Rick's b.log - entry 2018/08/10

On hating

Yet, the Eton educated Johnson - in his supposed support for the burka - slips in a crass gag that could easily be taken as a memetic insult towards those who are forcedchoose to dress in that way, it's no big deal? Bygones? What's all the fuss?

Yeah. Right.

While I am a believer in the idea of freedom of speech (another of the things being trotted out in defence of Johnson), the idea of freedom of speech does not mean freedom from consequences of such speech. The classical argument here is a person shouting "FIRE!" in a cinema. And, as I pointed out, there was no actual need for an educated man writing an article in defence of the right to wear such clothing to include any form of insult or derogatory comment.

My personal thoughts? I'm with France, Denmark, and various other countries. A person obscuring/hiding their face is downright creepy. Not to mention a concern with regards to security. It's just not a done thing. Even I, as an introvert (and thus no particular desire to interact much with others) don't obscure my face. Expressions say a lot about a person's feelings and motivations. Religion, being "a God thing", should not be used as a special right to allow people to completely obscure their bodies.
This isn't a matter of religious freedom, it's a matter of public security and wellbeing. I have no interest or concern what concept of creator a person prays to, nor care what they choose to wear at home. However in public, a person should try to dress in keeping with the norms of the place in which they are. And the norm around here is that pretty much the only times a woman wears a full face covering veil are marriages and funerals.

Brexit - FFS!

My God.

If this was Italy or someplace with a notoriously gonzo government, they would be endlessly pilloried in the British media for incompetence, corruption, and outright stupidity.

I could have talked about this. I could have talked about why the great vision of Rees-Mogg is going to be a disaster for everybody who isn't Rees-Mogg.

But I won't.

Because all last week it happened more and more. The talk of a crash-out Brexit. Even quoted (was it the bloke running the bank?) as being sixty per cent likely.

I know, I know, this is a childish scare tactic designed to get the EU to give in and cut the UK some slack from the fact that the UK keeps asking the same question over and over and being unable to accept "no" as the answer.

Even so...

Do you know what a crash-out actually means?

Do you actually think that's a good idea?

Do you really believe that mentioning it at all is going to "strengthen your hand"?

Is this what taking back control means?

FFS!

I don't want to be British anymore. It's no longer an embarrassment. It's now something worse. I don't have the words... I really don't.

Telescopes

I have seen the moons of Jupiter - through binoculars. Patrick Moore used to go on endlessly, that bins are better than cheap refracting telescopes.

This is very true. A refracting telescope is the long barrel type. It works by having a lens at each end to focus the light collected into a point which is where you put your eye.

The thing is, the ones you find in toy stores... they are utter rubbish. Let's see:

• Horrific abberations as a natural consequence of cheap mass produced plastic lenses (resulting in distortions and halos of red on one side of a star and blue on the other)
• Either a lack of a mount, or a flimsy tripod mount, which is utterly useless for tracking the movement of an object in the sky
• Such toy store telescopes often talk about how great their magnification is - 600X! Whoo! While a decent magnification is a good thing, too much magnification and you'll have a hell of a job trying to see anything.

Combine all of the above, then the only reasons you should buy an inexpensive (under 100 quid) refractor for your child is if you hate him/her and/or want to convince them not to be interested in astronomy.

The important thing that a telescope must offer is light collection. This is more important than magnification. It does work in tandem with magnification - you can magnify much more with a ten inch telescope than you can with one that's an inch if you're lucky. And by inches, I don't mean how long it is, I mean how wide the first lens is. You will notice from my telescope that it's a big barrel. Well, actually it's only three inches across so it's slightly more serious than a toy. A decent telescope should be in the region of 8-10 inches minimum (three times bigger!).

Proper telescopes support the use of interchangeable lenses, plus something called a "Barlow", which is a tube that slides in between the telescope body and the eyepiece and typically offers 2× increase in magnification. For those telescopes that present an upside down image (the reflectors), one can also buy an arrangement the uses clever placing of mirrors to flip the image. Do not use these for astronomy! It doesn't matter what way up the Moon appears. Get to know it and how it looks in your telescope. Every thing you insert in the path of the light will diminish the quality and brightness of what you see.

Three types of telescope are worthy of attention:

• Newtonian reflector
  This is my telescope. It works by increasing the apparent length of the telescope by having the light enter at the front, bounce off a curved mirror at the back, to be collected by a diagonal mirror that is usually attached to (or near) the front lens. The light then bounces off of this at a right angle and into the eyepiece.
  Generally speaking, the apparent "length" of a reflector is twice that of the body plus a little bit for the eyepiece tube. This makes them fairly compact, though hefty, even when we're talking models with an eight inch front lens.
  Reasonable smaller ones start in the order of 400-500.
• Dobson
  This is a weird sort of reflector that looks like it was built in a garden shed. It throws away the fancy equatorial mounting to replace it with a simple tilt and turn platform. Indeed, don't be surprised to see a Dobson that does away with the tube entirely and replaces it with a simple metal frame to hold the lenses. This is basically stripping a telescope down to its component parts and trading just about everything for sheer size. With that in mind, you should be able to get a larger Dobson for the same price as a standard reflector. It's a little trickier to use with the different mounting, but it is likely to be the lightest for its size and as such be more manageable.
• Schmidt-Cassegrain
  This takes the idea of the reflector one stage further by having the light enter at the front and bounce off a mirror at the back (just as the reflector). Here's where it changes. The reverse side of the entry lens holds another mirror that bounces the light right back, to a small hole at the back of the telescope. A big one (8 inch plus) will offer good views of celestial objects, but with their apparent "length" being about three times the length of the body, they are heavy and expensive. You're probably looking at upper three digits. If you are interested in doing serious astrophotography, pick a nice three digit number and then prefix it with a '2' and that's the ballpark you should be expecting.

So why does Patrick Moore talk so much about binoculars? Easy. For about twice the price of a not-entirely-rubbish toy telescope, you can get a pretty good pair of binoculars. The magnification isn't great (often in the order of 25×) but the lenses will be glass and the aperture at the front is going to be something in the order of two inches at least. This means you are going to have a small enough magnification to be able to find and track objects in the night sky (here's a tip - those big telescopes with higher levels of magnification? they will probably be using a computer controlled mounting to automatically track the object) and a large enough opening to let in sufficient light that things are bright and clear, and finally optics that are good enough not to make a mess of what you're trying to see.

If you are doing astronomy on a budget, binoculars are your best bet. Binoculars? Why not? Close one eye, you're now holding a telescope.

But most of all, unless you've won the lottery, do not splash out on a really big telescope. It's no good having a motorised equatorial mounting for a 12 inch Cassegrain (which would be pretty epic to use) if the setup is tedious, the telescope weighs a ton, and most nights you just can't be bothered with the hassle. Start with something more reasonable. My 3 inch is, as I said, only marginally better than a toy. But with it I've seen Jupiter's moons, I've examined our own Moon (and I prefer partial illumination to a full moon as it makes the craters really stand out), and... I've watched this:

Yup. That's a better way to end.

Your comments:

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David Pilling, 13th August 2018, 22:52

I liked the Saturn video, don't think I've seen that through the binoculars. Interesting to consider what current tech could do, which was not available when Patrick Moore was discussing bins and telescopes. For example a very low cost pan and tilt mount could point to anything in the sky for you - not like the old days having to painstakingly learn the constellations. You'd probably be better off watching the results on a screen - sensors better than your eye. Patrick M had to sit and make sketches because photos were so involved.

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