August 2007 - main

Digital cameras
by Peter Alcibiades 14 Aug '07

14 Aug '07

This is the advice a friend of mine gives. His cameras cost thousands and he is a prize winning photographer. I am not a photographer, so have no idea of the merits of his advice, but take an interest in it because of a general interest in technology and because I have someone else to buy for. Here is a summary. 1) OS does not matter unless you are using RAW. Otherwise you are using a card reader, and any OS will manage jpeg. If you are shooting in RAW the program to read it in is very important, and not all programmes come for all OSs. There is something about Macs and Canons - the best RAW software seems to come only for windows. 2) More megapixels are not better, in fact they are probably worse in compact cameras, because noise rises as the pixel size gets smaller. You will see this particularly in low light conditions. 3) There are two reasons why SLRs are better, and a lot better, than anything else, if quality is what matters. One is size of sensor. They have big sensors, less noise. The other is that they do not use power to deliver the view through the viewfinder. This means more rapid operation, less power consumption. The difference between the alleged semi-pro small sensor cameras and true SLRs is huge, and way out of proportion to the difference either in cost or size. I think his view is, though he doesn't say this explicitly, that the 'semi pro' ones which look like SLRs but are not, is like lipstick on a pig. The only thing to use, if you are serious about picture quality, is an SLR. The difference, he says, is huge. 4) When considering SLRs, worry about dust. Every time you do a lens change, dust will be attracted to the sensor. Cleaning up the dust in photoshop or equivalent will be inredibly time consuming. He uses these special brushes,very expensive, to get the dust off the sensor. There are different ways of getting the dust off automatically now with different makes. Worry about dust. Worry about how you are going to manage, how much its going to cost, whether you have to return for maintenance to get it done. Think hard about whether you actually need to change lenses, and if not, get the kind of lens that is flexible enough to leave in place forever. If you're a pro you can't avoid changing lenses. As an amateur, plan so you don't have to. 5) More optical zoom is not better. It is impossible to make 12 x optical zoom lenses that are as good at any given zoom as a non-zooming lens. So anything more than 4 or 5 x zoom means compromising quality at all zoom levels. 5) Image stabilisation is fine, but beware of processing that increases sharpness. What you want is a stabilised image, with as little processing as possible. If any sharpening is going to be done, do it yourself on the PC. Otherwise you risk ending up with a pre-processed image where further processing will just degrade quality. 6) He has cameras that cost 5k plus. Nevertheless, the ones that he is surprised to find give him excellent shots and surprisingly good quality are the 200 pound or so compacts with moderate MP and Zoom count. He particularly mentions a Fuji whose model number I have forgotten. It had quite a high MP count. I can find out if you want. 7) Some of these, particularly the more expensive ones, have all kinds of manual controls. He has been surprised to find that they don't appeal to him at all, though in SLRs he is very manual control oriented. He actually prefers simple point and click in compacts, and doesn't quite know why the ones which allow him the freedom he has with his expensive SLRs always seem to get left at home. I found these conversations interesting because they are so different from anything you read in reviews. As a consequence I bought for my nearest and dearest a then high end 3 x zoom 4MP camera, a couple of large compact flash cards, and a reader. It has worked brilliantly. Its easy to use, the quality is excellent, the zoom is about right, its purse or jacket pocket size, and it goes everywhere. Its certainly not what I had in mind before I asked him. Peter

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Respawning a script
by Richard Lewis 14 Aug '07

14 Aug '07

Hi ALUG, I have a Python script which seg faults occasionally. Its running on a server so I don't pay it much attention and the seg faults don't matter particularly. But I would like it to be running most of the time. Does anyone know of a way of making it automatically start again after it has crashed? I guess its kind of like respawning but I don't think I want init to be in control of it. I guess I could write another script which keeps an eye on the first script's pid and restarts the script when the pid disappears. But before I do, I was wondering if there's a more automatic or more elegant way of doing it? Cheers, Richard -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Richard Lewis http://www.richard-lewis.me.uk/ JID: ironchicken(a)jabber.earth.li -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

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Are there any Python and/or mail experts here?
by Chris G 14 Aug '07

14 Aug '07

I'm considering writing a python script to do some mailbox manipulation but I'm finding the documentation a little confusing, or at least a little lacking. I'm looking at:- http://docs.python.org/lib/mailbox-maildir.html http://docs.python.org/lib/mailbox-mbox.html What I can't quite get my mind round is why the Maildir sub-class of Mailbox has list_folders(), get_folder() etc. whereas the Mbox sub-class doesn't have these methods. >From the user's point of view maildir and mbox mail work the same, you can have a list of mbox folders in exactly the same way as you can have a list of maildir folders. In fact the Maildir sub-class documentation is not at all clear about what you get when you call list_folders(), a list of folders at what level in the hierarchy? -- Chris Green

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Digital Camera recommendations
by samwise 14 Aug '07

14 Aug '07

Anyone got any recommendations or hints / tips for buying a digital camera. Looking at a budget of £100 - £150, for general all-round use - preferably fairly compact. What should I look for when buying a camera for use with Linux? What are the main open source apps and what do they need the camera to support? Is one that connects as a USB mass storage good enough? or should I expect more integration than that with the right camera? Any recommended manufacturers which work best with open source software? Amazon link recommendations welcome! TIA, Peter. P.S. I'm running Debian Testing, if that makes a difference.

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Re: Are there any Python and/or mail experts, here?
by Matthew 14 Aug '07

14 Aug '07

MJ Ray said: > Think what you like, but at least Dovecot seems to share the > requirement. As you note, basic maildir seems not to allow folders at > all. The Python class seems to be using Courier maildir. It wouldn't > be the first time mutt coped with stuff that doesn't follow specs. There's a common restriction on IMAP servers that a folder can contain subfolders or messages, but not both. Is that related? Certainly Dovecot doesn't use true subfolders: it fakes them by prefixing the folder name you asked for with its ancestors, dot-separated. Matthew

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RE: [ALUG] Digital Camera recommendations
by Richard Bensley 13 Aug '07

13 Aug '07

The Casio Exilim is very nice; 7 MP, SD cards, slim, USB etc The Sony Cybershot's always get good reviews too. I also recommend grabbing a copy of What Camera to have a look at their buyers guide, and their roundup reviews. Richard -----Original Message----- From: main-bounces(a)lists.alug.org.uk [mailto:main-bounces@lists.alug.org.uk] On Behalf Of samwise Sent: Monday, August 13, 2007 3:21 PM To: main(a)lists.alug.org.uk Subject: [ALUG] Digital Camera recommendations Anyone got any recommendations or hints / tips for buying a digital camera. Looking at a budget of £100 - £150, for general all-round use - preferably fairly compact. What should I look for when buying a camera for use with Linux? What are the main open source apps and what do they need the camera to support? Is one that connects as a USB mass storage good enough? or should I expect more integration than that with the right camera? Any recommended manufacturers which work best with open source software? Amazon link recommendations welcome! TIA, Peter. P.S. I'm running Debian Testing, if that makes a difference. _______________________________________________ main(a)lists.alug.org.uk http://www.alug.org.uk/ http://lists.alug.org.uk/mailman/listinfo/main Unsubscribe? See message headers or the web site above!

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sshd messages in log, should I be worried?
by Chris G 11 Aug '07

11 Aug '07

I have suddenly started getting lots of messages like the following in my /var/log/messages:- Aug 5 06:59:01 home sshd[7886]: Connection from 193.128.168.195 port 63433 Aug 5 07:14:02 home sshd[7890]: Connection from 193.128.168.195 port 63995 Aug 5 07:29:01 home sshd[7893]: Connection from 193.128.168.195 port 64515 Aug 5 07:44:01 home sshd[2451]: Generating new 768 bit RSA key. Aug 5 07:44:01 home sshd[2451]: RSA key generation complete. Aug 5 07:44:02 home sshd[7897]: Connection from 193.128.168.195 port 65110 I can't see any other activity as a result, no attempted logins or odd processes running. Should I be worried? The IP address 193.128.168.195 seems to be unidentified. I get the occasional login attempt from other places but these are fairly obvious and my passwords are close to unguessable so they don't worry me too much. -- Chris Green

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Public WiFi Hotspots
by Matthew Holland 06 Aug '07

06 Aug '07

This is a little off topic, but since there are plenty of wireless users here and maybe some people with some regulatory/legislative sense, I thought I'd ask. (Out of interest, rather than current necessity, although a decent answer might give me a clue of whose counsel to seek should I ever need to know). What record-keeping responsibilities does a business running a WiFi hotspot for its customers have? They're effectively acting as an ISP, but if they're not keeping proper logs then 'customers' could perpetrate computer crime and be traceable only as far as the business's internet connection (for which they are responsible, of course). Matthew

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USB to serial converter, detected but not there - huh?
by Chris G 06 Aug '07

06 Aug '07

I am trying to get a USB to Serial converter working with my Slackware system. When I plug the converter into a USB port it works exactly as one would expect and hope, in /var/log/messages I see:- Aug 6 15:34:16 home kernel: usb 3-2: new full speed USB device using uhci_hcd and address 2 Aug 6 15:34:16 home kernel: usb 3-2: configuration #1 chosen from 1 choice Aug 6 15:34:16 home kernel: usbcore: registered new driver usbserial Aug 6 15:34:16 home kernel: drivers/usb/serial/usb-serial.c: USB Serial support registered for generic Aug 6 15:34:16 home kernel: usbcore: registered new driver usbserial_generic Aug 6 15:34:16 home kernel: drivers/usb/serial/usb-serial.c: USB Serial Driver core Aug 6 15:34:16 home kernel: drivers/usb/serial/usb-serial.c: USB Serial support registered for pl2303 Aug 6 15:34:16 home kernel: pl2303 3-2:1.0: pl2303 converter detected Aug 6 15:34:16 home kernel: usb 3-2: pl2303 converter now attached to ttyUSB0 Aug 6 15:34:16 home kernel: usbcore: registered new driver pl2303 Aug 6 15:34:16 home kernel: drivers/usb/serial/pl2303.c: Prolific PL2303 USB to serial adaptor driver if I unplug it and plug it back in I see:- Aug 6 15:53:18 home kernel: usb 3-2: USB disconnect, address 2 Aug 6 15:53:18 home kernel: pl2303 ttyUSB0: pl2303 converter now disconnected from ttyUSB0 Aug 6 15:53:18 home kernel: pl2303 3-2:1.0: device disconnected Aug 6 15:53:41 home kernel: usb 3-2: new full speed USB device using uhci_hcd and address 3 Aug 6 15:53:41 home kernel: usb 3-2: configuration #1 chosen from 1 choice Aug 6 15:53:41 home kernel: pl2303 3-2:1.0: pl2303 converter detected Aug 6 15:53:41 home kernel: usb 3-2: pl2303 converter now attached to ttyUSB0 The only (?!) problem is that I don't actually get a /dev/ttyUSB0, so what's wrong and/or how can I diagnose it? -- Chris Green

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Re: /etc/default files
by Matthew Holland 06 Aug '07

06 Aug '07

Sagr (>>) and Brett (>) said: >> ?????? Errrr... Does this mean that EVERY SINGLE PERSON who wants to use >> Apache will encounter the same problem as me???? > > No, just debian and ubuntu users. It's all a bit hit and miss. When I first started with Debian it tended to turn things on by default, and even now a lot of packages still seem to. While I can understand (and agree with) the logic of not dumping daemons onto a server and running them without configuring them, it's annoying how many packages seem to come without any configuration help. Even telling me which documentation to read first is better than nothing, but some don't even manage that. I should stop moaning and starting learning to maintain packages ;-) Matthew

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