Towa 339 plus

[philj]

Last year I modded my 1970s 80mm Towa 339 F15 with a 2" crayford to modernise it and so I could use binoviewers with it. Its been excellent that way but if I wanted to use it without binos I needed 130mm extension tubes which was making teh focusers eyes water. I said then I would make an extension to the OTA.

Finally I got round to it as my 1st project on my new upgraded lathe. This was machined from a piece of 85OD 65ID ali tube and I made it 130mm long so I could fit my fave 2" Celestron XLT diagional and still have plenty of focus each way.

The paint was dry enough to assemble earlier and I tested it on some distant trees and it works a treat. It looks very loooong:) but I like long refractors:)

Its removeable with just 3 screws so I can convert back to using binoveiwers if I so desire.

I shall get round to refurbing the main scope tube one day, it has a few blemishes and scratches but it works so no hurry

Anyrode here it is on my tripod with Giro II:

Philj

[Demon Barber]

Hi Phil ,another nice job! I wish i had me own lathe ,my local engineering firm are making a mint out of me,hope you are keeping well?

Regards

Mike

[nightfisher]

nice looking conversion phil, will have to keep in mind that you have a lathe;) i used to do manual turning on a colchester, so wish i had use of one of these

[philj]

Cheers guys cant wait to try it out now should be alot brighter image on Saturn without the bino viewers.

I love the binos on this scope but they do dim the image slightly and together with filters it reduces the mag I can go to on Saturn. The moon and Jupiter are no problems with it.

Ive had a mini lathe for a few years now and its been very restricting on what I can do so I scrimped and saved, sold a few ebay bits and got myself a larger lathe, Chester UK 920, its a beauty and I have a long list of projects I want to do on it. 1st Ive got to relearn thread cutting, last time I did this was about 35 years ago and I found it nerve wracking to do then:)

This little job was basic but it was still a little tricky as I had to make a support mandrel for the non chuck end to be supported by the tailstock. I got there eventually

Philj

[Leo.A]

Does the scope have a 900mm focal length?

It looks identical to my Tasco 80mm 17TR refractor.

I put the vixen ED series lens head on mine and the only mod was to have an external thread machined for the head to screw straight on. Cost me $10.00 at a local engineering shop and the difference in quality over the original cheap TAsco optics of the time is incredible. Of course the Vixen lens is worth more than the original cost of the scope back in 91, but insurance paid for it (that's another story) so it really cost me next to nothing.

I have since modified the original 1" focuser on the scope (I have so many nice eyepieces, seems a waste not to use them) and found with the aid of some shim brass it no longer thumps using the not so cheap (Cheap quality only) Tasco remote focuser, which used to throw the whole scope out of alignment, I'd be looking at a completely different part of the sky if I ran it fully out or in.

[philj]

Hi Leo

No its the 1200mm F15 Towa. If I had the 900 I wouldnt need to extend.

Towa did stuff for Tasco as can be identified by the manufacturers mark on teh nameplate, for Towa it would be a T in a circle, so even though its badged Tasco a circle T would mean its really a Towa. Some Prinz scopes were Towa as well.

Sounds interesting that scope, a Vixen ED lens would be a good upgrade from the 900mm F11.25 you would notice the difference if it was non Towa optics. With an F15 like this there would still be an improvement I suspect with an ED swap but it wouldnt be so noticeable.

Philj

[Guest]

Hello Phil.I was thinking of buying this type of refractor.They come with a 0.9 inch eyepiece barrel.If I were to buy a standard refractor focusser upgrade do yo think that there would be a problem bringing objects into focus.I ask this because youi have fitted an extension tube.

Thanks Martin

[Leo.A]

I'm in the process of having an adaptor machined at the moment so I can fit a William Optics focuser on my 80mm refractor much like Phil has done. My old focuser had an extremely long draw tube and the new focuser has none, but with the adaptor I've designed, it does give a slightly longer focal plane. I'm just hoping my adaptor design lets me get minimal focal distance too.

I will most likely need an extension tube of approx 40-60mm to match the range of my old focuser but I'll see how it works out without it first.

Now I have to go out and purchase some good quality 11/4" eyepieces since all mine are .98". I have however got some nice .98" eyepieces I purchased long ago which are good quality but when I have the cash I want to upgrade them. Now I need a 11/4 to .98" adaptor so I can use my old eyepieces till I can afford new ones. I've already tied too much up in a focuser and mount and have my sons 17th birthday next Tuesday so I'm short of anything for myself for a while.

Doesn't matter, it's still winter where I am and still tooo cold and miserable for viewing anyway.

[Polar Bear]

Lovely scope and a great modification.

One question, what is the improvement regarding the 2" diagonal and EP's over 1.25" parts ?

Paul

[Guest]

My first telescope was this Towa 80mm.I remember great views of the planets.I sold it to fund a newtonian.I wonder how it would perform using it for planetary imaging with the modifications?

By the way Leo thanks for touching a raw nerve with your line -

"I once had brown hair and grey matter. Now the situation has reversed!"

Martin

[Leo.A]

Definitely grey hair and brown matter now, I can't remember a thing, and all at 51. I'm glad I have a good relationship with my son because I think I'm going to eventually need help the way my once photographic memory (not too long ago) is dropping off rapidly.

[philj]

Hi Paul

Advantage over 2" for me is that I have some nice 2" eyepieces and a 2" filter wheel and these work a treat on this scope now. e.g. My favourite is a nice wide 2" 30mm Vixen Lanthanum which gives excellent views als I have a 2" 50mm for wide views. For planteary I stick with the 1 1/4" and binoviewers.

But having the 2" focuser enables me to use either size eps

Leo/Martin I feel your pain, I used to pride myself on my photographic memory and attention to detail now at 56 the photographic bit has become underexposed:D I loose stuff which I have just put down, go somewhere specioally to do or get something then forget it.

E.g. I was working at the bottom of the garden the other day. Suddenly remebered I had to get something from upstairs. Went in, took my shoes off, went upstairs and then stood there wondering what it was that I was suppossed to get/be doing there. Shrugged, went back outside got to the bottom of the garden then Doh! I remembered. and Im only 56:D

Philj