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Archive for the ‘Astronomy’

Catadioptric lenses

August 07, 2016 @ 21:01 By: gordon Category: Astronomy, Photography

I’m thinking about buying a Tamron SP 500mm lens from a friend, so he’s let me borrow it for a few days to try it out. It’s a manual focus lens and appears to be a fixed aperture (or I need to RTFM), so shutter speed and ISO speed are the things you play with to get the right exposure.
I set up my tripod on the balcony and aimed it at the moon. Other than cropping and some light processing using Lightroom Mobile on my iPhone, these are pretty impressive. 


One of the appealing things about the lens is that it’s roughly the same length as my 18-200mm at its shortest length. The lens is more like a little telescope than a traditional telephoto lens because it has a configuration of glass and mirrors that’s used in compound telescopes, aka a catadioptric lens. 

The bokeh (the blur of things outside the in-focus range) is pretty cool. Instead of the traditional “dots” you end up with “rings”. 

Mercury transiting the Sun (part 2)

May 09, 2016 @ 23:55 By: gordon Category: Astronomy, Photography

The photo I posted earlier is a bit small. I downloaded the photo directly from my camera to my iPad and I think it lost some quality in the process. I’ve reprocessed it and some of the other photos to see what I could find.

This is one of the better photos I took:

Mercury transit

Inside the circle is a tiny dot that is the planet Mercury. You can click the image to see a larger version.

I managed to take this photo by using my 18-200mm lens fully zoomed, holding a piece of #14 welder’s glass in front of the lens and experimenting with the exposure until I found a combination of shutter speed and f-stop that wasn’t massively overexposed. No tripods, no telescopes, just handheld while sitting on a bench in front of the building I work in. I’m sure this looked very odd to the people walking past, but who cares? They didn’t end up with a picture of Mercury transiting the Sun.

Mercury transiting the Sun

May 09, 2016 @ 13:27 By: gordon Category: Astronomy, Photography

I brought my DSLR to work along with my piece of #14 welder’s glass in the hopes that the sun would be visible at lunch. A small break in the clouds allowed me to capture a bunch of photos, including this one:


I believe the small dot in the bottom right quadrant is Mercury. Or dust on the sensor, but it’s appears in more than one photo taken on different parts of the sensor, so I think it’s Mercury because it matches the maps I’ve seen.

Spring forward, lose some sleep

March 12, 2016 @ 22:20 By: gordon Category: Astronomy, Current affairs, General

Time_vortex-red-forward.jpgHey, it’s mid-March, so that means it’s time to move the clocks forward in a futile attempt to save energy. Or so they say. As I’ve mentioned in previous years’ versions of this post, daylight save time hasn’t been shown to actually save energy.

What it has been shown to result in is an increase in accidents because people are discombobulated by the change in their sleep pattern, much like being jet lagged, and a 10% increase the likelihood that you’ll experience a heart attack during the days immediately following the time change. And you’ll probably feel a bit jet lagged, too. I’m really not convinced it’s worth it. (more…)

Falling backwards

October 31, 2015 @ 13:00 By: gordon Category: Astronomy, Current affairs, General

800px-Vortex_back.jpgHere we go again… rolling the clocks back an hour earlier at 02:00 Eastern Sunday morning under the pretence of saving energy. Read this to find out why it’s pointless.

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Springing forward: Sleep deprivation, accidents, and heart attacks

March 07, 2015 @ 18:49 By: gordon Category: Astronomy, Current affairs, General

Time_vortex-red-forward.jpgIt’s that time of year, again. It’s time to change the clocks for daylight saving time.

This evening most of North America sets its clocks forward an hour in a vain attempt to save energy. I say vain attempt because there hasn’t been any sound evidence that adjusting the clocks to chase the sunshine has actually resulted in any reduction in the demand for energy.

CBC had an article this morning that talks a little bit about the history of daylight saving time, and then points out that sleep experts say that many people who make the change will feel sleep deprived and probably take two or three days to fully adapt. If you’re already sleep deprived, well, good luck! As I mentioned last year, your risk of experiencing a heart attack goes up by 10% for the first couple of days, and you’re more likely to be in an accident.

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Time for the semi-annual silliness

November 01, 2014 @ 21:33 By: gordon Category: Astronomy, Current affairs, General

800px-Vortex_back.jpgSunday is the first Sunday in November. That means that most of North America will be turning their clocks backward by an hour at 2am (or whenever they remember).

“Why?” you might ask.

Very good question!

If you were to ask most people why we’re turning the clocks back the answer you get will probably be something like “because it saves energy”, “because it gives us more sunlight in the {morning|evening}”, or “because it helps the farmers”.

All good explanations, but all of them are wrong. The real reason will probably surprise you. (more…)