Saudi Arabia will be smack-dab in the middle of the upcoming Transit of Venus, the first one since 1888.
How can I view it? I was here for the total eclipse of the sun a few years ago and made a nifty viewer out of a box. Will the same thing work this time?
Nifty viewer will work, but not as well as #14 welding glasses
I was going to try and get a glimpse of it, but I’m thinking I’ll just watch the webcast that the link talks about.
I’m traveling to Vienna (from the US) for the Transit, not to mention all the other wonderful reasons to visit Vienna.
And by the way, the last was in 1882, not 1888, and yes, you can use the same pin-hole technique you used for the eclipse. But the dot of Venus passing across the sun will be much smaller than the effect of a total solar eclipse, so you might want to magnify it somehow.
I’ll be photographing the Transit, with a 500mm lens plus a 2x teledaptor, effectively creating a 1000mm lens. And I’m using a black polymer solar filter.
I’ll be making a shot approximately every 5 minutes, beginning 15 min. before first contact, and ending 15 min. after 4th contact. I’m hoping to catch a sliver of Venus’s crescent before and after the Transit.
I’ve got this worked out to the second for every shot. All that’s left is to pray for clear skies.
To heck with Venus! I reckon I speak for many in saying that I’m just glad you’re still with us, Paul in Saudi. Every time terrorists target westerners over there, your safety is on my mind…
But yeah, the Venus transit sounds really cool. I’ll try to remember to catch the images on the news that day.
This sunspotter from the starry night folks. Expensive though.
Don’t worry about me. I am as snug as bug in a rug. (So far at least.) We ex-pats are odd birds and I have no plans to bug out just yet.
I keep looking around and I have yet to see
anyone mention my method of eclipse viewing.
I’m pretty sure it will work for the Venus
transit as well.
All you need is a pocket mirror and a wall or
other flat surface that is in the shade. Stand
in the sunlight and use the mirror to reflect
sunlight onto the shady wall. That’s it! If the
distance from your mirror to the wall is large
compared to the size of the mirror, an image of
the sun is projected. (Specifically, the edges
of the mirror act as an aperture similar to the
pinhole camera effect.)
The resolution of the projected image is limited
a little bit by the flatness of the mirror, but
mostly by the ratio of the mirror size to the
wall distance. Doesn’t look like I’ll get a
chance to see if it’s sharp enough to see Venus;
the weather forcast for here (Tokyo) is for rain. 
And if no other solution presents itself try a pinhole camera. What have you got to lose?
Just did a bit of calculating and testing, and I had underestimated
the significance of flatness and overestimated the quality of your
average cosmetics mirror. I’m a retired laser engineer so the
character of the mirrors I have “lying around” is rather out of the
ordinary. Guess I took them more for granted than I should have.
I suppose you might get lucky and find a good mirror. It’s partly
cloudy here now, so I just tried a few between clouds. A dental
mirror I have is about 20mm diameter and threw an image 2 meters
away that was good enough to see the clouds passing by the sun.
(A ratio of diameter to distance at about a hundred seems good.)
A makeup mirror that one of my son’s girlfriends left behind failed
miserably. (What do you expect of something with Minnie Mouse
silhouetted on it? Or is that Mickey? You get the idea; it’s cheap.)
The platter out of an old hard disk worked okay (they’re very flat)
but they don’t all have bright plating. (Depends on the type.)
Maybe you’ll have to try the old pinhole thing after all. If it helps,
I can tell you that the hole doesn’t have to be as small as most
people think. It really a ratios thing again. The bigger the hole,
the farther away you have to be to have “clear” image appear.
A one millimeter hole placed 30cm from a white sheet of paper
sounds about right for an eclipse, but you’ll probably need more
resolution to see the shadow of venus. If you use a regular
hole punch (about 6mm diameter) then you’ll have to put it up on
a ladder to get it far enough from your image screen/paper.
(You could just hold it above your head, but then how would you
kneel down to examine the image? Maybe with a helper?)
Good luck! Let us know how if you work something out.
You can’t use a mirror by itself as it doesn’t focus an image.
Binoculars work great. DANGER! do not look through the binoculars even with #10 welding glass. Use the binoculars, or a spotting scope to project an image. You can use a mirror to reflect the image to a shaded area to get more contrast. I use this for eclipses but was too lat to see the transit of Venus.
:smack: D’oh! I forgot I learned my optics theory before the Internet came along
and wiped out all the counterintuitive aspects of physics.
Ahem. A pinhole camera works with apparently nothing to focus an image either.
Do you have any evidence to contradict my experiments and expertise or are you
just stating your instinctive belief in how light and images ought to behave?
Well folks, I just arrived back in the US from Vienna, and Tuesday’s Transit was SPECTACULAR! I photographed the entire transit, just as planned, from the park near the famous gold Johann Strauss Jr. statue. The skies were perfectly clear until the last 1.5 hours, during which only 5 shots were clouded. I couldn’t see a crescent Venus before and after contact, but I’ll see what happens when I get the film developed and scan the slides into Photoshop.
I plan to make an awesome composite image from all the phases.
The best other reason to visit Vienna: Klimpt. His paintings are far more gorgeous than any reproductions I’ve ever seen.
Calling Paul in Saudi, calling Paul in Saudi, come in please …
I haven’t had a good night’s sleep since the transit wonding about your luck in viewing it.
Quite the contrary. A pinhole camera works because by its nature everything is in focus. You essentially have a lens with an extremely high f number aperture. The aperture is so small that the optical part of the lens becomes inconsequental. For any given point in the scene there is one, and only one point in the created image. It’s not perfect, in exchange for virtually infininte depth of field there are diffraction limit problems when the pinhole gets to small and it doesn’t let in a lot of light (an advantage when viewing the sun).
A flat mirror is essentially the same as a pinhole camera with a small f number, a large aperture. For any given point in the scene there is a corresponding area that is in the shape of the mirror. All the light points in the scene produce overlapping images of the mirror in the projected image. The effect is the same as the bokeh of a convential lens where out of focus points take on the shape of the aperture which is round or in a polygon that matches the iris blades.
I’m a little late but…
During the eclispe while I lived in NYC (c 1994?), we used stacks (2-3 sheets) of exposed X-Ray film to view the eclipse. I was involved with biomedical research at the time so we had lots of film lying around.
Which is exactly the case for the pinhole camera, too. If you make your mirror smaller, then that convolution area will get smaller, too. If your mirror is small enough (or, equivalently, if your projection distance is large enough), then the convolution will be smaller than the details you’re looking at in the image, and it’ll look clear. A small flat mirror projecting onto a surface will work exactly as well as a pinhole of the same size projecting onto a surface the same distance away.
You can view the sun through two floppy discs (take off the door, and look through the actual flexible black disc.) If you only use one, though, it hurts your eyes.
Yes, but the difference lies in how in focus the image is. I’ll concede that the difference is more a matter of degree than an absolute. When a point of light is not in focus it is reproduced as a spot called a circle of confusion. The size of the circle of confusion in a non-lens systems like these is proportional to the aperture or lens. A pinhole produces a very small circle of confusion which may be considered to be in focus. Unless the mirror is pinhole size it will produce a circle of confusion that is proportional larger. This might be perfectly adequate for a normal solar eclipse, you can often make out the crescent shape of the sun when it is occulted by the moon but wil be inadequate for seeing the transit of Venus.
Fingers faster than brain, damnit.
You can often make out the crescent shape of the sun where the image projects through gaps in the leaves of a tree for example. You’ll see fuzzy images of the crescent sun while it is occulted by the moon but Venus is far too smal lto make out with such an out of focus image.