I acquired a free Sigma 24-70 f/2.8 lens that had a few issues–namely, autofocus was broken and the zoom was incredibly hard to turn. After using the lens in full manual for a while, I determined that I would attempt to repair it.

I first did a quick disassembly of the mount, exposing the autofocus motor and the top of the lens components. It was clear that the metal bracket on the AF/MF switch was broken, one of the metal arms that push down the gear was dangling from the bracket. I removed the bracket and mixed up some J-B weld to glue the pieces back together.

After some googling, I determined that the lens must have already been disassembled for repair (made apparent by scuff marks on screws) as the spring that engages AF was on the wrong side of the gear. This resulted in the bracket pushing down on the gear rather than pulling it up against the spring’s force, causing the bracket to break.

After gluing up the bracket, I continued disassembly to see if I could do anything about the sticky zoom. Taking the remainder of the lens apart was tough, as Sigma lenses have soldered-on ribbon cables instead of nice detachable ribbon cables like all Canon lenses have. In addition, you must remove a single setscrew to take off the zoom ring which is hidden under the zoom ring’s rubber grip.

When removing the bottom of the lens, I pulled a bit too hard and ripped the aperture drive motor ribbon cable–I didn’t even notice I had broken it until I looked inside the disassembled lens body. Be incredibly careful when pulling apart separate pieces–these ribbon cables are very fragile! I left the aperture cable broken for the time being, as it will take a fairly long amount of time to solder back up. Note: be very careful when removing focus/zoom rings from your lens, zoom/focus encoder brushes are also very fragile.

When I reached the zoom portion, I found several small plastic bushings which were apparently crushed. The previous owner of the lens must have dropped it, crushing the bushings and skewing the alignment of the zoom. Several screws for these bushings were loose, and tightening them did make the zoom a bit easier to use. However, I could not do any more to fix the stuck zoom issue.

I also noticed that the encoder brushes for the focus assembly were bent and broken. I attempted to bend these brushes back in, but I was largely unsuccessful. I couldn’t find any replacement brushes online that matched the brushes in this lens, so I left them as-is. Interestingly enough, AF worked fine without the encoder brushes.

After waiting for the J-B weld to cure, I reassembled the lens with the spring in the right location and tested it out. AF worked properly, and the zoom was a bit easier to use. Other than the aperture being stuck at F/2.8, this was a very usable lens.

I have since repaired the broken aperture cable, and I’ll throw together a post on that procedure in the near future.

With a couple bucks worth of cheap macro filters, you can get great macro video and photos with the Canon S3 IS (works with the S1 or S5 IS as well). All you need is a lens adapter that fits all of the canon S* IS models and a set of dirt-cheap filters.

I recommend this filter set from “Digital Concepts”. Despite the cheapness of the filters, the optical quality is quite decent. I haven’t noticed much in the way of blurry edges on any photos I’ve taken, although many reviewers have noted edge blur and a bit of chromatic aberration on some macro filter sets. If you’re looking for a much better quality lens, check out this Raynox.

Taking macro video requires that you not zoom in very far while taking video. The less magnification you use, the more you can zoom.

You can take very close shots using the camera’s super-macro mode and the macro filter (the 10x filter works quite nicely). You can also use the standard macro mode, and actually zoom in and still get great macro shots, even with the 10x macro filter. This has given me great results, it also gives an incredibly shallow depth of field. The shallow depth of field is a bit intense at F8, but it can produce some really interesting effects.

Sample Images/Videos:

• Macro Video Test (pardon the bad camera-holding)
• LED Display: 10x Filter + Circular Polarizer
• Chip: 10x, no CirPol, F8 or so
• PCB: 10x, no CirPol, F7
• Coffee Mill: 10x, F/2.7
• Caterpillar: 10x, F/2.7
• Fire: 10x, F/3.5

All of these photos/videos were shot on my S3 IS with the 10x macro filter

There are numerous guides about setting up Google Voice and an incoming sip number for free outgoing calling. Sadly, all of the guides I found were written for FreePBX or some other Asterisk bundle, and also used a shell script to do much of the work (scary!). I have compiled the minimal amount that you need to put in your asterisk conf files to make things work, GUI-free and variant-independent.

Prerequisites

First off, you need a sip number. I recommend sipgate or ipkall (I use sipgate, it’s much more user-friendly). If you google around, you’ll find out how to set up your sipgate/ipkall number as an incoming number in asterisk, I won’t waste time covering it here.

Secondly, you need a google voice number. Once you get said number, turn off call presentation. Also, assign the account a password that you don’t mind having plaintext in a conf file. In addition, you must add your incoming sip number as a phone in google voice. I’d recommend connecting a softphone to your sip number to set this up with google’s verification call, or redirect all incoming calls in Asterisk to your extension.

Thirdly, you need pygooglevoice. Download and install it, or use python’s easy_install command.

The outgoing rule

Now for the actual configuration. First you need to set up an outgoing call rule, so all calls to the outside world (in this case, 10-digit numbers preceded with a “9″) are directed though google voice.

[CallingRule_LocalCalls]
exten = _9XXXXXXXXXX,1,Goto(custom-gv,${EXTEN:-10},1)

Explanation: Any outgoing 10-digit number prefixed with a 9 will match this rule and go to the custom-gv section which we will set up later. The number that was dialed is passed (the “-10″ excludes the 9 prefix from this) at the first dialplan rule.

The GV dialer

Now we need to set up the custom-gv section:

[custom-gv]
exten => _X.,1,Verbose(0, Custom-GV Preparing to call and park call at number ${EXTEN})
exten => _X.,n,Wait(1)
exten => _X.,n,Playback(pls-wait-connect-call)
exten => _X.,n,System(gvoice -e me@me.com -p GVPassword call ${EXTEN} IncomingNum &)
exten => _X.,n,Set(PARKINGEXTEN=701)
exten => _X.,n,Park()

Explanation: After you dial an outgoing number, you’ll be dropped in here. The Verbose() function tosses some output in debug level 0 and up (see the console for this output). The System() command dials the number with google voice. Make sure you change the items in strikethrough to your own personal information. The call is then parked on extension 701 (70X extensions for parking are default. Switch to your parking extension range if you are using non-default options).

Routing GV callbacks

Now you need to set up an incoming call rule. Direct all incoming calls from your sip number at this rule.

[incoming-call-sifter]
exten = s,1,NoOp(CIDredirect)
exten = s,2,Verbose(0, Got incoming CID ${CALLERID(num)}, redirecting…)
exten = s,3,GotoIf($["${CALLERID(num)}" == "GVNumber"]?custom-park,s,1)
exten = s,4,Goto(section-to-route-normal-incoming-calls,s,1)

Explanation: If your google voice number rings your PBX, you know that it’s connecting you to the call you just dialed, so we need to reconnect it to the extension you dialed from. We’ll handle linking of the incoming GV call and your outgoing call (which is now parked) in the next section (custom-park).

Bringing it all together

The custom-park section links a google voice incoming call (which is actually ringing the person you originally dialed) with your original outgoing call (which is parked).

[custom-park]
exten => s,1,Verbose(0, Got incoming GV Callback! Connecting to your original outgoing call…)
exten => s,2,ParkedCall(701)

Explanation: After you dialed your external number, your call was parked as google voice started dialing the other number. This section joins your outgoing call with google voice’s incoming call, so you are connected to the party you originally dialed.

You’re done!

Well that turned out to be a bit longer than I expected, but if you know what you’re doing, you can just ignore the italicized text.

Well, the school year is over, so I thought I’d post up some information about my (extremely cheap and junky-looking but functional) door opener.

The door handle is turned by one 24v globe motor (which have encoders that I’m sadly not using at the moment), and is pulled open by another identical motor. A very affordable ($30) SparkFun RFID reader is attached to the back the door so cards can be scanned from the outside. An arduino controls the process, and drives motors and a cooling fan with 3 darlington transistors.

Power supply case housing arduino and circuitry, along with door-pulling motor and ridiculously ugly tie-dye duct tape

The arduino was attached to an old Dell laptop, which ran the Apache webserver. A small password-protected php web interface was created to allow door opening from anywhere on campus. KDE4 widgets allowed door opening from computers inside the room, letting my roommate and I avoid walking less than 8 feet (or less) away to open the door for someone.

Touchscreen mounted to wall, password widget not shown. And no, I did not actually go to school in Munich, Germany

I also put a password-protected KDE4 widget on our touchscreen mounted on the wall outside of our room, so if one of us forgot our RFID card, we could type in a password on the touchscreen, and the door would open. Fun stuff.

Unfortunately I don’t have too many pictures, and the entire thing is disassembled now. Hopefully next year I’ll improve it (encoders and PID for motion control?) and post some more information.

Popularized with the ever-present  iPhone and expanding into the tablet and desktop sector by companies such as Dell and HP, multitouch is becoming an interesting addition to today’s user interfaces. Overseas companies, such as Asus, are also taking advantage of the technology in new inexpensive tablets; even Gateway is offering a mulititouch tablet these days. Despite the popularity of multitouch, especially on the mobile platform, it seems like a technology with stunted growth and limited applications.

Key points (if you’re too lazy to read the article)

• Today’s interfaces are not designed for multitouch
• Multitouch would require redesigning and rethinking of most GUIs
  • Multitouch often wastes screen real estate
  • With multitouch, one often can’t see what’s under one’s finger
  • Multitouch requires larger on-screen items for finger interaction
• Do we need multitouch? What advantages does it pose?
  • Multitouch provides a more organic interface between human and computer
  • Multitouch allows simultaneous on-screen manipulation of multiple objects

No GUI Support

Most modern GUIs have little to no support for multi-touch technology. One prime example of this is Windows 7, which came with multitouch built-in, but the software updates have little impact on end-user experience. Multitouch is still limited to a specific audience in Windows 7, as navigating through the “All Programs” in the start menu, clicking on links in web pages, and using system tray icons are all quite challenging using one’s fingers. Also, multitouch gestures are not well-implemented into the operating system. To be extremely effective, Windows should have bindings for custom gestures, or at least include more default gestures for the base operating system itself.

Current applications are also severely limited with multitouch interactions, as most applications available today have small hard-to-tap virtual buttons. Including larger buttons wastes screen real-estate and can be a bit unsightly. Many applications also require keyboard input to accomplish a variety of functions. It would be extremely challenging to implement numerous keyboard-based functions into on-screen gestures and buttons. One other prominent issue with touchscreens in general is that one’s finger obscures the item that is being clicked, which makes clicking small objects extremely challenging.

No Need

Next comes the big question: do we really need multitouch? Many people have the opinion that navigation is much faster with a keyboard and mouse than a touchscreen. This is true for most applications, such as web browsing that involves a good deal of typing and link-clicking.

Advantages

Despite the downsides stated, multitouch does provide some advantages to human-computer interaction. For instance, multitouch allows manipulation of multiple objects, or multiple characteristics of objects, at the same time. One simple example of multi-object interaction would be a digital soundboard, where sliders and dials must often be adjusted simultaneously. This would be impossible using a single mouse pointer, and would not allow precise control of speed with a keyboard.

Multitouch also provides for more organic interaction with computers, allowing the manipulation of digital data in a more physical manner. This interaction could be flipping through photos, organizing files, or moving windows around the desktop.

Image courtesy of RobotSkirt