Monday, June 28, 2010

Analysis of Fader ND (mark I) filter image quality

In February 2010, I purchased an 82mm Fader ND Filter (ND2 to ND400) from the official eBay store for Light Craft Workshop.  The label on the filter reads "82mm  Fader ND [W]  HL-OPTICS".

The purpose of a Neutral Density (ND) filter is to reduce the amount of light, therefore allowing for slower shutter speeds.  A variable ND filter allows you to vary the amount of light by rotating the front of the filter.

When shooting video, the shutter speed is normally fixed - it is tied to the frame rate giving the required Shutter Angle (e.g. 180 degrees) controlling motion blur.  When shooting video, the only way to prevent over exposure in bright light is to Stop Down the aperture.  This limits your ability to use the aperture to control depth of field.

A variable ND filter is particularly useful for video, since it allows you to control exposure independently of the aperture and ISO.  Specifically you set your fixed shutter speed, choose your depth of field, then set exposure using a variable ND filter or ISO gain (for bright or dim light respectively).

Variable ND filters can be constructed by stacking a Circular Polariser (CPL) filter and a Linear Polariser (LP) filter.  However I heard some people had issues with colour shifts, and I preferred to just buy a variable ND filter ready to use.

I believed that I would be able to use the variable ND filter for normal photography and not just video.  I've found though that image sharpness is severely affected, and out-of-focus (Bokeh) areas of the image have a crazing pattern.

Sunday, June 13, 2010

More chickens

We've now got five chickens, having purchased another two today.

This is our family of hens.

"Beatrice" is a Silver Laced Wyandotte, purchased 13th June 2010.

"Snowball" is a White Wyandotte Bantam, purchased 13th June 2010.

"Dotty" is a Cuckoo Pekin Bantam, purchased 1st November 2009. Sadly she had to be put-down on 7th March 2011 after developing paralysis from a virus.

"Edna" is an Isa Brown, purchased 1st November 2009.

"Dora" is an Australorp, purchased 1st November 2009.

Click here to view more photos of our hens.

Saturday, June 12, 2010

New chicken coop

Recently I wrote about how I had designed an automatic door opener for our chicken coop by modifying an alarm clock.  Refer to this posting for more details of the design:

We've now replaced the old chicken coop with a much larger one.
Note the chicken coop is a one-off, home-made design purchased off eBay, which we've then modified to suit our needs.

There's plenty of space in the nesting boxes for our hens.  In fact it's probably too big now, so we'll definitely have to get some more girls.

Plus the most important thing, I've converted my automatic door opener to suit.  Now it operates vertically, and hence why the clock is on a 90 degree angle.
The operating mechanism is much less prone to error.  Specifically there is less friction, and dirt/grit doesn't collect in the tracks.  It may also be less prone to forced entry by cunning animals (e.g. raccoons) that you have in other countries.

Here's a video of the automatic door opener in action. Our three hens come out in the order Dora first, then Dotty the bantam and then finally Edna pushes past.

Thursday, June 3, 2010

Resolving FOSCAM connection dropouts

I bought a FOSCAM FI8908W wireless IP webcam off eBay recently. It has lots of features for the price.

However, I've had problems with being unable to connect to the camera after a period of time (an hour or so). Power cycling the camera would fix the problem.

I've tried upgrading to the latest firmware (version is supposed to fix WiFi disconnection problems), but it did not fix my problem.

The problem is not related to my browser or the wireless network. I've tried disabling DHCP (router based static IP). It turns out the problem is that the webcam simply ceases to respond to ARP requests (once in this broken state).

The ARP protocol is a mechanism to translate between IP addresses and Ethernet MAC addresses. Without ARP, you cannot perform IP communications over Ethernet (since all Ethernet traffic must be destined to MAC addresses). The ARP protocol allows network devices to discover the MAC addresses of the designated IP address.

Simply adding a static ARP entry on your PC will restore communications. This show how on Windows to determine the MAC address of your webcam (e.g. IP address and then create a static ARP entry:
c:\> ping

Pinging with 32 bytes of data:

Reply from bytes=32 time=7ms TTL=64
Reply from bytes=32 time=3ms TTL=64
Reply from bytes=32 time=3ms TTL=64
Reply from bytes=32 time=3ms TTL=64

Ping statistics for
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 3ms, Maximum = 7ms, Average = 4ms

c:\> arp -a
Interface: --- 0x10003
Internet Address Physical Address Type 01-12-23-34-45-56 dynamic

c:\> arp -s 01-12-23-34-45-56

c:\> arp -a
Interface: --- 0x10003
Internet Address Physical Address Type 01-12-23-34-45-56 static
To make this change persist after rebooting, simply add the "arp -s" command to a batch file that you run from your Windows startup folder.