Towa 339

[Lady Isabella]

Hi

I picked one of these up this morning for a good price. http://www.spacealberta.com/equipment/80mm/80mm.htm

They seem to get good reviews from owners. Hoping it will make an excellent planetary and double star scope, as they seem to handle magnification very well. All the parts are there, and all came in the original plywood box, just needs putting together and a quick clean.

Being f/15, it should give some wonderful colour-free views, I will post review of its performance shortly.

[Lady Isabella]

After reading reports about these scopes, I decided to test the scope

out and for a bit of fun I thought it would be interesting to

compare this 30 year old scope against a recently purchased Chinese

Skywatcher Evostar Achromat refractor.

First a bit of information about the Towa. It was made in the late 70s

or very early 1980s, and it is clear from the start that the Towa must have

cost the first purchaser a large sum of money. I was buying telescopes at this time,

and can well remember how expensive even very basic scopes were.

The Towa is very well built indeed, the OTA does not have one bit of plastic on it.

The rack and pinion focus mount is silky smooth, and one very big surprise was

the 0.965" eyepieces, they are fantastic quality and give superb images.

The equatorial mount was yet another surprise. At first glance it looks like it's not

up to the job, particulary when you consider how long the optical tube is.

But here again it all works very well with smooth slow motion controls.

After 30 years, the Object Glass was in need of a clean, Baader Wonder Fluid did a great

job, after re-fitting, all was re-collimated very easily.

The following accessories also came along with the package, eyepieces 25mm, 22mm, 15mm,

12.5mm, 6mm, one prism diagonal, one prismatic erector unit, two moon filters, Solar

projection screen and an amazing (original) quality 12.5mm thick plywood packing case to put

everything in.

When I saw it for sale at a local second-hand market, everything was in bits,

including the OTA, so I haggled with the seller and picked up the entire package

for the knockdown sum of £40.

For the skywatcher I made a 80mm aperture mask, making it an 80mm f/15, 31.7mm eyepieces were used

in both scopes using the Japanese style for observing.

The following tests were made over the course of the last week.

First light was a star test on Vega at 200x, both scopes produced an excellent

out of focus star test. In focus a tiny amount of C.A. was visible in both scopes. The Towa produced

a wonderful Airy disk and diffraction ring. The skywatcher produced more glare with

a slightly brighter diffraction ring.

Next came the double star Delta Cygni. At 200x, I could straight away see the faint companion

star with the Towa. With the Skywatcher, I had to spend some time trying to pick it up as the

image was not as sharp and crisp as that seen with the Towa. This turned out to be the case

with all the other doubles that were observed. A few days later, the Towa gave a wonderful split of Rigel.

Several hours later, the scopes were turned onto Saturn. Both scopes gave a wonderful

view of the planet. The edge-on ring was seen as a dark band crossing the globe,

the north polar region was dusky in appearence, while in the south a band was observed.

One thing that was noticed, was that the contrast in the Towa was better than that seen in the skywatcher.

A couple of days later, the targets were Venus, Jupiter and the Moon.

Venus, produced C.A. in both scopes, however the Towa handled the C.A. better than the Skywacther.

The shape of Venus was easily seen in both scopes. As both scopes are Achromats, I was very pleased by

the views that they were giving.

With Jupiter, both scopes gave a very nice image, with no C.A. being visible.

The equatorial belts were clear and crisp, and the moons were a very nice sight.

The Moon was simply excellent in both scopes. I could not detect any C.A. on the limb in

either of the scopes. The shadows in the craters were as black as a black cat in a coal bunker in a

power cut. Both scopes handled high magnification extremely well, with 266x to 322X being used.

In a head-to head magnification shoot-out, the Towa just had the edge over the Skywatcher.

It is clear that a long focal ratio Achromat refractor gives superb visual performance.

Both scopes were superb, but the winner turned out to be the 30 year old Towa.

I like the build quality of the Evostar scopes, but the Towa has a few nice touches which I like.

The screw-on dewcap is nice, the finder scope is a wonderful little unit that accepts other eyepieces,

but the selling point is the silky-smooth R&P focus mount.

With optical performance, the Towa lens looks like it's coated with Magnesium Fluoride, while the Skywatcher

is Multi-coated. In use, the difference in image brightness was ever so slight. The Skywatcher was a bit

(and I mean a tiny bit) brighter than the Towa. However the Towa produced an image that was slightly better

in contrast, and the lens reached higher magnification before image breakdown.

I guess that an old lens that is figured very well with old coating methods will perform just as well as any

modern scope. In the star test, the Towa produced identical views both in and out of focus.

What a cracking buy the Towa has turned out to be.

[dweller25]

Great find & nice review :hello1:

[kniclander]

great review - v interesting. Where on earth can you get an F15 refractor these days?

[Lady Isabella]

Hi

This scope just gets better. As the sun was setting this evening, I observed Venus

and managed to see features on the disk without the aid of filters.

Both the areas around the cusp-caps were white, while another white circular feature was seen near to the limb. There was virtually no C.A., only now and again did some flicker into view.

Had the scope set-up next to a Chinese APO scope and was comparing the views of the moon this evening. I could barely notice the difference between the two. The Towa was giving outstanding views, more APO than Achromat. The shadows had the same intensity in both scopes and the view was just as sharp as that seen in the APO scope. In both scopes the area around the Moon appeared jet black. The view of Plato at 200x was (pardon the pun) out of this world. It is now becoming clear that the object glass in this scope is very, very good. And to think that these scopes were once sold under the Tasco name. I know that certain Tasco scopes are highly prised instruments, now I can see why.

Finished off with the occultation of Lambda Piscium, the Towa gave a great view as the star made a reappearance on the bright lunar limb.

[thing]

That's an excellent write up and a good find!