TAL125R - First Impressions

[Qualia]

Using higher power (a 6.3mm)...didn't seem so good - seemed like a smudged rainbow of light off to one side.

Eyepieces..in my experience the supplied eps are "ok", except for the Tal 25mm plossl, which I believe is exceptional

Thanks for the report, Mark. You know this already, but just to add a note of reassurance, the Tal's supplied 6.3mm isn't that good. I think I've only used it once and made the mental note of never bothering with it again. On the other hand, as Dave argues, the 25mm is the business and apart from its slightly more limited FOV, I cannot fathom much difference between it and the X-Cel LX 25mm.

I also had a little trouble pulling off the dewshield on the Tal 100rs and for a wee while was convinced it was glued on! Nevertheless, as Dave again suggests, with a gentle twist and pulling motion it does slide off. The only downside to all this is that although I was able to clean the outer surface of the glass, for the first time I found dust on the inside of the lens and there's no way I'm taking apart the Tal to clean it.

I'm sorry to hear about the bad weather you guys are having, but, then again, as you know, it's not really the best time to be out with a scope. I'm finding that from the city, with the LP and summer sun, it's just not getting dark enough until the earlish hours of the morning and even then, there's still a full moon and those wild, sporadic summer storms we have in Spain to compete with. As I am aware, July and August aren't generally good months in the UK but things should get better come September time, so here's a great opportunity to practice your Zen-like patience skills which can only serve you well in this life of trials and tribulations .

One last thing, I see you mentioned something about a reduction on the focuser and was wondering the following: I imagine this will reduce the f/ratio, so there ought to be a widder field of view, right? But for purely visual pleasure, am I able to do such a thing with the f/10 and is it worth doing with a refractor and if so, what do I use, an EP screw on reducer or some kind of focuser-extender? The reason I had this in mind is because I imagine around Christmas I'd like to buy myself an 8" Newt, but wanted to see - even with my more limited aperture - what an f/5 looks like with the eye.

Best regards, Mark

Rob

[Marki]

Thanks for the helpful comments and support Dave and Rob. Point noted on the 6,3mm. I've ordered a 5mm ortho which I hope will give me the high magntifications my current ep collection lacks. I do like the 25mm though. I actually do have a WO 2" diagonal, but I find some difficulties bring images to focus with it when using 1.25" eps with it. Having said that, I do have a 30mm 2" which works fine in the bigger diagonal. I aslo have the Hyperion 8-24mm mkIII zoom - haven't fitted it with the 2" adaptor yet for use with the WO diagonal. I really ought to give that a go. Thanks for the reminder on cool down times for the larger objective...I am very impatient .

[F15Rules]

No problem Mark ..a 5mm should give you around 220x, but the scope will take more on some targets in good seeing, I had up to around 350x occasionally on tight doubles and the Moon on good nights. Just on the Baader MK III, you can get a mini barlow for this zoom, FLO have them at around £89, so not cheap, but they are superb quality (i have one), and you can use them for other eps...it's a 1.25" thread and just threads up onto the bottom of the zoom. And you can still use the 2" sleeve to drop directly into your WO diagonal, or an adapter to 1.25" if you prefer. Using the barlow changes the zoom range from 8-24mm to 3.5-10.5 mm so giving you a moderate/high power zoom in the range roughly 100-320x in your 125R. Some objects, like globulars and nebulae will take higher powers well, and the sky just looks darker and darker as you increase the magnification, so enhancing contrast.

Just hope you don't have to wait too much longer for a proper first light!

cheers

Dave

[Neil English]

Hi Mark,

Fondest congrats on acquiring the Tal 125R. I hope it brings you many years of nice views........that is, once this dreadful weather clears off.

Best wishes,

Neil.

[Marki]

Thanks for your kind words, Neil. Will be sure to post a first light/review as soon as the rain/clouds permit (or else tell you how I converted it to a schnorkel for use in flood conditions!).

[nightfisher]

you will get there Marki, a lot of us are still waiting on first light for me its an apo and about 7 eyepieces, just console your self that it is the worst time of the year as it dont get dark properly, not long now

[Marki]

Well ok. Finally. Big Sister gets a decent first light.

This report is based on two sessions, a two hour stint on Friday/Sat, and a two and a half hour stint on Monday/Tuesay night (last night). In both cases, I was observing from my new location, a relatively dark (at least compared to where I used to live!) back garden in York. Both nights were after hot sunny days, with perhaps "seeing" affected but reasonably good transparency. My views are somewhat restricted to the west and east particularly, but better to the south. The TAL125r was mounted on an eq5 on grass, and seemed reasonable steady, with vibration damping quickly.

Session 1 - scope left to cool for 25-30 minutes prior to starting. The diagonal used was that supplied with the scope.

I first fitted a 20mm Teleskop-Service wide angle (GSO clone), giving x56, and was rewarded with some beautiful starfields through Cygnus. Some slight distortion of individual stars to the sw or 7 o'clock postion (if that makes sense), but otherwise the stars were sharp and even across the field of view. Nice view of the Ring Nebula as well, something I have never seen from a city before. M13 looked gorgeous at this magnification, a real 3-d presence with the outer stars resolved. Fantastic depth of view! Turning the scope on Vega, there is clear purple haze, but I can live with that. This effect did not prevent me appreciating the colours of Albireo. At this magnification the diffraction patterns were pretty much spot on inside an doutside of focus on individual stars, notwthstanding the distorition mentioned. At this point I was pretty pleased and decided to ramp up the magnification by inserted a TS 8mm (BST explorer clone), for x140. Urghh! Soft images, hard to focus and Vega was just a huge shiny blur, spilling colour everywhere. Racking inside and outside of focus the diffraction rings were trending heavily to the south-west 7 o'clock position and not even visible on the other sides of the star. What a mess! A bit disappointed now! By way of contrast, I put the TAL100RS out and although not cooled Little Sister performed way better than her big sibling at high magnifcations. I went to bed perplexed!

Session 2 - the 125 was left to cool for a good 50 minutes before the session started, having reread Dave's (F15rules) comments above. I used the diagonal from my Tal100rs this time.

Again I started with the 20mm wideangle with the same results as mentioned above. Beautiful starfields... . Went to 8mm again, and the images were better than session 1 although the same distorton was still apparent when moving over and under focus. Colour spill seemed a little better this time, though. The images were still soft and hard to focus. After about an hour I nipped inside and got the Hyperion Mk III zoom out. Big Sister was noticeably performing better the longer she was out, and the quality optics now helped as well. Despite the difficulty in focus an dsoftness of the image (and still distinct distortion and difraction rings appearing in the lowerleft part of the star circle - wish I could explain myself better), I went on a double hunt. Split the double double cleanly at x140 and x96 and slightly less cleanly at x70 (pushing it, maybe a touch of the eye of faith here... .). Hit a number of other nice doubles cleanly at x140 as well (notes not here with me so won't list now). The ring nebula was stunning, real form and structure merely lacking colour. M13 was breath-taking too. A much happier experience altogether, but still marred by the distortions mentioned above.

Conclusions:

I have to be honest here. I am a relative newbie still, in a new location, after two hot days. I don't know how big a part the "seeing" is playing here. It is clear that Big Sister needs a significantly longer cool down than her smaller sibling. I felt I was only getting a half-way decent performance after an hour and a half - I had a feeling this scope would be wonderful in crisp cold winter skies (maybe Big Sister misses her Siberian climate )! Despite allowing for "seeing" and cooldown, I still feel there is a minor distortion, and I'm not sure collimation is solely the cause. It has been suggested that overtightening of the retaining ring may cause some "pinching", or there may be a slight misalingment of the lens elements. I'll consider this and see if I can follow this up. For now I think I need more time at the eyepiece (was meant to be clear again tonight, but clouded over now here in York). I also think that the shorter focal length means that Big Sister is less tolerant of "lower" budget eyepieces (she's gonna be high maintainence!).

This scope has great potential - the light gathering is great, the depth of view and resolving ability (if that's the right term) are lovely, if I can get over the issues described above. So, I'll persevere and see if a little tweaking and if required, some professonal help, can't bring out the full potential of this beautiful telescope. Little Sister is going to be jealous of the time her Big Sister will be getting from me... !

One last thing...I'm going to need a pier extention, observing near Zenith mean my head is at knee height!

As ever your comments, criticisms and suggestions are welcome.. .

[Qualia]

Beautiful set up, Marki and what a great report. I'm happy that you finally found an opportunity to put the big sister Tal to good use and that to all extents and purposes it behaved as it should.

On a negative tip, I'm in no position to say anything but with the fame of Tal optics, maybe with quality eyepieces that softness will be diminished? There's a PDF included below written by John which might also give some help on what may be the problem.

Other than that, I can't wait to read another instalment and hope that others can give a bit more constructive advice than this poor slop has been able to.

Nice one, Mark and congratulations.

Tal Apolar Review 05-11.pdf

[John]

Very interesting report Marki. Cool down might be something to do with it - the tube walls of the TAL's are quite thick and the air temps inside the tube will take some time to equalise with the outside temps. With my refractors I mount them and let them cool with the diagonal upwards and no dust cap in place - I hope that this lets the warmer air escape from the tube, out through the diagonal, easier.

I tend to judge the ultimate collimation of a refractor by the star test, looking for concentric diffraction rings, ideally (but not always !) looking similar either side of focus and a tight and perfectly circular airey disk placed centrally within the diffraction rings. At focus star like Polaris should show the tight airey disk and one, maybe 2 faint diffraction rings. I do these tests at quite high magnification - 200x plus.

There are also some tight binary stars such as Pi Aquilae which are, I feel, a good test.

I've found there are 2 critical factors with refractor collimation:

1. The squaring, or otherwise, of the focuser with the optical axis of the scope.

2. The tilt of the objective lens.

1. can be tested with a collimated laser collimator - the beam should exit right in the centre of the objective lens ideally.

2. can be tested with the cheshire collimator - I think you have already done this.

Hope that helps a bit !

[nightfisher]

sounds like your just over halfway to getting the best out of this enigma of a telescope, dont be afraid to pm neil english for advice, he really is the achro man, also orthoscopic ep`s are going to really bring out the potential with this scope. Im sure you wil soon have the "tiger tamed"

[John]

..... It has been suggested that overtightening of the retaining ring may cause some "pinching", or there may be a slight misalingment of the lens elements. I'll consider this and see if I can follow this up. .....

To address this you need to mount the scope and have it pointing upwards. Remove the dew shield. Loosen the objective lens retaining ring. You may need a tool of some sort to do this. On the refractors I have the retaining ring has two holes 180 degrees apart - I use a jewelers screwdriver in each side to create two "handles" and then use these to gently rotate the ring to loosen it. Once it is loose, you gently "slap" the objective lens cell evenly all the way around. This should allow the lens elements to settle into place if they have been disturbed a bit. The tighten the retaining ring just enough to stop the lens elements from rattling but no tighter than that.

On eyepieces, F/9 is not that fast really - decent plossls and orthos will be fine.

[Marki]

Thanks for the advice John. I was planning to do another star test with my 2" WO dialectric and the Hyperian zoom and barlow fitted tonight, but it has clouded over here now. Once I've done that and looked at sorting out the two TAL diagonals (reckon they can both do with some tweaking), I'll look at the focusser. Very brief check with laser collimater showed the beam was not central - possibility of a small amount of give in the focusser (i.e., a wee bit of play and not quite square in the tube) to be examined? I'll see if I can address it via the diagonals and get an improvement before I start playing with the objective .

Cheers for all the help and encouragement!

[nightfisher]

Im not sure about this, but i think the focusser MIGHT be adjustable, the draw tube runs on small bearings that might be slightly movable

[F15Rules]

Hi Marki,

I think you've been given some great advice on the previous posts.

I do know that Neil English' 125R was in awful optical shape when he acquired it, very mushy views, and he did send the objective to an optical expert, I believe in Cambridge. I'm sure he will help in any way he can.

If, having satisfied yourself that the collimation is good, you're still seeing less than perfectly circular diffraction rings, or distorted at some part of the circumference, then it just might be that the two lens elements are misaligned..it does seem unlikely, given that the Russians are normally pretty good on this, but if the tube did have any rough vibration during it's long (by road) trip to Italy, and given that I believe they are air spaced, they could have rotated just enough to mess the views up.

The good news is that if this is what happened, and the lenses aren't actually damaged, it should be quite simple for an expert to fix - but I would NOT try it myself and would advise you not to try. Do what Neil did and get it sent off to an expert. And although that seems like a pain to have to do, consider how much effort you went to in order to find one of these beauties..and ask Neil if he thinks having his sent away for some TLC was worth it!

I hope that the collimation sorts it for you, but keep the faith and you'll get there. Good luck!

regards

Dave

[Marki]

Thanks Dave. I'll do some work on the diagonals and collimation and star test again if I can this weekend (weather looking good for tomorrow night). Hopefully all will go well. If not, well, I'm not about to abandon this yet...I've already made some enquiries about professional help, and I'll drop Neil a pm to see if he might have any suggestions for me. Having got this far I feel there is potentially a fantastic scope here; I just need to invest some TLC as you say to get the best out of it! Thanks again to all for the encouragement and advice!

[Qualia]

Did a little digging and maybe these places could offer some advice or even service, Mark?

Optical Repairs

Kay Optical

Spectral Optics

I see that this place repairs binoculars but maybe they might know someone in the know: Optical Repairs II

I guess these kind of things are sent to test us, experiencing life with all its pain in the **** bits and its more pleasurable times. You have yourself a rare and beautiful telescope, Mark and with a little tweaking, everything will turn out fine.

[EyeintheSky]

Hellow,

I am Francis from Malorca (Spain) id like to ask Marki for the TAL 5'' .

Do you check finally your scope for colimation?

Did you finalley get to correct the problems?

Sorry for my test but i WANT ONE after Christmas when my birythday

but i am a little worried for your test.

I also own a TAL 100 RS is mine is mine and i do not change it for any other (included a TAKAHASHI OR TMB).

Hellow to all member of stargazers who owned a TAL scope.

Frank

[Marki]

Hi Frank! Welcome to the forum:).

I've done a quite a bit of tinkering, collimation and reseating the objective (and collimating the diagonal which was way off too). My last test at the weekend in very cold conditions (well, -2c is very cold for me ) showed a significant improvement from when I first received the 'scope (maybe seeing was better, and maybe my Siberian beauty just loves the cold!). Most people seem to be very happy with their 125r, and mine is certainly better than when I got it - I just think it had been bashed about in transit from Italy to the UK. The scope is really nice for planets and the moon, and really begins to resolve the edges of things like M13 globular cluster.

I love your enthusiasm for the 100RS - I used mine again recently and it is just such a great telescope - I still think the best views of the moon i ever had are with that scope! I'd let most of my telescopes go before that one (and it'd be a really tough choice between that and the 125r if I am honest). On the other hand, I;ve never had the chance to look through a Tak or a TMB yet... .

Back to the 125r - you shoud read some of the articles Neil English has written about his experiences with this telescope - he really raves about his

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

All the best and clear skies,

Mark

[EyeintheSky]

Uepppp!!!

Thanks for your prompt reply!

-2ºC :shocked: Now i am living in Palma city but when two years ago i was living in a village, we had once that temperature and a blooded humity of 70-90%. Very bad for scopes.

I think is an important factor the quality of our eyepieces, i am lucky of owning very good eyepieces.

Thanks for the Neil English's link, very interesting.

I am hesitating buying the 125, when reading your opinions about to chose the 100RS or 125R, maybe the 100RS is the best of them

I am in an Ocean of doubts if buying it or not.

Sorry if sometimes my english is like SITTING BULL from far west

Salut!!

Frank

[nightfisher]

Uepppp!!!

Thanks for your prompt reply!

-2ºC :shocked: Now i am living in Palma city but when two years ago i was living in a village, we had once that temperature and a blooded humity of 70-90%. Very bad for scopes.

I think is an important factor the quality of our eyepieces, i am lucky of owning very good eyepieces.

Thanks for the Neil English's link, very interesting.

I am hesitating buying the 125, when reading your opinions about to chose the 100RS or 125R, maybe the 100RS is the best of them

I am in an Ocean of doubts if buying it or not.

Sorry if sometimes my english is like SITTING BULL from far west

Salut!!

Frank

Frank, dont worry about your english, its pretty good.............go for the tal 100rs, they are superb telescopes

[Marki]

Hehe - no problem Frank! Your English is way better than my Spanish !

I suppose it is a question of what you want to do with the telescope. The 125r will go "deeper" - that extra 25mm does make a difference. But given the conditions here in the UK, there aren't that many nights when I can push the magnification above x175 to x200 anyway, whether with the 100rs or the 125r. In that case the extra aperture allows better resolution, but not neccesarily greater magnification.

For me the 100rs cost about two and half times less than the 125r (c. 300 eu as opposed to c. 750 eu), but it isn't 2.5 time as bad . I think the 100rs is about the best achromatic refractor you can get for the money. On the other hand my 125r is waaaaay cool!

By the way, what eyepieces do you like to use with the 100rs?

[Qualia]

It might be an idea to see if there's an astro-club around where you live, so you can check out something like an ED120 to see if the upgrade would be worth it in your eyes. The Tal 125r is a pretty rare beast, so I imagine very few own one in Europe, let alone in Spain. Anyway, it's great to see another Spanish member owning the beautiful 100rs; that must make two of us

Bienvenido a SGL, EyeintheSky y espero que quedes con nosotros

[EyeintheSky]

Hellow from Spain once more again!!

Marki, my idea when buying the 125R is to use it for planetary, i would like to try making some captures of Jupiter and Saturn with a CCD camera or a webcam, obviously using a barlow.

By other hand, my familiy of eyepieces are composed by :

Baader Eudiascopic 35 mm

Takahashi LE 30 mm

Super Plossl TAL 25 mm (the eyepice included with the TAL 100rs).

TeleVue Radian 18 mm

Genuine Ortho Baader 12,5 mm

TeleVue Radian 10 mm

TeleVue Radian 6 mm

Takahashi LE 5 mm.

For me they are all very good eyepieces, some of them a little expensive but the CA in my tal 100rs it is very very little using them.

My favourite eyepieces, that i enjoyed more are the TAL 25 mm (for the price is really a marvellous) and the Genuine Ortho Baader of 12,5 mm, and the

35 mm Eusiascopic with this last i am feeling like a little boy when i saw the pic point stars with my tal .

I agree with you, the TAL 100RS is absolutly the best achro nowdays, i always will remember when i received my box containing the scope "ohhhhhhhhhhhhhh" that is wat some member has defined as "TAL effect".

Qualia, thans for your spanish words!!

Es un placer estar en este foro con mis compañeros de afición en Gran Bretaña y otros lugares de habla inglesa.

Pienso quedarme mucho tiempo en el foro.

Yesssss, here in Mallorca we are about 8 people owning telescopes that sometimes go out for observations at some Star Party but noboy has an SW ED-120 .

so i really will have to assume thew risk if i go for the 125r.

Which part of Spain are you living ? I am from Mallorca you know.

Regards!!

[Astro_Baby]

It may need setting up by a pro. There was someone on CN who had one and said. It wasnt so good. It was sold to someone else who ha it set up properly and after that it worked very well...this is from memory of a vew months ago now. I cant recall what theroblem was as I didnt follow the thread closely. I just had a look and cant find it...perhaps someone else could advise.

[EyeintheSky]

Hellow astro-baby, do you refer to Sky Watcher ED-120?

Thanks!