Tuesday, May 25, 2010

DIY Macro Filter

I've a 70mm f=500mm (astronomical grade) objective sitting idle from a finished experiment, so I was always thinking how could I use it in the best way.

When I heard that a macro filter is just an optical lens to bring the focus point closer, I begin to think that it might be just a converging lens! For example, if you have a 500mm focal length lens, if your subject is at 500mm from this objective, parallel ray will go out from the other side of the lens. Yes, parallel ray, that means, if your camera lens will focus at infinity, it will accept parallel ray! In that case, if my lens would focus as close as 1 meter, if I add this f=500mm lens in front of it, it will focus as close as, at least, 500mm now.

To do that, I will only need to buy a suitable threaded ring and stick it in the lens cell like the following:

So now I can put it on and take it off easily, and the result:

Not bad, right?

Network Convergence

We have the following networks:

1. telephone (fax)
2. television
3. internet
4. mobile phone

Telephone Company: ADSL is to use the telephone network for internet connection, and to go a step further, video on demand can be made to work with ADSL. In that sense, the telephone network is now to provide TV, internet as well.

Cable TV: Cable modem is to use the cable TV network for internet connection, and voice over IP can be made to put telephone services on the same network. In that sense, the cable TV network is now to provide TV, telephone and Internet.

Mobile Network: Recently, I've subscribed a service which is based on mobile phone network to provide internet access, as well as conventional telephone service. It's not very fast, but then I believe it's fast enough for most people. Of course, it can support video on demand as well.

Who will win finally in the war of network convergence? Personally, I think Internet will rule in the form of optical fibre services provider since it's fastest and thus it can provide all sorts of services nicely, and the second candidate should be the mobile phone network, since nothing else could replace it.

Friday, May 21, 2010

Replacing the tap of the bathtub

It was found broken earlier today... it's a public holiday today but thank God, I managed to find a shop to buy a replacement, so the question is, how to replace it?

I did measure that the distance between the two water pipes (hot and cold) are around 6 inches. So I went to the shop and asked, whether it's standard or not, the answer is positive. But then you know what, you can hardly be exact especially when the water pipes are coming from inside the wall! So, how to accomodate the difference?

The key lies in the following picture:

Yes, you can rotate it along with the threaded pipe from inside the wall, so the difference can be accomodated.

Saturday, May 1, 2010


Last week, I dropped my eye-glasses and it broke into two pieces... So, I did a google on a simple phrase "邊度配眼鏡好" and I come up with this:


It is so close to my home and it's relatively cheap, so I went. The service is good, I would say. No sales will come to you, and so you've a lot of time to choose from a extensive collection of glases. They price range is big so that you can find something really cheap to some really famous brand.

Once you're ready, you can go for eye checking and they will measure by machine first and then you will be served by a professional optician.

The best thing about this shop is that, they can have your new pair of glases ready in half an hour!