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For the last transit of Venus I rigged up a pair of binoculars to project one sight onto some posterboard a few feet away for the entire duration. It was great,

For the last transit of Venus I rigged up a pair of binoculars to project one sight onto some posterboard a few feet away for the entire duration. It was great, Venus was about the size of a dime on the image. That was with a crappy old pair of binoculars I didn’t care about one way or another. Now I have a nice pair, do I risk damaging them by doing this?

dreamcompiler 7y ago
Yes. You risk overheating the adhesive that bonds the glass components internally, unless you use a solar filter on the front (sun end) of one tube of the binoculars, and complelely cap the other tube with its lens cap. My advice is to skip the binoculars. Instead use a simple magnifying glass like you can buy at an office supply store -- a round one, not a square one -- and a piece of poster board just like you did last time. It will work fine. The image will be upside down but who cares? If you can't get a magnifying glass, use a second piece of poster board and put a whole in the middle with a pin, or tack. The image on the other poster board will be very dim but almost as good.
hazeii 7y ago
Make a couple of cardboard disks that cover the front lens with smaller circular cutouts, effectively reducing the diameter of the front elements. If you make the holes say half the radius, you'll reduce the light by a factor of 4 (telescopes often comes with a front lens cover that have this sort of arrangement built in, either for solar projection or for observing the mount). Shouldn't need to say it here, but never, ever, look at the sun through binoculars or a telescope (even with filters or reducers). You won't get a second chance. [edit] Here's a pic from the 2003 transit, taken by projecting an image of the sun onto an A4 sheet of paper, using a 90mm refractor stopped down to about 25mm (Mercury at mid-upper left, the lower blob is a sunspot). http://hazeii.net/images/mercury_transit_2003.jpg http://hazeii.net/images/mercury_transit_2003.jpg
- penagwin 7y ago
  Also same goes for non-Mirrorless Cameras as well!
- leeoniya 7y ago
  > Shouldn't need to say it here, but never, ever, look at the sun through binoculars or a telescope (even with filters or reducers). You won't get a second chance. i was considering this one: https://www.celestron.com/products/eclipsmart-solar-filter-6-sct https://www.celestron.com/products/eclipsmart-solar-filter-6... bad idea?
  - CydeWeys 7y ago
    Proper sun filters are fine and the best way to view the eclipse. They better be real and not knock-off, though!
  - hazeii 7y ago
    From a reputable company (like Celestron) it ought to be ok. However, if anything goes wrong (filter burns through, cracks, drops out) the damage will will likely be irreversible. Think of it as the risk of standing at the wrong end of a loaded gun. Even if you avoid looking directly at the sun, it's possible to make mistakes. On a transit of Venus I was having trouble getting a telescope lined up, so without thinking I bent down to have a look through it to see where the sun was. Luckily the resultant burn made me whip my head back before my eye got to the eyepiece.
jcims 7y ago
I did the same with an old clearance aisle 6” reflector scope. I was with my kids and explaining something to them when i caught a whiff if melting plastic. Definitely potential for damage, esp with all of the elements in binocs.

dreamcompiler 7y ago

Yes. You risk overheating the adhesive that bonds the glass components internally, unless you use a solar filter on the front (sun end) of one tube of the binoculars, and complelely cap the other tube with its lens cap. My advice is to skip the binoculars. Instead use a simple magnifying glass like you can buy at an office supply store -- a round one, not a square one -- and a piece of poster board just like you did last time. It will work fine. The image will be upside down but who cares? If you can't get a magnifying glass, use a second piece of poster board and put a whole in the middle with a pin, or tack. The image on the other poster board will be very dim but almost as good.

hazeii 7y ago

Make a couple of cardboard disks that cover the front lens with smaller circular cutouts, effectively reducing the diameter of the front elements. If you make the holes say half the radius, you'll reduce the light by a factor of 4 (telescopes often comes with a front lens cover that have this sort of arrangement built in, either for solar projection or for observing the mount). Shouldn't need to say it here, but never, ever, look at the sun through binoculars or a telescope (even with filters or reducers). You won't get a second chance. [edit] Here's a pic from the 2003 transit, taken by projecting an image of the sun onto an A4 sheet of paper, using a 90mm refractor stopped down to about 25mm (Mercury at mid-upper left, the lower blob is a sunspot). http://hazeii.net/images/mercury_transit_2003.jpg http://hazeii.net/images/mercury_transit_2003.jpg

penagwin 7y ago
Also same goes for non-Mirrorless Cameras as well!
leeoniya 7y ago
> Shouldn't need to say it here, but never, ever, look at the sun through binoculars or a telescope (even with filters or reducers). You won't get a second chance. i was considering this one: https://www.celestron.com/products/eclipsmart-solar-filter-6-sct https://www.celestron.com/products/eclipsmart-solar-filter-6... bad idea?
- CydeWeys 7y ago
  Proper sun filters are fine and the best way to view the eclipse. They better be real and not knock-off, though!
- hazeii 7y ago
  From a reputable company (like Celestron) it ought to be ok. However, if anything goes wrong (filter burns through, cracks, drops out) the damage will will likely be irreversible. Think of it as the risk of standing at the wrong end of a loaded gun. Even if you avoid looking directly at the sun, it's possible to make mistakes. On a transit of Venus I was having trouble getting a telescope lined up, so without thinking I bent down to have a look through it to see where the sun was. Luckily the resultant burn made me whip my head back before my eye got to the eyepiece.

jcims 7y ago

I did the same with an old clearance aisle 6” reflector scope. I was with my kids and explaining something to them when i caught a whiff if melting plastic. Definitely potential for damage, esp with all of the elements in binocs.