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Wednesday, 18 October 2017 Dereel Images for 18 October 2017
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Lens image stabilization?
Topic: photography, technology Link here

When I bought my Leica DG Vario-Elmarit 12-60 mm f/2.8-4, one of the first things I did was to test the image stabilization. One of the drawbacks of using a non-Olympus lens was that I could have lens stabilization or body stabilization, but not both. And it turned out that the body stabilization was much better than the lens stabilization, so that feature wasn't worth much.

Now I have the M.Zuiko Digital ED 12-100 mm f/4.0 IS PRO, my first stabilized Olympus lens, so of course I wanted to see how much difference that makes. According to the hype, it's 6.5 “shutter speed stops”. You've got to savour this. Originally, the term “stop” referred to the detent on the aperture ring of the lens, in those days clearly 1 EV apart. I've never heard it applied to the shutter before. But basically it's the base 2 logarithm of the amount of light, just like EV is. So what they're really saying is that you can extend the shutter speed by a factor of 2 raised to the power of 6.5, or about 90. That's quite impressive, if it's true. Conventional wisdom has it that you can hand-hold a lens at 1/f, where f is the full-frame focal length equivalent. So at 45 mm (90 mm equivalent) I should normally be able to hand-hold the camera at 1/90s. With the promised image stabilization, it's 1s.

Testing proved more complicated than I thought. With the IS switch turned on, the camera reported (Exif). Here output first from exiftool, then from my exifx script:

Image Stabilization             : On, Mode 4
Stabilization:  Body

All well and good, but that's exactly what an unstabilized lens reports. What happens when I turn the switch off?

Image Stabilization             : Off
Stabilization:  Off

OK, RTFM time. The camera “manual” doesn't mention stabilized lenses at all. The lens manual is more informative.

IS switch

ON: Stabilizing functions in the lens and camera operate. The IS operates according to the IS setting in the camera.

OFF:Stabilizing functions in both the lens and camera are off.

OK, that matches. But it begs the question why they bother to put a switch there. You can do exactly the same thing from the camera. It's also a lot less control than I have on the Leica lenses, where the switch does make a difference (between lens and body stabilization). My exifx says:

File IBIS-Test-2-detail-2.jpeg
Stabilization:  Body

File OIS-Test-1-detail-2.jpeg
Stabilization:  Lens

Margaret Swan in town
Topic: food and drink, general Link here

Margaret Swan arrived today to look after Chris Bahlo's house until Chris gets back on Friday. Over to the house again to confirm that the pump and irrigation are still OK. In Rev's pen we found:


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That's the new tap, and it works correctly, but why is there so much water around the area? We were concerned that there might be a leak under the ground, but we couldn't see any evidence, and Yvonne said that Rev had knocked over his water bucket, so we're hoping that that's the explanation.

In the evening, do-it-yourself noodle soup:

 
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Garden sprinkler failure
Topic: technology, gardening, opinion Link here

It's getting warmer, and I've been keeping an eye on the soil moisture. Today I discovered that the sprinkler system wasn't working At All.

Further investigation revealed an interesting reason: the sprinkler controller was off the net. For quite some time I haven't really been doing much with my “Class C” network block, but it's probably about time. All my systems at home are in the top half, so I can do things with the other half, including migrating the web site to that area.

That seemed straightforward enough until I discovered that our sprinkler system wasn't working any more: a network configuration error. The sprinkler controller was one of the few devices in the first /25.

I suppose that's a first.


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:


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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