Canon DSLR attached to Skywatcher ED80, with Vixen Flip Mirror

Finally, I got the Canon DSLR 1000D attached to my Skywatcher refractor.  I’ve been waiting for the T-mount adaptor and it arrived a day or two ago.  

It has a Canon EOS fitting on one side (you remove the camera lens and the adaptor slots in, in its place), and a “T” thread on the other side (perfect for screwing into my Vixen flip mirror).

Here’s a picture of the arrangement, on the right..

It seems to attach really well.  And of course, with the flip mirror, I can switch in a second between an eyepiece and the camera.

I’m now waiting for some clear skies to try it on an astronomical target.  There has been so much cloud, recently.

Distant trees with the camera and telescope

I took this picture in daylight of some distant trees, through the telescope..

 And here’s another shot, showing the camera with its ‘Live View’ facility turned-on. Like this, you can see what the camera is seeing, live on the screen, enabling you to adjust focus and other settings, before taking the shot. Particularly important if you are doing an astro image with a long exposure.

Canon with its Live View on the screen

Vixen Flip Mirror

I wrote a few weeks ago I had bought a Skywatcher ED80 Refractor and I’m very pleased with it (in spite of the excess of grey cloudy skies, we seem to have had recently!).

Well.. I’ve just added a great accessory to the refractor..

It’s a Vixen Flip Mirror.  

And I’m also very pleased to have come across this well-made gadget, because it’s already making my observing so much better.

The flip mirror allows you to have two devices attached to the telescope and flip between them, simply by turning the knob you can see in the image to the right.

In this way, you can be using say, two 1.25″ eyepieces of different focal lengths, at the same time.

Use a low-power to find the object, then flip to a higher-power to observe.  Or, you could have one eyepiece for alignment and one camera for imaging.

Whatever the combination, you can quickly alternate between the two ports, according to your needs.  Much better than trying to swap eyepieces or cameras, in the dark!

One eyepiece tube unscrewed to reveal t-thread

Lots of uses…

And as well as this flexibility to have two devices attached to the telescope, the flip mirror has also solved two other problems I was having..

Problem 1 Solved! As I mentioned in the previous post, the telescope needs some form of extension tube to bring an eyepiece to focus. Previously, I was using a separate extender tube.  Now, the flip mirror provides the extra length of light path and does the job.

Problem 2 Solved! Using the right-angle port, makes it comfortable to view objects high up in the sky, without needing an excessively tall tripod or other support.

Vixen Flip Mirror attached to ED80 Skywatcher

Here’s a picture of the Vixen flip mirror attached to my 80ED refractor.
It’s going to prove a very good buy, I think.  I paid £53 (about $80).
The picture shows it with two 1.25″ eyepieces attached.

It has a problem with the slow-motion drive on the declination axis.  The screw thread and rack section drive, no longer mesh properly.  So the dec drive does not work.

We decided last week, to replace the drive with a new worm wheel and worm set, to be supplied by Beaconhill telescopes in Louth, Lincs.

But careful dial-gauge measurement, revealed a run-out on the dec axle (‘wobble’), which would jeopardise the smooth working of the worm.

So we were back at  square one.

The final solution remains distant in the future.

But we have found a stop-gap.  

We will re-vitalise an alternative dec slow-motion control, which was fitted to the telescope decades ago..  It should help us get the telescope working, soon.

My new telescope was delivered two days ago, so here are the first impressions.

It’s a Skywatcher 80ED refractor from the Evostar Pro series. This means it has an 80mm diameter, high quality objective lens, made from fluorite glass.

This special glass material is used to eliminate false color as much as possible from observations and keep them sharp.

ED1 OTA Version (optical tube assembly only)

It’s the first high-quality (apochromatic) refractor I’ve owned. Before purchase, I asked experienced astronomers and this telescope was well-recommended for it’s image quality and value for money.

Skywatcher 80ED showing necessary extension tube

I bought the ED1 version – this is the bare optical tube (OTA) only. You can also get the ED2 version. It’s exactly the same optical tube, but comes also with 2 eyepieces, finderscope, diagonal and case.

I already had eyepieces so I decided to save money and just get the OTA, which cost £235 (about $420) delivered.

Attaching To A Mount

First impressions were good.

The tube assembly is a handy size and weight. And with a focal length of 600mm (f7.5), it’s fairly short.

It was easy to attach to the equatorial mount, I already had.

You can see from the photo, I have used the white Skywatcher tube rings it was supplied with, but have attached them to the existing bar on the mount.

Because of this, the rings are rather too close together.

I have retained the Skywatcher supplied (longer) dovetail bar and will use it on the next mount. (I intend to get a much better quality, motorised polar mount for this telescope, in the next few weeks)

First Light Through The Scope

Observing Chair and Skywatcher 80ED

Amazingly, the sky was very clear on the first night, so I did some observing.

First thing to point out, is the focus tube is too short to allow use of an eyepiece, ‘as is’.

You need either an extension tube or a star diagonal, to lengthen the optical path and bring the image to focus.

Remember I mentioned above, the ED2 version comes with a 90 degree diagonal attachement.

I used an extension tube I already had. I have annotated the photo above, to highlight this extension.

Observation

Jupiter is bright, but rather low in the South at present. It made a good first target for the new refractor.

I was very pleased to get a good sharp image of Jupiter, using a 9mm eyepiece. I could clearly see the darker bands on the planet.

The crayford focuser of the scope is very smooth and nice to use.

I really needed higher magnification, but the 9mm eyepiece is the shortest focal length I have at present. With the 600mm focal length of the telescope, it gives only 66 times magnification. (600 divided by 9)

I’m confident I will see clear views at much higher power, so I am well pleased with the new refractor.

I will report progress over the next few weeks.

In my previous post here, I said the restoration of the Alan Telescope was nearly finished.

We had a meeting on Monday night and there is a problem with the Declination axis motor drive.

It has worked OK up to now, but the 30 year old arrangement has now given up.

The telescope has a fine pitch worm screw, driven by a reversible DC electric motor. The worm acts on a small rack section, which we unbolt and move around a large (30 inch diameter) declination circle, made from metal.

The screw has started to slip and there is no obvious remedy, other than replacement.

So I have have been talking to telescope specialists, such as the excellent Beacon Hill telescopes, about how to fix it for the long term.

We may have to purchase and fit a large worm wheel and worm set, to provide a more accurate, reliable drive.

This will cost a fair bit of money.

Alternatively, we are considering a “tangent arm” threaded rod arrangement. this will be cheaper and easier to fit.

I shall let you know here, what happens next…

This 22.5 inch reflector carried out important work on supernovae in the 1970′s and 80′s, operated at Burwash in Sussex, by it’s designer and builder Alan Young.

It then lay dismantled and unused for many years, before coming into the hands of Cranbrook School. Volunteers at their astronomy society have worked over the last couple of years to restore the telescope to operation.

The restoration project is now reaching the final stages.

Here’s a close-up picture of the recently fitted Crayford focusser with a custom motordrive. The arrangement will permit careful adjustment of the focus, from the observatory floor level. This is essential…

As you can see here, from this picture of the Mintron camera being fitted to the focusser. It is many feet up and requires an access tower to reach safely.

In the bottom picture, the declination axis drive is being adjusted.

The telescope is expected to be fully operational soon.

Neptune is the furthest out of the “Gas Giant” planets and is right out at the limits of our Solar System, 2800 million miles from the Sun.

The story of its discovery is fascinating…

Neptune

Neptune’s existence was suspected long before it was actually discovered.

Astronomers in the early 1800′s found that they could not reconcile the observed position of the newly discovered planet Uranus, with the position they expected through calculations.

So some astronomers began to suggest that perhaps there was an undiscovered planet in the same area of the Solar System, that was affecting the orbit of Uranus.

Various people became involved in the search for the new planet. Notably, these included a young French mathematician called Urbain Le Verrier and a young English mathematician called John Couch Adams.

Both of these men calculated where in the sky, they would expect Neptune to be found. Adams did not publish his work, but Le Verrier did by means of two notes, in 1845 and 1846.

The search to find Neptune observationally began.

John Challis, Professor of Astronomy at Cambridge, used the Northumberland 11.6 inch refractor but did not find it.

(Incidentally, this telescope can be visited and is still used at the present time, in Cambridge. I have seen it and it is a wonderful piece of astronomy history)

Reviewing the episode later, after the new planet had been discovered, Challis found that he had actually seen and recorded Neptune almost immediately in the predicted position, but he had not realised it. I bet he was cross!

Meanwhile, Le Verrier had sent his calculations and predictions to Johann Galle at the Berlin Observatory.

With this valuable information, Galle looked and found very quickly. Neptune was discovered on his first night’s observation in 1846.

Later, it was discovered that Adams had also been correct with his predictions of Neptune’s position, but unfortunately, it had just taken too long for the English astronomers to follow it through to the observation stage.

Neptune is not actually that difficult to see with a telescope, if you know where to look and what you are looking for.

Through a telescope, the Neptune’s disk looks blue. Like Uranus, this is due to light absorption by methane.

Neptune is also very similar in size to Uranus.

The largest of Neptune’s moons, Triton was discovered soon after the planet itself in 1849, but the second moon, Nereid, took much longer (1949). It is close to the planet and hard to see.

The most significant recent event was the Voyager space mission. It flew past Neptune in 1989.

Voyager found six additional satellite moons, together with a faint ring system – another similarity with Uranus.

However Neptune does not share Uranus’ extreme axial tilt. Neptune’s axis is inclined at just 29 degrees to the plane of the orbit. Only a few degrees more tilted than Earth.

Voyager also succeeded in measuring the period of rotation. Neptune’s “day” was found to be 16 hours 7 minutes long.

Generally, this is a very good thing. You can now buy a very capable, powerful instrument for a remarkable price.

It is not unusual for amateurs to obtain a 6 inch, 8 inch, or even 10 inch aperture telescope, quite possibly as their first serious instrument for astronomy. And, built-in computerised control is becoming common.

As I say, this is good.

However, I think a few words on the real-world practicalities of using these telescopes, may be helpful to beginners, before they part with their money.

I am certainly not trying to put you off buying a decent sized telescope. I encourage you to do so, assuming you are interested in astronomy and can afford it.

Just think through these practical aspects in advance and it will be all the more enjoyable.

Storing The Telescope

Telescopes are large items and they have an awkward shape. They take up quite a lot of space in a small house, even if they can be partly dismantled, say by removing the tripod.

They need to be protected when not in use, from dust, moisture, excessive heat and cold, being knocked over and inquisitive children who want to take them to pieces.

Consequently, you need a large cupboard or a corner of a special room, that can be set aside to store your telescope.

Assembling The Telescope And Moving It Outside

Telescopes are heavy, particularly if they are larger than 6 inch aperture.

Also, you may have to do some limited reassembly, like putting it back onto the tripod, before it is ready for use.

At 8 inch aperture and above, moving the telescope safely is really a two-person job. Think about this before you spend thousands on a large telescope

Firm Mounting

To get good results, you need a flat, solid area to site the telescope. When you use even moderate magnification, any movement in the floor surface will drive you mad, as you try to track faint objects.

A wobbly wooden deck is not much good.

Concrete is firm, but if it has been heated by the Sun, it generates thermal air currents moving upwards past the telescope. This spoils the image.

Grass, providing it is dry and firm, is surprisingly good as a base for your telescope, as thermal effects are limited.

Cooling Down Time

A refractor or schmidt cassegrain telescope is sealed and so it does not need very long to aclimatise to the outside temperature.

A reflector is very different, however.

Don’t think you can take one out of a warm room and put it outside where the temperature is 20 degrees lower, and then immediately see good images.

A reflector takes up to two hours to settle to thermal equilibrium with the outside temperature. Only then will it provide good images.

As any telescope cools, dew starts to form on the lenses and mirrors. This is frustrating. A dew shield can help, but some people experiment with mild electrical heating to dispel the moisture.

Aligning The Telescope

“Go-To” computer controlled telescopes are very tempting, especially for beginners who do not know their way about the night sky and generally, they are very good.

This type of telescope is common now. It has a computer that will automatically point the telescope at the celestial object you want to observe. Telescope dealers use this as a BIG selling point.

However, the Go To system will find nothing unless the telescope has been accurately aligned.

This involves entering certain settings for latitude, date and local time into the computer and then going through an alignment process, usually involving the finding of two bright stars.

In my experience, many people find this alignment process difficult and time-consuming.

It can totally spoil the idea of “just popping outside with the telescope” to observe something.

So please bear in mind, that Go-To controllers need proper setting up, if they are to work as promised.

If you find it difficult to use a computer, say to find and use websites on the internet, you will find it tricky to use a computerised telescope Go-To system properly.

Summary

None of these points are meant in any way to put you off buying a good telescope. Modern commercially produced telescopes offer fantastic value for money, compared to what used to be available.

I suggest only that you give these practical considerations some thought before you purchase. Then your new telescope should give you the rewarding experience, it is surely capable of delivering.

In recent years however, various hybrid types have become available, which attempt to combine the best features of the two traditional types. But we will discuss more about hybrid designs in a moment.

Refracting telescopes use a main lens made from glass and called the objective lens. This lens bends (or refracts) the incoming rays of light as they pass through it, so they come to a focus. This was the type of telescope that Gallileo famously used back in the early 1600′s to make the first astronomical observations of the Moon and Jupiter.

Reflecting telescopes on the other hand, do not use an objective lens, instead they use a main or primary mirror. The surface of this mirror is specially shaped into a concave curve called a parabola, which has the handy property of reflecting all incoming light rays to a focus.

Let’s look at these two traditional types in more detail.

Refractors

Refracting astronomy telescopes have a main lens ranging in size from about 60mm (2.5″) in diameter and then on upwards. The cost increases quickly, as it is expensive to make good quality lenses, so it is rare to see an amateur instrument with a size greater that 150mm (6″).

Refractors have the advantage of allowing all the light collected by the objective lens, to pass unobstructed through the telescope to the eyepiece at the other end of the tube. Consequently, even small diameter instruments can work well. A decent quality 70-80mm refractor is still an excellent telescope for amateur use.

The problem with refractors however, is so-called chromatic abberation. This simply means that false colour can be introduced to the image you are observing. This happens because the different colours of light within white light, are bent by the lens through slightly different angles, resulting in slightly different focal points.

This used to be a big problem until it was discovered that by sandwiching two (and more recently three) lenses into a doublet or triplet lens, and also by using special glass, these false colour effects in the image could be removed.

Refractor telescopes with colour correction are called achromatic and the best ones, using the multi-element lenses are called apochromatic.

However, the manufacture of these clever lenses is expensive, although the prices of achromatic refractors has come down greatly in the last few years because of Far Eastern factory production.

Reflectors

The reflecting telescope was invented by Sir Isaac Newton in the early 1700′s. As we have said, it uses a mirror to focus incoming light.

This has two big advantages – firstly mirrors are cheaper to make than lenses and you can make them in large sizes, and secondly, mirrors do not have the problem of false colour.

As a result, you can get a much bigger reflector for your money and they have always been very popular amongst astronomers. The largest telescopes in the World all use mirrors.

The disadvantage however, is that you need a bigger reflector to get the same light-gathering power as a refractor because it is necessary to use a second mirror (the secondary) to divert the focussed light beam into the eyepiece. This second mirror within the telescope tube, blocks out some of the light.

Hybrid Telescope Designs

Recently, we have seen the emergence of hybrid designs which combine mirrors and lenses. These catadioptric reflectors are compact telescopes that are capable of producing high quality images, while being available at reasonable cost (typically a few hundred £ or $).

These hybrid telescopes use a lens called a corrector plate at the top of the tube, together with a primary mirror at the bottom. Mounted inside the tube is a secondary mirror. This reflects the light a second time back down the tube and out through a central hole in the primary mirror, and into the eyepiece (or other imaging device).

There are a few disadvantages, but they usually work very well and have consequently become very popular amongst amateur astronomers.

However there is a problem…

As soon as you try observing the heavens with a handheld pair of binoculars, after just a few minutes, you will find out that it is not very comfortable.

Standing upright, trying to hold a pair of binoculars steady up to your eyes while gazing straight upwards, soon gets tiring and becomes a literal “pain in the neck”.

I have tried quite a few different ways for observing with binoculars in comfort, over the years.

Here are some ways you can try…

1. Use a deckchair or a reclining garden chair. This works pretty well. You can adjust the angle, depending on whether you want to observe up near the zenith, or at lower altitude in the sky. It is fairly comfortable, particularly if the garden chair has arms that you can position so you can rest your elbows and cut down the hand wobble.

2. Lay back, flat on the ground, preferably on a rug or groundsheet and maybe with a cushion under your head. Observing the stars through binoculars while in this position, can be amazing. If you let your imagination go, you can get a feeling of being “at one with the Universe”. But it does not give your arms or hands any support.

3. Get a tripod for your binoculars. This is perhaps the more dignified, grown-up approach. However not all binoculars and tripods will attach to each other. It tends to be only the large and specialist binoculars that come with a fixing point for a tripod. Also, and importantly, with a tripod you lose the easy mobility of a handheld pair of binoculars.

4. Make a special support frame to help your observing with binoculars in comfort. I have seen a simple wood frame made from 2″ square timber to provide support for the arms and binoculars. It has two legs, each with a “foot” and a crossbar. You lie on your back on the ground, with the frame over your chest. The crossbar should then be in the perfect position for resting your forearms and therefore, for supporting the weight of the binoculars. It might sound a bit weird, but with a couple of hours handy carpentry work, you could give it a try!

If you can come up with a comfortable arrangement for binocular observing, I am sure you will enjoy your astronomy much more.