Archive for August, 2009


Swine Flu precautions

Filed Under: Miscellaneous, bookmarks
Aug.07, 2009

The deadly Swine Flu has reached the Indian shores following the global outbreak and now, claimed one life. However, Swine Flu is certainly one of those diseased where an ounce of prevention is worth a pound of cure. Here are ten tips for you to keep away from the pandemic.

1. Wash your hands frequently

Use the antibacterial soaps to cleanse your hands. Wash them often, at least 15 seconds and rinse with running water.

2. Get enough sleep

Try to get 8 hours of good sleep every night to keep your immune system in top flu-fighting shape.

3. Drink sufficient water

Drink 8 to10 glasses of water each day to flush toxins from your system and maintain good moisture and mucous production in your sinuses.

4. Boost your immune system

Keeping your body strong, nourished, and ready to fight infection is important in flu prevention. So stick with whole grains, colorful vegetables, and vitamin-rich fruits.

5. Keep informed

The government is taking necessary steps to prevent the pandemic and periodically release guidelines to keep the pandemic away. Please make sure to keep up to date on the information and act in a calm manner.

6. Avoid alcohol

Apart from being a mood depressant, alcohol is an immune suppressant that can actually decrease your resistance to viral infections like swine flu. So stay away from alcoholic drinks so that your immune system may be strong.

7. Be physically active

Moderate exercise can support the immune system by increasing circulation and oxygenating the body. For example brisk walking for 30-40 minutes 3-4 times a week will significantly perk up your immunity.

8. Keep away from sick people

Flu virus spreads when particles dispersed into the air through a cough or sneeze reach someone else’s nose. So if you have to be around someone who is sick, try to stay a few feet away from them and especially, avoid physical contact.

9. Know when to get help

Consult your doctor if you have a cough and fever and follow their instructions, including taking medicine as prescribed.

10. Avoid crowded areas

Try to avoid unnecessary trips outside.

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DSLR - Zoom and Magnification

Filed Under: Miscellaneous, bookmarks
Aug.06, 2009

I was searching for formula to calculate Zoom ‘x’ for DSLRs, While searching I found this nice and detailed answer regarding this by some person named ‘Jim_T’

Answer was ->

Zoom and magnification have little to do with each other.. They’re two different things.

Zoom only describes how much you can change the focal length of a lens. For instance, if you have a 28-135 lens that’s set to 135mm, and you’re too close to get your whole subject in the viewfinder, you can ZOOM OUT to a smaller focal length to make things fit.. It’s common to think zoom is designed to bring things closer.. but you have to consider you can zoom ‘away’ or ‘out’ as well.

When you twist a zoom lens in and out, your subject appears to rush towars you, or away from you… Or in other words, zoom close or zoom far.. Or zoom in and zoom out.. Zoom is a verb that’s used to describe this apparent motion caused by varying the focal length.

The amount a lens can zoom in (or out) is determined by dividing the maximum focal length by the minimum focal length.. 135/28 = 4.82 X (135mm is 4.82 times greater than 28mm)

A fixed lens (ie EF 1200 f/5.6L USM) has NO zoom. That’s right.. 1200mm and you have NO zoom. You have a fixed focal length, you can’t zoom in or out.. (You have to use your feet :) ) You’ll never find a fixed focal length lens described as a zoom lens.

If you go to the Canon lens site.. You’ll see they do not call *any* of their prime lenses ‘zoom’ lenses.. http://www.usa.canon.com/eflenses/lineup/index.html

The magnification of a lens gets complicated. It depends on what format they’re designed for.. A 100mm lens for a medium format camera will have less magnification than a 100mm lens designed for a 35mm camera.

Generally, it’s accepted that for the 35mm film format, a 50mm lens approximates the human eye.. (Not exactly, but close). You’ll notice that the 50mm prime lens is described as a ‘Normal’ lens or a ‘Standard’ lens. As focal lengths decrease, you move towards wide angle and as focal lengths increase, you move towards telephoto.

Since 50mm is roughly what we see.. You can get an approximate of lens magnification by dividing by 50. So a 100mm lens would magnify like a 2X telescope. A 300mm lens would be like a 6X telescope.

The 10D/300D have a 1.6 crop factor, so you have to take that into account. 300mm nets the same field of view as a 480mm lens.. So a fixed 300mm lens on a 10D/300D will give you no zoom and 9.6X magnification..

If you have a 15-30mm lens, you have 24-48mm.. Despite the fact the lens has a 2X zoom rating, at the maximum of 48mm, it has no magnification at all..

Zoom and magnification are two different things.

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