. Click on the images to view them in original size for the full effect.

Published on Leave a comment on First holidays with the G1

I remember I didn't write anything about my Easter holidays yet. I went skiing in the Italian Dolomites, to a nice little town in the province of Trento named Moena. Its in the middle of Fassa Valley, a valley in the region of Trentino-Alto Adige where people speak an ancient Rhaeto-Romance language called Ladin. I know this region since I was a kid, we used to go skiing there with all of our family, quite regularly for more than ten years. Moena lies at the foot of the Cantinaccio mountain range, home to the legendary dwarven king Laurin, who was said to having kept a garden of beautiful roses high up near the mountain top. Stories tell he fell in love with a beautiful woman and abducted her. He was defeated by the womans brother and a band of brave knights and taken away into custody, but as a last action he put a ban on his rose garden turning it invisible day and night. But he forgot about dusk, which is not day or night and thus you can sometimes see the mountains glow red of roses in the last rays of daylight when the time is right. So they say.

Easter was late this year but reportedly it had been snowing heavily throughout most of March and April and the conditions were said to be quite good so I took the chance to go there and spend a week skiing and trying my new camera equipment. I had recently bought a Lowe Pro Slingshot 200 back pack that is big enough to hold all my gear, the G1, 14-45, 45-200 and the Canon FD 50 1.4 lens, together with a small tripod and cables, filters, charger, etc. I didn't take the Metz flashgun with me, I have found that it's a part of my equipment I almost never use and since it adds considerable weight I left it at home. I didn't miss it.

I wasn't going there alone. We were a group of around 15 people and we had rented a house for the whole group. A couple of them I knew already from earlier trips to Moena, some of them even from the time I went there together with my parents and brother. The area of Trevalli (Three Valleys) offers quite a number of skiing opportunities. If you have a car, the selection of resorts within 20 minutes travel distance is quite impressive. The image to the left was taken from the top of Col Margherita, which is part of the San Pellegrino skiing resort. Looking at the pictures its hard to believe it was already beginning of April. Not often have I seen this amount of snow that late. However, the warmth of the approaching Spring time was busy melting the snow and even though there was lots of it, its quality degraded massively during the day. So we got up early every day and tried to be on the ski piste soon. That worked rather well, by the time the snow turned soft around 3pm we usually had enough for the day and enough time left to chill, drinking marvelous Italian coffee and eating ice cream.

All the time I carried the Slingshot pack on my back. It was working really well on the piste, I almost didn't feel the weight of the gear and when it was time to enter the lift I could just swing it around from back to front and sit down comfortably. My sun glasses turned out to be a bigger problem, I had to take them off for taking pictures together with my gloves. The viewfinder worked pretty well under the bright sun, I just had to shield it a bit with my hand. The LCD turned out to be mostly useless. I tried to take photos with all the lenses I had, most of them with the 14-45, but some with the 45-200 as well. Sometimes I used a polarizer filter to improve the sky colors and cut down the haze a bit, but still I had to post process most of the images to correct white balance and levels. I used only digikam for raw development and corrections and it handled the task pretty well. I had also taken the MSI U100 netbook with me which allowed me to download the images every evening and inspect them.

I've uploaded a selection of images taken during my stay to Flickr, there's a set named Dolomites. All in all I'm quite satisfied with how the G1 performed. The only thing I'd have wanted is a bit more of dynamic range. One stop more might have made a difference in some situations.

Published on Leave a comment on Old Gear, too

Old Gear, too
Originally uploaded by thinkfat

Today a big jumble sale of photo equipment was held at a university facility, it takes place only once a year and it was the first time I went there. It was quite amazing, the mass of gear for sale was huge. Wide selection of stuff from all old and recent camera makers. The selection of Canon FD lenses was not too rich, though.

Still, I was quite successful and got a 28mm f/2.8 for very little money and a 50mm f/3.5 macro lens in very good condition for considerably less than the cheapest ebay offer.

I was tempted to buy a 24mm f/2 and had another good offer for a 24mm f/2.8, but the difference in speed and field of view was too little against the 28mm I already had in my bag and I declined. Instead I took the 50mm f/3.5 macro, I think it will be nice for flower shots and might work as a portrait lens as well.

The 28mm is a particularly nice lens. It's very light and the effective focal length of 56mm is close to a typical film standard prime. I think I'll like it. The 50mm macro is a bit long physically, but also quite light. Not something to have on the camera all the time, but still something to have in your photo bag.

Some first images with both lenses can be found in my flickr photo stream.

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Published on 2 Comments on Cumulative Weekend Update

Sony Vaio Z21 News:

Some good stuff to talk about since the last weekend update. Lots of activity around Z21 support in the sony-laptop platform module, enough to publish an updated 0.8 release, which Eva has done already through the usual channel. A big update patch was posted on the linux-acpi mailing list, I took parts relevant to the sony-laptop platform module, merged them into our code, fixing some bugs in the way hotkey events were mapped to input events and pushed the fixes back to linux-acpi in order to keep upstream and our version better in sync.

A couple of new features supported now, mostly about wireless kill switch and hotkeys:

  • all hotkeys mapped to input events properly
  • better wireless kill switch support
  • compiles on 2.6.27 to 2.6.29

On special request I added a new load option to the module, if you insmod sony-laptop.ko with 'speed_stamina=3', the module will not touch the Nvidia graphics card power state any more. This is for people who need the Nvidia card so badly that booting through Windows is the lesser problem.

The Speed/Stamina switch now also reports ACPI events and I've found a way to read the switch position from the embedded controller, that means I can generate distinguishable ACPI events for either switch position.

Regarding enabling Speed mode I have been pointed to the "Nouveau" project which aims to provide a free replacement for proprietary Nvidia drivers. Maybe it's possible to reuse some code from this project to initialize the Nvidia card up to a state where a regular Xorg driver would be able to work with it. That sounds like major additional work, not sure I'll be able to do that on weekend time alone. The learning curve appears to be rather steep. However, since it's likely something that involves userspace code as well, it appears to me the correct way for now is just to report the switch position via ACPI and let userspace code handle the actual switching. Policies should not be hardcoded in kernel drivers anyway.

Digital Photography News:

After trying a Canon FD to µ4/3rds adapter from a Polish ebay seller and finding that it has got a couple of problems with infinity focusing and limits the available aperture stops to f/8, I tried to get a better version from a shop in China. It arrived on Friday a little more than a week after I ordered it and it's in a quite different arena regarding quality.

The Polish one is very simple, cut from just one block of aluminum on a CNC lathe. The adapter from China has a separate bayonet flange screwed to a CNC lathed body and also features an aperture control ring. It works correctly for all F stops and also allows infinity focusing. I'm very happy with it. I also got an almost mint 50mm f/1.4 lense for little money, including even a one year warranty against yet undiscovered defects. Both arrived in time before my easter holidays. I'll be going skiing in Italy, of course taking the camera and all lenses with me and hopefully finding enough time to enjoy both a lot.

Published on Leave a comment on Z21 News

Looks like there is some movement on the Z21 front again. Matthew Garret posted a patch to the linux-acpi mailing list with an rfkill based implementation of dealing with wireless devices. Interestingly, his patch also enables all the hotkey events so now I even get an ACPI event when I flip the speed/stamina switch. But still no idea about how to enable speed mode safely.

Eva made a new release with the rfkill changes integrated, which means you can now control all your wireless devices for even more power saving. Grab it from the usual place.

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Published on 5 Comments on Vintage glass and digital backs

If you're into photography a bit, you probably know the term register distance. It's the distance between the flange of the lens and the sensory plane of the camera body. It's one important factor in lens design and every camera system has its own, a parameter carefully chosen because it has a huge impact on the overall design of all future cameras a maker is creating.

It also defines how easy it is to use lenses of a different system on your own camera. If your camera has a larger register distance than the lens you want to use, it's not doable with just a distance piece, you need some lens in between, which makes it expensive.

Now, the µ4/3rds system, by lack of the mirror box, has about the shortest register distance of any modern digital camera system, which means it's particularly easy to adapt any lens ever made. Just recently a friend, owning a large collection of Canon FD lenses, has bought an adapter to try some pieces of his collection on my camera and by that I got the chance to try some of them myself - and I found it's really a lot of fun.

I'm especially addicted to some of the fast 50mm because they easily offer apertures around f/1.8 and larger, making them very attractive for portrait photography and still motives, the shallow depth of field offering choices in composition impossible with the set of native lenses available for µ4/3rds today. Another interesting choice is long focal length lenses, the photo above was shot using a 500mm reflex lens, quite a compact design and effectively a 1000mm now due to the cameras crop factor.

This experience has considerably changed my plans for future native lenses to buy. Originally I planned to get the 14-140 as a walk-around lens, but it seems it's not going to be as good as the Pana/Leica 14-150 for 4/3rds yet almost as expensive. I'm afraid Panasonic invested too much into making a video lens and sacrificed optical quality, at least the MTF charts suggest that. So, with my newly discovered love for fast primes I'll rather have the 20mm f/1.7 which is supposed to be out late this year.

In the mean time I'll satiate my lust for experiments with vintage glass bought cheap off flea markets or ebay. Having to operate the camera manually is not really a burden and I find the results with the 50mm f/1.4 quite pleasing, and sharper than what I can achieve with the 14-45mm kit lens.

Of course the crop factor has its downsides. It's impossible to find a decent wide angle lens, I tried a Russian made 16mm fish eye and it's not coming out really wide just heavily distorted. I also tried a 24mm f/1.4 "L" for an effective 48mm, and while it works quite well the make is just not fitting the purpose: too bulky, too heavy, all in all not a good fit. I don't want to carry that pound of glass and only use a small fraction of it 🙂 So that limits the choice to around 50mm, or really long telephoto equipment, I think that's a good variety already.