Prague Square
Sunday, December 31, 2006
After a long break from posting pictures from my Europe tour, here's another one:
By the way, it's another 5 months to graduation. Anyone started planning on their graduation trip? How does Australia OR China OR Southeast Asia sound? If you're interested in these locations, maybe we can work out something together.
posted byWilliam at 4:23 PM 0 comments
Chemistry Party!
Went to Wansi's place for a Chemistry Party. The darn bus 170 was so hard to wait (waited for 40 min and still haven't arrive) that I ended up taking a cab so that the gals would wait so long for me at the bus-stop. It was a booze party: Vodka, Sheridan's Cream liqueur, Hoegaarden, Cabernet Sauvignon and Chardonnay.
Weather was a little disappointing initially with the drizzle wetting the pit. The fire was a little difficult to setup but no problem for the BBQ gang which got the flame going finally. Weather turned for the best towards 9pm: it was windy and the rain stopped. I thought the atmosphere of the party was very good. There was the usual talking-cock period, the "grilling" session, and the sit-together-and-finish-the-booze ending.
More pictures...
P.S. We had a discussion on the raw material for Vodka. I remembered Chris (my Swedish corridormate) telling me potatoes and I told the rest. Did a Google... Yup, traditional Russian and Polish Vodkas use potatoes; the modern Vodkas are usually made from grain, especially corn.
posted byWilliam at 1:57 AM 0 comments
An Essay on Lens
Saturday, December 30, 2006
Photography technical geeks are always on the look-out for the best lens on the market. One of the points to note in selecting a lens is its image quality and it is quite difficult to quantify the quality by a number. The sharpness of a lens is very often talked about and is a quality which is very subjective.
There are two important parameters that we should look at when we are judging the clarity of the image, or the sharpness: the image contrast and the resolution of detail. A lens can give good contrast but poor resolution and alternatively, a lens can give poor contrast but good resolution. The latter will give better sharpness at a normal viewing distance of say, 30cm; while the former will be perceived to be sharper at 2m away. This is because our eyes can no longer see the fine details produced by the higher resolution lens; contrast of the lens becomes the determining factor for image sharpness at long viewing distance.
Lens manufacturers cannot quantify the quality of their lenses based on subjective characteristics. They publish an extensive test report in a graph known as the “modular transfer function” (MTF) information. In this test, the subject is a test chart of grids. A grid consists of pairs of black and white lines. And the number of line pairs per millimeter (lp/mm) is quoted. The larger the lp/mm means that in 1mm we squeeze more B/W pairs (high spatial frequency) into that space; the ability for a lens to resolve the lines means that we have a high resolution lens. Low lp/mm represents a coarse detail or low spatial frequency. Now we have taken care of the resolution part when it comes to determining the sharpness of a lens.
The next term is modulation. This term is a quantification of the change between the black and white lines. A perfect lens would give 100% black and 100% white at the border of a line pair. In a real world, aberrations and diffraction would make the black line fade gradually into the white line (the black becomes less black and the white becomes less white). The original 100% contrast between a black line and white line on the test subject grid becomes graduated when the light from the subject is transferred through the lens. Modulation is therefore always <100%.
What happens if we plot two lenses MTF on the same graph and plotting percentage modulation against a wide range of lp/mm? It doesn't tell us anything about image quality across the image field, but it makes it easy to see how responses worsens as details become finer. The greater the area under the curve, the better the lens. If a lens is good at resolving broad details, it would make a good video camera lens while a lens good at resolving fine details would make it a better photographic camera lens.
Lens should be bought for a specific purpose in mind. We can always fit an extension tube to a telephoto and focus closer but the image quality will not be as good as a macro lens which is specialized for close-up photography. An aerial survey lens will give results for distant subjects. A lens for enlarging or copying will have optics correction for close subjects. A shift lens will have a very large covering power (to achieve this, the lens aperture is not likely to be large), therefore, likely a wide angle (Have we seen a telephoto shift lens?). By right, digital backs camera is giving very high resolution compared to silver halide films. Therefore, digital optimized lenses should have their circle of confusion (the smallest optical spot) no larger than the distance separating pixels on a CCD or CMOS.
And a tip here, do not clean your lens too often. You will cover your lens with scratch marks. This will more seriously affect the quality of your image than a speck of dust.
I haven't post any images here to illustrate how to read a MTF graph. This is to prevent any infringement of copyrights. We can have a chat if you are really interested to learn how to read one.
posted byWilliam at 1:02 PM 0 comments
Christmas Eve-Eve
Saturday, December 23, 2006
I haven't been on a date with anyone so I took my camera to Bugis Junction trying to capture a bit of the Christmas spirit.
posted byWilliam at 11:36 PM 0 comments
Party Again!
Friday, December 22, 2006
Here is the link to the group-portrait-photoset on Flickr:
http://www.flickr.com/photos/69533277@N00/sets/72157594431707823/
posted byWilliam at 1:15 AM 0 comments
Nano-Outing: 2006 Christmas Edition
Saturday, December 16, 2006
posted byWilliam at 4:45 PM 0 comments
Surprise Party!
posted byWilliam at 4:43 PM 0 comments
Went Swimming
Wednesday, December 13, 2006
I went swimming at Jalan Besar Swimming Complex. I was trying out some front crawl techniques but I just can't seem to be able to get my flutter kick right. It's more like a psycho-motor problem. I can get the flutter kick right when I am just kicking; but it develop into a very ugly, energy inefficient movement when I start rowing my upper body during breathing . I have neglected the front crawl for a long time. My breast-stroke, like most of you all, is quite ok: reasonably fast and sustainable for more than 10 laps. But 2 laps of front crawl will leave me panting like a mad-dog. When will I improve?!
The 7-11 slurppy machine turned to a spewing machine on me. The Atomic Green Apple flavor slurppy is so incredibly-hulky that it spat on me. Sux... got my hand all sticky. Thankfully the cashier was very prompt in her service and came over to help me. Oh yah, she was not grouchy. In the end, I strolled to Sim Lim Square with a cup of too-sweat, no-flavor slurppy along Jalan Besar enjoying the sights that I have missed when I travel in a vehicle.
I was looking for Sony rechargeable batteries in Sim Lim Square and it seems almost all the shops are not carrying them. Some carried the less popular AAA when all the AAs are sold out. Is Sony still interested in manufacturing rechargeables? Should I switch to Maha Powerex?
Then I met Wei Qiang, my army friend, whom I have not met for a year. His computer is driving him crazy: 6 repairs in a year! Hopefully after the change of the graphics card and a clean install of the whole system, it will turn out good.
The night was spent familiarizing (even though I have bought it for a year, I haven't unleashed the full power of this photographic tool) myself with the operation of the Sekonic L358 meter and organizing some of my computational results.
posted byWilliam at 12:13 AM 0 comments
Prof Li's Lab BBQ + Bug Attack
Saturday, December 09, 2006
The day started with the, as usual, Friday lab meeting. Those who were having exams were exempted from presenting this time. I felt especially light today. There wasn't any academic stuff (books, paper or even a pencil) in my bag; the only items were a frisbee, a lighter, some plastic bags and old newspaper for the BBQ.
So after the meeting, Minqi, Yumin, Liling, Peiting and I went to K-lunch. And we wondered why the waitress was speaking so fast. Not just the one serving us but, in general, all the K-box people speak very fast. Yumin suggested that they have been through some speech training and I won't be surprised. Or do they seive out the fast-speakers during interviews? The soy chicken rice was quite nice. Yumin and I both agreed it was some kind of microwave meal but it was tasty. The gals were a little surprised that I recognize quite many songs and I thought it could be due to me listening to FM93.3 almost 24 hours during the reading week. As usual, I 走音like crazy and everyone had a laughing-good time. This time the waiter and waitress super onz about the timing... we kena chased out very punctually at 2pm. We thought we could stay one for quite some time but at around 2.10pm we kena a "time's up" warning again. We, being a nice bunch of people, decided to leave before they come the third time.
BBQ delivery was from 2-4pm. I had to be at the West Coast Park carpark during this period. I called up BBQ Wholesale and was told that the delivery will be made at 2.45 pm. Not much time left... We went to buy some taiwanese sausages, chips and water from NTUC and took a bus to the Park.
The delivery man was late; he came at 3.15pm. The salad and bee hoon were not well-packed and some had spilled out. He was a nice guy: he apologized on the spot and he further called us after the delivery to apologize. West Coast Park is under massive renovation and the seaview was blocked by large pieces of metal sheets. The BBQ area was super buggy: ants, flies and bitting mosquitoes. I didn't get much mosquitoes' bits but the ants liked my legs alot.
Although the BBQ was to start at 4.30pm, the rest only came at 5.30pm. So during the first 2 hours of the BBQ, the party was very exclusive to the five of us. And it's kind of fun with us cam-whoring. I was super dandruffy with the charcoal ashes flying all over me.
We spent the night playing Polar Bear, charades, 007... with Boss! Yup, I enjoyed myself and I think everyone did, even though we were all smoky, sweaty and swollen with bugs' bit.
Thank you Minqi, Yumin, Liling and Peiting for helping me carry all the heavy stuff from the carpark to the BBQ pit!
posted byWilliam at 9:11 PM 0 comments