Reusing a connection
Anyway, today I wanted to present another advanced feature, one I only stumbled upon while learning for an upcoming exam. The slides mentioned the possibility to share connections on one SSH-channel (to the same destination, obviously). Now, why do you need more than one connection in the first place? Well, sometimes you just need the space, and using screen just doesn’t cut it. Or you use git or scp to the same host you’re logged in already interactively. In that case, you just have to establish one connection and any further connection will use the first one. The benefit? Login is way faster, almost instantly, because the whole handshake and authentication doesn’t have to take place again. The caveat: You’ll have to close your master-connection last, otherwise the other connections will drop too. For me that’s no problem, since the host I use most of the time is also the host I’ve got a session open with 24/7 (IRC).

I’m just gonna show the fully automated version here, though you can use it manually as well, just when you need it. A better description can be found here. To automate it, put this in your ~/.ssh/config (you don’t have a config yet? shocking!):
ControlMaster auto
ControlPath /tmp/%r@%h:%pAs usual, you can put it at the very top to apply for all hosts or you can activate it for specific hosts by putting below a Host declaration. Now all you have to do is use ssh host as usual. You’ll see it’s working when you terminate the connection:
Shared connection to host.de closed.

Reverse tunnel
Yes, you can tunnel with OpenSSH. You can even have it act as a SOCKS proxy, which is really neat when combined with Firefox-plugins like FoxyProxy. But you can also reverse-tunnel your way out of a closed network (or NATed network for that matter) when you don’t have access to any intermediate host (like the router/firewall). It’s easy:
ssh -NR 12345:localhost:22 home.deThis assumes you’re issuing the command from the machine that you want to access (from home) later on. It will bind the port 12345 on home.de so that it is forwarded to port 22 (SSH) on the local host. Yeah, it requires some reverse thinking too to get it right ;) The -N-switch prevents a login, by the way. Obviously it is of little use if your home.de has a flaky dialup connection, so you might want to reverse-tunnel to a stable endpoint (or use something like autossh).

A few weeks ago I decided to finally buy a flash. I didn’t hesitate long and bought the Canon 430EX II. Before that (and while waiting for DHL) I read a lot of strobist.com, so that I hit the ground running when the flash did arrive. The nice thing about buying flashes is that you don’t have to worry so much about capabilities/size, because you can buy a bigger one which can act as master at some point in the future should you feel the need to. Along with the flash I ordered some small utilities, like the Phottix Tetra radio-triggers for off-camera flash, the Roscoe Strobist Gel collection (gel from “gelatine”. It’s called “Effektfolien” in german) and a small diffuser (just for fun). The Phottix Tetra have been great as well, especially considering the price-tag of about 30€, which is next to nil compared to other wireless triggers which quickly add up to ten times that much. However the Phottix triggers don’t support TTL, which is a measuring-system so the camera knows how to adjust for the flash. Well, what better time to really get acquainted with the M mode ;)

Aachen Open 2010, which just ended today, was the only real event I looked forward to, photography-wise, and it turned out really nice. Not only was the event itself a smashing success (no other way to put it, the organisation was flawless, the attendance was record-breaking and the venue perfect for our needs), but also meant many diverse personalities to photograph. You can see my complete photos of the event here: photos.heipei.net/Aachen_Open_2010/ and photos by other people will be collected here: http://cube.hackvalue.de/ao10/media-de.

Tonight I salvaged an old (and broken) Umbrella and simply covered the inside with white xerox paper. I sawed of the round part of the handle and now it fits into the grip of my tripod. The Phottix has a mount option for standard tripods. The results are amazing, and as usual I now feel much better when I buy an umbrella (I’m not quite sure whether I want reflective or shoot-through or both ;)

Results
When are the effects of a softbox most obvious? Probably when there is absolutely no other light-source around (see my Black/White collage). It becomes even more obvious if you photograph something in front a background where it casts shadows. One thing I had to do was to increase my flash exposure compensation (i.e. make it brighter), and in a few cases I had to manually set the white balance, though that’s something I do very often anyway. And using the P-mode seems like the only usable way to incorporate the flash easily. I guess I’ll have to read up on the difference between “Green Square” and “P” again. If you can I’d try to build a bigger box and of course the flash should be close to the center (which can’t be done with the internal flash).

Bottom line
After quite a few shots (photographing people is probably the most rewarding) with my selfbuilt softbox and I know now that the money for a professional one will be well spent ;) If anyone knows of good brands for a) flashes (for Canon) b) softboxes c) remote flash triggers (wireless), let me know!

Rest assured, I’ll be there, but probably less cubing and more photographing. So be sure to come by, even if just to get a glimpse of hardcore-nerds in a different area than your own profession. In case you missed the last Aachen Open, be sure to check out last years website for impressions.