TAL125R - First Impressions

[Marki]

Is this a theory based on some scientific fact or just an observation that the TAL scopes seem to work better when cold? As a materials scientist I am genuinely interested in any weird material behaviour. A 10 or 15 degree change in temperature should have zero effect on the structure of any glass but........stranger things have happened.

Thanks

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Hi Stu - I'd assumed it was more to do with the contraction or ottherwise of the tube/cell affecting how the glass sits, rather than the glass itself. Not a materials scientist so no idea really...would different thicknesses or shaping of glass mean lens elements could be susceptible (as opposed to a piece/sheet of glass of a standard thickness or profile)? Or could the fact that air in the space between the two elements (the crown and flint) would contract/expand affect the spacing and hence the performance?

It may simply be that the coldness equates to lateness and less lighting sources etc.,...although I'd not noticed that really. However, I have not seen a similar apparent gain in performance with my other 'fracs when exposed to such low temperatures over the course of a session. Perfectly willing to accept it may just be me, though .

[AndyH]

Hi.

If you or anyone should take apart the lens cell, the thickness of the spacers(on the 125R) should be .............

Andy.

[nightfisher]

Hi.

If you or anyone should take apart the lens cell, the thickness of the spacers(on the 125R) should be .............

Andy.

Well done that man, earning the title of russian informer Top work andy

[John]

Is this a theory based on some scientific fact or just an observation that the TAL scopes seem to work better when cold? As a materials scientist I am genuinely interested in any weird material behaviour. A 10 or 15 degree change in temperature should have zero effect on the structure of any glass but........stranger things have happened.

Thanks

Sent from my iPad using Tapatalk

Probably best to ask Neil himself. Here is a link to his "world of refractors" website:

http://neilenglish.net/

I've owned a 4" TAL refractor and before that a Japanese made Vixen 4" and the performance of both seemed very similar to me in all respects.

@Marki: I've removed and cleaned a few doublet objective lenses up to 6" in aperture. It's quite straightforward with a few precautions. It would enable you to check i) the orientation of the lens elements (they use index marks on the lens edges to show how the pair should be matched) and ii) that the foil spacers are in place and have not been doubled up on one side. Small things like this can have a marked effect on objective lens performance.

[AndyH]

Mr Agas(designer) also has a discussion about adjusting the 125R's lenses. The translation is a bit iffy with my Firefox autotranslation, so I'll put it through a few of my translators* and see if one makes for better reading. If so, I'll post it up.

Andy.

* Every translator seems to turns up something different, so it's a case of finding the best.

[AndyH]

The discussion starts on page 16, continuing onto the next.

http://npzoptics.ru/forums/index.php?showtopic=60&st=225

Andy.

[nightfisher]

I have just read through both pages, that was hard work, but fairly informative

i am intrigued by the thickness of the spacers 0.8 mm, it is possible that in the factory 100rs ones had been used by mistake, long shot but possible, most lens i have fettled with would appear to be around 0.4mm spacers

I am at phil`s tomorrow working on the antares so will have a bit of a chat regarding the tal

[AndyH]

I have just read through both pages, that was hard work, but fairly informative

i am intrigued by the thickness of the spacers 0.8 mm, it is possible that in the factory 100rs ones had been used by mistake, long shot but possible, most lens i have fettled with would appear to be around 0.4mm spacers

I am at phil`s tomorrow working on the antares so will have a bit of a chat regarding the tal

Yup, considerably smaller for the 100RS spacing = 0.3mm +/- 0.005mm

So I was told by Yuri at the factory, a while back.

Could do with someone else having a peek through the scope, I reckon. At the very least to reasure Marki, that he's not getting paranoid etc. 200% not bashing you mate, no not all, but I know how these things really get to ME. The very 1st time I tinkered with my Klev, I totally freaked out for weeks.

I have pretty much zero doubt that the scope was in tip top shape when it left Northern Italy. Surfing some Italian forums, he's got a good rep. But how many thumps has the crate taken on it's way. Most times, no effect. Have you been super unlucky?

As it was me that flagged up Tecknosky as 125R stockists, it's really bugging me that your scope aint perfect. I feel a tiny bit responsible, which probably sounds super silly, but I honestly do. I'm weird that way.

Andy.

[EyeintheSky]

Well - I hope Giuliano comes up with some good answers and prices for you!

And Merry Christmas to you too

Thanks a lot!!!

He has already answered me, the price dont't change but i do not mind, we both agree it is a very good refractor it worth it ,dont´ we?

The payment conditions if i do not mistake can be pay when delivery and i will use a transport firm, it's quicker althoung is 20 euros plus.

[John]

Thanks a lot!!!

He has already answered me, the price dont't change but i do not mind, we both agree it is a very good refractor it worth it ,dont´ we?

The payment conditions if i do not mistake can be pay when delivery and i will use a transport firm, it's quicker althoung is 20 euros plus.

I think the issue for me is that I've known of just 3 TAL 125R's in this country and 2 of them have had optical issues. Add that to the issues I saw with the TAL Apolar 125's that I was sent for review and, speaking personally, I would find it difficult to recommend a major investment in one of these at the current time. I'd really like to feel differently about these scopes but it's difficult to.

You have to make your own mind up on whether you are prepared to move though, of course.

[EyeintheSky]

Very good work Andy!!!

That russian amateur pages are marvellous to learn a lot.

Well, what about if i present you with a new review of Klevtsov 250K, comparing TAL Klevtsov and Vixen VMC-260L?

Its very interesting, because the buyer of Vixen found some "incredible" disigned problems with Vixen scope.

I hope you enjoy reading it altough is written in spanish, you shouldn´t have too may problems.

http://astronomico.enfoque-creativo.com/pruebas/Tal250_Vixen260_OCTUBRE11.pdf

Regards

[Marki]

@Andy

Top investigative skills! 0.8mm seems quite a lot (although I have nothing to compare this with!). Mmmm...wonder if Kipling pie trays meet that criteria (more mince pies...nom nom!). I think I just got unlucky and the scope has suffered in transit - my wife told me the delivery guy could barely manage the crate out of his van, and I'm pretty sure it had been knocked about a fair bit. And please don't worry, I am grateful to you for giving me the heads-up in the first place! The scope offers lovely views at low to medium power, and thanks to advice I've had so far on collimation etc, is better than before, and I can go higher than when I first got it. Just needs that little bit more "love" to get it totally there.

@EyeintheSky

If you go ahead, I think your idea to pay more for a different shipper to transport to you is very sensible. I wish I had done that (and paid more) to reduce the risk.

@John

I completely understand your concern. Thanks to the advice I received from you and other SGLers at least I went into this with my eyes open! As ever you input is very much appreciated. The next step has to be to overcome my fear and get to grips (literally!) with the business end of the scope, as you suggest! Might practice on my100rs first though .

@Nighfisher

Hi Jules - hope we can sort out a date over the xmas break! Looking forward to getting the second opinion Andy recommends - plus taking you up on your offer of help to look at the spacing! BTW, what are doing with the Antares?

Cheers all!

[AndyH]

Very good work Andy!!!

That russian amateur pages are marvellous to learn a lot.

Well, what about if i present you with a new review of Klevtsov 250K, comparing TAL Klevtsov and Vixen VMC-260L?

Its very interesting, because the buyer of Vixen found some "incredible" disigned problems with Vixen scope.

I hope you enjoy reading it altough is written in spanish, you shouldn´t have too may problems.

http://astronomico.e...0_OCTUBRE11.pdf

Regards

Thank you.

Excellent link. My translator does a good job. 100% understandable.

Both scopes have had very few reviews, especially the big Vixen. I shall pass this link onto the Tal_250K yahoo group. Interesting review especially as the Vixen is very nearly twice the cost of the 250K.

Cheers,

Andy.

[AndyH]

Marki - I am sure it just needs a final tiny tweek. I'm hoping, but think so.

Andy.

[nightfisher]

Marki,

the antares would not come to focus when i got it as the tube is to short, so phil is machining an extension to fit between focuser and tube, just to make a long tube even longer!

[Astro_Baby]

Mark,

Try a # 8 light yellow. Get a decent one. Lumicon are considered the best but mines a Meade 5000 and is fine. Most astro shops sell filters but you may struggle to buy a single one. Quite often they get sold in groups of four unless you soend on on something like a Lumicon.

Check out ebay as they are often around on there, i got al of mine from an astro bring and buy sale sometime back and have a huge collection bu I almost neve use them.

[Marki]

Thanks Mel, will keep my eyes open then:).

Cheers!

[Marki]

Marki,

the antares would not come to focus when i got it as the tube is to short, so phil is machining an extension to fit between focuser and tube, just to make a long tube even longer!

That thing is going to be enormous by the time you have finsihed with it

[EyeintheSky]

Thank you.

Excellent link. My translator does a good job. 100% understandable.

Both scopes have had very few reviews, especially the big Vixen. I shall pass this link onto the Tal_250K yahoo group. Interesting review especially as the Vixen is very nearly twice the cost of the 250K.

Cheers,

Andy.

The jewel of reviews, with this one i knew for the first time TAL scopes, it is a review of TAL 100RS, the prior model with rack and pinion, i bought the

spanish magazine in 2005 and finally in 2009 i bought my TAL 100RS, with tne new Crayfor focuser.

I hope you enjoy it : http://www.observarelcielo.com/images/stories/elcielo/Sala_de_pruebas/Refractores/tal100rs.pdf

Cheers,

Frank

There´s also another interesting reviex about TAL 200K, it was printed almost 8 years ago, it is shorter buy quite interesting too:

[AndyH]

Thanks again Frank.

That's the type of 100RS I bought many years ago.

If you ever get the chance to post the 200K review, that would be appreciated.

Cheers,

Andy.

[EyeintheSky]

Thanks again Frank.

That's the type of 100RS I bought many years ago.

If you ever get the chance to post the 200K review, that would be appreciated.

Cheers,

Andy.

Hellow, Yes i will, the problem is i thought it was on a web to be dowload, but not, i will need to sacan it from a magazine an upload with a pdf file, as soon as i have free time.

[philj]

That thing is going to be enormous by the time you have finsihed with it

Yeah but it looks like a real scope now :grin: We had to move the front passenger seat forward to get it in

Stripping an objective is relatively easy provided you take your time and take not of how everything comes apart, also if it isnt marked on the edges to indicate alignment of the lenses and order then just mark the edge with 2 pencil lines in a vee with the point of the vee pointing forward, then its easy to see which lens goes where and which way it points.

Andy, well done on that info of 0.8mm. The scope that gave me problems still had 2 original spacers in there so I just micrometered them and made new.

Phil

[Marki]

Well, I finally got around to getting my TAL looked at by an optical engineer. Misaligned optics dianosed and now aligned. Artificial star test looked very much better on the bench. Quick squizz at actual stars last night with uncooled tube very promising indeed, focus staying sharp at x225. I'm praying it'll stay clear for some proper testing!

[nightfisher]

Great to hear things are looking up for this enigmatic scope, i tried ringing last night to en-quire as to the progress............fingers crossed Marki  

[Marki]

Ah, thanks Jules - was on way back from Scotland last night  - usually have phone turned off, or stuffed in a pocket when I'm driving so I don't get tempted to answer. I can't work out the hands free thingy in my car - too hi-tec for me and I'd need a "young person" to show me how to do it (and then keep them permanently in the car for every time I needed to use it again!).

Was going to put scope out tonight, but some ominous looking clouds out there just now - its a shame as I don't have to get up early for work tomorrow! Will keep you all posted as to progress.