Transit of Venus

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IMG_4623_TransitCropped_600.jpg

Transit of Venus, Boulder, Colorado, June 5, 2012. This picture was taken by projecting an image of the sun onto a smooth, white cardboard, using an 8x25 monocular fixed to a tripod. The eyepiece of the monocular was adjusted to project an image approximately 0.5 m from the eyepiece. The monocular had a pair of erecting prisms, so the image at the focus of the objective is erect; the image on the screen is therefore inverted. The printing on the cardboard was an aid to focusing; the camera was handheld. Unfortunately, there was a cloud cover most of the day; if you look closely, you can see both clouds and sunspots.

Venus-transit.jpg

Photograph by David Young. This picture was taken with an SLR camera with a 270-mm lens and a solar filter, all mounted on a tripod.

5 Comments

I had the same problem with cloud cover. I got about a five minute window during a break in the clouds; and then the clouds filled in for the test of the day, clearing up completely immediately after sunset (Murphy’s law).

I kluged together a telescope made out of some PVC pipe couplings, some glued-in lens caps (with the backs cut out) that I used for anchoring my 300 mm and 28 mm Nikkor lenses from my cameras into the coupling, and an eye piece from an old, broken telescope.

I used a 2 ft x 2 ft, thin, flat piece of Styrofoam packaging material with a hole punched in the center and placed around the eyepiece tube in order to cast a large shadow onto the area where I placed a screen on which I projected the image.

That gave me a pretty good close-up that I had hoped to see the first contact with the Sun. However, I didn’t get a break in the clouds until about a half hour into the transit. After that, five minutes of viewing was about all I got.

Today’s Astronomy Picture of the Day is nice; also found on YouTube.

I am kind of jealous of this picture and this one, which appeared as a still photograph in the print edition of yesterday’s Boulder Daily Camera.

Conditions hadn’t been looking too cool for being able to see it at sunset at my location (central North Carolina,) but we got a break in the could cover that made not only for dramatic conditions, but reduced the light levels enough, well before sunset, that I could work without a solar filter. Granted, those images are at 1/4000 second and f40, but what works, works ;-)

I kluged together a telescope made out of some PVC pipe couplings, some glued-in lens caps (with the backs cut out) that I used for anchoring my 300 mm and 28 mm Nikkor lenses from my cameras into the coupling, and an eye piece from an old, broken telescope.

My reading comprehension was down this afternoon. 3 lenses seems like 1 too many. What was the layout?

Matt Young said:

I kluged together a telescope made out of some PVC pipe couplings, some glued-in lens caps (with the backs cut out) that I used for anchoring my 300 mm and 28 mm Nikkor lenses from my cameras into the coupling, and an eye piece from an old, broken telescope.

My reading comprehension was down this afternoon. 3 lenses seems like 1 too many. What was the layout?

The 28 mm lens is an inverter between the 300 mm objective lens and the eyepiece because I also use the setup as a terrestrial telescope.

The 28 mm lens is mounted backwards at the other end of the PVC pipe coupling. This gives me some additional control on the overall focal length of the telescope.

A sliding piece of PVC pipe goes between the 28 mm lens and a second PVC coupling that holds the rack-and-pinion eyepiece tube.

I had an old chipped inverting prism (the old telescope got dropped and broken), but I got a brighter image by using the 28 mm lens as the inverter. It also gave me an easy-to-reach, fine-focusing ring as well as a variable magnification between using the rack-and-pinion focusing and the focusing on the 28 mm lens. For example, with a 9 mm eyepiece, I can zoom between magnifications of about 300 to 400.

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This page contains a single entry by Matt Young published on June 11, 2012 12:00 PM.

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