Apr 102019
 

So earlier today, I had a need to mount a disk image from a virtual machine on the host, and discovered a “new” method before remembering I’d made notes on this in the past. So I’m recording the details in the probably vain hope that I’ll remember this post in the future.

The first thing to do is to add an option to include partition support in the relevant kernel module, which I’ve done by adding a line to /etc/modprobe.d/etc-modules-parameters.conf :-

options nbd max_part=63

The next step is to load the module:

# modprobe nbd

The next is to use a Qemu tool to connect a disk image to a network block device :-

# qemu-nbd -r -c /dev/nbd0 /home/mike/lib/virtual-machine-disks/W10.vdi
# ls /dev/nbd0*
/dev/nbd0  /dev/nbd0p1  /dev/nbd0p2  /dev/nbd0p3

And next mount the relevant partition :-

# mount -o ro /dev/nbd0p2 /mnt

All done! Except for un-mounting it and finally disconnecting the network block device :-

# umount /mnt
# ls /dev/nbd0*
/dev/nbd0  /dev/nbd0p1  /dev/nbd0p2  /dev/nbd0p3
# qemu-nbd -d /dev/nbd0
/dev/nbd0 disconnected
# ls /dev/nbd0*        
/dev/nbd0

The trickiest part is the qemu-nbd command (so not very tricky at all).

The “-r” option specifies that the disk image should be connected read-only, which seems to be sensible when you’re working with a disk image that “belongs” to another machine. Obviously if you need to write to the disk image then you should drop the “-r” (but consider cloning or taking a snapshot).

The “-c” option connects the disk image to a specific device and the “-d” option disconnects the specific device.

Old Metal 2
Mar 202019
 

(This is definitely a work in progress; I’ve still got more lens adaptors to buy and more lenses to test)

So I have a new Fujifilm GFX50R with one native lens (63mm) and my fortunes don’t extend to buying more lenses any time soon. Yet I hear that some 35mm lenses will work even though they’re designed to cover the smaller sensor of 35mm (or in many of the cases below 35mm film).

As someone who has been sticking third-party lenses (and I don’t mean Sigma lenses with an EF mount) on my Canon cameras for years the obvious thing to do is buy some adaptors to test the lenses I have.

And on the grounds that I would find this information useful if someone else had posted it (and I’d found it), I decided to put this out there. No guarantees on the accuracy though!

Caveats :-

  1. No, the images aren’t meant to look good; most of this testing was done inside after a long day staring at a computer screen. The subject is boring, the focus may be off, and if you think these images represent what I’m capable of I’ll just roll about the floor laughing (and I’m not that good). When of course I add the images to this posting.
  2. If you have to have a “smart” lens adaptor for Canon EF lenses, choose a good one. The first one I bought was rubbish; I’ve since gone with a Kipon branded one.
  3. The column for “soft vignetting’ is particularly dubious; I’m not great at spotting it in the first place and until I move the images onto a computer screen and take a closer look I wouldn’t guarantee anything.
Lens Photo? Soft Vignetting Hard Vignetting Sample (links)
Zeiss Makro-Planar 2/100mm ZE No No 1
Zeiss Distagon 21/2.8 ZE No Yes 1
MC Zenitar 16/2.8 Yes
Sigma 12-24 @ 12mm No No
Sigma 12-24 @ 24mm Yes Yes
Canon 24-105mm f/4.0 L Yes Yes
Canon 200-400mm mk1 @ 200 No No
Canon 200-400mm mk1 @ 400 Yes
Leica Elmarit-R 2.8/19mm (1977) Yes
Leica Summilux-R 1.4/50mm (1971) Below f/11 No
Leica Elmarit-R 2.8/35mm (1984) Yes No
Leica Elmarit-R 2.8/180mm (1975) No No
Leica Elmarit-R 2.8/90mm (1966) No No 1
Leica Macro-Elmerit-R 2.8/60mm (1977) Below f/4.0 No
Leica Summicron-R 2/50mm (1965) TODO TODO TODO
Olympus OM 18mm f/3.5 Yes
Olympus OM 85mm f/2.0 Yes No
Olympus OM 35mm f/2.8 Yes No
Carl Zeiss Jena 3.5/135mm No No 1

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