1994 TAL-1 - A few questions

[Flapper]

Hello!

My wife has been getting into astronomy via the various TV programmes and books out at the moment, and had - half-jokingly - suggested that she wanted a telescope for Christmas. After a bit of reading on the various forums I took the plunge and bought a second-hand 1994 TAL-1 telescope for £40. I like fixing things up and thought that this was money better spent than on a cheap new equivalent.

 

It's here and I've cleaned it (a bit), oiled it and set it up - What a beautiful (heavy) piece of equipment! Such lovely play in the various stand adjustments.

I've aligned the internal mirrors, and the finder scope now holds the same view as the main scope. I've been looking at pine needles a mile away so it seems to work! Not tried it at night yet - that will have to wait until after Christmas, unless I get excited on a clear night and present it to my wife early

 

As it came second hand and in bits I have a few queries, if I may:

1) What's this for?

2) It came with 25mm, 15mm eyepieces and a x3 Barlow. I've read that this old TAL will not take modern eyepieces (but that modern ones would work with the barlow). See the picture below. These metal inserts - do I have the round the correct way (i.e. wide one in the 25 and smaller aperture in the 15)?

3)Is this 25mm meant to be as wide ope as this? It seems to work, but I have to 'relax' my eye and keep it some way off the glass. Do I need to buy an eye cup or something?

4)It seems there's a hole in the end of a scope that will take a screw cap. This isn't present. Do I need to buy one. Is it necessary? It's also missing caps for the finder scope.

 

I'm very excited to use it at night and to see what my wife makes of it. Is there any problem keeping it in a dry but unheated outbuilding?

Thanks for any advice.

Sam

 

 

 

[domstar]

Don't know, but what a wonderful present. It looks fantastic.

[Joseki]

Hi, that's a fantastic amount of scope for £40, it'll make a fab Christmas present.  Sounds like you've already done your research aligning/collimating the mirrors and setting up the finderscope.  Not having had a Tal1 I can't say for certain about your questions but my guess would be: 

1) to help collimating the mirrors - i.e. put it in the focuser and adjust the secondary mirror so the crosshairs meet on the center of the primary mirror.

2) I think so - it'd make sense I guess.

3) An eye cup might help or be nice but is not essential (and might be tricky to source anyway).

4) You won't need a screw cap, or end caps for the finder (unless you get a proper solar filter and start pointing the scope at the Sun).

5) no problem keeping it in an unheated outbuilding if dry.

 

[ronin]

Not sure what the cross hair one is, first thought was a bubble level but I guess not. As it is a cross in it the it has to be to centre something.

If 1.25" eye pieces do not fit then it is 0.965", they were on older scopes. Doubt there is a converter for a TAL1 simply because the "converter" is more common when it is a diagonal and they are not applicable to a reflector (in general).

Getting 0.965" eyepieces can be a bit of a search. Antares used to produce a set of 4, and Rother valley sell Antares, but not sure about 0.965" eyepieces any more. Always thought that Joys Optics on ebay sold 0.965" eyepieces but cannot see any there at present. Sure they were sets of 4 and thought maybe useful to get a set for use in the scope as it is.

You can get eye cuts if there is a ridge for one to clip into.

The end plate may or may not be missing. Vague memory says that I read that TAL stopped putting one on the rear as people tended to remove them in order to check and set the collimation. In efect as they were getting in the way of general maintenance they just dropped the idea of supplying one.

If you locate any 0.965" eyepieces then get plossl ones, I think some are the older Huygens or Kellners and plossls are somewhat better. To get a converter I half suspect it means a small machine shop and a lathe and a bit of an idea what it needs top accomplish - thinking here of getting the eyepiece in enough to reach the primary focal plane.

Meant to add in that the TAL's are well built, and as one person siad "When the sun goes nova in 4 or 5 billion years time it is expected that someone on earth will likely be watching it through a TAL1."

 

Edit2:
Try: http://stores.ebay.co.uk/Joys-Optics/Telescope-and-Accessories-/_i.html?_fsub=2848145011&_dmd=2&_nkw=965

The eyepieces are Huygens so not sure, personally I would not but for £15 you get 4 of them and at least 2 probably 3 will be useful. Also there are converters shown, they may be more relevant.

In case the link is off then search on Joys for "965".

[moriniboy]

I have owned a few early TALs including one which had similar ep's to these (see attached photo)

Item 1 looks like a push fit reticule which you insert into the bottom of eyepieces, not much use really unless you are using it to precisely centre the finder scope (which already has one built in) with the main scope.

Item 2 TAL ep's from this era were (i think) slightly bigger than modern 1.25" ep's, see if you can borrow one to check, you may be ok but it might have a loose fit.

Item 3 no its fine

Item 4 Your scope will work fine without the plug, it may even help with cooling it down quicker as well.

Do not buy any 0.965" ep's they are too small

[Putaendo Patrick]

TALs are great telescopes - built like a Russian tank!

According to an online catalogue from the manufacturers at http://rus.telescopes.ru/manuals/tal1/tal1_manual.phtml

"Telescope is completed with additional reticle with cross for eyepiece F=25mm. User can adjust an optical axes parallelism of telescope tube and finderscope."

This may be the accessory in your first question?

I think Tal changed the diameter of their eyepieces at around the date of your telescope, so you may want to check the measurements. If the focus tube is under 1 inch (0.9), it is the old style and I don't believe quality new eyepieces in this size are now made - but they do sometimes come up second-hand. Modern eyepieces are generally 1.25 inch, although I think Tal also made some tubes a fraction wider to take eyepieces which clicked into the tube. You may find that a layer of electrical insulating tape round the EP takes up this slack.

Even if the telescope does take 1.25 inch EPs, they may not come to focus. Before you buy anything, I would suggest carefully trying them out. If you have an astronomy club near you, they may have observing sessions and members will probably be happy to lend you a modern EP to try out.

As you may have gathered, Tals have their quirks - but it's well worth persevering!

[Flapper]

Thanks all very much for your advice.

I think the mystery object must, indeed, be a reticule that you can put in the 25mm to check that the finder and main telescope are pointing at exactly the same thing.

I've done a bit more reading: I think the focuser on this old TAL will accept 1.25 eyepieces (Possibly with a bit of tape round them), but won't focus them to infinity, except - perhaps - with the barlow, so I'd have to look at the various modding ideas, or just live with the current set which, from what I've read, will be more than adequate for starting out.

Cheers all.

[nightfisher]

Nice scope, as said dont get 0.965" as they wont work, think about the ep`s you have,  this gives you a combination of a 25, 15, 8.1 and 5mm, that is plenty

[Matt Lancaster]

I've recently got one of these too. Any hints on how to correctly colimate the scope? There's no central marking of the primary mirror and chances of getting a Cheshire for this are slim. A start would be a guide to the pairs of screws on the back of the primary mirror!

Thanks for any hints.

[Putaendo Patrick]

There's a very interesting old thread started by Bambuko on making a collimator for 1994 vintage Tals - well above my particular skills set, but lots of information and photos on Tal focuser problems etc.

 

[Matt Lancaster]

As a further link to the previous post though I have this set of bits no reticle or filters and nothing to help alignment.

They seem to be 1.25 inch though.....

[Matt Lancaster]

Here's the plate off the back of mine but what gets me is the lack of focussed at the eyepiece.