Sunday, September 4, 2011

Taking apart a disposable camera

For a future DIY photography project, I need to disassemble a couple of disposable cameras. Such single use cameras contain some interesting electronics! Most notably a small high voltage generator (330V), a rather large flash capacitor (330V, 120μF) and a xenon flash tube.

You can probably get used ones for free at your local photography shop. If they sell disposable cameras, chances are that most of the used ones they receive will be the same model (this is good!). In my case, this happened to be a 'Fujifilm Quicksnap Fashion'.

Detailed instructions on how to take these babies apart after the jump. But first, I'd like to thank my local photography shop, Fovico, for supplying me with a bag full of used disposable cameras!

Wednesday, July 13, 2011

Linux driver for old serial Wacom tablets (Intuos and Intuos2)

So I bought an old Intuos1 tablet from eBay. I knew that USB tablets were perfectly supported, and that there was some difficulty getting serial tablets to work. Sadly, I misread the description (it said "connects via USB adapter"), interpreting it as an USB tablet, while it actually was a serial tablet with a serial-to-USB adapter included. (note to self: Properly read eBay descriptions next time!).

Now, support for old serial Wacom tablets was dropped from xf86-input-wacom quite some time ago due to a large refactoring and the lack of developer resources to keep this part of the code maintained.

However, literally only a couple of days ago, an initial driver was released by Julian (tokenrove) that supports old serial protocol IV tablets. Right now it has tested support for Digitizer II tablets, and it should also (untested as of yet) support Cintiq, Cintiq2, Penpartner and Graphire serial tablets. The initial announcement and code can be found here.

I created a fork of this driver to implement support for my (protocol V) Intuos tablet. Currently, all features are implemented and working (pen and eraser movement, pressure, tilt; mouse movement and buttons). The driver is still a work-in-progress at the time of writing, but it should already be sufficiently stable and functional for every day use with an Intuos tablet.

I still need testers with an Intuos2 tablet to test that part of the code and/or testers with an Intuos tablet with extra tools (eg airbrush, ...).

The code can be found at my github repository wacom_serial5. Development discussions can be followed in this thread on the ubuntu forums and the linuxwacom-devel mailing list.

Monday, July 4, 2011

DIY reverse ring for macro photography

This is my take on making a reversing ring for high quality macro photography on the cheap. It is based on an old UV filter and a small M42 extension tube segment.

I'm using an extension tube instead of the more custom method of using an old body cap because
  1. I did not have an M42 body cap and
  2. the extension tube is made of metal, whereas pretty much all body caps are plastic -- this is a plus!

Full details and a tad of theory after the jump.

Saturday, February 19, 2011

Friday, January 7, 2011

Extreme contrast and skin detail using unsharp mask

The exams are approaching and it's time to study. Sometimes that makes me feel a bit desperate. Hence this self portrait:
Note: this one only really works in full resolution. Click for the full res image (hosted on deviantArt).

This was shot with self timer on a tripod with my old modified strobe in my right hand. I found the harsh lighting, desaturation and steep, dark contrast very fitting. A more in-depth view of how I got such contrast and skin-details (with the regular kit lens) after the jump!

Tuesday, January 4, 2011

When rsyncs go wrong

Ok, so a few days ago I wanted to sync some photos between by laptop and my desktop. My desktop has my entire photo collection and I have a subset of that on my laptop. I frequently sync directories between the two using rsync. The desktop doubles as a backup, the files are on a RAID1 array for redundancy -- of course that isn't enough to be safe, and yes, I found out.

The directory structure is very simple, I've set it up as


with yyyy the year, mm the month and dd the day of the month.

After having done some editing in the current month on my laptop, I wanted to sync it to my desktop.

I have a small script that uses rsync to synchronize the current working directory from my laptop to my desktop. I had deleted some bad photo's and obviously wanted them removed from the desktop as well. So I gave the script the --delete flag, which it handed over to rsync.

I ran the script and was greeted by screenfulls of lines saying deleted xxx or yyy. Hmm, I didn't delete that much pictures. I glance at the files that are being deleted, hmm, wait a minute, those aren't the right ... AAAAAH!


FUUUUUCK! I'm bashing CTRL-C for my life here! Finally it kills itself and gives me a shell prompt. I look at the current working directory:


That should of course have been


And as I said, I don't have a full mirror of all the photos on my laptop (not enough hard disk space there), so it started pruning all the older ones from my desktop. Ouch.

I've shut down the desktop asap and haven't booted it since. I'm probably going to try my luck with extundelete after the exams. Fingers crossed.

TL;DR Be careful with the --delete flag in rsync. It will fuck you up sooner or later!


Friday, December 24, 2010

Vaporizing some aluminum, taking some pictures

Part of our bachelor project was working with a small scale single turn coil apparatus for creating high magnetic fields. This allowed for some nice plasma pictures!

The principle of single turn coils in a nutshell: you dump a whole lot of energy from a capacitor bank in a (single turn) coil. Once you get a few kiloAmperes flowing, you get a pretty high magnetic field, but the coil also endures intense magnetic stresses and a lot of Joule heating. Ultimatly the coil snaps after the peak field is reached and the vaporized metal turns into a nice plasma. The remains of the coil fly off outwards, keeping the sample intact.

I photographed the plasma and pieces flying off with a long exposure in a dark room. I was slightly worried about frying the sensor, as there is a lot of high energy UV light coming from the plasma. I actually stacked on two UV filters just for some peace of mind. I was still constantly checking the sensor during the first few images.

This is the best picture, it's an aluminium foil completely flying to pieces on our little testing apparatus (Click for deviantArt page where you can see the full resolution version)

This was done as a long exposure in a dark room with a 250mm lens stopped down to f/11 on ISO 100. It was one of the first photos I shot, I did some f/32 shots at first (to protect sensor), but those coil shots were less bright, so I opened up the aperture. Then this one blew up much brighter then before and kind of took me by surprise. The sensor is still OK though!

These pulses can reach about 2T, hence the catchy title 'Two Tesla Plasma' (go ahead, say that out loud. It has a nice ring to it, right?)

I also tried to get a 3D image by using a second camera from a friend of mine. Click the image below to see the effect (WARNING: I can NOT be held responsible for possible epilectic seizures)

The parallax looks a bit odd because both images were shot at 250mm on a cropped sensor. Using a focal lengtch that matches the human eye more closely would probably have made the effect much better, but I'm not too fond of getting the cameras that close to the glowing metal pieces flying everywhere.

So, everyone go and study physics: where you can blow stuff up and get pretty pictures -- for science!

[Edit] For those interested in more info, you can skim through the paper hosted at github (Don't mind the bleek results, we had some problems and serious time constraints).