Author Archives: Paul McKay

DIY Polar Scope Illuminator for EQ5 Mount

I recently bought a 2nd hand Sky-Watcher Explorer 200P on an EQ-5 mount off AstroBuySell UK.com and was pleased to discover that it came with a polar scope. For the unitiated, these are used for aligning the polar axis (that’s the extra one that alt-az mounts don’t have) to the north celestial pole so that objects can be tracked by moving the scope in the Right Ascension (RA) plane only. Alignment requires sighting Polaris through the polar scope so that it aligns with a specially engraved reticule inside the polar scope eyepiece. The problem is that when its dark, the reticule markings cannot be seen so have to artificially illuminated (but not too much otherwise it swamps the stars!)…by a polar scope illuminator. Of course, you can buy one at £23 but reviews of them were very mixed so I researched how to make one, after all it’s only a fancy dim torch how difficult can it be?

The description below is really a prototype (with help from utube) as I tried various options while making it. The bought ones fit on the eyepiece but mine fits on the inside the hole in the mount at the ‘objective’ end.

Parts Needed – plastic

From Screwfix, Wickes or Discount Store, Swadlincote

  • 32mm plastic equal tee with compression joints –– about £3.
  • 32mm socket plug – £1.20
  • 40mm socket plug – £1.20
  • 32mm PVC pipe – £2.40 for 3m – we need about 250mm! Try to find an off-cut.

Parts Needed – electrical

From RS Potts Babbington Lane, Derby

  • Small red LED
  • Small rocker switch
  • AA double battery holder
  • 1W rated resistor
  • Small connectors (3)
  • Low voltage cable
  • Insulating tape, or earth wire insulation
  • M4 screw, nut and washer
  • 2 x AA batteries

I had some of these already but I bought the LED, resistor and battery holder for a total of 94p.

Method – refer to photos

Cut the pipe into 2 pieces: 100mm for battery/switch compartment and 50mm for inserting into mount. The longer piece and the branch stub of the tee need to be cut to fit the rocker switch, making sure it faces downwards for easy access when looking through the polar scope. Cut away the flange of the 40mm plug to form a neat end for the battery compartment.

For my mount, I needed to reduce the diameter with a rasp/coarse emery for it to fit snugly inside the hole in the mount. This was a pain by hand but would take only minutes in a lathe.

I made a support (12mm x 150mm but length depends on your mount) for the wires to the LED from a 150mm length of pipe and bolted it to the bottom stub of the tee with M4 screw/nut. Tape wires to the support to keep them out of the field of view.

The 32mm plug is just a cap for the top plug when not in use. My photo shows the branch of the tee curving upwards but it’s better to arrange it curving downwards (remember mine is a prototype!).

Wire up the battery compartment, switch, resistor and LED (polarity is important for the LED). Carefully measure the lengths of wire needed to avoid excess. Soldering is better but I used small plastic connectors. Use tape or insulation to cover any bare wire connections.  Fit the batteries and test. If all ok, carefully thread the wired assembly into the tee piece and your ready to try it out. The support and position of the LED may need to adjusted/bent to avoid it shining directly into the polar scope.

You have a polar scope illuminator for about £10. At the next opportunity, I will attempt to take a photo of the view through the polar scope when illuminated and add to this post. Feel free to ask questions. To finish I would like to hear details from anyone who uses a 90 degree viewfinder on their polar scope, its a long way down to the eyepiece without one.

Illuminator Fitted to EQ5 Mount
Finished Assembly
Exploded View

Wake up to Venus and the Moon

My first shot of Venus at 7.40am on Friday 30th November through my Skywatcher 200p with a Canon EOS60D. I assume the blurry image is due to it being quite low and that the planet is always cloud covered.

Just to check it was not any fault of the optics I took a few shots of the Moon high in the sky at 3rd quarter, always a fascinating photographic subject. I particularly like the way the Sun is catching the peaks of the Apennine range.

Morning astronomy sessions seem to suite me more than late evening ones but there is always the race against time before the Sun rises. I need to set everything up the night before!

Many thanks to Lee for checking and collimating my scope and explaining a few of the basics to me on a busy evening last Friday.

Moon through SW 200P

Hi All Having just acquired my first telescope I was keen to try it on the easiest of objects, the Moon. To a relative novice, the detail visible was truly awesome. I am not set up with T ring and adaptors yet to connect the Canon DSLR but could not resist putting my compact Panasonic TZ4 to the eyepiece, hence to low photo image quality. My only criticism of the EQ5 mount is finding and reaching the RA control knob around the bulk of the 200mm tube. Control cables are now on the Christmas list.

Big thank you to our chairman, Andy for his advice and guidance on checking out a secondhand telescope.

Skywatcher Explorer 130P with AZ EQ Mount

Hi All , I have been reviewing what telescope to buy for a while and at the forthcoming IAS I hope to see some in the flesh and decide. While on the internet, I found on a mount that can be converted from Alt Az to EQ used on the Skywatcher Explorer 130P – see link and photo (although I would prefer the 150P).

https://www.harrisontelescopes.co.uk/acatalog/skywatcher-explorer130avant-130.html#tab-4

Does anyone have experience of this type of mount. I have no experience of actually using an astronomical telescope, but can any EQ mount be used in Alt Az mode just be aligning the polar axis vertically? I would be interested in the views of anyone with experience of a mount designed to be converted  from one type to another? Are they a compromise that end up not performing well in either mode? Thanks in advance.

GCSE Astronomy – Result!

Hi All

I’m still a new kid on the RAG block but some of you will know that I completed an online Astronomy GCSE this year. Well, I have just received my result:

a Grade A (83.5%) overall, 78%  in written exam and 100% for my coursework. I am feeling very pleased, especially as I thought the exam was really tough. If anyone wants advice on doing this over the coming year then please ask. Its a great way to grasp the basics of man’s oldest science that pre-dates the written word!

Open University Astronomy Course

Hi All Having taken a GCSE in Astronomy this year, I am now thinking of progressing to an Open University course called Astronomy and Planetary Science. It is a level below degree but looks ideal for me. Before I take the plunge (its quite expensive) I wondered whether anyone has any experience of this or other OU astronomy courses?

Also, does anyone or the Group have copies of the 2 textbooks?

An Introduction to Sun and Stars 2nd edition (2015) by Green and Jones,

An Introduction to Galaxies and Cosmology 2nd edition by Jones and Lambourne.