Polarex 80mm spotting scope

In 1973 I saw at an optometrist shop in Arnhem (which still exists and is taken over by the son and they still sell scopes, but only from Bresser and Meade) who also sold telescopes, some nice telescopes from Polarex, the most way beyond my budget but I saw two nice ones, both on a tabletop mount: a 70mm and 80mm spotting scope the first for € 127 and the 80mm with slow motion control for € 163. Nice aperture much more than the 50mm I was used to and a turret with four eyepieces for 20, 30, 40 and 60x. Of course I did not expect the quality of the Polarex astronomical telescopes as this telescope is designed for low power use and terrestial obervations (a 'spotting scope'), but that was alo my main reason to use it for wide field deep sky observing. Surely I observed planets. But I was very happy, much brighter images of the sky, really nice ! On 10 Dec 1973 I observed a small partial lunar eclipse and the noght after an occultation of Saturn.
This brochure of 1973 shows the specs of the original telescope. As shown this telescope is designed for terrestial viewing and therefore the optics is not optimized for high magnification astronomical use. But for low power deep sky viewing it is a nice telescope.
In 1983 I did some astrophotography with a Canon SLR piggyback on this telescope and for this purpose I built a simple equatorial mount to put the whole table top tripod in a clamp which can be adjusted to the latitude and used it on trips to destinations from South Africa to the South Pacific. See picture below. From 1991 on I used the Vixen SP mount for this.

Polarex 80mm spotting scope
Simple equatorial mount for the Polarex built in 1983 some slight changes later. (Photo taken in 2012)

About 20 years later I modded this scope by replacing the poor quality eyepieces with a 45° Amici prism turret by a 1.25" opening and a standard 1.25" diagonal allowing use of more (and better) contemporary eyepieces. The performance of this scope is OK as long the power does not exceed 80x otherwise color errors become apparent. When I put a Nagler 13mm type 6 (82° apparent angle) the image was really amazing, nearly as good when I put the same eyepiece in my 100mm Televue Genesis ! Also using Vixen Plössl eyepieces gave a dramatic increase in image quality, despite the average performing objective lens. Moreover I adapted the table tripod mount in order to mount the scope on a standard 1/4" - 20 tripod thread and use the original tripod for cameras as well. So I purchased a Vixen Super Polaris mount in 1991 where I put this telescope on sometimes as tracking scope and using the Canon T90 (now the Canon EOS 7D) for astrophotography. It is a convenient small scope of only 1.4 kg which is a very good deep sky performer particularly when a Nagler eyepiece is used.
This telescope has a very useful table tripod and the OTA is still very lightweight (1.6kg with the new objective) due to a simple helical 1.25" focuser. In 1995 I modded the table tripod to allow mounting the quick release clamp with the OTA on a photo tripod or an equatorial mount. In 2010 I added altazimuth setting circles on it to allow (when set level) reading altitude and azimuth.

Polarex 80mm spotting scope
December 2009: Telescope equipped with tripod mount adapter and 1.25" star diagonal but before repaint

Polarex 80mm spotting scope
June 2012: Same pictures, but telescope repainted, new objective and altazimuth setting circles

Modded Polarex 80mm in original box
June 2012: Telescope and table top tripod completely refurbished with better optics in its original cabinet

But, still at powers of 38x or more the triangular spikes are apparent at brighter objects and at higher it is more obvious. I have always had this problem. But in the 1970s I had no idea that this 'haze' around planets was actually an optical error so I accepted it. Actually I could return it to the shop and get a better copy. It was not the crappy Huygens eyepieces as a Nagler with a Powermate 2.5x (96x) shows the same errors. So I decided (June 2012) to do a star test with the same eyepieces as with the Televue Genesis but without Amici diagonal (no diagonal at all). I pointed the scope at Arcturus and used the Vixen LV6mm and the Televue Powermate 2.5x which is a magnification of 210x. While the Genesis showed nice round diffraction rings when defocusing, this scope showed ugly triangular diffraction images which were obviously very tight strain in the lens cell.

spikes animation
Animation of Arcturus taken with a Canon Powershot S100 filming behind the eyepiece at 210x power while changing focus.

I posted this animating image to forums and all replied indeed 'pinched optics' with lots of strain on the lens cell. So I tried loosening the rings over the front lens but to no avail. it was mounted VERY TIGHTLY. Now I decided to replace the objective. There was one 80x480 FPL-53 available at Telescope Service Ransburg near München Germany for € 440 but it has a very long (> 3 months) delivery time. So I put an ad on a Dutch astronomy products trading mart and by surprise, the next day I got a reply from a guy 20km from here who had a good 80x500 achromat for only $25. Same focal length. So for that price I got it and it turned out to have an excellent quality, both mechanical and optical. I did a test run by mounting it temporarily on the telescope tube with duct tape (!) and even at 210x the images were unexpectedly razor sharp, but as expected blue halos around it. I tested it side by side with a Televue Genesis at 210x power and it turned out that the images on tis scope were as sharp as the Genesis but the Genesis was (obviously) brighter ( (10cm / 8cm )2 = 1.56x) and lacked the blue halos. But the blue halos were not really annoying. From now on this telescope gets a real astronomical telescope.

So I decided to let somebody I know from Astrotechniek in Velden near Venlo to make an adaptation ring to mount the objective on the scope. The guy from Astrotechniek said it has an excellent mechanical quality with an iron containing alloy in the lens cell (a magnet sticked on it). 'It should have been a part of an expensive optical device built in the 1980s' he said. It is definitely not a so-called RR (Rainpipe refractor) objective which were imported by Hans Winkelaar of Sky Objectives from China / Taiwan in the early 2000s.` After slightly more than a week it was ready: a nice lathed aluminum ring which fits perfectly. Only thing: it had 3cm too much backfocus so I have to use a 1.25" rear tube extender to get focus. But that saves weight. Despite the rather heavy objective and solid aluminum ring the OTA weight increased only from 1.4 to 1.6 kg. Now I pained the inside of the ring with black matte stove spray (Hammerite 'High Temp') which made the inside excellently black matte as it should on the inside of telescope tubes.

The vertical movement (altitude) is somewhat problematic when pointing high in the sky. As the table mount is designed for terrestial use (as it was a 'spotting scope'), when pointing high in the sky it tends to topple backward and can only be boved by unscrewing the vertical fix screw, moving and screwing it.
In April 2014, I finally put a spring between the tripod thread screw and the base of the mount which keeps the telescope stabilized when moving up/downward when the fix screw is only loosely tightened. This allows use the telescope like a Dobson, i.e. just moving upward and downward by hand. Horizontal motion was already possible this way.


Test setup, Televue Genesis and this scope side by side.
The testsheet comprising ISO 12233 , USAF 1951 test sheets and 20 euro banknotes
The objective lens mounted with duct tape (!) on the scope tube
Close-up of the "new" 80x500 objective lens
Design of the adapter ring © Astrotechniek
The telescope with its original (spiky!) objective
The objective unmounted and the new objective and adapter ring
The new objective mounted
Ready for spraying the inside
Inside sprayed with Hammerite stove spray
The adapter ring finally painted black matte inside
The outside and the telescope tube repainted with gray Hammerite
The newly painted OTA adapter
Close-up of the mounted objective
Alt azimuth setting circles
The telescope in its original cabinet with extra eyepieces
A spring stabilizing the vertical movement

The telescope fits in its original cabinet with extra eyepieces : Vixen LV6, Televue Nagler 13T6 and Televue Panoptic 24. Furthermore a Baader Amici prism.
Still to be done:
  • Tripod mount adapter is too thin aluminum strip as it is a bit wobbly.
  • Altitude arrow too short which makes reading altitude scale difficult Already done.
  • Sun / dew cap
Finally sky tests were very good. Epsilon Lyrae at 83x was easily to be separated which one would expect from an 80mm. Planets (Saturn, Venus) and the Moon showed flawless images even at 210x with only minimal blue/violet fringing. Not as good as the Televue Genesis but the aperture is smaller. But for a short (f/6.3) achromat it provides an excellent image. But (when seeing allows) it does show black shadow spots during Jovian satellite shadow transits and even a moon in front of Jupiter when near the edge. Also, the Red Spot can be seen (although not really red which requires a much larger aperture).