TAL125R - First Impressions

[John]

Neil English bought the TAL 125 that Astro_Baby refers to above. He had it checked and adjusted by the optical expert E S Reid and it's now a decent scope. Here is the story:

http://www.cloudynights.com/item.php?item_id=2765

TAL 125's are rare everywhere it seems, not just in Spain. With two of three examples I know of having some issues I guess most folks might hesitate before ordering one.

I can highly recommend the ED120 though

[Astro_Baby]

Well found John, I was looking for the thread and never thought to look in the reviews section.

I was seeking a 125 but gave up in favour of the 180 Mak which I have come to love. It has the drop on the TAL in aperture, focal length and physical size. Personally I'd get a 125 if one ever showed at the right price but I wont bust a gut or pay over the odds.

I kee hoping Glenn over at Lyra will find a 125 equivalent ......sighs

[F15Rules]

Having owned both the Tal 125R and several Tal 100s from the original awful focuser "r" version to the much improved RS versions, I can vouch for their optical excellence. I think that in terms of performance to price, the Tal 100RS wins: it has a crayford which is truly excellent (the 125R doesn't), and at F10 the CA is noticeably less than the 125R at F8.9. On the plus side for the 125R, it has the extra 25mm aperture and this is noticeable on deep sky objects, clusters etc. It also looks very cool, with it's tapered tube! On planets I think there is little to choose, as the higher CA level to my eyes limits the value of the additional 25mm. But I did see the E star in Trapezium from my home site, which I never managed in the 100R, and you do see many more faint stars when cruising the Milky Way etc.

Just to throw in some confusion..if I was buying a new achromat now, I'd either go for the Lyra F11 102mm or the Evostar 150 F8..Why? because the Lyra has a build quality far above the Tals, and in my opinion optics which are even better than the Tal 100s for not that much more money (about £380 new for the Lyra, versus £260 or so for the Tal), and because the Evostar 150 has much higher light grasp and goes much deeper than either the Tal or the Lyra. That said, it needs at least a CG5 rated mount with upgraded puck and William Optics or equivalent dovetail, to keep it rigid. The CA on the F8 evostar is not that much worse than the Tal 125R.

Hope this doesn't muddy the waters too much: the fact is that any of the above scopes will not disappoint, but for me, the Lyra takes some beating: whether Glen at Lyra can ship overseas, I don't know - but he is a top guy to deal with. ( I have no interest or relationship with Lyra Optics, other than as a satisfied customer).

Oh, and for what it's worth, I also owned an ED120. It was a nice scope, but I felt it was well overpriced at the £900 it cost me secondhand, and left me feeling, well, underwhelmed. I didn't keep it for long. For the money it cost, I could have got a brand new Evostar Black Diamond 150 OTA plus a decent CG5 mount and dovetail/puck upgrade - or the OTA and some very good eyepieces!

cheers

Dave

[AndyH]

Hope this doesn't come over as nit picky, 100% not meant to be

Just a tiny correction to your excellent post Dave.

The more recent 125R's do have the same crayford as the 100RS. It was the very early ones that had the 2" R&P, which were actually the same as the equally early 100RS(not to be confused with the 100R 1.25" R&P)

Something to bear in mind if you are buying a 2nd hand 125R.

Cheers,

Andy.

[F15Rules]

Hi Andy, no problem at all, thanks for the correction!

My 125R was I think a 2004 or 2005 model, so I quite accept that the focuser has been upgraded since, and it will be the better for it..actually, the original one I had worked well, I think partly because Dave Gibbons, who owned it before me had fitted large brass knobs onto it - apart from looking great, they did help fine focus as they were much larger diameter than the originals..

thanks again Andy.

regards

Dave

[AndyH]

2006 rings a bell, when talking about the change over to the Crayford.

Totally agree regarding oversize focuser wheels. Even one, kind of takes the place of a 10:1 fine focus knob, if it's about 2"/50.8mm or bigger. Got drawings for a few of my scopes regarding this, that hopefully one day will come to fruition when I'm financially better off. Not that it'll cost the earth to get em made up.

Andy.

[Marki]

The 125R I have has the same Crayford as the 100RS, and is absolutely fine. TO update, I have done about as much as I risk doing with my 125r now - I daren't split the glass elements (I am an opitcal coward and prone to dropping things... ). Hoping we get a some clear skies to night so I can do final set of tests. Will let you know how it goes.

Interested in F1's comments on CA in the 125r - i agree it is more noticeable than with the 100 (although I find it doesn't really bother me that much). Having read some suggestions here and elsewhere, I am wondering about getting a fringe killer or semi-apo filter and seing what differnce that makes. I'd be interested to hear peoples' experiences with a 150mm f8 though (suffering another bout of recurring aperture fever...).

Been hearing a lot of very nice things about the Lyra 4", so I can only agree with Astrobaby that Glen should make a five inch version!

I have noticed that my 125r performs significantly better in colder tempreatures (even allowing for adequate time to cool to ambient; I'm talking 2+ hours outside here), and this does not neccesarily seem to be related to weather/seeing conditions. The two best nights I have had with it were both at zero and sub-zero tempreatures (and in indifferent seeing) - is it possible that contractions in the glass elements or cell or tube could be such that the spacing or alginment of the elements could change fractionally (and apparently for the better) in the cold? Or am I simply imagining it and that the seeing may have in fact been better than I gave it credit for?

[John]

Neil English has a theory that the TAL glass, coming as it does from Siberia, performs a little better when temperatures get very cold. There might be something in that.

I've owned a few 150mm F/8's and used them with Chromacor's and the last one with a William Optics VR-1 filter for a while. The Chromacors are rare and expensive but reduce CA and SA considerably giving you similar performance to an ED doublet. I reckoned the WO VR-1 filter reduced the CA by around 50% on the moon and bright stars.

[F15Rules]

Interesting to think of Tal glass performing well in the cold. I wonder if it's also just because the cold nights are darker? I've had few really good sessions in the summer, just doesn't seem to get dark enough, and the atmosphere seems more unsteady with heat rising from the ground? I do think the expansion rates of the doublet might be a factor as well though.

I have found that generally, apart from double stars where you are trying to resolve two tight points of light, it's rare to get really satisfying images much above x50 per inch, so around x200 for a Tal100 or x250 for the 125R...and normally this sort of magnification is plenty anyway...what do you guys find with your scopes?

I do find that I can go significantly higher on magnification with my Intes Mak...but that is a 150mm mirror, with obstruction I'd expect it to be similar to a 5" lens, but can sometimes go well over x300 with pretty good image quality - on a good night.

Regarding filters, I have tried them (Fringe Killer) and didn't like the colour cast that they impart to the image. I'd rather put up with the CA tbh...as Neil says, it can even be quite attractive at lower magnifications on some objects..I would say that the difference in CA between the F8 150mm fracs and the 125R is similar order to that between the 125R and the 100R...not too bad, but noticeable. But for me, the extra light grasp is worth it. Of course, the best of all outcome is if you can find a matched Chromacor like John did! :-)

cheers

Dave

[Marki]

I've owned a few 150mm F/8's and used them with Chromacor's and the last one with a William Optics VR-1 filter for a while. The Chromacors are rare and expensive but reduce CA and SA considerably giving you similar performance to an ED doublet. I reckoned the WO VR-1 filter reduced the CA by around 50% on the moon and bright stars.

I guess not neccesarily a cheaper option than a second hand ED doublet then:).

Not sure on the cold thing really with the 125 - it was just a feeling I;ve had for a while. Maybe a combination of things, including darker skies as you say (hadn't really thought about that), and maybe I'm just developing a higher tolerance of the scope's quirks! I love this about telescope owning, it isn't one of those "straight out of the box"/point and click type hobbies, and there doesn't seem to be any one answer to most aspects.

As for the magnifications, some of this is a learning thing for me. Since I started using a telescope in February, I've noticed that can now usefully observe at higher magnifications than I could when I started. Havind said that, I rarely get the 100rs over x150, but it will go higher in the best conditions, but I've not pushed it over x200 yet. The 125r is now ok generally to x160-175 (this is an improvement on how it was when I got it), but even in the best conditions struggles above that. I have pushed it above x200 but only in exceptional circumstances and when it is very cold is the image at all useful (and even then never "sharp") - it usually breaks down pretty quickly after x170ish. The Skylight f13 (100mm) I have will regularly go a bit higher - I think the extra focal length over the 100rs helps, and the carton objective is better than the TAL; I can get this to x175 pretty comfortably, and in the right conditions will push over x200 happily (I expect this to get better as I get used to what the scope can do and how to get the best out of my current ep/barlow combos).

I may look into a filter then - have got a older Baader Moonlight/Skyglow (neodymium) filter - not sure if this is the same as the one marketed as a fringe killer or semi-apo. I'll see what Santa brings .

[John]

....I guess not neccesarily a cheaper option than a second hand ED doublet then:).....

There simply aren't many 6" ED doublets around. The Vixen ATLux ED 150 F/9 is one that springs to mind but there are less than 10 of those in the UK. The last one that was sold used went for around £1,800 for the OTA I recall. I was very lucky and managed to find Chromacors and matched 150mm achromats for around £500 a time. They are big beasts though so I'm happy to live with the much more manageable ED120 now as my largest aperture refractor

With the ED120 I find that I use my 3.5mm Pentax XW for 257x reasonably often, especially on the moon, Saturn, Mars and tight binary stars. I've contemplated a 3mm for the latter but I think the tiny exit pupil would make the floaters I have in my eye a bit too distracting.

180x-225x has been optimum on Jupiter over the last few nights I've observed it.

[EyeintheSky]

I am sure the TAL scopes, needs more time than other ones to be well acclimatized by the characteristics we all know.

Thans for the advices about the 125r John i will hesitate a bit more.

For me the rudge construction of TAL and good quality optics is a factor very important, otherwise, to see some more CA wont be a problem( i suppose) for me if it is not too high,i consider CA not as a deffect of building itself, its a normal physical property of lenses, not normal other optical aberrations.

In fact i have read optical reviews of achormatics which has better flat field than some ED or included triplets and also is well known that ED like TeleVue 85 mm has CA at high magnifications , and a TeleVue scope for that price should be almost "perfect".

The ED-120 is a nice scope surely, it is a petty the TAL 125 APOLAR finally were so expensive, but the lens cell is amazing.

Ok what about if i show you a link of russian users of TAL 100RS? it´s quite interesting to read what they think about TAL but you are needing to use a google translator because they write in "klingon"

http://www.astronomy.ru/forum/index.php/topic,94911.0.html?PHPSESSID=1dnj6r7rtu7vd2luqskc09sd14

Regards

[John]

.....The ED-120 is a nice scope surely, it is a petty the TAL 125 APOLAR finally were so expensive, but the lens cell is amazing.....

I had a chance to test a TAL 125 Apolar a while back. I posted a review on the forum if you are interested:

[EyeintheSky]

mmmm i 've already konown it John, very good review, and thans a lot for remember me the link, and talking about the review ...what a terrible dessapointment when the firt APOLAR that is was given you had an scratch lens!!!!

Thanks a lot again for your advices i have an offer in Spain for one : 1350 euros, is not bad because the price is 1.500 euros.

[EyeintheSky]

Hellow,

Definitely i have already chosen my new scope, not an achro, i will change to a mirrow.

http://www.firstlightoptics.com/clearance/hubble-cassegrain-reflector-telescope.html

The only doubt is collimation and price

[John]

Hellow,

Definitely i have already chosen my new scope, not an achro, i will change to a mirrow.

http://www.firstligh...-telescope.html

The only doubt is collimation and price

Make sure you get the later model with the fixed optics. The early one had a badly figured mirror

[F15Rules]

...and the optimum operating temperature was fairly low, I believe??

[John]

...and the optimum operating temperature was fairly low, I believe??

Yep - a very large bobble hat is a must

[EyeintheSky]

:grin:

Oh my god!!!

It 's true i can remember when NASA discovered there were an error with the mirrow, very very little error but it was as blind as a bat

Temperature???? ufffff

Well, talking of our scopes, just to tell you i have contact with tecnosky in italy for the scope- TAL 125R to know a little more payment conditions and transport.

well, after Christmas there will be a decision!!!

Eyyy Merry Christmas from Mallorca, Spain!!!!!!!!! and thanks to all of you for the nice forum

[philj]

Hi Marki

Only just found this thread, not been onSGL much either so sorry to come in on the thread a bit late.

I read your 1st and early lights and my ears pricked up regarding ghosting and what sounds like some flaring, is the scope still suffering from it? If so then I am pretty confident that this is misalignment between the elements (usually the spacers). Having read Neils experiences in his CN article this has more or less confirmed it.

I have restored and refettled many refractors overe the years and ghosting is a surprisingly common occurance, usually because of previous owners trying to strip and clean objectives without really knowing how to put them back together correctly.

One of my scopes actually had one of the foil spacers replaced at some time in its life with a bit of fag packet foil, this looked the part but was several thou thinner than the other 2 spacers. This tilted the elements enough to give a faint ghost image of bright objects and a faint flare also. No amount of collimation would sort it. I stripped the objective, found the culprit and made a set of new spacers out of a Mr Kipling apple pie foil base Mr Kipling makes exceedingly good objective spacers :grin:

On reassembly the lenses were now in line and properly spaced and the 1st star test showed all was sorted.

As I said this is a common problem with SH scopes and I would not expect it from a respected manufacturer like TAL or on any new scope for that matter but things do happen like Neils experiences show.

So if you still suffer from those problems then may I suggest a look at the spacers if collimation makes no difference. This could also explain temperature problems to some extent, if the elements are skewed then they wont expand/contract correctly.

Hope that helps

Philj

[Astro_Baby]

On CA you can always try and kill it with a pale yellow filter. This works well on bright objects like Jupiter and Saturn as it also marginally boosts contrastand as the planets are a yellowish hue anyway a pale yellow filter doesnt really introduce false colorimg. Pale yellow filters are a lot cheaper than Semi APO and Fringe Killer filters. Might be worth you trying this as its a cheap alternative and if you dont like it you can always use the pale yellow filter for general contrast boosting.

[Marki]

:grin:

Oh my god!!!

It 's true i can remember when NASA discovered there were an error with the mirrow, very very little error but it was as blind as a bat

Temperature???? ufffff

Well, talking of our scopes, just to tell you i have contact with tecnosky in italy for the scope- TAL 125R to know a little more payment conditions and transport.

well, after Christmas there will be a decision!!!

Eyyy Merry Christmas from Mallorca, Spain!!!!!!!!! and thanks to all of you for the nice forum

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

And Merry Christmas to you too

[Stu_2011]

Neil English has a theory that the TAL glass, coming as it does from Siberia, performs a little better when temperatures get very cold. There might be something in that.

I've owned a few 150mm F/8's and used them with Chromacor's and the last one with a William Optics VR-1 filter for a while. The Chromacors are rare and expensive but reduce CA and SA considerably giving you similar performance to an ED doublet. I reckoned the WO VR-1 filter reduced the CA by around 50% on the moon and bright stars.

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

[Marki]

Hi Marki

Only just found this thread, not been onSGL much either so sorry to come in on the thread a bit late.

I read your 1st and early lights and my ears pricked up regarding ghosting and what sounds like some flaring, is the scope still suffering from it? If so then I am pretty confident that this is misalignment between the elements (usually the spacers). Having read Neils experiences in his CN article this has more or less confirmed it.

I have restored and refettled many refractors overe the years and ghosting is a surprisingly common occurance, usually because of previous owners trying to strip and clean objectives without really knowing how to put them back together correctly.

One of my scopes actually had one of the foil spacers replaced at some time in its life with a bit of fag packet foil, this looked the part but was several thou thinner than the other 2 spacers. This tilted the elements enough to give a faint ghost image of bright objects and a faint flare also. No amount of collimation would sort it. I stripped the objective, found the culprit and made a set of new spacers out of a Mr Kipling apple pie foil base Mr Kipling makes exceedingly good objective spacers :grin:

On reassembly the lenses were now in line and properly spaced and the 1st star test showed all was sorted.

As I said this is a common problem with SH scopes and I would not expect it from a respected manufacturer like TAL or on any new scope for that matter but things do happen like Neils experiences show.

So if you still suffer from those problems then may I suggest a look at the spacers if collimation makes no difference. This could also explain temperature problems to some extent, if the elements are skewed then they wont expand/contract correctly.

Hope that helps

Philj

Hi Philj - thanks for this reponse; very helpful. I keep meaning to look at this aspect...but I keep worrying about breaking/dropping the elements as I can be a bit clumsy. The scope is certainly better than when I got it after lots of advice and tinkering, but I'm too scared to pull it apart - maybe I should practice on a cheaper/easier to replace scope ! Another SGL member has kindly offered to have a look wiith me over the holidays, so hope to make some time for this soon.

As for Mr Kipling's spacers...so long as I get to eat more mince pies that sounds like an excellent solution!

[Marki]

On CA you can always try and kill it with a pale yellow filter. This works well on bright objects like Jupiter and Saturn as it also marginally boosts contrastand as the planets are a yellowish hue anyway a pale yellow filter doesnt really introduce false colorimg. Pale yellow filters are a lot cheaper than Semi APO and Fringe Killer filters. Might be worth you trying this as its a cheap alternative and if you dont like it you can always use the pale yellow filter for general contrast boosting.

Thanks Astrobaby - sounds like a good plan - do you know what Wratten number might be good ? Dumb question time ...where do you buy colour filters...camera shops? Or do I need to go to a specialist supplier?