TAL-120

[bambuko]

Anyone here owning this particular scope?

and willing to share their experiences of it?

In particular I am interested in how does it compare with straight TAL-1 ??

I know it is relatively rare beast, so will not be surprised if there is no replies... but you never know

[AndyH]

Never seen one in the flesh, but I'm sure I knew someone, or knew someone, who knew someone, that had one.

The following you probably already know, but I'll post em up here for folks reading this thread.

Discussion on the NPZ/Tal Russian language forum -  http://npzoptics.ru/forums/index.php?showtopic=86

Translated - http://translate.google.com/translate?&ie=UTF-8&sl=&tl=en&u=http://npzoptics.ru/forums/index.php?showtopic=86

Some nice pics of the scope here - http://www.hoo-germany.de/popup_image.php/pID/79/imgID/0

Some discussions on TalScopes yahoo group. There's probably more, but the following linked page has quite a few regarding the 120. - http://tech.groups.yahoo.com/group/TALScopes/messages/12635?l=1

If I were to be asked to choose between the Tal 1 & Tal 120, whithout having viewed through a 120, I think I'd plump for the Tal 1. Mind you, if a 120 came up for a good price in good condition(vital to check the condition of the cemented doublet, to make sure the optical cement hasn't started to delaminate), I most certainly would NOT say no.

Andy

[bambuko]

Coming up with goods again   - thanks Andy.

Very useful info - sounds like it is not a best choice...

on the other hand useful for parts   apart perhaps from the spherical mirror, which at f/5.75 (without corrector lens) is not really good for anything else.

If the price is right...

[AndyH]

Oh aye. If the price was right, I'd take one, if only to add to my collection of quirky scope designs. I've no doubt, if in good condition, it would provide lovely views in a super small ota.

[nightfisher]

There was one on ebay last week went for well under a ton, also a second one on at same time but looked to be a TAL 1

[AndyH]

There was one on ebay last week went for well under a ton, also a second one on at same time but looked to be a TAL 1

Yeah, there's a 120 on fleabay at the mo. Down Devon way. Not described as a 120, or even as a Tal, but the pics, especially of the secondary, makes it unmistakable as a Tal 120 newt. Cheap, so far and may stay that way, as the description is so poor.

[bambuko]

shush... keep it quiet

I am just round the corner from this one (and guess who is bidding on it)

[AndyH]

shush... keep it quiet

I am just round the corner from this one (and guess who is bidding on it)

Consider me muzzled. Good luck.

[bambuko]

Got it for £25 - collecting tomorrow.

Report will follow

[AndyH]

Got it for £25 - collecting tomorrow.

Report will follow

Reeezult !!

25 quid could be the going rate for the finder alone !!

If you can, stick a bit of paper between the diagonal mirror and the corrector lens. This'll help gauge the condition of it, without the 2 mirrors getting in the way.

The following XXX rated pic is an example of an horrific case of delaminating of optical cement. The worst I've ever seen....

[bambuko]

Not to mention nice GEM mount

Like you say, even if the scope is pants there is enough there to be worth £25

On another hand it would be nice for it to work - that could be handy grab and go reflector for all the times I can't be bothered to set up something bigger.

Thanks for the picture - no doubt I will be back with more questions ...

[AndyH]

I will be expecting many detailed pics n measurements of the 120. Probably the least known scope in Tal's stable, even although there's probably quite a few floating about, here in the UK.

Fleabay is pretty carpy these days, but now and again it spits out an unusual, potential gem.

[bambuko]

It's double edged sword living where I do - on one hand I miss a lot of deals up country, on another... if it is here, few people can be bothered to drive down to the wilds of Devon to collect some old scrap

My two scopes (TAL-1 and TAL120) costed me less in total than one cheapo eyepiece...

[AndyH]

Fingers crossed everything is A-OK inside, optically. It looked quite tidy from the provided pics.

[John]

Nice to get bargains like that from time to time 

[bambuko]

Well... it is here

I hesitate to call it "immaculate" (there is some dust on it and couple of minor issues) but it is definitely in excellent condition.

Mirror is perfect, optical element appears to be OK and collimation is spot on.

The mount looks very strong in relation to OTA size and I hope it will be very steady.

Focuser rack and pinion will need shimming up to eliminate slight wobble when using focusing knob.

Otherwise it is smooth and working fine.

And that BTW is my first question - how do you take apart focuser and secondary?

They are secured to each other and only then screwed to the tube (for obvious reasons).

It would appear that I will have to somehow remove secondary and than I should be able to withdraw focuser and spider out?

Possibly some info here?

All the rest is fine and same as TAL-1, although this one is 1.25" (unlike my old TAL-1 which was 32mm).

There is 25mm TAL Plossl (OK, I guess?), 15mm TAL Kellner(nothing to shout about?) and x3 TAL Barlow (as disappointing as the other TAL Barlow...)

Pillar is one piece (on my TAL-1 it is in two pieces), otherwise identical.

Tube is identical as TAL-1 i.e. 5.5" OD (0.1" thick wall) aluminium tube, only shorter (620mm compared to TAL-1 810mm).

BTW it is not a mistake - the tube is definitely imperial size.

Took it out before the storm and clouds:

... and had a quick look at Venus using both original TAL eyepieces and my other pieces.

On Venus 6mm was a bit too much, 8mm was about OK, but best view was with longer focal length pieces.

Can't wait for some decent weather!!!

BTW - no labels on it, so no idea of the year of manufacture, but the guy selling it mentioned something about it being 10 years old.

More pictures and reports will follow.

[AndyH]

Lovely ! Looks pretty tidy.

 If the focuser has the small plastic plug on the lower back, then you should/might be able to dismantle it without needing to remove the whole assembly from the tube. Then a re-shim and grease can be done. Have you tried altering the focuser tension. That 'might' improve it's smoothness. 

These aluminium tubes usually were about 140mm O/D and had a 2.5mm wall thickness. I'll have to measure my Tal 1 with my imperial calipers

I take it that the primary is fixed? Collimation done via the secondary only?

Does the 25mm plossl have a knurled outer body? I like that style the best. Commonly called the MkII. The 15mm Kellner, whilst not having the greatest eye relief, is actually quite decent for dim objects. Good light throughput. Probably works that bit better on slower scopes though. Of all the barlows Tal make, the 2x is the best of the bunch. One of it's elements is lananthum(sp?), which probably helps.

Anyway.  Looks teeny compared to the Tal 1. The mount works really well with that one, so should be equally good with this. Good news regarding the corrector lens.

Andy.

[AndyH]

I notice what looks like an extension tube on the focuser. Reminds me of the Tal 2M focuser. On that, you screw it off, revealing an M42x1 Russian camera thread. Same on this one?

[bambuko]

5.5" = 139.7mm

0.1"=2.54mm

so it is quite likely that I am talking out of my rear orifice and it is something metric?

No plastic plug on the back of focuser - I will need to investigate it further.

Yes, you are right primary is fixed and only adjustment/collimation is on the secondary.

The Plossl looks like this:

Looks dinky indeed compared to TAL-1 and it has slightly larger mirror as well (which I guess is possible because of simple fixed design)

[bambuko]

I notice what looks like an extension tube on the focuser. Reminds me of the Tal 2M focuser. On that, you screw it off, revealing an M42x1 Russian camera thread. Same on this one?

Yeap!

TAL-120 is very easy to use for astrophotography:

is that Saturn?

[John]

Love those TAL plossls 

Unusual secondary support design on the 120 - looks like two vanes going across to the secondary holder from the focuser side - or is the photo misleading ?

The whole scope looks very reminiscent of my old TAL 100 RT which I bought new in December 1999. So a decade(ish) old sounds about right.

[bambuko]

No the photo is not deceiving:

The design of the spider is to do with "...integral multi-coated negative achromatic lens in the base of the focuser to provide an effective focal length of 805mm in a very short tube..."

[John]

Wow ! - looks like a prop from Star Wars 

[AndyH]

Year on manufacture - Mmmm. I think, going by the mount, plus the eyepiece type, I think I'd guesstimate, '98-'00.

One thing I don't have, is a copy of the user manual for a 120. I presume there was such a thing. I'll have a look about the net.

[AndyH]

Found one.

But it's a rar file.  Trying to convert it to a pdf.

BUT it's in Russian. Better than nothing.