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Thursday, 19 October 2017 Dereel Images for 19 October 2017
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New sourdough starter
Topic: food and drink Link here

I've been concerned for some time about the slowness of my sourdough, so a couple of weeks ago I bought a starter on eBay. It arrived a few days ago, all 50 g of it, and I've spent the intervening time making 3 full-size (144 g) starters out of it. It didn't seem noticeably faster in action than my own.

Today I baked the first loaf of bread. Yes, much faster. Breads from my starters were taking 5 hours and more to rise, and then barely made it past the top of the tin. This one was done in a good 2 hours, and in the oven was noticeably higher:


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We'll see how it tastes, but I'm not expecting any surprises there.


Network foot-shooting
Topic: technology Link here

Part of repartitioning my (IPv4) network is to reset the net masks. Previously they were full /24 spaces (netmask 0xffffff00), and now they need to be set to /25 (netmask 0xffffff80). On my external machine the interface configuration looked like this:

xn0: flags=8843 metric 0 mtu 1500
        options=503
        ether 00:16:3e:06:34:53
        inet6 fe80::216:3eff:fe06:3453%xn0 prefixlen 64 scopeid 0x2
        inet 208.86.226.86 netmask 0xfffffffc broadcast 208.86.226.87
        inet 192.109.197.81 netmask 0xffffff00 broadcast 192.109.197.127
        nd6 options=29
        media: Ethernet manual
        status: active

OK, that's simple enough:

=== root@www (/dev/pts/0) ~ 6 -> ifconfig xn0 inet 192.109.197.81 netmask 0xffffff80

No response. Oh. This machine isn't local—in fact, it's about as far from here as you can get on the earth's surface. How do I access the console? I've done it before, but forgotten the details. Where are the messages I got from RootBSD? Found plenty of them, but not what I was looking for. Call Mark Price? OK, have the number, do that, but by this time it was 16:19, so in North Carolina it was 1:19, not a time I could reasonably expect him to be there.

Gradually I pieced it together. The connection is via VNC. What do I use for that? vnc? No, no program of that name. File name completion gave:

=== grog@eureka (/dev/pts/38) ~ 1 -> vnc
vncconnect  vncpasswd   vncserver   vncviewer

Which of those? For some reason (possibly misspelling) I couldn't find the man pages. vncconnect sounds good, but running it does nothing, not even a non-zero completion code. OK, what installed it?

=== grog@eureka (/dev/pts/38) ~ 4 -> pkg which /usr/local/bin/vncconnect
/usr/local/bin/vncconnect was installed by package tightvnc-1.3.10_4

OK, off to http://www.tightvnc.com/, which offers me documentation that refers only to

If you have a question about TightVNC, or experience a problem, the first place you might want to look is the TightVNC FAQ.

Well, no, the first place I want to look is the manual. But I haven't been able to find one. The rest of the page went on to discuss implementations for “Windows”. And the FAQ doesn't include the all-important “How do I use the bloody thing?”.

I forget how I finally found it, but the correct answer is vncviewer, for which I found a long man page which didn't even tell me how to enter a password (only how to specify the name of a file with a stored, encrypted password). But that's not necessary. It prompts for the password, something that the man page doesn't mention:

=== grog@eureka (/dev/pts/12) ~ 96 -> vncviewer lemis.rootbsd.net:5672
Connected to RFB server, using protocol version 3.8
Performing standard VNC authentication
Password:
Authentication successful
Desktop name "lemis.rootbsd.net"
VNC server default format:
  32 bits per pixel.
  Least significant byte first in each pixel.
  True colour: max red 255 green 255 blue 255, shift red 16 green 8 blue 0
Warning: Cannot convert string "-*-helvetica-bold-r-*-*-16-*-*-*-*-*-*-*" to type FontStruct
Using default colormap which is TrueColor.  Pixel format:
  32 bits per pixel.
  Least significant byte first in each pixel.
  True colour: max red 255 green 255 blue 255, shift red 16 green 8 blue 0

So finally I was able to connect to the machine. What did I see? I only had one IP address on the interface. The all-important main IP address was gone, so there was no way for the machine to talk to the word. My mistake was to omit the alias keyword:

=== root@www (/dev/pts/0) /home/grog 6 -> ifconfig xn0 inet 192.109.197.81 netmask 0xffffff80 alias

Moral of the story: don't sit on the branch you're chopping off. Use a ladder.

In summary:


Friday, 20 October 2017 Dereel Images for 20 October 2017
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The future of cars
Topic: general, technology, opinion Link here

Margaret Swan has a new car—well, a different, newer one, a Subaru Forester with all bells and whistles. She's having difficulty with some of the bells (or was that whistles?), so I came over today and took a look.

There are two main issues of confusion: first, how do you start the car? For every car I have ever driven, there's an ignition key, usually coupled with a starter. Not on this car. Yes, there's a key, if you can reinterpret the information in the 300 page manual, which tells you to press in the wrong place, but you don't need it, and it doesn't help start the car. The key module communicates wirelessly with the car electronics and permits starting the car. And that's done by pressing a button.

Problem: what if you just want to turn the radio on? With conventional ignition keys there's an intermediate position that turns on most of the electrics, but not the ignition. You'd expect to find how to do the equivalent in the manual—after all, it's thick enough—but it's a generic manual with a description of all models, including information about left-hand drive models, models with old-fashioned ignition keys, and what kind of petrol the car needs in Beijing and the rest of China (but no information about what to do if you move between one and the other). We didn't find the information we were looking for.

Finally we found it by trial and error:

Living with Subaru Forester electronic start system

  1. For any kind of interaction, the electronic key module must be within about 1 m of the car.
  2. To start the engine, ensure that the gear lever is in the P position, put foot on brake (important), and press the “Start” button. The LED in the button lights green. To stop, press again.
  3. To turn the dash electrics on, ensure foot is not on brake (important), and press the “Start” button. The LED in the button lights amber.
  4. To turn more dash electrics on, ensure foot is not on brake (important), and press the “Start” button. The LED in the button remains amber.

I haven't been able to establish the exact difference is between states 3 and 4, but some trip computer comes on when you press the button again.

How to steal a Subaru Forester with electronic start system

This works best with two people. One engages the owner in conversation near the car, preferably close to the front passenger door. The other approaches the driver door, waves at it (it will obligingly unlock), gets in, starts the car, and drives off. The car will not stop when the key module disappears.

In general, I'm left wondering what the advantage of this whole system is, and why it is so badly documented.

Subaru Forrester GPS

The other thing that Margaret couldn't fathom was the GPS system (for which there is another manual with a title something like “Onboard SD Card System”). The documentation is voluminous and verbose, but I managed to find enough (marginally correct) information to start the thing. And surprise, surprise, it was the same iGo software that my el-cheapo GPS navigator uses. Well, almost. It seems to have been castrated: lots of functionality is missing, like the all-important “use unpaved roads”. This is iGo version 9, while mine is version 8. Has it been deliberately restricted, or is this a sign of the times? In any case, Margaret doesn't like it, and would prefer her old Garmin GPS, which at least has the advantage that she knows how to use it.

On the positive side, it displays a compass. I need to check if there's a way to enable that on my navigator.

Apart from that, it's nice to have the unit mounted in the dashboard, where it doesn't bounce or fall off on poorly paved roads. But, like the speedometer of the Mini 50 years ago, it points straight over your shoulder, and there's no way to tilt it. In a car with so many unnecessary “comforts”, you'd think they would have done something about that.


More mystery flowers
Topic: gardening Link here

Petra Gietz in today after a drive down Misery Creek Road, bearing a present:


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What's that? The leaf shape is certainly interesting. I put it in a glass with some water, and when I came back I had a surprise:


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That looks like so many of the flowers I've seen in Enfield State Park. But did any of them have these pointed leaves? To be investigated.


DBDRV responds
Topic: Stones Road house, opinion Link here

Call from Maggie Keenan of the Domestic Buildings Dispute Resolution Victoria regarding the complaint that I entered in June. It has finally come to the top of the queue, and it looks like we will have a session together on 11 December. In the meantime, she needs more information. It seems that it needs to be in particular places: the additional information that I supplied in my complaint should have been put in the (Microsoft Word!) document, because otherwise it can't be processed. But she asked for my permission (granted) to move it there. I wonder what will happen to the layout. She also needs addition documentation: all mail exchange with JG King, and also the contract, building plans, and building permit. Why? No idea, but then I'm a mere mortal.


Focus stacking revisited
Topic: photography Link here

Dale Brabham started a thread on the M43 Tech Talk Facebook Group today: how do you use the focus stacking in practice? I've done a reasonable amount of focus stacking work, but I still have a lot of questions and an incomplete (read: barely started) page on the subject.

Out to do some more experiments today, this time with the M.Zuiko Digital ED 12-100 mm f/4.0 IS PRO, which doesn't support in-camera stacking, and the M.Zuiko Digital ED 30 mm f/3.5 Macro lens, which does. Took photos along a wall of the house and saw what it did. I forgot to check the focus differential setting, but it was set to 2. Here's the result of the in-camera focus stacking:


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Reading the Exif data was interesting. Here's the 12-100 with “focus bracketing”:

Focus:          MF 2.25 m (1.76 - 3.11 m)
Focus:          MF 3.55 m (2.47 - 6.33 m)
Focus:          MF 8.435 m (4.12 m - infinity)
Focus:          MF infinity (8.01 m - infinity)
(etc)

And here's the 30 mm with “focus stacking”.

Focus:          MF 2.825 m (2.06 - 4.50 m)
Focus:          MF 1.455 m (1.22 - 1.80 m)
Focus:          MF 1.92 m (1.53 - 2.57 m)
Focus:          MF 5.34 m (3.13 - 18.29 m)
Focus:          MF 48.07 m (6.49 m - infinity)
Focus:          MF infinity (7.50 m - infinity)
(etc)

As advertised, “focus stacking” jumps backward and forward. Why? The most difficult thing I have found with focus stacking of either kind is to set the start focus. With “focus bracketing” it's relatively easy: just in front of the closest point you want sharp. You still (currently) have to guess where it will finish. But with in-camera “focus stacking” you don't know either point!

The other thing is the question of overlap. These images were taken with the lenses at 30 mm and f/8. My depth of field program comes up with different depths of field from exiftool. Mine are based on a circle of confusion of 8 μm, and give:

Subject        Focal plane     Magnification  Exposure       Near        Far         Depth of
distance (m)   distance (mm)                    comp  (EV)   limit (m)   limit (m)  field (m)
   2.25           30.405        0.01             0.0         1.940      2.679     0.739
   3.55           30.256        0.01             0.0         2.834      4.749     1.914
   8.44           30.107        0.00             0.0         5.272     21.078    15.806

Based on those figures, there are gaps in the depth of field, though they're not significant. If you can accept a 10 μm circle of confusion, they overlap. So maybe the way to look at focus stacking is to hypothesize that the focus differential is related to the size of the circle of confusion. For that to be the case, the steps would have to change with focal length and aperture. Time for some more test photos.

The other thing that occurs to me is that it's really not that interesting to actually process the images, so I can make them as small as I like (since I hate throwing away any image that I have taken). But I can see a lot of playing around ahead of me: try focus stacks with different focal lengths and apertures, and with both of the cameras that can do it.


This page contains (roughly) yesterday's and today's entries. I have a horror of reverse chronological documents, so all my diary entries are chronological. This page normally contains the last two days, but if I fall behind it may contain more. You can find older entries in the archive. Note that I often update a diary entry a day or two after I write it.     Do you have a comment about something I have written? This is a diary, not a “blog”, and there is deliberately no provision for directly adding comments. But I welcome feedback and try to reply to all messages I receive. See the diary overview for more details. If you do send me a message relating to something I have written, please indicate whether you'd prefer me not to mention your name. Otherwise I'll assume that it's OK to do so.


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