Playing with filters

In my Cabinet-o-Gear at work, I found a couple of old darkroom safelight filters. One of them is an amber/brown Kodak #6B filter, and the other is a green one.

According to this Kodak document, the brown 6B filter is used for blue-sensitive x-ray film with transmission bands between 560-660 nm (a fairly wide band covering green to orange) and > 740 nm (getting into the infra-red).

The green one (it’s not marked but I’m guessing it could be a Kodak 7B) has a transmission band between 500-580 nm (covering most of the green band of the spectrum). It transmits the light from my green laser pointer (532 nm) pretty well, but completely blocks my red laser pointer (625-680 nm).

I thought it would be interesting to see what my camera saw through the filters. They’re pretty old and a little beat up so they don’t exactly have the best optical qualities but they still created some interesting photos.

The images with the green safelight filter look pretty neat

Green safelight filter

Green safelight filter

The brown filter produces a neat look

Brown safelight filter

Brown safelight filter

The green filter images turned out a lot brighter than I expected for a band pass filter. Most digital camera sensors use RGB Bayer filters to produce colour images which explains the higher than expected sensitivity with the green filter.

I’ll have to see if I can clean and polish up these filters and play with them some more.

Tour de Q

For my second Gowalla trip, I created the Lowcountry BBQ trip.

Most of the destinations are drawn from previous Lowcountry BBQ meatups so with the exception of a couple of places, I’ve sampled the BBQ fare at all of them. It’s probably not a definitive tour, but all the places on it are what I would consider trip-worthy.

Go take the tour. I’m pretty sure you’ll enjoy every bite of it.

Random Charleston memory: Not what I thought

Just a few days after moving to Charleston, I was in an oddly named grocery store called Publix (at the time I thought it was an odd name).

Walking to the checkout lines, I saw this girl wearing shorts. A fairly ordinary pair of shorts, except printed in great big letters was the word “COCKS”. Right on her butt. Pretty hard to miss.

“Wow, that’s pretty bold advertising” I thought. I mean really, it said “COCKS” in great big letters right on her ass. What else was a guy supposed to think?

It wasn’t until a few of weeks later, after getting a little more settled in and a little more familiar with the local vernacular that I realized her shorts must have referred to the USC Gamecock, and not the other thing I originally thought of.

Things that don’t change

Keeping track of – signs has always been the bane of my attempts at math. Somehow I always manage to lose track of at least one – sign during the course of working out a problem.

On one notable occasion working on a homework assignment for a boundary value problems class (partial differential equations galore), one question evolved into 13 pages of math scribblings. Eventually I decided it was far too ugly to be any kind of correct, so I pitched it all and started over. I found my mistake in a single – sign on the second page and wrote the solution up in 4 pages.

20 years later, things haven’t changed. Still making the same mistakes with – signs or other silly little math errors. On the BioE 846 quiz I got back today, one of the easier questions I ended up getting wrong because of an off-by-1 mistake.

One positive: with the additional years of experience, I’m at least catching most of my stupid little mistakes earlier.

Stuff I used to know

Classes have been going on for about 3 weeks now, and it hasn’t been too bad so far. BioE 846 (Biomedical Basis for Engineered Replacement) has turned out to be essentially an intro physiology course and BioE 820 (Biomechanics) has just been math review so far (all about tensors).

Basically I’ve been resurrecting a bunch of stuff I learned back in undergrad and grad school oh so many years ago.

Hopefully things will get more interesting soon.