More Sun Spotting!

Yesterday I started fiddling around to see if I could make something that would allow me to view the Sun safely and indirectly. That post is here, and it's in preparation for the upcoming Venus transit, which you can read more about here.

Yesterday's card-with-a-hole-in-it didn't really cut the mustard, so this morning I showered, shaved and finished off a roll of toilet paper with a view to using the cardboard tube inside.


The Problem

The problem is this: to get a bigger view of the Sun I had to move the card-with-the-hole-in-it and the card-for-projecting-onto away from each other. The issue is that as the image gets bigger it also gets dimmer, meaning that there's a point at which it disappears entirely, having been outshone by the ambient light. This is a big problem as, necessarily, there's going to be a lot of ambient light when trying to view the Sun.


The (sort of) Solution

The bogroll tube comes in here: with the card-with-the-hole-in-it stuck over one end the tube itself blocks out much of the light that's getting in the way. Using the toilet-roll tube improved matters a bit, but the image was still unhelpfully small at the other end. Testing the principle was what mattered here, though.

Luckily, @Squiggle7 remembered that for the past five years we've had a poster tube stuffed down behind one of our sofas, so I repeated the experiment with a cardboard tube about ten times longer than the toilet-roll tube. This saw a noticeable improvement on the image size, but still nowhere near what I achieved with the binoculars yesterday, though this doesn't really come as a shock.
Here she is! Thing is, she needs to be BIGGER.



Next Steps

There's no way I'm going to replicate the success of the binoculars with a cardboard tube, but I still want to see how far I can go. I've put out a couple of appeals for some longer tubes- a bit of drainpipe, or a couple of poster tubes stuck together might work.

I've also still got to consider the ambient light issue. Whilst the tube cuts out much of the light along the focal length of my sunscope, there's still an issue at the viewing end. I'm thinking of solving this by sealing the viewing end with the projection-screen card, cutting a hole in the side and making an angled 'eyepiece' out of more bogroll-tubing.

I've only got just over a week until the transit, and work's going to get in the way! If anyone's nearby and wants to join in, get in touch.


Oh, and by the way, we seem to have found where the little waspy-blighters were trying to make their nest yesterday. We think we have persuaded them to look elsewhere. For now...

Comments

Popular Posts

My Blogs